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The geology of the Ecstall-Quall Rivers area, British Columbia. Padgham, William Albert 1958

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THE GEOLOGY OF THE ECSTALL-.QUAAL RIVERS AREA BRITISH COLUMBIA by WILLIAM ALBERT PADGHAM B.A.Sc., University of B r i t i s h Columbia, 1 9 5 5 A Thesis submitted In P a r t i a l F u l l f i l m e n t of the Requirements for the Degree of MASTER OF APPLIED SCIENCE in the D i v i s i o n of GEOLOGY We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1 9 5 8 i ABSTRACT The Ecstall-Quaal Rivers area i s i n the Skeena Mining D i v i s i o n of western B r i t i s h Columbia. The area i s underlain by intrusive rocks of the Coast Range Complex Bat h o l i t h and by older rocks of the E c s t a l l metamorphic complex, the " E c s t a l l Septum". A thick group of impure c l a s t i c sediments including minor calcareous beds and lenses have undergone extreme dynamothermal metamorphism to give s c h i s t , gneiss, quartzite, and marble. Although the amount of c a t a c l a s t i c or dynamic metamorphism has been very high, the minerals present are usually i n the lower grades of the amphibolite f a c i e s . Retrogressive metamorphism of b i o t i t e , and hornblende to s e r i c i t e and c h l o r i t e i s common i n most of the metamorphic rocks. The o r i g i n a l sediments would be those expected under unstable shelf conditions. It appears that the granodiorite which borders the septum on the east and west, has reached i t s present position by some type of in t r u s i v e action. It i s c e r t a i n l y not a "metamorphic" or "metasomatic" granite. In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head o f my Department or by h i s r e p r e s e n t a t i v e . I t i s understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada. i i TABLE OF CONTENTS Chapter Page ACKNOWLEDGMENTS v i : INTRODUCTION v i i I. PHYSICAL FEATURES 1 Location and Access 1 Previous Work 3 Climate, F l o r a , and Fauna 4 Topography and Gla c i a t i o n . . . . 7 G l a c i a l and Recent Deposits 10 II. GENERAL GEOLOGY 13 II I . PETROLOGY OF THE METAMORPHIC AND IGNEOUS ROCKS. . 20 1. Metamorphic Rocks . . . . . 20 A. Metasediments 20 Gneiss 20 Quartzite 54 Schist 60 S i l t s t o n e and P h y l l i t e s 120 Calcareous Rocks 130 B. Meta-igneous Rocks 151 Hornblende D i o r i t e .' . 151 Hornblendite 154 2. Igneous Rocks , . 169 Coast Intrusions 169 Late Intrusions 175 IV. STRUCTURAL GEOLOGY 180 V. GEOLOGIC HISTORY 189 Origin of the Metamorphic Rocks 189 Metamorphism i n the Septum 192 Effects of Intrusive Rock on the Metamorphic Rocks 194 VI. CONCLUSIONS 199 BIBLIOGRAPHY 200 i i i LIST OF FIGURES Page Number 1. Index Map of Western B r i t i s h Columbia 2 2. Photograph of view Of area underlain by metamorphic rocks 4 3. Photograph of view of g r a n i t i c rock exposure . . 6 4. Photograph of view of timber covered metamorphic rocks 6 5 . Map of Geomorphological Features i n middle E c s t a l l V a l l e y 12 6. Map of General Geology of Western B r i t i s h Columbia 14 7 . Photomicrograph of 0 r - l 5 2 5 8. Photomicrograph of 0 r - l 5 2 5 9. Photomicrograph of Or-8 . . 27 10. Photomicrograph of B-66 29 11. Photomicrograph of B - 7 0 31 12. Photomicrograph of B-70 31 1 3 . Photomicrograph of B - 7 0 32 14. Photograph of Douglas Channel Augen Gneiss . . . 3 5 1 5 . Photograph of polished section of B - 5 2 3 6 16. Photomicrograph of B - 5 2 3 8 1 7 . Sketch of c l i n o z o i s i t e grains 3 8 18. Photomicrograph of B - 5 2 3 9 19. Sketch of zoned plagioclase grains 40 v 20. Photomicrograph of B-46 41 21. Photograph of B - 5 1 42 . 22. Photograph of B - 5 1 43 2 3 . Sketch of porphyroblast of plagioclase 4 5 24. Photomicrograph of B - 5 1 46 2 5 . Photomicrograph of B-48 48 26. Sketch of 0R-1 5 2 2 7 . Photograph of 0 R - 1 . . . 5 2 28. Sketch of 0 R - 1 5 3 2 9 . Photomicrograph of 0 R - 1 1 5 9 30. Photomicrograph of 0R-11 5 9 3 1 . Photomicrograph of B-3 • 62 3 2 . Photomicrograph of B-3 62 33. Photograph of B-41 64 34. Photograph of carved boulders of b i o t i t e -hornblende schist 67 3 5 . Photograph of carved boulder of b i o t i t e -hornblende schist 67 36. Photomicrograph of Z J - 2 3 68 37. Photomicrograph of ZJ-30 . 71 38. Photomicrograph of ZJ-19 74 39. Photomicrograph of ZJ-19 . 74 40. Sketch of ZJ-19 • • 75 i v Number Pa%e 41. Photomicrograph of W-15 76 42. Sketch of grains of pyr i t e 77 43. Photomicrograph of ZJ - 3 7 78 44. Photomicrograph of OR-2 80 45. Photomicrograph of B-40 82 46. Photomicrograph of B-40 83 47. Photomicrograph of B-40 84 48. Photomicrograph of B-40 84 49. Sketch of Feldspar fragments 87 50. Photomicrograph of OR-22 88 51. Photograph of B-25 88 52. Photomicrograph of ZJ - 5 2 93 53. Photograph of ZJ - 5 5 94 54. Photograph of Or-20 96 55. Photomicrograph of Or-20 97 % . Photomicrograph of Or-20 98 57. Sketch of B-92 99A 58. Photomicrograph of B-93 101 59. Sketch of B-93 . 101 60. Sketch of plagioclase grains 103 61. Sketch of three plagioclase grains 106 62. Photomicrograph of ¥-34 108 63. Photomicrograph of OR-16 114 64. Photomicrograph of OR-16 114 65. Photograph of B-95 119 66. Photomicrograph of ZJ-28 121 67. Photomicrograph of P-2 125 68. Photomicrograph of P-3 127 69. Photomicrograph of P - 5 128 70. Sketch of banded quartzite 129 71. Sketch of folded beds 131 72. Photomicrograph of OR-12 133 73. Sketch of OR-13 134 74. Sketch of folded rocks 136 75. Photomicrograph of B-54 138 76. Photograph of W-10 141 77. Photomicrograph of ¥-10 142 78. Photomicrograph of ¥-10 . 143 79. Photograph of OR-25 144 80. Photomicrograph of OR-25 145 81. Photomicrograph of OR-25 146 82. Sketch of magnetite grains 148 83. Photo of banding of OR-21 149 84. Sketch of hornblende cr y s t a l s . 151 8 5 . Photomicrograph of sausseritized hornblende d i o r i t e 152 86. Photomicrograph of W-17 160 87. Photomicrograph of ZJ-24 163 88. Photomicrograph of white amygdule 176 89. Photomicrograph of hornblende phenocryst . . . . 177 90. Photomicrograph of pyroxene grain 178 91.. Photomicrograph of lamprophyre dyke 179 V Number 92. G e o l o g i c Map of E c s t a l l - Q u a a l R i v e r s Area '1 w « p 93 . G e o l o g i c a l C r o s s - s e c t i o n s r Cohinet 94. S t r u c t u r a l Map of E c s t a l l - Q u a a l R i v e r s Area J ^ v i ACKN OWLEDGMENT The writer wishes to thank Dr. W.R. Bacon and the other o f f i c e r s of the E c s t a l l Mining Company for permission to use the information presented i n t h i s thesis and for the use of company maps, a e r i a l photographs, and th i n sections. Assistance during the preparation of the thesis by Drs. W.H. White and K.C. McTaggart i s g r a t e f u l l y acknowledged. Most deeply and most d i r e c t l y , the author i s indebted to his wife, Theresa, whose numerous suggestions, wise counsel, and stimulus to scholarship have contributed greatly to the work. v i i INTRODUCTION This thesis i s based on f i e l d work done while the writer was employed by the E c s t a l l Mining Company during the summer of 1957. Messrs J . Jambor and S. Zajac assisted with the geologic mapping and their work has been drawn on i n the preparation of the the s i s . The mapping program was on a reconnaissance basis. Locations were obtained by p l o t t i n g on a e r i a l photographs and on 2,000 feet to the inch topographic maps with 100 foot contour i n t e r v a l s . Where time permitted traverses were run on about one mile i n t e r v a l s , but much of the area was covered by wider spacings. The main f i e l d of investigation of t h i s thesis w i l l be the petrology and structure of the metamorphic rocks of the " E c s t a l l Septum". L i t t l e time was spent investigating the i n t r u s i v e rocks on the flanks of the septum so these rocks w i l l not be discussed i n d e t a i l . Over 300 rock specimens were coll e c t e d during the summer. The petrologic study i s based on these specimens and thin sections cut from some of them. A e r i a l photographs were used i n locating i n t r u s i v e contacts, f o l i a t i o n , and bedding i n areas not mapped i n d e t a i l . They were also of help i n c o r r e l a t i n g rock types between traverses. CHAPTER I I. PHYSICAL FEATURES Location and Access The Ecstall-Quaal Rivers area i s located i n the Skeena Mining D i v i s i o n of north western B r i t i s h Columbia. The area mapped, some 2 0 0 sq. miles, l i e s between latitudes 5 3 ° 3 0 ' and 5 4 ° north, longtitudes 1 2 9 ° and 1 2 9 0 3 5 * west. Kitimat, 3 0 miles northeast, at the head of Douglas Channel, i s the nearest town, but Prince Rupert, 7 0 miles north of the E c s t a l l Mine, has been the general trading centre for the area for many years. Although there are no roads or horse t r a i l s into or within the Ecstall-Quaal area, i t can be reached e a s i l y by boat; either up the E c s t a l l r i v e r , which i s navigable f o r shallow draught vessels from i t s confluence with the Skeena to the E c s t a l l mine, some 2 0 miles upstream; or along Douglas Channel which forms the southern boundary of the area. Above the E c s t a l l Mine the E c s t a l l r i v e r i s navigable, with three portages, for small boats. From K i t k i a t a Inlet the Quaal r i v e r may be ascended at least ten miles by small boats. Float equipped a i r c r a f t can land on eight large lakes within the Ecstall-Quaal area. S i x smaller lakes have been used occasionally by high powered a i r c r a f t . Thus the area can be reached at any time by boat, and provided the weather i s 2 FIG: 1. INDEX M A P OF W E S T E R N BRITISH COLUMBIA S H O W I N G " E C S T A L L - Q U A A L R I V E R S A R E A s t/1 ' I f S o ( A a. 2 AT B R I T I S H C O L U M B I A o IOO aoo jow u ^ 3 good, by plane. Transportation within the area, however, i s extremely d i f f i c u l t because of the heavy timber cover, pre-cipitous slopes and the swampy va l l e y f l a t s . Previous Work The Coast Mountain area of B r i t i s h Columbia has re-ceived l i t t l e attention from prospectors and geologists. Mapping and prospecting has been intensive along the eastern contact of the Coast Intrusions but l i t t l e has been done i n the heart of the i n t r u s i v e complex. This i s because of the extreme ruggedness of the area, the s c a r c i t y of outcrop, the heavy timber cover, the heavy r a i n f a l l , the d i f f i c u l t y of moving about within the area, and the few large mineral deposits found. Between Stewart on the north and Vancouver on the south only four large deposits (Anyox, E c s t a l l , Surf I n l e t , and B r i t t a n i a Mines) have been found. A l l of these are massive and disseminated sulphides of i r o n , lead, z i n c , and copper i n shear zones i n the metamorphic rocks. Prospecting and mining exploration has been done i n the immediate v i c i n i t y of a l l of these deposits. Government geologists have inspected and mapped small areas around those mines which have operated. In 1951 extensive develop-ment work was done at the E c s t a l l mine. At that time geologic mapping was carried out i n an area of 30 square miles ad-joining the mine. In 1912 R.G.McConnell mapped the mouth of the Skeena r i v e r along the Grand Trunk P a c i f i c Railway and i n 1921-22 4 V. Dolmage mapped the n o r t h e r n h a l f of the coast l i n e o f B r i t i s h Columbia. L i t t l e work has been done s i n c e . C l i m a t e , F l o r a , and Fauna The E c s t a l l - Q u a a l r i v e r s area i s c h a r a c t e r i z e d , as i s the whole of the Coast Mountains by extremely heavy p r e -c i p i t a t i o n . Rain f a l l s on about one day i n three d u r i n g the summer months and the heavy bush i s almost c o n s t a n t l y wet. Because of the heavy r a i n f a l l and the m i l d w i n t e r s p l a n t growth i n the E c s t a l l - Q u a a l a r e a i s l u x u r i a n t . Here and there i t approaches the t h i c k n e s s and i m p a s s a b i l i t y of a j u n g l e . C o n i f e r s are the most abundant t r e e s ; hemlock, ye l l o w cedar, and balsam f i r grow i n a l l p a r t s of the a r e a , w h i l e s i t k a spruce, jack p i n e , j u n i p e r and red cedar are l o c a l l y abundant. F i g u r e 2. Typical.metamorphic a r e a h e a v i l y covered by timber to the c r e s t s of the r i d g e s . The heavy  cloud cover shown i s t y p i c a l of a m a j o r i t y of the days d u r i n g the summer. 5 In the metamorphic complex even the steepest slopes are heavily timbered. Only on the quartzites and some of the quartz-feldspar gneisses, where s o i l development i s l i t t l e advanced, are thick growths absent. On the g r a n i t i c rocks, however, large areas are bare of both s o i l and plant cover, or support only scattered, scrub growth. With the exception of bears and various b i r d s , animal l i f e i s very scarce i n the Ecstall-Quaal area. Beavers and squ i r r e l s are seen occasionally, as are mountain goats, at high elevations. In the l a t e summer and early autumn salmon of many kinds pass up the main streams to spawn. 6 F i g u r e 3 . G r a n i t i c rocks exposed on Hakesbury I s l a n d . Note hanging U-shaped v a l l e y j h e a v i l y timbered  lower slopes and bare r i d g e s , t y p i c a l of the  areas u n d e r l a i n by i n t r u s i v e g r a n i t i c r o c k s . F i g u r e 4. T y p i c a l heavy timber cover on the metamorphic  ro c k s . T h i s r i d g e developed on s c h i s t , i s  sharp c r e s t e d r a t h e r than g e n t l y rounded as are  r i d g e s of more . r e s i s t a n t , rock types. 7 Topography and G l a c i a t i o n The Ecstall-Quaal r i v e r s area i s i n the P a c i f i c Ranges of the Coast Mountain area, part of the Western System of the Canadian C o r d i l l e r a . The E c s t a l l and Quaal Rivers are the main streams i n the area mapped. They occupy the northern and southern parts respectively of a major v a l l e y system which st r i k e s about north 1 5 ° west, more or less p a r a l l e l to the main trend of the C o r d i l l e r a i n B r i t i s h Columbia. The E c s t a l l r i v e r bends back on i t s e l f around Pros-pect H i l l , forming two p a r a l l e l v a l l e y s . South of the Quaal r i v e r the trend of the main v a l l e y i s obscured by a high transverse ridge, but there i s a low pass which leads into Kiskiosh I n l e t , a southern extension of the main v a l l e y . A series of secondary north to north-west trending valleys are tributary to Douglas Channel on the eastern side of the map sheet. The largest of these i s occupied by K i t k i a t a Lake and K i t k i a t a Creek. These v a l l e y s , and the main Ecstall-Quaal Valley, p a r a l l e l the s t r i k e of the metamorphic rocks. Two large transverse valleys are also present. The southern of these i s the Agnes Lake-Kitkiata Inlet v a l l e y . Ten miles to the north l i e s the Amoeba-Lower lake v a l l e y which i s continued eastwards by the upper Quaal v a l l e y and by Foch Lake. Pleistocene g l a c i a t i o n has been an important force shaping the topography of a l l the Coast Mountain area. At 8 present g l a c i a l e r o s i o n i s i n s i g n i f i c a n t i n a l l but the h i g h e s t p a r t s of the mountains but stream e r o s i o n i s v e r y a c t i v e because of the steep s l o p e s and heavy r a i n s . In the E c s t a l l - Q u a a l area evidences of g l a c i a t i o n are abundant. Great U-shaped v a l l e y s , w i t h hanging U-shaped t r i b u t a r y v a l l e y s are t y p i c a l of the r e g i o n . A l l of the peaks i n the E c s t a l l - Q u a a l area have a g e n t l y rounded contour suggesting they were o v e r r i d d e n by i c e and thus the i c e must have reached a great depth. Numerous l a r g e and s m a l l rock b a s i n l a k e s occur i n the area mapped. A l l of these lakes are v e r y deep, and many have steep rock w a l l s which commonly show f l u t i n g s , g r o o v i n g s , s t r i a e , and g l a c i a l p o l i s h . The o u t l e t streams from such l a k e s flow over rock b a r r i e r s and o f t e n form cascades. Foch l a k e , at an e l e v a t i o n o f 1760 f e e t , i s a s p l e n d i d example. I t s o u t l e t stream f a l l s t o sea l e v e l a t Foch Lagoon i n a d i s t a n c e of 1.75 m i l e s , i n the l a s t 2,000 f e e t i t drops 1,500 f e e t . Two c o n s i d e r a b l y d i f f e r e n t types of land forms can be rec o g n i z e d i n the E c s t a l l - Q u a a l a r e a . One of these has de-veloped on the i n t r u s i v e rocks of the Coast Range Complex B a t h o l i t h , the other has developed on the o l d e r metamorphic r o c k s . Because of the massive nature of the g r a n i t i c i n -t r u s i v e s they are much more r e s i s t a n t to chemical and p h y s i c a l weathering than are the metamorphic rocks and thus areas under-l a i n by the i n t r u s i v e rocks s t a n d , on the average, 500 to 9 1500 f e e t h i g h e r than those areas u n d e r l a i n by meta-sediments. Summit l e v e l s i n the g r a n i t e s commonly reach above 4 , 0 0 0 f e e t but i n the metamorphic areas the summits r a r e l y r e a c h 3»000 f e e t . Post g l a c i a l stream e r o s i o n and s o i l f o r m a t i o n i s much l e s s advanced on the igneous rocks than i t i s on the metamorphic r o c k s . Large areas of the i n t r u s i v e rocks are completely bare of s o i l and p l a n t cover and show g l a c i a l s t r i a , f l u t i n g s , and groovings. Many smooth g l a c i a t e d s u r -faces are v e r t i c a l or overhanging. Because the metamorphic rocks are s t r o n g l y f o l i a t e d and s t r o n g l y j o i n t e d and because they commonly c o n t a i n e a s i l y weathered mafic bands they are eroded much f a s t e r than the g r a n i t i c r o c k s . Most of the major n o r t h - s o u t h v a l l e y s of the Coast Mountains are u n d e r l a i n by metamorphic r o c k s . G r e n v i l l e Channel and the E c s t a l l - Q u a a l v a l l e y are two important ex-amples. In the g r a n i t i c areas the stream v a l l e y s appear to be c o n t r o l l e d by j o i n t i n g and f a u l t i n g but i n the metamorphic rocks the streams are u s u a l l y p a r a l l e l to the bedding or f o l i a t i o n d i r e c t i o n . A e r i a l photographs can be used to d i s t i n g u i s h areas u n d e r l a i n by metamorphic rocks from those u n d e r l a i n by g r a n i t i c rocks by the banding of the metamorphics which common-l y shows through the s o i l and p l a n t cover and by the numerous s t r i k e v a l l e y s and the heavy timber cover of the metamorphic r o c k s . 10 G l a c i a l and Recent Deposits Very few g l a c i a l deposits were found i n the area, probably because most of the g l a c i a l debris was carried out to lower l y i n g regions which are now under water. Large granite e r r a t i c s were found l y i n g on outcrops of metamorphic rocks i n various parts of the area. Good examples are on the f l a t s north east of Lower lake, and along the top of a ridge two miles south-east of Barbara Lake. Just south of Barbara Lake large granite e r r a t i c s are scattered across the f l a t s . Here they l i e on the Barbara Lake granite rather than on meta-morphic rock. Blue clays were observed i n the v a l l e y of the Quaal r i v e r and K i t k i a t a creek at elevations of 50 to 100 feet above sea l e v e l . These clays are p l a s t i c and become very sl i p p e r y when wet. One outcrop of such material contained f o s s i l s of pelecypods and gastropods In a sandy lens. Probably these clays were deposited i n an arm of the sea. On K i t k i a t a creek a bed of mussel she l l s were found about 30 feet above sea l e v e l . These s h e l l s are a chitonous type almost i d e n t i c a l to l i v i n g forms which abound i n shallow portions of K i t k i a t a and E c s t a l l lakes. Such s h e l l s may mark the location of a former lake. Since the retreat of glaciers a considerable amount of f i l l i n g has gone on i n some of the larger v a l l e y s . In the middle reaches of the E c s t a l l r i v e r , above E c s t a l l lake, many meanders have formed and the r i v e r has aggraded i t s channel forcing t r i b u t a r i e s to form yazoo streams. Large swamps and lakes have developed and numerous bayous are present along the break i n slope at the margins of the v a l l e y f l o o r . Figure 4 i s a sketch map of part of the middle reaches of the E c s t a l l r i v e r , just above E c s t a l l lake. It shows the various features developed on the v a l l e y bottom, the f l a t nature of the bottom and the sudden change i n slope at the contact of the v a l l e y and the steep v a l l e y walls. Oxbow lakes and meander, scars have been formed along the lower reaches of the Quaal River. Many of the t r i b u t a r i e s to the mouth of the Quaal display barbed junctions with the main stream. Similar barbed junctions were noted i n the estuary of the E c s t a l l r i v e r a few miles north of the E c s t a l l Mine. A l l these barbed t r i b u t a r i e s are i n the zone of t i d a l action at the mouths of the r i v e r s . Probably they are re-lated i n some way to t i d a l currents. 12 13 MIDDLE E C S T A L L V A L L E Y SHOWING GEOMORPHIC F E A T U R E S DEVEVELOPED IN VALLEY FILL S W A M P _ H J W A T E R |~Z] R O C K S C A L E I " = 2 C O O ' C O N T O U R I N T E R V A L |QO CHAPTER II GENERAL GEOLOGY The geologic formations present i n the Ecstall-Quaal Rivers area are of metamorphic and igneous o r i g i n . Because of intense metamorphism and numerous intrusions the geology i s complex and d i f f i c u l t to solve. The metamorphic complex probably has the form of a "septum". That i s a series of steeply to v e r t i c a l l y dipping rocks bounded on both sides by large i n t r u s i v e masses. The metamorphic rocks extend to an unknown depth and may or may not be underlain by i n t r u s i v e rocks. Early workers considered the metamorphic bodies of the Coast Range to be roof pendants, however, i t i s now appar-ent that the Coast Range "Batholith" i s not a single i n t r u s i o n but rather a complex of in t r u s i o n of varying age and thus the old rocks are more l i k e l y to be "screens" between separate in t r u s i v e masses, rather than downward projections of the overlying roof of a ba t h o l i t h . The E c s t a l l "Septum", or "Roof Pendant" has been traced for eighty miles from Gardiner Canal i n the south to the Skeena r i v e r i n the north. Probably i t continues north of the Skeena to Portland Canal, and south of Gardiner Canal to Graham Reach. This would add 50. miles to each end of the Septum making i t about 180 miles long, one of the largest "inclusions" or "septa" of older rocks i n the Coast Range Composite Batholith. 15 The metamorphic rocks are those to be expected from the regional metamorphism of a dominantly sedimentary sequence i n which basic rocks of volcanic or i n t r u s i v e o r i g i n have been included. Three major metasedimentary rock types can be recognized. These are, i n order of abundance, gneiss, s c h i s t , and quartzite. Other types are present but they are generally found interbedded with one of the main types of rock and often cannot be correlated between exposures. TABLE OF ROCK UNITS Age Pleistocene and Recent Unconsolidated deposits clay, sand, gravel, etc. Age Unknown Basic Dykes Hornblende Lamprophyre Jurassic-Cretaceous Coast Range Intrusions Pegmatites A p l i t e Granite dyke Granodiorite Age Unknown Metamorphic rocks A. Meta-igneous rocks Hornblende d i o r i t e Hornblendite Hornblende schist Hornblende granulite 16 Metasediments 1. Gneiss Quaal River Gneiss Q uar tz-K-feldspar Quartz-K-feldspar-plagioclase Quartz-plagioclase with minor quartzite and s c h i s t Douglas Channel Gneiss Quartz-plagioclase-hornblende Quartz-plagioclase-hornblende + K-feldspar augens with minor limestone, quartzite, and schist K i t k i a t a Lake Gneiss Qu a r t z - p l a g i o c l a s e - b i o t i t e - c l i n o -z o i s i t e granitoid gneiss 2 . Quartzite Agnes Lake Quartzite Thin bedded quartzite with i n t e r beds of hornblende s c h i s t . The section contains minor hornblendite and gneiss Mine "Series" C h l o r i t i c quartzite, Quartz-chlorite s c h i s t With minor limestone, a r g i l l i t e , s e r i c i t e s c h i s t and c h l o r i t e s c h i s t Barbara Lake Quartzites Thin bedded quartzite Minor b i o t i t e - f e l d s p a r gneiss, b i o t i t e s c h i s t , and calcareous beds 3. Schists K i t k i a t a Schist B i o t i t e s c h i s t Biotite-hornblende schist S e r i c i t e s c h i s t C h l o r i t e s c h i s t Garnet s c h i s t With interbeds of quartzite, gneiss, and calcareous rocks. Johnson Lake Schist Knotted s c h i s t Biotite-quartz schist Hornblende sch i s t Quartzite 4. S i l t s t o n e and P h y l l i t e Prospect H i l l Group Undifferentiated quartzite, t h i n bedded quartzite s i l t s t o n e s , c h l o r i t e s c h i s t , s e r i c i t e s c h i s t , calcareous s c h i s t , and limy beds. 5. Calcareous Rocks Many thin limy beds occur i n t e r -calated with the other main rock types. They are generally two thin to map separately. The oldest rocks i n the area are the meta-sediments but no features are preserved i n them to indicate age r e -lations within the group. Gneiss i s the most abundant meta-sediment. This rock, which i s composed predominantly of quartz and feldspars, underlies three large areas; the Quaal River v a l l e y , underlain by the "Quaal River Gneiss"; the area between Douglas Channel and the granite contact just south of Foch Lake, underlain by the "Douglas Channel Gneiss and a smaller area along the east side of K i t k i a t a lake, underlain by the " K i t k i a t a Lake Gneiss". Quartzite, another important rock type, forms a thick unit along the west contact of the E c s t a l l Septum. South of Amoeba Lake the quartzite i s c a l l e d the "Agnes-Lake Quartzite". North of this lake the quartzite becomes c h l o r i t i c and i s c a l l e d the "Mine Series". Many smaller quartzite units were found i n the area, but only one, the 18 "Barbara Lake Quartzite" i s large enough to be mapped separately. The Barbara Lake Quartzite crops out on the ridge top about a mile southeast of Barbara Lake. A thick unit of schist underlies the eastern part of the Quaal Val l e y , and most of the K i t k i a t a Valley. This unit the " K i t k i a t a S c h i s t " , i s the largest single rock group i n the area, and contains examples of a l l the various types of s c h i s t . The Johnson Lake Schist i s predominantly quartz-feldspar-biotite s c h i s t . It appears to be the northern extension of the Douglas Channel Gneiss. Numerous thi n units of schist occur i n the other main rock types but they have not been mapped i n d e t a i l . S i l t s t o n e and p h y l l i t e have been noted i n many places i n the E c s t a l l Septum. P h y l l i t e i s p a r t i c u l a r l y common i n the Mine Series and the Johnson Lake Series, but i s much rarer i n the southern part of the septum. Thin beds of s i l t s t o n e or f i n e grained quartzite, occur i n many of the major rock units. P h y l l i t e and s i l t s t o n e form an important part of the "Prospect H i l l Group" which crops out along Prospect H i l l and along the east side of the E c s t a l l v a l l e y just north of Lower Lake. A number of masses of metamorphosed hornblende d i o r i t e cut the metasediments i n the Prospect H i l l area. These rocks were emplaced before the Coast Intrusions, (which are un-metamorphosed) and probably before or during the metamorphism of the sedimentary rocks. 1 9 Many of the metamorphic rocks do not c o n t a i n e q u i l i -brium assemblages of m i n e r a l s , many others have r e t r o g r e s s i v e c h l o r i t e and/or s e r i c i t e i n them. In g e n e r a l the assemblages correspond to the a m p h i b o l i t e f a d e s . G r a n i t i c rocks from g r a n i t e to d i o r i t e i n c o m p o s i t i o n form the bulk of the Coast Range Mountains. In the E c s t a l l -Quaal area the i n t r u s i v e rocks are coarse grained g r a n o d i o r -i t e s . They are g r a n i t i c t e x t u r e d and o n l y r a r e l y do they show any f o l i a t i o n . Hornblende i s the most abundant m a f i c , but b i o t i t e may be l o c a l l y abundant. Both the metamorphic rocks and the Coast Range I n t r u s i v e s have been cut by l a t e b a s i c dykes which show most of the c h a r a c t e r i s t i c s of lamprophyres. These dykes may be g e n e t i c a l l y r e l a t e d t o the Coast Range I n t r u s i v e s , or to a much l a t e r phase of igneous a c t i v i t y . CHAPTER I I I PETROLOGY OF THE METAMORPHIC AND IGNEOUS ROCKS Specimens of the common rock types were c o l l e c t e d i n the f i e l d . S e c t i o n s cut from these specimens were s t u d i e d i n the l a b o r a t o r y . A d e s c r i p t i o n of each rock type, i t s c h a r a c t e r i s t i c s i n outcrop, hand specimen, and t h i n s e c t i o n , f o l l o w s : 1. Metamorphic Rocks Metamorphic rocks have r e c e i v e d the most i n t e n s e study. They can be d i v i d e d i n t o two main groups, the Meta-sediments and the M e t a - i n t r u s i v e s . F u r t h e r d i v i s i o n s are g i v e n i n the Tabl e of Rock U n i t s , (Table I ) . Metasediments Most of the rocks i n the E c s t a l l Septum are metamor-phosed sediments. R e c r y s t a l l i z a t i o n and s h e a r i n g d u r i n g dynamic metamorphism of the rocks has destroyed p r a c t i c a l l y a l l t r a c e s of sedimentary t e x t u r e s . A number of major rock u n i t s can be recognized i n the metasediments. These u n i t s are based on mineralogy and t e x t u r e . G n e i s s r Q u a r t z - f e l d s p a r gneiss i s the most abundant r o c k type i n the E c s t a l l Septum forming three major rock u n i t s which underly about 40$ of the septum and a l s o forming p a r t o f the other major rock u n i t s where i t i s interbedded w i t h the main rock type. The gneiss i s both banded and f o l i a t e d . In hand specimens bands of l i g h t and dark, and/or coarse and f i n e g r a i n e d m a t e r i a l are apparent, w h i l e w i t h i n the bands the m i n e r a l g r a i n s are o r i e n t e d w i t h t h e i r long axes i n the plane of banding. Where b i o t i t e or hornblende Is abundant the f o l i a t i o n w i t h i n the bands i s p a r t i c u l a r l y w e l l d i s p l a y e d . Quaal R i v e r Gneisst The Quaal R i v e r Gneiss u n d e r l i e s most of the Quaal r i v e r v a l l e y , E c s t a l l l a k e , and a narrow zone south of the Quaal r i v e r between Barbara l a k e and K i s k o s h i n l e t . Outcrops are u s u a l l y good as the rock i s v e r y r e s i s t a n t t o weathering. The rock i s white to l i g h t grey on the f r e s h s u r f a c e , weathering to a darker grey or a r e d d i s h brown i f i r o n s u l -phides are abundant. Most outcrops show w e l l developed band-ing of dark and l i g h t c o l o u r e d m a t e r i a l . B i o t i t e , the o n l y abundant dark c o l o u r e d m i n e r a l i n the rock, i s present i n amounts of about 1 0 $ . On c l o s e i n s p e c t i o n of f r e s h l y broken p i e c e s of Quaal r i v e r g n e i s s i t i s seen t h a t the l i g h t bands are composed of coarse elongate g r a i n s or " l e a v e s " of quartz w i t h some f e l d s p a r and the darker bands are composed of f i n e g r a i n e d f e l d s p a r w i t h f i n e - g r a i n e d q u a r t z , b i o t i t e i n v a r y i n g amounts and minor amounts of a c c e s s o r y m i n e r a l s . Weathering i s much more r a p i d along the f i n e - g r a i n e d bands than along the coarse q u a r t z - f e l d s p a r bands and thus the c o a r s e - g r a i n e d bands form r i d g e s of white quartz 2 2 a n d f e l d s p a r w h i l e t h e f i n e - g r a i n e d b a n d s f o r m d e p r e s s i o n s w h i c h b e c o m e d a r k e n e d b y d e c o m p o s i t i o n p r o d u c t s a n d m o s s e s a n d l i c h e n s w h i c h g r o w a l o n g t h e m . D r a g f o l d i n g i s r a r e i n t h e g n e i s s b u t common i n t h e n a r r o w z o n e s o f s c h i s t w h i c h a r e i n t e r b e d d e d w i t h t h e g n e i s s . M i n e r a l l i n e a t i o n s a r e p r e s e n t w i t h i n t h e b a n d s o f t h e g n e i s s . S u c h l i n e a t i o n s a r e b e s t s e e n i n t h e b i o t i t e r i c h b a n d s . T h e c o m p o s i t i o n o f t h e Q u a a l r i v e r g n e i s s i s q u i t e v a r i a b l e . Some c o n t a i n a f e w p e r c e n t o f a c c e s s o r y m i n e r a l s , m o s t l y b i o t i t e , o t h e r s c o n t a i n 1 0 t o 20% a c c e s s o r y m i n e r a l s , a g a i n m o s t l y b i o t i t e . T h e t y p e a n d a m o u n t o f f e l d s p a r i s a l s o v a r i a b l e . Some s p e c i m e n s c o n t a i n o n l y K - f e l d s p a r , u s u a l l y b o t h m i c r o c l i n e a n d o r t h o c l a s e w i t h o n e o r t h e o t h e r p r e d o m i n a n t , o t h e r s c o n t a i n b o t h K - f e l d s p a r a n d s o d i c p l a g i o c l a s e , ( o l i g o -c l a s e ) , s t i l l o t h e r s c o n t a i n m o s t l y p l a g i o c l a s e w i t h m i n o r a m o u n t s o f K - f e l d s p a r s . T h e a m o u n t o f q u a r t z p r e s e n t i n t h e s e r o c k s a l s o v a r i e s . I n p l a c e s t h e y g r a d e i n t o q u a r t z i t e s , i n o t h e r s i n t o s c h i s t s o r c a l c a r e o u s t y p e s o f r o c k . A n u m b e r o f a c c e s s o r i e s may b e p r e s e n t i n c l u d i n g b i o t i t e , a n d c l i n o z o i s i t e , t h e c o m m o n e s t ; c h l o r i t e , s e r i c i t e , h o r n b l e n d e , g a r n e t , a n d s p h e n e , f a i r l y common b u t n e v e r p r e s e n t i n l a r g e a m o u n t s ; a n d r u t i l e , a p a t i t e , p y r i t e , w i t h m a g n e t i t e a n d o t h e r o p a q u e m i n e r a l s . D e t a i l e d p e t r o g r a p h i c d e s c r i p t i o n s o f f o u r s p e c i m e n s a n d t h i n s e c t i o n s o f t y p i c a l Q u a a l R i v e r g n e i s s f o l l o w s : 23 Or - 1 5 A specimen from a m i l e and a h a l f n o r t h - e a s t of Gordon Lake: The hand specimen i s a coarse grained banded rock o f very l i g h t c o l o u r on f r e s h s u r f a c e s , weathered s u r f a c e s are darkened by l i c h e n s and weathering p r o d u c t s . Three s e t s o f bands can be seen i n t h i s rock. A dark s e t c o n t a i n i n g the acc e s s o r y m i n e r a l s , a w h i t i s h set c o n t a i n i n g f i n e - g r a i n e d f e l d s p a r and f i n e q u a r t z , and a w a t e r y - l u s t e r e d s e t o f coarse elongated quartz g r a i n s . On weathered s u r f a c e s f r e s h un-a l t e r e d quartz bands weather i n t o r e l i e f a g a i n s t the other bands. A zone of weathered rock extends from a h a l f an i n c h to an i n c h inwards from the weathered s u r f a c e s . In t h i s zone the f e l d s p a r s have been whitened and broken down by the weathering but the quartz although s t a i n e d brown by i r o n oxide i s f r e s h . The m i n e r a l s making up the dark bands are v e r y f i n e g r a i n e d , and cannot be i d e n t i f i e d i n hand specimen. A few minute red g r a i n s of r u t i l e can be seen s c a t t e r e d through the rock. A t h i n s e c t i o n o f Or - 1 5 has the f o l l o w i n g composition: Quartz, 35$; m i c r o c l i n e , 30$; o r t h o c l a s e , 30$; w i t h shreds o f highe r r e l i e f f e l d s p a r , ( a n o r t h o c l a s e or a l b i t e ) ; b i o t i t e , a l t e r i n g to c h l o r i t e and s e r i c i t e ; c l i n o z o i s i t e ; s e r i c i t e shreds i n some of the f e l d s p a r s ; sphene; hornblende; opaque b l a c k g r a i n s , and one g r a i n of garnet. 24 K - f e l d s p a r g r a i n s o f v a r i o u s s i z e s occur between long leaves o f s t r a i n e d q u a r t z , ( F i g s . 7 and 8 ) . Some of the quartz l e a v e s show an i m b r i c a t e s t r u c t u r e under c r o s s e d n i c o l s , p o s s i b l y "Boehm l a m e l l a e . " Such s t r u c t u r e s are a r e s u l t o f s l i g h t v a r i a t i o n s i n the c r y s t a l l o g r a p h i c o r i e n t a t i o n w i t h a s i n g l e l e a f o f q u a r t z . F i g s . 7 and 8 show the t y p i c a l t e x t u r e s o f the rock. F i g u r e 8 shows a l a r g e p o r p h y r o b l a s t o f o r t h o c l a s e i n v e r t i n g to m i c r o c l i n e along some edges. Many o f the s m a l l e r g r a i n s of o r t h o c l a s e show such i n c i p i e n t i n v e r s i o n s . Some show m i c r o p e r t h i t i c i n t e r g r o w t h o f a high e r r e l i e f f e l d s p a r , p e r -haps a n o r t h o c l a s e or a l b i t e . S i m i l a r higher r e l i e f m a t e r i a l occurs along some of the g r a i n boundaries. Q u a r t z - o r t h o c l a s e myrmekite are abundant i n F i g u r e 8, along the boundaries o f the o r t h o c l a s e p o r p h r o b l a s t . Such m a t e r i a l i s not seen i n other p a r t s o f the s l i d e . F e l d s p a r g r a i n s between the quartz bands show signs of s t r a i n and deformation but they are a l s o intergrown w i t h one another t o g i v e an i n t e r l o c k i n g t e x t u r e which c o u l d not have developed i f the rock had undergone only dynamic meta-morphism w i t h no l a t e r r e c r y s t a l l i z a t i o n . Probably d e f o r -mation and m i n e r a l growth occurred contemporaneously. My-l o n i t e can be seen along the boundaries of the coarse quartz bands i n F i g s . 7 and 8. T h i s m a t e r i a l i s a r e s u l t o f extreme b r e c c i a t i o n along the r e s i s t a n t quartz bands. 25 F i g u r e 7 . Photomicrograph of Or - 1 5 (Crossed N i c o l s X 1 6 )  showing leaves of quartz w i t h f i n e r g r a i n e d k- f e l d s p a r s between them. One quartz l e a f shows  w e l l developed i m b r i c a t e s t r u c t u r e . P l a i d  twinning i s w e l l developed on some of the mi c r o - c l i n e . The band of v e r y f i n e i r r e g u l a r g r a i n s  c o n t a i n s accessory m i n e r a l s . F i g u r e 8 . P o r p h r o b l a s t of o r t h o c l a s e (Crossed N i c o l s X 1 6 )  i n v e r t i n g along i t s edges to m i c r o c l i n e . Myrma- k i t i t i c intergrowths of quartz i n o r t h o c l a s e a l s o  occur. Textures as i n F i g u r e 7 are a l s o shown. 26 O r - 8 T h i s s p e c i m e n was o b t a i n e d a h a l f m i l e w e s t o f D o u g l a s l a k e . Q u a r t z a n d f e l d s p a r m a k e s up o v e r 9 0 $ o f t h e r o c k . E x c e p t f o r a q u a r t e r - i n c h - w i d e z o n e o f w h i t e l e a c h e d r o c k a l o n g t h e s i d e t h a t w a s e x p o s e d t o t h e w e a t h e r , t h e w h o l e s p e c i m e n i s s t a i n e d a r e d d i s h b r o w n b y i r o n o x i d e s . B r o k e n s u r f a c e s s h o w b a n d s o f q u a r t z , b a n d s o f f e l d s p a r , a n d b a n d s o f d a r k e r m a t e r i a l m u c h a s i n 0 r - l 5 . A t h i n s e c t i o n f r o m O r - 8 c o n t a i n s : q u a r t z , 4 5 $ , m i c r o c l i n e , 3 5 $ ; p l a g i o c l a s e , ( s e c t i o n p e r p . t o ( 0 1 0 ) x ( 0 1 0 ) = 13° f o r A n 2 g ) a t l e a s t a s c a l c i c a s o l i g o c l a s e 1 5 $ ; w i t h t h e r e m a i n d e r m u s c o v i t e , b i o t i t e , m a g n e t i t e , c h l o r i t e , a n d r e d a n d b r o w n i r o n o x i d e s . T e x t u r a l l y t h e r o c k i s v e r y s i m i l a r t o 0 r - l 5 . F i g u r e 9 s h o w s w e l l d e v e l o p e d b a n d s o f c o a r s e q u a r t z g r a i n s w i t h f i n e r f e l d s p a r s b e t w e e n . M u c h o f t h e m i c r o c l i n e i s o n l y w e a k l y t w i n n e d a n d t h e t w i n n i n g d o e s n o t a p p e a r i n t h e p i c t u r e . A l l t h e a c c e s s o r y m i n e r a l s , e x c e p t m u s c o v i t e , a r e v e r y f i n e g r a i n e d . T h e m u s c o v i t e o c c u r s a s a f e w v e r y l a r g e c o l o u r l e s s g r a i n s a s s o c i a t e d w i t h f i n e s h r e d s o f b i o t i t e , w h i c h i t a p p e a r s t o b e r e p l a c i n g . Some b i o t i t e g r a i n s h a v e a l t e r e d p a r t l y t o c h l o r i t e . I r o n o x i d e o c c u r s a l o n g f r a c t u r e s a n d c l e a v a g e p l a n e s i n many o f t h e m i n e r a l g r a i n s a n d a l o n g some g r a i n b o u n d a r i e s . 2 7 F i g u r e 9. Photomicrograph of Or-8 X 1 6 . Note the  quartz bands and the f i n e r g r a i n e d f e l d - spars i n the bands between the long quartz  g r a i n s . P l a g i o c l a s e and m i c r o c l i n e w i t h  s m a l l rounded g r a i n s of quartz occur i n  the f i n e grained bands. Evidences of s t r a i n are abundant i n the t h i n s e c t i o n . Most of the l a r g e quartz leaves show undulatory e x t i n c t i o n , p l a g i o c l a s e twins are s l i g h t l y bent, and some m i c r o c l i n e g r a i n s show i r r e g u l a r twinning s u g g e s t i v e o f broken g r a i n s . Many o f the m i n e r a l g r a i n s , however, are intergrown suggest-i n g s h e a r i n g and the growth of the g r a i n s occurred t o g e t h e r , f o r such an i n t i m a t e i n t e r l o c k i n g of g r a i n s would be destroyed by s t r a i g h t dynamic metamorphism. B-66 Specimen B-66 was taken a q u a r t e r of a m i l e e a s t o f E c s t a l l l a k e . I t i s a f i n e grained l i g h t grey banded rock w i t h a w e l l developed cleavage along zones h i g h i n micaceous miner-a l s . Cleavage s u r f a c e s of the rock have a g r e e n i s h t i n g e and weathered s u r f a c e s are grey-brown. The rock i s f i n e g rained hard and compact and has a g r a n u l a r t e x t u r e , i t appears to be a m y l o n i t e . Two q u a r t e r - i n c h quartz v e i n l e t s cut a c r o s s the banding of the rock at a low angle. A t h i n s e c t i o n of t h i s rock i s composed of: q u a r t z , 50$; s o d i c - p l a g i o c l a s e , 25$; s e r i c i t e , 20%; w i t h 1-2% epidote; about 1% c a l c i t e ; and t r a c e s of c h l o r i t e , and hornblende. F i g u r e 10 shows the t e x t u r e of the rock. Bands of l a r g e , elongated s t r a i n e d quartz g r a i n s l i e between m i l l e d out aggregates of much f i n e r g rained p l a g i o c l a s e and q u a r t z . The s e r i c i t e and the c h l o r i t e i n the s e c t i o n i s i n s c a l e y g r a i n s of v a r y i n g s i z e a l i g n e d p a r a l l e l w i t h the quartz bands. A l l the p l a g i o c l a s e i n the s e c t i o n has n e g a t i v e r e l i e f a g a i n s t quartz and very s l i g h t p o s i t i v e r e l i e f a g a i n s t balsam i n d i c a t i n g i t i a near a l b i t e , probably about A n 1 0 , but no s e c t i o n l a r g e enough and w e l l enough twinned c o u l d be found f o r exact measurement. 29 F i g u r e 10, Photomicrograph of B-66 (Crossed n i c o l s X 16)  T h i s photo, shows the f i n e grained f e l d s p a r s  and quartz m i l l e d out between bands of coarse  elongated quartz g r a i n s . No sharp angular  fragments are present s u g g e s t i n g the s h e a r i n g  occurred d u r i n g the growth of the m i n e r a l s or  there was r e c r y s t a l l i z a t i o n a f t e r the s h e a r i n g . B-70 Specimen B-70 was taken about a h a l f m i l e n o r t h of specimen B - 6 6 . T h i s rock i s most unusual as i t i s s t r i p e d green and white by bands of w h i t i s h q u a r t z , and bands of f e l d s p a r mixed w i t h green micaceous m i n e r a l s . I t i s a hard r e s i s t a n t rock w i t h a f a i r cleavage along the micaceous bands. Weathered s u r f a c e s are grey to grey b l a c k . A zone of b l e a c h i n g extends i n t o the rock 1/4- i n c h from the weathered s u r f a c e s . In t h i n s e c t i o n B-70 i s seen to be composed o f : q u a r t z , 50$; f e l d s p a r , probably p l a g i o c l a s e A n i o or so, 20$; 3 0 s e r i c i t e , 25$; b i o t i t e , 2 to 3$; e p i d o t e , 1-2$; w i t h garnet, c h l o r i t e and some opaque g r a i n s . F i g s . 11 and 12 show the t e x t u r e of the rock. The bands of coarse elongated quartz g r a i n s are separated by very f i n e g r a i n e d f e l d s p a r , quartz and micas. The f e l d s p a r i s so f i n e g r a i n e d t h a t l i t t l e o f i t shows any twinning. Some a l b i t e twinned g r a i n s a r e present and w i t h the r e l i e f , which i s j u s t about balsam, suggests the f e l d s p a r i s p l a g i o c l a s e about An-^Q. Micas a r e a l i g n e d p a r a l l e l t o the quartz bands. Most of i t i s s e r i c i t e which c o n t a i n s here and there shreds of b i o t i t e . E i t h e r the b i o t i t e i s a l t e r i n g t o s e r i c i t e or the s e r i c i t e i s changing to b i o t i t e . Some b i o t i t e g r a i n s , w h i l e s t i l l r e t a i n i n g t h e i r b i o t i t e c o l o u r and ple o c h r o i s m , have u n u s u a l l y h i g h b i r e -f r i n g e n c e . Perhaps such g r a i n s a r e p a r t l y a l t e r e d to s e r i c i t e . Some b i o t i t e seems to be a l t e r i n g to c h l o r i t e , perhaps a way p o i n t on the a l t e r a t i o n t o s e r i c i t e , as p a r t s of such g r a i n s a l s o are a l t e r i n g t o s e r i c i t e . (see F i g u r e 13> page 32) . E p i d o t e i n t h i s s e c t i o n shows l i g h t y e l l o w p l e o -chroism and g e n e r a l l y low and o f t e n anomalous blu e b i r e -f r i n g e n c e c o l o u r s . I t does not appear t o be the same as the c l i n o z o i s i t e which i s abundant i n the Douglas Channel g n e i s s , and i n some of the other r o c k s . 31 Figure 11. Photomicrograph (B-70 Plane Polarized Light X 16) Figure 12; Photomicrograph of B-70. Same area as seen above with crossed n i c o l s (X-16). The mvlonite be-tween the large ouartz grains i s much darker than the quartz grains under p l a i n l i g h t . The darker  areas are s e r i c i t e , b i o t i t e , etc. 3 2 F i g u r e 1 3 . P h o t o m i c r o g r a p h o f B - 7 0 p l a n e p o l a r i z e d l i g h t  X - 4 0 . B i o t i t e a l t e r i n g t o s e r i c i t e . B i o t i t e  d a r k , l a t h e s ^ s e r i c i t e c o l o u r l e s s l a t h e s . C l i n o z o i s i t e I r r e g u l a r h i g h r e l i e f w i t h q u a r t z  a n d f e l d s p a r . B - 7 0 h a s u n d e r g o n e e x t r e m e c a t a c l a s t i c m e t a m o r p h i s m a s h a v e a l l t h e o t h e r r o c k s d i s c u s s e d a b o v e . S u c h m e t a -m o r p h i s m i s t y p i c a l o f t h e Q u a i l r i v e r g n e i s s . T h e m i n e r a l a s s e m b l a g e o f q u a r t z , K - f e l d s p a r , s o d i c p l a g i o c l a s e ( o l i g o -c l a s e ) , w i t h s m a l l a m o u n t s o f b i o t i t e f i t s t h e p o t a s s i u m r i c h g r o u p o f t h e s t a o u r o l i t e - k y a n i t e s u b f a c i e s o f t h e a m p h i -b o l i t e f a c i e s . R o c k s i n w h i c h K - f e l d s p a r i s p r e s e n t a r e n e v e r t h e l e s s s u f f i c i e n t l y h i g h i n K^O t o i n h i b i t t h e f o r m a t i o n o f s t a o u r o l i t e - k y a n i t e s u b f a c i e s w h i c h a r e d i a g n o s t i c o f r o c k s o f t h e s t a u r o l i t e - k y a n i t e s u b f a c i e s d i f f i d e n t i n K2O. Muscovite and c h l o r i t e r e p r e s e n t r e t r o g r a d e m i n e r a l s r a t h e r than e q u i l i b r i u m assemblages. No evidence f o r metasomatic s u b s t i t u t i o n of elements was found and thus the rocks are probably of o r i g i n a l s e d i -mentary composition. O r i g i n a l l y the r o c k s were q u a r t z o -f e l d s p a t h i c sandstones, a r k o s i c sandstones, or perhaps a r g i l l a c e o u s s i l t s t o n e s . Douglas Channel Gneiss The Douglas Channel Gneiss crops out along the shore of Douglas Channel beginning at a p o i n t 4.5 m i l e s n o r t h - e a s t of Gertrude P o i n t and c o n t i n u i n g as f a r as the e a s t e r n edge of the E c s t a l l Septum. Inland the extent of these rocks has not been e s t a b l i s h e d . A e r i a l photographs i n d i c a t e they cover most of the a r e a between the g r a n i t e c o n t a c t j u s t south of Foch l a k e and Douglas Channel. Outcrops of s i m i l a r gneiss occur a l o n g the r i d g e and i n the v a l l e y between Foch and K i t k i a t a l a k e s . Northwest of t h i s v a l l e y n o t h i n g i s known of these r o c k s . They do not crop out along the E c s t a l l r i v e r nor south and south-east of Johnson l a k e . Perhaps the gneiss u n d e r l i e s the a r e a between Johnson l a k e and the g r a n i t e con-t a c t on the east edge of the septum, an a r e a so f a r unexplored. The Douglas Channel gneiss i s s i m i l a r i n composition to the Quaal R i v e r gneiss being composed predominantly of quartz and f e l d s p a r s but i t i s d i f f e r e n t i n that f e l d s p a r i s more abundant than q u a r t z , and p l a g i o c l a s e i s more abundant 3 4 than K - f e l d s p a r . F u r t h e r the p l a g i o c l a s e i s c o n s i d e r a b l y more c a l c i c than that i n the Quaal g n e i s s averaging about An^Qj and o l i g o c l a s e - a n d e s i n e , versus a s o d i c o l i g o c l a s e i n the Quaal r i v e r g n e i s s . B i o t i t e , hornblende, c l i n o z o i -s i t e and garnet are more abundant i n the Douglas Channel gneiss a l s o , making up 20 to 40$ of the rock almost twice the amounts u s u a l l y found i n the Quaal r i v e r g n e i s s . T e x t u r a l l y the Douglas channel g n e i s s i s a l s o d i f f e r e n t than the Quaal r i v e r g n e i s s . Most of the Douglas channel gneiss contains l a r g e augen shaped p o r p h y r o b l a s t s o f o r t h o c l a s e , (see F i g u r e 14), p l a g i o c l a s e , hornblende or o c c a s i o n a l l y garnet. Few of them c o n t a i n the quartz bands common i n the Quaal gneiss and few c o n t a i n m y l o n i t e such as that i n B-70. Interbeds of ca l c a r e o u s r o c k s , p a r t i c u l a r l y c l i n o z o i -s i t e hornblende types are very common i n the Douglas channel g n e i s s . Q u a r t z i t e , b i o t i t e s c h i s t , and hornblende s c h i s t are a l s o common. A l l such rocks are much r a r e r i n the Quaal r i v e r g n e i s s . A number of t y p i c a l specimens of Douglas channel gneiss are d e s c r i b e d i n d e t a i l below. F i g u r e 1 4 . Douglas Channel augen g n e i s s . T y p i c a l exposure of v e r y f r e s h  c o a r s e - g r a i n e d gneiss along Douglas channel. The white  augen-shaped g r a i n s are probably  i l l o r t h o c l a s e . B-52 was taken  from nearby. Specimen B-52 i s a coarse g r a i n e d augen g n e i s s . I t was taken along the shore of Douglas Channel about h a l f way between Gertrude and P a i s l e y P o i n t s . In hand specimen i t i s l i g h t grey o v e r a l l but has b l a c k b i o t i t e r i c h bands, white f e l d s p a r bands, and numerous l a r g e augens of f r e s h untwinned f e l d s p a r s . Red garnets about 1/2 mm. i n diameter are s c a t t e r e d here and there i n the b i o t i t e bands, and green prisms of epidote up to a mm. i n l e n g t h are abundant through-out the rock, p a r t i c u l a r l y i n the b i o t i t e bands. F i g u r e 15. Photo of p o l i s h e d s e c t i o n of B - 5 2 showing, l a r g e o r t h o c l a s e augen shaped p o r p h r o b l a s t . In t h i n s e c t i o n the composition of B-52 i s : p l a g i o -c l a s e , 35$; o r t h o c l a s e , 25$; q u a r t z , 10$; c l i n o z o i s i t e , 15$; b i o t i t e , 10$; w i t h garnet, sphene, and a few shreds of s e r i c i t e and c h l o r i t e . The p l a g i o c l a s e occurs as s m a l l subangular g r a i n s around the borders of l a r g e r g r a i n s of K - f e l d s p a r , and as much l a r g e r i n t e r l o c k i n g elongated g r a i n s . Much of i t i s untwinned and none shows w e l l developed cleavage. S e c t i o n s 1 to (010) gave angles of 16.5° and 17.5° f o r X1/^ (010) f o r An^ij. Combined w i t h the r e l i e f , which i s equal to or j u s t below t h a t of q u a r t z , depending on the o r i e n t a t i o n of the g r a i n s , the above determinations are f a i r l y c e r t a i n , making the p l a g i o c l a s e o l i g o c l a s e - a n d e s i n e . Most of the o r t h o c l a s e occurs as l a r g e augen-shaped p o r p h r o b l a s t s which have g r a i n s of p l a g i o c l a s e , q u a r t z , and quartz p l a g i o c l a s e myrmakitic intergrowths c o n c e n t r a t e d around the borders of the augen. O c c a s i o n a l g r a i n s of q u a r t z , p l a g i o c l a s e , b i o t i t e , and c l i n o z o i s i t e are s c a t t e r e d throughout the augen. S m a l l g r a i n s o f o r t h o c l a s e a l s o occur mixed w i t h the p l a g i o c l a s e i n the groundmass of the rock. C l i n o z o i s i t e i s v e r y f r e s h , q u i t e coarse g r a i n e d , and has a prominent cleavage w i t h a w e l l developed p a r t i n g i n many g r a i n s and two d i r e c t i o n s of p a r t i n g i n some g r a i n s . I t i s p r a c t i c a l l y c o l o u r l e s s but has a r e d d i s h or g r e e n i s h c a s t . The r e l i e f of the c l i n o z o i s i t e g r a i n s have ragged and somewhat embayed margins which are p a r t i c u l a r l y w e l l d e v e l -oped along c o n t a c t s w i t h b i o t i t e . These embayments suggest the c l i n o z o i s i t e has been a t t a c k e d along i t s c o n t a c t s by other m i n e r a l s or l i k e l y these embayments are the r e s u l t of i n t e r f e r e n c e between the v a r i o u s m i n e r a l s d u r i n g growth. 3 8 F i g u r e 1 6 , Photomicrograph of B-52 crossed n i c o l s X 16 A l a r g e p o r p h y r o b l a s t of o r t h o c l a s e surround- ed by quartz and p l a g i o c l a s e and c o n t a i n i n g  quartz and c l i n o z o i s i t e i n c l u s i o n s . F i g u r e 1 7 . S k e t c h of a c l i n o z o i s i t e g r a i n showing z o n a l  v a r i a t i o n i n the b i r e f r i n g e n c e c o l o u r s . 39 Some c l i n o z o i s i t e g r a i n s have many s m a l l i n c l u s i o n s , probably of q u a r t z , i n them. Except f o r a few s m a l l g r a i n s which seem to be p a r t l y a l t e r e d to s e r i c i t e and c h l o r i t e the b i o t i t e i s very f r e s h . Sphene occurs as a few w e l l developed diamond shaped g r a i n s . Most of the garnets are f r a c t u r e d probably by f o r c e s d e v e l -oped i n them as they were growing. The t e x t u r e of the rock, the l a r g e augen-shaped p o r p h r o b l a s t s of o r t h o c l a s e , the poor twinning, and l a c k o f cleavage i n the p l a g i o c l a s e ; and the unbent and unbroken nature of the b i o t i t e and c l i n o z o i s i t e suggest the rock was deformed as the m i n e r a l s grew, and that no s t r o n g deformation took p l a c e a f t e r the m i n e r a l s stopped growing. Figure 18. Photomicrograph of B-52 plane polarized l i g h t X40  C l i n o z o i s i t e showing twinning, cleavage and well  developed parting, with b i o t i t e . Note the embayed  nature of the contact between the b i o t i t e and c l i n -o z o i s i t e and the very strongly embayed edges of the b i o t i t e grains. B-46 i s another specimen of gneiss from Douglas channel. I t has dark bands of l u s t r o u s b i o t i t e and horn-blende and l i g h t bands of p l a g i o c l a s e . A l l the m i n e r a l s are f r e s h and u n a l t e r e d . The bands are i r r e g u l a r , p i n c h i n g and s w e l l i n g and i n p l a c e s forming augen shapes. Weathered s u r -faces are very rough as the dark m i n e r a l s weather out l e a v i n g bands and knots of f r e s h p l a g i o c l a s e s t a n d i n g above the s u r -f a c e . B i o t i t e and hornblende form about 30$ of the r o c k s , g r e e n i s h y e l l o w c l i n o z o i s i t e forms about 5$» most of the r e -mainder i s p l a g i o c l a s e . A t h i n s e c t i o n of B - 4 6 c o n t a i n s the f o l l o w i n g m i n e r a l s zoned p l a g i o c l a s e ( A n ^ to AU^Q) 55$, quartz 15$» hornblende 15$, b i o t i t e 10$, c l i n o z o i s i t e 3 to 5$ and a few b l a c k opaque g r a i n s . The p l a g i o c l a s e occurs as l a r g e and s m a l l w e l l twinned g r a i n s , some showing z o n i n g . A few of the g r a i n s have bent twinning l a m e l l a e and u ndulatory e x t i n c t i o n . One s e c t i o n _L <L gave an angle of 2 0 . 5 ° f o r X*A (010) (An^r,). Another s e c t i o n a showed r e v e r s e d zoning as shown i n F i g . 19. F i g u r e 19. S k e t c h of zoned p l a g i o c l a s e X n i c o l s X 8 0 , S e c t i o n a x 1 (010; For zone A = 23° An^g B = 1 0 . 5 ° An 2 8 C = 1 6 ° A n 3 3 41 The hornblende i s s t r o n g l y a c o l o u r e d v a r i e t y , p l e o c h r o i c deep blue green, w i t h cleavage N-S, and y e l l o w o green w i t h cleavage E.W. S e c t i o n s ± X gave values o f 2 3 f o r Z A C The min e r a l s are o p t i c a l l y n e g a t i v e w i t h a v e r y l a r g e o p t i c angle. The above d a t a i n d i c a t e the m i n e r a l i s a common v a r i e t y of hornblende, probably lower i n alumina than the deep brown v a r i e t i e s . T h i s type of hornblende i s the most common one i n the rocks of the E c s t a l l septum. Only a few of the h o r n b l e n d i t e s have d i f f e r e n t v a r i e t i e s . B i o t i t e occurs i n long deeply c o l o u r e d l a t h s . None of i t i s a l t e r e d , although, some g r a i n s are s l i g h t l y bent. F i g u r e 2 0 shows a t y p i c a l s e c t i o n of the s l i d e . F i g u r e 2 0 . Photomicrograph of B-46 Plana p o l a r i z e d l i g h t X 16  B i o t i t e i s dark and occurs i n long b l a d e s . The  dark equidimensional g r a i n s w i t h two cleavages  are hornblende. C l i n o z o i s i t e i s grey, c l e a v e d , and f r a c t u r e d . P l a g i o c l a s e w i t h minor quartz  forms the ground mass. 42 B-51 i s a h o r n b l e n d e - p l a g i o c l a s e - c l i n o z o i s i t e g n e i s s from the shore of Douglas channel. The hand specimen has b l a c k bands of hornblende and white and green bands of p l a g i o -c l a s e and c l i n o z o i s i t e . The bands are f o l d e d as can be seen i n F i g u r e s 21 and 22. One s i d e of the rock c o n t a i n s about 40$ hornblende and t h i s s i d e has some dark red g a r n e t s , one about 1/4 i n c h i n diameter. The hornblende, which forms about 25 to 30$ of the specimen, occurs as elongated l e n t i -c u l a r g r a i n s . Some of them are q u i t e l a r g e , over 1/2 i n c h long by 1/8 i n c h t h i c k . In the hand specimen these horn-blende g r a i n s appear to have been f o l d e d and sheared, t o p r o -duce w i t h i n each l a r g e g r a i n , v a r i a t i o n s i n o r i e n t a t i o n . F i g u r e 21. B-51 Hornblende, b l a c k , o u t l i n e s a f o l d plunging; towards the r u l e r . White i s f e l d s p a r , grey Is  c l i n o z o i s i t e . F i g u r e 22. Photograph of an end s e c t i o n across B-51 shoving the f o l d and the f e l d s p a r r i c h and  hornblende r i c h areas. A t h i n s e c t i o n shows B-51 has the f o l l o w i n g compo-s i t i o n ; c l i n o z o i s i t e , 35$; p l a g i o c l a s e , 25$; hornblende, 25$; q u a r t z , 10$; b i o t i t e , 2-3$; w i t h some garnet. S e r i c i t e and a white opaque m i n e r a l has r e p l a c e d some of the p l a g i o c l a s e g r a i n s . C l i n o z o i s i t e occurs as s m a l l subhedral elongated g r a i n s about a mm. l o n g . A l l of i t i s v e r y f r e s h and c r i s p -l o o k i n g , w i t h a good cleavage (001), and a w e l l developed p a r t i n g . In some g r a i n s t h i s p a r t i n g i s p a r a l l e l to twin planes as shown i n F i g u r e 17 of B - 5 2 thus the p a r t i n g appears p a r a l l e l t o (100) the common twin p l a n e , but i n many elongated 44 s e c t i o n s the p a r t i n g shows up and thus cannot be p a r a l l e l to the b a x i s . Measurements on the f l a t stage on g r a i n s showing v e r t i c a l (001) cleavage and maximum e l o n g a t i o n i n d i c a t e the p a r t i n g cuts both b and c a x i s i n a r a t i o o f b:c = 1:4. S e c t i o n s cut p e r p e n d i c u l a r to b show the p a r t i n g does not cut the a x i s . The i n d i c e s o f t h i s p a r t i n g should be approximately (041). The c l i n o z o i s i t e i s almost c o l o u r l e s s w i t h a y e l l o w i s h t i n t . I t i s weakly p l e o c h r o i c , has a l a r g e 2V and i s o p t i c a l l y p o s i t i v e . Many g r a i n s show c o l o u r zoning under c r o s s e d n i c o l s as shown i n F i g u r e P l a g i o c l a s e occurs i n s h a r p l y twinned g r a i n s some of them zoned. S e c t i o n s j.3 gave X'A (010) = 17 . 5 ° f o r A* 1^* One g r a i n was zoned A n ^ a"t the center and A n ^ a t the o u t s i d e . S e c t i o n J- a X'A (010) = 30° and 1 5 ° r e s p e c t i v e l y ) . Some of the p l a g i o c l a s e g r a i n s are very l a r g e elongated p o r p h r o b l a s t s w i t h many i n c l u s i o n s of c l i n o z o i s i t e , q u a r t z , and some hornblende. In F i g u r e 23 one of these g r a i n s of p l a g i o c l a s e has been drawn. A l l the g r a i n has s i m i l a r twinning and each p a r t i s almost i n o p t i c a l and c r y s t a l l o g r a p h i c alignment w i t h the other p a r t s . The s l i g h t v a r i a n c e i n e x t i n c t i o n seen i n v a r i o u s p a r t s o f the g r a i n i s p r o b a b l y a r e s u l t of deformation. A few p l a g i o c l a s e g r a i n s have bent twinning l a m e l l a e , others show undulatory e x t i n c t i o n and anomalous p r o p e r t i e s suggesting movement of pa r t of the g r a i n i n r e l a t i o n to the r e s t of the g r a i n . 4 5 F i g u r e 23. S k e t c h of a p o r p h r o b l a s t of p l a g i o c l a s e . The three s e c t i o n s of the g r a i n s are not  q u i t e p a r a l l e l c r y s t a l l o g r a p h i c a l l y . Most of the hornblende i s a blue green v a r i e t y s i m i l a r to that i n B-46 but w i t h a s l i g h t l y browner c a s t . F i g u r e 22 shows a g r a i n of v e r y brown hornblende embayed by c l i n o z o i s i t e g r a i n s and r e p l a c e d by c l i n o z o i s i t e along the f r a c t u r e s . Most of the hornblende occurs i n a few v e r y l a r g e g r a i n s , or groups of g r a i n s that may once have been one g r a i n . A l l show w e l l developed s i e v e t e x t u r e of quartz and c l i n o z o i s i t e i n -c l u s i o n s . Most of the g r a i n s have f r a c t u r e s along which s l i p p a g e has occu r r e d p a r a l l e l t o the cleavage. 46 F i g u r e 24. Photomicrograph of B-51 X 16 G r a i n of brownish hornblende r e p l a c e d by  c l i n o z o i s i t e along f r a c t u r e s and around  borders. Dark grey - normal type of  hornblende, l i g h t h i g h r e l i e f c l i n o z o i s i t e  white p l a g i o c l a s e and some qua r t z . 4 7 B-48 i s a rock c o n t a i n i n g at l e a s t 5 0 $ c l i n o z o i s i t e w i t h hornblende, b i o t i t e , and f e l d s p a r . I t has a g r e e n i s h cast caused by the l a r g e amounts of e p i d o t e . The hornblende occurs as l a r g e l e n t i c u l a r g r a i n s which are somewhat a l i g n e d g i v i n g the rock a poor f o l i a t i o n . A t h i n s e c t i o n of B - 4 8 c o n t a i n s : c l i n o z o i s i t e , 5 5 $ ; p l a g i o c l a s e , ( A n ^ ) 1 5 $ ; hornblende, 1 5 $ ; b i o t i t e , 8 - 1 0 $ ; q u a r t z , 5 $ ; w i t h s e r i c i t e , c h l o r i t e , and sphene. The c l i n o z o i s i t e i s the same as d e s c r i b e d i n the previous r o c k s . The hornblende occurs i n l a r g e s i e v e - t e x t u r e d g r a i n s i n which c l i n o z o i s i t e i s the most abundant i n c l u s i o n . Many of the hornblende g r a i n s and some of the b i o t i t e g r a i n s are a l t e r i n g to l i g h t green c h l o r i t e , as shown i n F i g u r e 2 5 . P l a g i o c l a s e i s i n anhedral g r a i n s of v a r y i n g s i z e ; most are w e l l twinned and some s t r o n g l y zoned. One g r a i n x a gave values of X ' A ( 0 1 0 ) = 10.5° and 1 8 . 5 ° f o r i n n e r and outer zones r e s p e c t i v e l y . Thus the g r a i n i s r e v e r s e l y zoned A ^ g to An^£. Another g r a i n gave values of Z A ( 0 1 0 ) = 7 7 ° i n a s e c t i o n JL to X , f o r A n ^ ^ / j . -B i o t i t e , hornblende, and p l a g i o c l a s e a l l show s i g n s of f r a c t u r e , shear, and s t r a i n s u g g e s t i v e of l a t e deformation. 48 F i g u r e 2 5 . Photomicrograph of B - 4 8 p l a i n l i g h t X U n a l t e r e d hornblende dark grey, c h l o r i t e  a l t e r a t i o n l i g h t e r grey, c l i n o z o i s i t e f i n e grained l i g h t grey, p l a g i o c l a s e almost  white. A few g r a i n s of b i o t i t e are p r e s e n t . They are l i g h t grey and have one d i r e c t i o n  cleavage. 4 9 B - 5 8 i s a s p e c i m e n o f h o r n b l e n d e - c l i n o z o i s i t e g n e i s s f r o m D o u g l a s C h a n n e l . I t i s a n u n u s u a l r o c k , c o m p o s e d o f b a n d s o f l a r g e b l a c k h o r n b l e n d e b l a d e s , i n t e r l a y e r e d w i t h b a n d s o f l i g h t g r e e n s u g a r y c l i n o z o i s i t e , a n d a f e w b a n d s o f h i g h l y f r a c t u r e d q u a r t z . A l e n s e o f r u t l i e c o n f o r m a b l e w i t h t h e o t h e r b a n d s o c c u r s I n t h e s p e c i m e n . A l l t h e b a n d s h a v e b e e n s e v e r e l y f o l d e d a n d d e f o r m e d . T h e y p i n c h a n d s w e l l a s i f t h e y w e r e d e f o r m e d i n a p l a s t i c s t a t e . I n t h e o u t c r o p t h e r u t i l e " v e i n " w a s a b o u t a f o o t l o n g a n d v a r i e d f r o m a n e i g h t h i n c h t o a b o u t t h r e e - q u a r t e r s o f a n i n c h i n t h i c k n e s s . I n p l a c e s i t w a s d i s c o n t i n u o u s a s i f d r a w n o u t a n d s e p a r a t e d b y t h e f o l d i n g . A f e w g r a i n s o f r u t i l e a r e s c a t t e r e d h e r e a n d t h e r e i n t h e r o c k , a w a y f r o m t h e m a i n r u t i l e b a n d . R u t i l e c a n o c c u r i n c e r t a i n r o c k s o f t h e a m p h i b o l i t e f a c i e s , a n d t h u s c a n b e e x p e c t e d i n m a n y o f t h e r o c k s o f b o t h t h e Q u a a l R i v e r a n d D o u g l a s C h a n n e l g n e i s s e s w h i c h a p p e a r t o b e m e m b e r s o f t h e a m p h i b o l i t e f a c i e s . T h e m i n e r a l a s s e m b l a g e s p r e s e n t i n m o s t s p e c i m e n s o f D o u g l a s c h a n n e l g n e i s s - p l a g i o c l a s e ( o l i g o c l a s e - a n d e s i n e ) h o r n b l e n d e , q u a r t z , K - f e l d s p a r , c l i n o z o i s i t e , a v a r i e t y o f a l m a d i n e g a r n e t , b i o t i t e , a n d o f t e n s p h e n e , a n d i r o n o r e s f i t n o s p e c i f i c a s s e m b l a g e o f t h e m e t a m o r p h i c f a c i e s . P r o b a b l y t h e r o c k s f a l l ' i n e i t h e r t h e a l m a d i n e - d i o p s i d e - h o r n b l e n d e ft T u r n e r a n d V e r h o o g e n , 1951 subfacies or the staurolite-kyanite subfacies of the amphi-ft b o l i t e s . The Douglas channel gneiss contains excess potash as do the Quaal r i v e r gneiss, but they are considerably richer i n aluminum, and calcium hence they have a higher con-tent of c l i n o z o i s i t e , feldspar and garnet and less quartz than does the Quaal gneiss. O r i g i n a l l y the Douglas channel gneiss was probably a sediment s i m i l a r to the metamorphosed to give the Quaal r i v e r gneiss but ri c h e r i n argillaceous and c a l c a r -eous material. C a t a c l a s t i c features are not as well developed i n the Douglas channel gneiss as they are i n the Quaal r i v e r gneiss. P a r t i c u l a r l y s i g n i f i c a n t i s the lack of mylonite i n the Douglas channel gneiss. Thus the l e v e l of dynamic metamorphism was not as high i n these rocks as i t was i n the Quaal gneiss. The s e r i c i t e and c h l o r i t e i n these rocks appears to be products of retrograde metamorphism of the hornblende b i o t i t e , and feldspars. K i t k i a t a Lake Gneiss: The K i t k i a t a lake gneiss underlies the northern hal f of the east shore of K i t k i a t a lake. (See Geological Map, Figure 9 2 ) . I t extends Inland to the contact of the K i t k i a t a lake stock. In some areas the gneiss contains many interbeds of hornblende schist and unusual epidote-hornblende rocks. In contrast to the more wide-spread Douglas channel and Quaal r i v e r gneisses which contain many variations of the k Turner and Verhoogen, 1951 51 " g n e i s s " rock type, the K i t k i a t a l a k e gneiss c o n t a i n s o n l y one type o f rock. Hand specimens of t h i s rock type c o n t a i n r o d -l i k e c o n c e n t r a t i o n s of quartz and f e l d s p a r some of which are connected t o other rods to form i r r e g u l a r bands. Between the rods and the bands a r e s c h i s t o s e l a y e r s of b i o t i t e and l i g h t green e p i d o t e . F i g u r e 26 i s a s k e t c h of an end s e c t i o n of one of the hand specimens (Or - 1 ) showing the c r i s s - c r o s s i n g nature of the b i o t i t e l a y e r s . F i g u r e 27 i s a photograph of a s e c t i o n across the banding of Or - 1 . ( F i g s . 26 and 27, p. 52) Such a s t r u c t u r e c o u l d be the r e s u l t o f extreme s m a l l s c a l e f o l d i n g combined w i t h s h e a r i n g i n the d i r e c t i o n p a r a l l e l to the e l o n g a t i o n o f the f e l d s p a r - q u a r t z rods. Or - 1 i s a specimen o f the K i t k i a t a Lake g n e i s s . I t shows the r o d - l i k e bands of q u a r t z and f e l d s p a r t y p i c a l o f the rock. I t i s a very f r e s h r o c k w i t h t h i n l a y e r of weather-ed m a t e r i a l on the outer s u r f a c e . The b i o t i t e i s b l a c k and l u s t r o u s and many of the l a m e l l a e are bent. Outer s u r f a c e s of the rock show many i r r e g u l a r s t r i p e s of q u a r t z - f e l d s p a r w i t h b i o t i t e p a r t i n g s between the s t r i p e s . ( F i g u r e 28) A t h i n s e c t i o n of Or - 1 c o n t a i n s the f o l l o w i n g : p l a g i o c l a s e , A n ^ 30$; q u a r t z , 30$; e p i d o t e , 20$; b i o t i t e , 20$; The p l a g i o c l a s e was i d e n t i f i e d as A n ^ i n s e c t i o n s A t o X which gave angles of Z A (010) of 8 6 . 5 ° and 8 5 ° . S m a l l almost c o l o u r l e s s g r a i n s of ep i d o t e abound throughout the s l i d e . They are s i m i l a r i n a l l r e s p e c t to the c l i n o z o i s i t e i n the p r e v i o u s l y d e s c r i b e d rocks but they have a s m a l l e r o p t i c angle and a n e g a t i v e s i g n . F i g u r e 2 6 . S k e t c h of End S e c t i o n o f Or-1 shoving r o d - shaped masses of Quartz and f e l d s p a r (Q),  separated by b i o t i t e " ( b l a c k ) . F i g u r e 2 7 . Photograph of End S e c t i o n of Or-1 showing  Q u a r t z - f e l d s p a r rods separated by b i o t i t e F i g u r e 2 8 . ; S k e t c h o f O r - 1 X 2 . s h o w i n g ; t h e b a n d s o f  b i o t i t e d a r k , a n d t h e r o d s o f q u a r t z -f e l d s p a r T w h i t e . A l l t h e m i n e r a l s i n t h e s l i d e s h o w s i g n s o f c a t a -c l a s t i c d e f o r m a t i o n . M a n y o f t h e p l a g i o c l a s e g r a i n s h a v e i r r e g u l a r s u t u r e d c o n t a c t s . Some o f t h e s e c o n t a c t s h a v e m i n u t e r o u n d e d g r a i n s a l o n g t h e m . S o m e o f t h e c o n t a c t s a r e v e r y r a g g e d a n d a n g u l a r . M o s t o f t h e q u a r t z g r a i n s s h o w u n -d u l a t o r y e x t i n c t i o n a n d some o f t h e m s h o w w h a t may b e " B o e h m l a m e l l a e " . A n ( 0 0 1 ) c l e a v a g e a n d a p a r t i n g a t a h i g h a n g l e t o t h e c l e a v a g e i s w e l l d e v e l o p e d I n m a n y o f t h e e p i d o t e g r a i n s . Some o f t h e g r a i n s h a v e f r a c t u r e s i n o t h e r d i r e c t i o n s a s w e l l . T h e t e x t u r e s i n t h e s l i d e s u g g e s t a f a i r l y i n t e n s e p e r i o d o f c a t a c l a s t i c d e f o r m a t i o n p r o b a b l y s t o p p i n g b e f o r e t h e r e c r y s t a l l l z a t i o n o f t h e r o c k w a s c o m p l e t e . T h e m i n e r a l o g i c a l s i m i l a r i t i e s b e t w e e n t h e K i t k i a t a l a k e g n e i s s a n d t h e o t h e r t w o g r o u p s o f g n e i s s s u g g e s t s a s i m i l a r o r i g i n f o r a l l t h e g r o u p s . P r o b a b l y t h e K i t k i a t a l a k e g n e i s s w a s o r i g i n a l l y a s e d i m e n t a r y r o c k w h i c h h a s u n d e r g o n e e x t r e m e d y n a m o - t h e r m a l r e g i o n a l m e t a m o r p h i s m . T h e m i n e r a l s p r e s e n t i n t h e K i t k i a t a g n e i s s f i t t h e same f a c i e s a s t h e o t h e r g n e i s s e s . Q u a r t z i t e Q u a r t z i t e i s o n e o f t h e t h r e e m o s t a b u n d a n t r o c k t y p e s i n t h e a r e a . I t o c c u r s a s t h r e e m a j o r u n i t s , A g n e s L a k e q u a r t z i t e , B a r b a r a L a k e q u a r t z i t e , a n d " M i n e S e r i e s " . Q u a r t -z i t e a l s o o c c u r s i n t e r b e d d e d w i t h a l l t h e o t h e r r o c k g r o u p s , p a r t i c u l a r l y t h e g n e i s s e s a n d t h e P r o s p e c t H i l l g r o u p . A g n e s L a k e Q u a r t z i t e : T h e t h i c k e s t q u a r t z i t e g r o u p i s t h e A g n e s L a k e q u a r t -z i t e w h i c h f o r m s a w e d g e s h a p e d b o d y a l o n g t h e w e s t e r n c o n t a c t o f t h e s e p t u m . ( S e e F i g u r e 92) N e a r i t s n o r t h e r n e n d , a l o n g t h e A m o e b a - L o w e r L a k e t r a n s v e r s e v a l l e y , i t r e a c h e s i t s maximum w i d t h o f a t l e a s t t w o m i l e s . S o u t h o f t h i s v a l l e y t h e q u a r t z i t e g r a d u a l l y p i n c h e s o u t b e t w e e n t h e Q u a a l R i v e r g n e i s s o n t h e e a s t a n d t h e A g n e s L a k e g r a n o d i o r i t e o n t h e w e s t . N o r t h o f t h e A m o e b a - L o w e r L a k e v a l l e y t h e q u a r t z i t e a s s u m e s a d a r k e r g r e e n c o l o r a n d h a s b e e n c a l l e d t h e " M i n e S e r i e s " . ^ T h i s g r o u p o f r o c k s w a s n o t s t u d i e d d u r i n g t h e f i e l d s e a s o n a n d n o s p e c i m e n s a r e a v a i l a b l e f o r p e t r o l o g i c d e s c r i p t i o n s . A H o l y k , W. 1952 55 T h e A g n e s L a k e q u a r t z i t e c o n s i s t s o f p u r e a n d i m p u r e q u a r t z i t e b a n d s i n t e r b a n d e d w i t h h o r n b l e n d e - r i c h s c h i s t , g n e i s s , a n d h o r n b l e n d e - e p i d o t e - r i c h b a n d s . N o s p e c i m e n s o f t h e q u a r t z i t e i t s e l f w e r e t a k e n b u t some o f t h e i n t e r b a n d e d s c h i s t a n d g n e i s s w e r e c o l l e c t e d . S p e c i m e n O r - 5 w a s t a k e n w i t h i n 3 0 f e e t o f t h e i n -t r u s i v e c o n t a c t o n t h e s o u t h s i d e o f A g n e s l a k e . T h e h a n d s p e c i m e n i s d a r k g r e y w i t h m a n y l e n t i c u l a r b a n d s o f g r e e n -b l a c k h o r n b l e n d e . I n c r o s s s e c t i o n t h e s e b a n d s h a v e " a u g e n " s h a p e s . A f e w e p i d o t e - f i l l e d f r a c t u r e s c u t t h e s p e c i m e n . I n a t h i n s e c t i o n 0 r - 5 i s s e e n t o c o n t a i n s p l a g i o c l a s e , 5 0 $ ; h o r n b l e n d e , 4 0 $ ; e p i d o t e , 5 $ ; w i t h m u s c o v i t e , o p a q u e m a t e r i a l , a n d i r o n o x i d e s . T h e p l a g i o c l a s e i s f i n e - g r a i n e d , m o s t l y u n t w i n n e d a n d h a s a h i g h r e l i e f a g a i n s t b a l s a m . N o a c c u r a t e d e t e r m i n a t i o n c o u l d b e made b u t o n e s e c t i o n s h o w i n g a l b i t e t w i n n i n g g a v e a n a n g l e o f 22° f o r X ' A ( 0 1 0 ) f o r A n ^ Q w h i c h w o u l d b e a m i n i m u m c o n t e n t o f a n o r t h i t e . H o r n b l e n d e o c c u r s i n l e n t i c u l a r a g g r e g a t e s o f d e f o r m e d g r a i n s . I n p l a c e s b o t h t h e p l a g i o c l a s e a n d t h e h o r n b l e n d e h a v e b e e n a l t e r e d t o a m a s s o f e p i d o t e , s e r i c i t e , a n d l o w r e -l i e f f e l d s p a r . I r r e g u l a r e l o n g a t e d a g g r e g a t e s o f b l a c k o p a q u e m a t e r i a l , p r o b a b l y m a g n e t i t e , a r e a b u n d a n t i n t h e a l t e r e d a r e a s . E x t r e m e l y f i n e g r a i n s o f e p i d o t e s h o w i n g a n o m a l o u s b l u e b i r e f r i n g e n c e c o l o u r s h a v e d e v e l o p e d a l o n g n a r r o w f r a c t u r e s . Some l a r g e r g r a i n s o f e p i d o t e e x t e n d i n t o t h e m i n e r a l s o n t h e e d g e s o f t h e f r a c t u r e s . S i m i l a r e p i d o t e i s a b u n d a n t i n t h e r o c k s o f t h e A g n e s l a k e i n t r u s i v e s . P r o b a b l y t h e e p i d o t e i n O r - 5 o r i g i n a t e d t h r o u g h a l t e r a t i o n r e l a t e d t o t h e n e a r b y i n t r u s i o n . B - 8 4 i s a f i n e g r a i n e d h o r n b l e n d e - p l a g i o c l a s e s c h i s t . I t i s g r e y - b l a c k o n f r e s h s u r f a c e s b u t o n w e a t h e r i n g i t t u r n s a w h i t e i s h g r e y . I n o u t c r o p t h e r o c k i s j o i n t e d a n d b e d d e d t o g i v e i t a b l o c k y f r a c t u r e . A t h i n s e c t i o n f r o m t h i s r o c k c o n t a i n e d ! p l a g i o c l a s e , 50$; h o r n b l e n d e , 4 0 $ ; c h l o r i t e , 8 $ ; p l u s o p a q u e m a g n e t i c g r a i n s . M o s t o f t h e p l a g i o c l a s e i s v e r y f i n e - g r a i n e d , u n -t w i n n e d , a n d s h o w s n o c l e a v a g e . N o i d e n t i f i c a t i o n c o u l d b e m a d e , b u t i t h a s a r e l i e f s l i g h t l y h i g h e r t h a n t h e b a l s a m . On o n e s i d e o f t h e s l i d e t h e h o r n b l e n d e i s i n f a i r l y l a r g e l a t h e s , p e r h a p s a mm. i n l e n g t h . A s t h e s l i d e i s c r o s s e d t h e h o r n b l e n d e b e c o m e s l e s s a b u n d a n t a n d m u c h f i n e r g r a i n e d . T h e c o a r s e h o r n b l e n d e i s a v e r y l i g h t y e l l o w - b r o w n c o l o u r a n d i s a l m o s t n o n - p l e o c h r o i c . A s i t b e c o m e s f i n e r t h e h o r n b l e n d e l o s e s a l l i t s c o l o u r a n d b e c o m e s n o n - p l e o c h r o i c . T h i s m a t e r i a l i s p r o b a b l y a v a r i e t y o f t r e m o l i t e . M u c h o f t h e f i n e h o r n b l e n d e i s a s s o c i a t e d w i t h g r e y c h l o r i t e o c c u r r i n g a s l a t h e s a n d r a d i a t i n g c l u s t e r s o f l a t h e s w h i c h i n p l a c e s a p p e a r t o b e r e p l a c i n g t h e h o r n b l e n d e . B o t h t h e s p e c i m e n s d i s c u s s e d a b o v e s h o w a l e v e l o f m e t a m o r p h i s m , a m p h i b o l i t e f a c i e s , m i n e r a l o g i c a l l y s i m i l a r t o t h a t o f t h e g n e i s s . S i m i l a r r e t r o g r e s s i v e m e t a m o r p h i s m i s p r e s e n t i n b o t h r o c k g r o u p s . B o t h t h e s p e c i m e n s came f r o m r e l a t i v e l y c l o s e t o t h e c o n t a c t w i t h t h e A g n e s l a k e g r a n o -d i o r i t e m a s s (30 f e e t a n d a b o u t 200) a n d n e i t h e r s h o w a n y p r o n o u n c e d d i f f e r e n c e s t o r o c k s f o u n d m a n y t i m e s a s f a r a w a y . B a r b a r a L a k e Q u a r t z i t e ; T h e B a r b a r a L a k e q u a r t z i t e i s a g r o u p o f r o c k s o f u n -k n o w n e x t e n t t h a t c r o p o u t o n a r i d g e s o u t h e a s t o f B a r b a r a L a k e . ( S e e F i g u r e 92). T h e y a r e t h i n b e d d e d a n d c o n t a i n p u r e a n d i m p u r e q u a r t z i t e w i t h i n t e r b e d d e d s c h i s t s . D r a g f o l d i n g i s w e l l d e v e l o p e d i n o u t c r o p s o f t h e s e r o c k s . U n d o u b t e d l y t h e y h a v e b e e n s t r o n g l y d e f o r m e d . Some o f t h e b e d s a r e c o m -p o s e d o f m i l k y w h i t e q u a r t z w h i c h i s v e r y r e s i s t a n t t o w e a t h e r -i n g f o r h e r e a n d t h e r e g l a c i a l p o l i s h i s p r e s e r v e d o n t h e m . M o s t o f t h e r o c k s i n t h e g r o u p w e a t h e r a l i g h t b r o w n . A g r o u p o f c a l c a r e o u s r o c k s i n c l u d i n g l i m e s t o n e , b i o t i t e s c h i s t , a n d b i o t i t e - f e l d s p a r s c h i s t b o r d e r t h e B a r b a r a L a k e q u a r t z i t e s o n t h e w e s t . T h e y a r e i n c l u d e d i n t h e q u a r t -z i t e map u n i t . B e d s o f m a s s i v e q u a r t z i t e w e r e f o u n d i n m a n y o f t h e o t h e r r o c k t y p e s . Or-11 i s a s p e c i m e n f r o m o n e s u c h b e d 1/2 m i l e w e s t o f D o u g l a s l a k e . T h e s p e c i m e n i s p r e d o m i n a n t l y w a t e r y - v r t i i t e q u a r t z w i t h a f e w p a r t i n g s l i n e d w i t h s i l v e r y -g r e e n m i c a s , a n d some i r r e g u l a r a r e a s o f b l a c k q u a r t z . One s i d e o f t h e r o c k i s c o a t e d w i t h i r o n o x i d e c o n t a i n i n g a f e w p y r i t e c u b e s . 58 A t h i n s e c t i o n c u t f r o m Or-11 c o n t a i n s ; 90$ q u a r t z ; 3-4$ m u s c o v i t e ; 5$ b l a c k o p a q u e m a t e r i a l ; a n d a f e w b r o k e n g r a i n s o f p y r i t e , g a r n e t , a n d p e r h a p s r u t i l e . Some r o u n d e d g r a i n s o f K - f e l d s p a r a r e a l s o p r e s e n t . T h e q u a r t z i s i n l a r g e a n d s m a l l g r a i n s w i t h i r r e g u l a r s u t u r e d c o n t a c t s ( S e e F i g u r e 29) m a n y o f t h e m o u t l i n e d b y b l a c k o p a q u e m a t e r i a l ( S e e F i g u r e 3 0 ) . M o s t o f t h e q u a r t z g r a i n s s h o w u n d u l a t o r y e x t i n c t i o n . M u s c o v i t e i s a m e t a m o r p h i c p r o d u c t , a r e s u l t o f t h e m e t a m o r p h i s m a n d r e c r y s t a l l i z a t i o n o f t h e r o c k . T h e p y r i t e g r a i n s may b e e i t h e r d i a g e n e t i c o r a p r o d u c t o f t h e m e t a -m p r h i s m . T h e y a r e b r o k e n a n d s h a t t e r e d , e s p e c i a l l y a t t h e c o r n e r s , s u g g e s t i n g t h e y w e r e p r e s e n t d u r i n g t h e m e t a m o r p h i s m . T h e g a r n e t , r u t i l e ( ? ) , a n d o r t h o c l a s e a r e o r i g i n a l s e d i m e n t a r y g r a i n s f o r t h e y a r e b r o k e n o r r o u n d e d , a n d a r e i n t e r s t i c i a l t o g r a i n s o f q u a r t z . T h e b l a c k a r e a s i n t h e h a n d s p e c i m e n a r e s e e n t o b e i n t h i n s e c t i o n j u s t o p a q u e c e m e n t i n g m a t e r i a l a r o u n d t h e q u a r t z g r a i n s . T h i s b l a c k m a t e r i a l i s o p a q u e , w i t h a l o w l u s t r e , n o n m a g n e t i c , a n d a p p e a r s t o b e s o f t . P r o b a b l y i t i s c a r b o n -a c e o u s m a t t e r , p e r h a p s g r a p h i t e . 59 Figure 29. Photomicrograph of Or-11 crossed n i c o l s X-16  The sutured contacts of the quartz grains are  c l e a r l y shown. Figure 30. Photomicrograph of Or-11 plana polarized l i g h t  X-16. Sutured contacts of quartz grains out- l i n e d by graphite. (Same area "as i n Figure"~29). Schist Schist i s second only to gneiss i n volume i n the E c s t a l l septum. It forms two large groups of rock, the K i t k i a t a schist and the Johnson Lake s c h i s t , and also occurs abundantly interbedded with other rock groups, p a r t i c u l a r l y the quartzite groups. Schist w i l l be discussed under i t s two main groupings, and then the schists occurring interbedded with other rocks w i l l be discussed. Hornblende r i c h s c h i s t s , rocks containing 50$ or more hornblende, are common i n a l l the rock groups i n the E c s t a l l septum. These rocks may have been sedimentary or igneous, o r i g i n a l l y ; probably there are representatives of both types present. A l l of them appear conformable with the rocks en-closing them, so l i t t l e evidence i s available to prove t h e i r o r i g i n . In order to compare more e a s i l y such hornblende r i c h rocks they w i l l a l l be discussed together under the meta-igneous rocks as hornblendic schist and hornblendite. K i t k i a t a s c h i s t : The K i t k i a t a schist underlies a large area bounded on the south by Douglas Channel, where they crop out for 4 . 5 miles from Gertrude point north-eastwards, and K i t k i a t a i n l e t , where they form a mile long section of shear c l i f f s , (see Geologic Map, Figure 9 2 ) . They continue northwards underlying K i t k i a t a creek, most of K i t k i a t a Lake, and the east edge of the southern part of the Quaal v a l l e y , (see Figure 9 2 ) . 61 K i t k i a t a s c h i s t occurs e x t e n s i v e l y east of E c s t a l l Lake but n o r t h - e a s t of the l a k e no mapping has been done. In t h a t area they a p p a r e n t l y are cut o f f by the Johnson- lake-Douglas channel rocks which s t r i k e north-north-west across the E c s t a l l r i v e r . (See F i g u r e 9 2 ) . B i o t i t e S c h i s t : B - 3 i s a specimen of b i o t i t e s c h i s t from an outcrop on K i t k i a t a I n l e t at the o u t l e t of K i t k i a t a creek. I t i s an extremely f i n e - g r a i n e d rock w i t h a w e l l developed s c h i s t o s i t y . Two s e t s of c r e n u l a t i o n s are present on the planes of s c h i s t o s i t y , c o n s i s t i n g of a s m a l l p o o r l y developed set c r o s s i n g a w e l l - d e v e l o p e d set at an a c u t e angle. A t h i n s e c t i o n of B - 3 c o n t a i n s : q u a r t z , 2 5 $ ; p l a g i o -c l a s e , 2 5 $ ; b i o t i t e , 2 0 $ ; c h l o r i t e , 1 5 $ ; s e r i c i t e , 1 0 $ ; e p l d o t e , 5 $ ; w i t h a few opaque g r a i n s and one or two c u b i c shaped, dark-green, almost opaque g r a i n s , (perhaps a s p i n e l ) . Tabs of quartz are a l i g n e d p a r a l l e l w i t h the micas t o form the s c h i s t o s i t y , which i s i n p l a c e s s t r o n g l y deformed. S m a l l whorls of micas, q u a r t z and f e l d s p a r s are common. B i o t i t e appears to have a l t e r e d to s e r i c i t e a l o n g some bands and to c h l o r i t e along others (see F i g u r e s 3 1 and 3 2 ) . A few l a r g e c h l o r i t e g r a i n s have grown a f t e r the s h e a r i n g f o r they l i e at acute angles across the s c h i s t o s i t y . P l a g i o c l a s e occurs i n groups o f very f i n e i r r e g u l a r g r a i n s which here and t h e r e i n c l u d e groups o f l a r g e r g r a i n s , which may be the beginnings of augen s t r u c t u r e s . Both a r e i n bands mixed w i t h micas and s m a l l amounts of q u a r t z . Most of 62 Figure 31. Photomicrograph of B-3 plane polarized l i g h t X-40  Magnetite, black, with b i o t i t e which i s altering"" to s e r i c i t e and c h l o r i t e . Large lathes of c h l o r i t e  have developed at an angle to f o l i a t i o n . Figure 32. Photomicrograph of B-3 Plane polarized l i g h t X-40  Black grains are magnetite, dark lathes b i o t i t e , grey radiating lathes and grey lathes with  b i o t i t e are c h l o r i t e a l t e r a t i o n s . the p l a g i o c l a s e i s so s m a l l and i n t e n s e l y deformed that o n l y one or two g r a i n s i n a l l the s l i d e show p o l y s y n t h e t i c twinning. The r e l i e f , however, i s v e r y h i g h a g a i n s t q u a r t z , i n d i c a t i n g i t i s at l e a s t as c a l c i c as An,,-,. 40 The opaque m i n e r a l i s mostly magnetite but a few gra i n s o f p y r i t e are a l s o p r e s e n t . B-41 i s a garnet bearing c a l c a r e o u s b i o t i t e s c h i s t taken from the shore o f Douglas Channel. Grains o f brown garnet about 1 mm. i n diameter are f a i r l y abundant forming perhaps 1$ of the rock. B i o t i t e , as l a r g e deformed y e l l o w brown f l a k e s , i s the most abundant m i n e r a l , making perhaps 50$ of the rock. C a l c i t e i s a l s o abundant as s m a l l subrounded g r a i n s forming 35$ o f the rock and up to 70$ o f c e r t a i n s t r o n g -l y f o l d e d white bands (See F i g u r e 33)• Quartz i s pr e s e n t i n some p l a c e s forming s m a l l pods of sand s i z e g r a i n s . F e l d s p a r may a l s o be present t o form, w i t h the q u a r t z , the r e s t o f the specimen. U n f o r t u n a t e l y no t h i n s e c t i o n of t h i s rock i s a v a i l a b l e . 6 4 F i g u r e 33. Photo of specimen B - 4 1 shoving extremely con- t o r t e d w h i t i s h c a l c i t e r i c h , bands i n b i o t i t e -c a l c i t e ground mass, Or - 3 i s a knotted b i o t i t e s c h i s t from the west s i d e of K i t k i a t a l a k e . In hand specimen i t appears to be predominantly b i o t i t e , but i f examined c l o s e l y i t i s seen to c o n t a i n l a r g e amounts of f e l d s p a r , q u a r t z , and g r e e n i s h c l i n o z o i s i t e . The rock has a good f o l i a t i o n and a w e l l developed augen s t r u c t u r e , A t h i n s e c t i o n shows Or - 3 to c o n t a i n : p l a g i o c l a s e , 30$; q u a r t z , 25$; b i o t i t e , 30$; c l i n o z o i s i t e , 15$; w i t h s m a l l garnets and a few blades of c h l o r i t e . The t h i n s e c t i o n appears t o be a l l q u a r t z - f e l d s p a r and e p idote i n c o n t r a s t t o the hand specimen which appears to be a l l b i o t i t e . B i o t i t e and elongate g r a i n s of c l i n z o i s i t e are a l i g n e d p a r a l l e l t o the s c h i s t o s i t y . The quartz and f e l d s p a r 65 a r e s o m e w h a t e l o n g a t e a n d a r e s i m i l a r l y o r i e n t e d . A u g e n s h a p e d z o n e s o f q u a r t z o c c u r h e r e a n d t h e r e i n t h e s e c t i o n a n d t h e r e i s a s l i g h t p i n c h i n g a n d s w e l l i n g o f t h e m i c a c e o u s b a n d s a r o u n d t h e m . P l a g i o c l a s e i s f i n e - g r a i n e d , z o n e d , a n d p o o r l y t w i n n e d . S e c t i o n s x t o Z g a v e a n g l e s o f + 7 ° , + 3 ° , a n d 0 ° f o r X/\(010) f o r , A n 2 2 j A n 2 g a n d A n 2 q . Some o f t h e b i o t i t e i s s h e a r e d a n d s h o w s t w i n b a n d s a t a n a n g l e t o t h e c l e a v a g e . A f e w b r o k e n b i o t i t e g r a i n s h a v e b e e n a l t e r e d t o c h l o r i t e . H o r n b l e n d - B i o t i t e S c h i s t : R o c k s c o n t a i n i n g b o t h b i o t i t e a n d h o r n b l e n d e f o r m a l a r g e p a r t o f t h e s o u t h e r n s e c t i o n o f t h e K i t k i a t a s c h i s t s . T h e y a r e p a r t i c u l a r l y w e l l e x p o s e d a l o n g t h e s h o r e o f D o u g l a s C h a n n e l a n d K i t k i a t a I n l e t i n t h e l a t t e r p l a c e f o r m i n g s h e a r c l i f f s a l o n g t h e w a t e r e d g e . M a n y l a r g e a n d s m a l l b o u l d e r s o f b i o t i t e - h o r n b l e n d e s c h i s t a r e s c a t t e r e d a l o n g t h e n o r t h s h o r e o f K i t k i a t a I n l e t . Some o f t h e s e b e a r u n u s u a l c a r v i n g s , a s s h o w n i n F i g u r e s 34 a n d 35. Z J - 2 3 i s a t y p i c a l s p e c i m e n o f b i o t i t e - h o r n b l e n d e s c h i s t o b t a i n e d a b o u t a m i l e e a s t o f S p o r r a n L a k e j u s t n o r t h o f t h e m o u t h o f t h e Q u a a l R i v e r . I t i s a d a r k g r e y b r o w n , t h i n b a n d e d r o c k w i t h l a r g e f l a k e s o f b r o w n b i o t i t e l y i n g o n t h e p l a n e s o f s c h i s t o s i t y . I m p r e s s e d a c r o s s t h e b i o t i t e a r e a c i c u l a r c r y s t a l s o f d a r k g r e e n - b l a c k h o r n b l e n d e . T h e s e c r y s t a l s o f h o r n b l e n d e l i e w i t h i n t h e p l a n e o f s c h i s t o s i t y b u t a r e r a n d o m l y o r i e n t e d w i t h i n t h a t p l a n e . S e e F i g u r e 66 A t h i n s e c t i o n o f Z J - 2 3 c o n t a i n s : p l a g i o c l a s e , 35$; q u a r t z , 25$; b i o t i t e , 20$; h o r n b l e n d e , 15$; e p i d o t e , 3$; p y r i t e , 2$; w i t h s e r i c i t e , c h l o r i t e , a n d g a r n e t . T h e s c h i s t o s -i t y i s d e v e l o p e d b y t h e a l i g n m e n t o f b a n d s o f b i o t i t e a n d b a n d s o f e l o n g a t e d q u a r t z a n d f e l d s p a r g r a i n s . M o s t o f t h e p l a g i o c l a s e i s p r e s e n t a s m i n u t e r o u n d e d g r a i n s , m o s t o f t h e m l e s s t h a n 1 0 m i c r o n s i n d i a m e t e r . F e w s h o w t w i n n i n g a n d a l l a r e t o o s m a l l t o g i v e a n o p t i c f i g u r e . T h e i r r e l i e f i s m u c h h i g h e r t h a n q u a r t z i n a l l o r i e n t a t i o n s s o t h e p l a g i o c l a s e m u s t b e a t l e a s t a s c a l c i c a s A n ^ . G r a i n s o f e p i d o t e . o f s i m i l a r m i n u t e s i z e a r e m i x e d h e r e a n d t h e r e i n t h e p l a g i o c l a s e r i c h b a n d s . T h e h o r n b l e n d e i s i n l a r g e p o i k i l o b l a s t i c c r y s t a l s a v e r a g i n g a q u a r t e r i n c h i n l e n g t h . T h e y a r e p l e o c h r o i c d e e p g r e e n - b l u e (E N - S , y e l l o w - g r e e n (E E-V- , p r o b a b l y a h i g h c a l c i u m , l o w a l u m i n u m h o r n b l e n d e . P o s s i b l y t h e h o r n b l e n d e i s a p r o d u c t o f c r y s t a l l i z a t i o n a f t e r t h e s h e a r i n g f o r some o f t h e m l i e a c r o s s t h e p l a n e s o f f o l i a t i o n a n d a r e o b v i o u s l y l a t e . F i g u r e 36 s h o w s t h e t e x t u r e t y p i c a l o f Z J - 2 3 a n d f a i r l y t y p i c a l o f a l l t h e h o r n b l e n d e - b i o t i t e s c h i s t s . ( F i g u r e 36, p a g e 68) A f e w a n h e d r a l p y r i t e g r a i n s a r e p r e s e n t t h r o u g h o u t t h e s l i d e . S u b h e d r a l r e d d i s h g a r n e t s a r e a l s o p r e s e n t . Some g r a i n s o f h o r n b l e n d e a r e p a r t l y a l t e r e d t o c h l o r i t e a n d o n e o r t w o g r a i n s o f b i o t i t e h a v e a l t e r e d t o s e r i c i t e a n d c h l o r i t e . 6 7 F i g u r e 34. View of boulder s c a t t e r e d beach on K i t k i a t a I n l e t . A l l the rocks In the p i c t u r e are b i o t i t e - h o r n - blende s c h i s t . The planes of s c h i s t o s i t y are  v i s i b l e on some of the s t o n e s , but many have p o o r l y  developed s c h i s t o s i t y and appear massive. The  c a r v i n g appears t o be a h i g h l y s t y l i z e d woman. Fi g u r e 3 5 . C l o s e up of the l a r g e s t and most o r n a t e l y carved  boulder of b i o t i t e - h o r n b l e n d e s c h i s t . 68 F i g u r e 36. Photomicrograph of ZJ - 2 3 shoving the t e x t u r e o f  the rock. Plane p o l a r i z e d l i g h t . X 15. Large  g r a i n s are hornblende, except f o r a f e v f l a k e s  of b i o t i t e showing only one cleavage. Quartz  and f e l d s p a r make up the ground mass. 69 B - 3 8 , a specimen of h o r n b l e n d e - b i o t i t e s c h i s t from Douglas channel, i s a dark grey rock c o n t a i n i n g prominent long dark l e a v e s o f hornblende. I t has a poor f o l i a t i o n i n which the hornblende leaves appear o r i e n t e d t o g i v e the rock a l i n e a t i o n . A t h i n s e c t i o n , cut across the banding, c o n t a i n s : p l a g i o c l a s e , 45$; q u a r t z , 20$; hornblende, 20$; b i o t i t e , 15$; garnet, 1$; w i t h opaque g r a i n s . The p l a g i o c l a s e i s f a i r l y coarse grained and w e l l twinned. Most grai n s a re s l i g h t l y zoned. One g r a i n , cut-Lto (010), gave angles o f 6 . 5 and 4 ° f o r X'A (010), f o r A n 2 ^ at the c e n t e r , and A n 2 2 a * * n e borders. A number of g r a i n s cut -L to (010) gave angles o f 6 . 5 ° f o r X 1 (010) f o r An 2(- and a s e c t i o n JL to X gave an angle o f Z (010)= - 5 ° f o r An 2^. The quartz i n the s l i d e i s a l s o q u i t e coarse and shows evidence o f s t r a i n i n the undu l a t o r y e x t i n c t i o n and elongated shape of some g r a i n s . The hornblende i s s i m i l a r t o t h a t i n Z J - 2 3 , t h a t i s the low alumina member common i n most o f the rocks o f the septum. In the t h i n s e c t i o n much of the hornblende i s a l i g n e d p a r a l l e l to the s c h i s t o s i t y and enough g r a i n s are unoriented t o suggest the hornblende was formed a f t e r the main she a r i n g which produced the s c h i s t o s i t y i n the rock. ZJ - 3 0 i s a g r e e n i s h hornblende r i c h rock. On weathered s u r f a c e s l a r g e g r a i n s of hornblende are st r u n g out i n the f i n e grained groundmass. A t h i n s e c t i o n of t h i s rock c o n t a i n s : hornblende, 30$; p l a g i o c l a s e , 45$; b i o t i t e , 15$; e p i d o t e , 10$; and some opaque g r a i n s . 70 P l a g i o c l a s e occurs i n two completely d i f f e r e n t forms. One i n extremely f i n e rounded, g r a i n s , a v e r a g i n g about 10 microns i n diameter, and having a very h i g h r e l i e f ; the other i n much l a r g e r w e l l twinned g r a i n s c o n t a i n i n g many s m a l l g r a i n s of c l i n o z o i s i t e . Grains of the l a r g e p l a g i o c l a s e , c u t J - t o (010) gave maximum angles of 16° f o r X ' A (010), = A n ^ j o n e cut J . t o X gave an angle of Z A( 0 1 0 ) = 7 2 . 5 ° } f o r An^, The f i n e r g r a i n e d p l a g i o c l a s e has a much high e r r e l i e f a g a i n s t the coarse c l i n o z o i s i t e b e a r i n g m a t e r i a l , and a l s o has l e s s c l i n o -z o i s i t e w i t h i t . T h i s suggests that the c l i n o z o i s i t e was developed by r e c r y s t a l l i z a t i o n of the p l a g i o c l a s e , as a more so d i c v a r i e t y thus f r e e i n g CaO to form the c l i n o z o i s i t e . Two s i z e s of hornblende are a l s o p r e s e n t . S m a l l blades and i r r e g u l a r broken g r a i n s , a r e most abundant but th e r e are a few ve r y l a r g e deformed g r a i n s as w e l l . (See F i g u r e 37). Both s i z e s of hornblende g r a i n s a r e a deep blue-green c o l o u r excepting f o r areas which are bleached white, perhaps an a l t e r a t i o n t o t r e m o l i t e . Such white areas always show a much h i g h e r b i r e f r i n g e n c e than the r e s t of the g r a i n s , perhaps because t h e r e i s l i t t l e masking e f f e c t by the c o l o u r of the m i n e r a l . A sheave o f extremely b r i l l i a n t green n e e d l e s , and some areas of v e r y b r i g h t green m a t e r i a l , p o s s i b l y the same m i n e r a l , are present as an a l t e r a t i o n of the hornblende. T h i s m a t e r i a l may be a c t i n o l i t e . 71 F i g u r e 37. Photomicrograph of ZJ-30 p l a n a p o l a r i z e d l i g h t X 16  A l a r g e broken c r y s t a l of hornblende f i l l s much of  the p i c t u r e . A few l a r g e fragments of the same  c r y s t a l s are strung out along the planes of s c h i s - t o s i t y .just out of the p i c t u r e . The r e s t of the  m a t e r i a l i s p l a g i o c l a s e e p i d o t e . and hornblende. Note the bleached areas i n the g r a i n . Blades of b i o t i t e have developed across some o f the f r a c t u r e s i n the hornblende c r y s t a l s . T h i s must be l a t e r than the hornblende. The r e s t o f the b i o t i t e i s a s s o c i a t e d w i t h broken g r a i n s o f hornblende, and p r o b a b l y i s a l s o l a t e r than the hornblende. A few g r a i n s o f p y r i t e are present i n the s l i d e , a l l have red i r o n o x i d e , probably hematite, surrounding them. Some g r a i n s o f p y r i t e have completely a l t e r e d to i r o n oxide but show a zoning s i m i l a r to those s t i l l c o n t a i n i n g p y r i t e at the c e n t r e . 7 2 The t e x t u r e s i n t h i s rock suggest that f o l l o w i n g a p e r i o d when l a r g e c r y s t a l s o f hornblende formed, the rock was sheared and the hornblende broken down i n t o much f i n e r m a t e r i a l . B i o t i t e , s o d i c f e l d s p a r and c l i n o z o i s i t e were produced d u r i n g the l a t t e r p e r i o d by the a l t e r a t i o n o f c a l c i c p l a g i o c l a s e and hornblende. The a l t e r a t i o n o f the hornblende t o a c t i n o l i t e , and the b l e a c h i n g of p o r t i o n s of the l a r g e g r a i n s may be a l a t e phase, corresponding to the development of c h l o r i t e and s e r i c i t e i n other r o c k s . S e r i c i t e s c h i s t : S e r i c i t e s c h i s t i s found along v a r i o u s zones of extreme s h e a r i n g w i t h i n other rock groups, p a r t i c u l a r l y but not e x c l u s i v e l y , i n the K i t k i a t a s c h i s t s and the Mine S e r i e s . S e r i c i t e s c h i s t may be the r e s u l t o f a d d i t i o n of potassium, removal o f c a l c i u m and magnesium and the a l t e r a t i o n of most of the i r o n to p y r i t e i n the rocks along such shear zones. ZJ-19 i s a t y p i c a l s e r i c i t e (or muscovite) s c h i s t . I t i s composed of muscovite, q u a r t z , p y r i t e and f e l d s p a r ; the l a t t e r i n augens around which the muscovite p l a t e s bend. The rock i s a s i l v e r y - g r e e n c o l o u r except where s t a i n e d brown by decomposing p y r i t e or where a few dark green f l a k e s of c h l o r i t e are p r e s e n t . Quartz i s abundant but i s v e r y f i n e -g r a i n e d and so i n t i m a t e l y mixed w i t h the f o l i a o f muscovite that i t can h a r d l y be seen. On a p o l i s h e d s u r f a c e white augens of p l a g i o c l a s e a re v i s i b l e . A t h i n s e c t i o n o f ZJ-19 c o n t a i n s : q u a r t z , 30$; 73 muscovite, 55$; p l a g i o c l a s e , 10$; w i t h e p i d o t e , c h l o r i t e , p y r i t e , g a r n e t , and opaque m a t e r i a l ; some as f l a k e s ( g r a p h i t e ) , and some as i r r e g u l a r g r a i n s (magnetite?). Two t h i r d s o f the muscovite i s present as l a r g e p l a t e s which appear t o fl o w around the augens of p l a g i o c l a s e , and which en c l o s e between them elongate g r a i n s of q u a r t z . The remaining one t h i r d o f the muscovite i s present as f i n e mashed m a t e r i a l i n whorls p a r t l y surrounding the p o r p h y r o b l a s t s o f f e l d s p a r and a l s o i n whorls forming t r a n s i t i o n areas between bands o f c o a r s e r mica. F i g u r e s 38, 39 and 40 show the t e x t u r e developed i n the ro c k . The p l a g i o c l a s e i s twinned i n o n l y one or two s m a l l areas; i t has a r e l i e f equal t o and below quartz; and a s e c t i o n approximately j_ to X gave an angle o f 1 7 ° f o r Z A ( 0 0 1 ) f o r An^g. Textures present i n the ro c k , see F i g u r e s 38, 39» 40, on the f o l l o w i n g pages, i n d i c a t e i t has undergone v e r y i n t e n s e s h e a r i n g . ¥ - 1 5 i s a s e r i c i t e s c h i s t , somewhat s i m i l a r to ZJ - 1 9 , but of a more s i l v e r y c o l o u r and c o n t a i n i n g more p y r i t e (10 to 15$). Quartz i s abundant on weathered s u r f a c e s where the masking s e r i c i t e has been eroded away. Drag f o l d s and s t r a i n -s l i p - c l e a v a g e are very w e l l developed i n the specimen. ' They show up p a r t i c u l a r l y w e l l on a p o l i s h e d s u r f a c e cut across the banding. 7 4 F i g u r e 3 8 . Photomicrograph of Z J - 1 9 . plana l i g h t X 1 5 . The l a r g e muscovite f l a k e s and the opaque  f l a k e s appear to s w i r l around the porphyro-b l a s t of p l a g i o c l a s e . F i g u r e 39. Same as i n F i g u r e 3 8 , but crossed n i c o l s X I f f . The  t r a i n s o f quartz i n the p l a g i o c l a s e , and the tabs  of quartz between the l e a v e s of muscovite are  v i s i b l e . F i g u r e 40 i s a s k e t c h of a l a r g e r s e c t i o n  around the same g r a i n s of p l a g i o c l a s e . 7 5 F i g u r e 40; S k e t c h of a l a r g e r s e c t i o n around the same g r a i n s o f p l a g i o c l a s e as shown i n F i g u r e 3 9 . 76 A t h i n s e c t i o n of W-15 c o n t a i n s : muscovite, 65$; q u a r t z , 30$; p y r i t e , 5$; and a few g r a i n s of c h l o r i t e . Most of the muscovite i s i n the form of l a r g e p l a t e s o u t l i n i n g the f o l i a t i o n . Quartz tabs l i e between the mica f l a k e s . F i g u r e 41 shows the drag f o l d i n g and the s t r a i n - s l i p - c l e a v a g e which has developed i n the rock. F i g u r e 41. Photomicrograph of W-15 c r o s s n i c o l s X15. Quartz and muscovite make up most of the  s e c t i o n . The b l a c k opaque g r a i n s whose  form appears to be c o n t r o l l e d by the s c h i s - t o s i t y are p y r i t e . Note the w e l l developed  drag f o l d i n g . The p y r i t e i s present i n l a r g e subhedral g r a i n s , and as elongate g r a i n s w i t h i n mica bands. ( F i g u r e 42). The l a r g e r p y r i t e g r a i n s must have formed a f t e r the main s h e a r i n g otherwise t h e i r complex form would not have p e r s i s t e d . The long t h i n tabs on the other hand e i t h e r grew duri n g the shear-in g or t h e i r growth was c o n t r o l l e d by the s c h i s t o s i t y . F i g u r e 42. S k e t c h of v a r i o u s g r a i n s o f p y r i t e . Y e l l o w -p y r i t e . s t r i p e d mica. Z J - 3 7 i s a g a r n e t - s e r i c i t e s c h i s t from the shore of Douglas Channel. I t i s s i l v e r y - g r e e n which i s t y p i c a l of s e r i c i t e s c h i s t u nstained by i r o n o x i d e s , and con t a i n s dark red-brown garnets up t o an e i g h t h of an i n c h i n diameter. A dark band cuts through the c e n t r e o f the specimen p a r a l l e l i n g the s c h i s t o s i t y . The rock i s i n t e n s e l y sheared and shows w e l l developed drag g o l d i n g and s t r a i n - s l i p - c l e a v a g e . 7 8 F i g u r e 4 3 . Photomicrograph of Z J - 3 7 . Plane p o l a r i z e d l i g h t , X-J5. The b l a c k f l e c k s "are g r a p h i t e . the c l e a r areas are q u a r t z , and the grey  h i g h r e l i e f f l a k e s are s e r i c i t e ^ A t h i n s e c t i o n of ZJ-37 c o n t a i n s : s e r i c i t e , 70$; q u a r t z , 20$; garnet, 5$? c h l o r i t e , 5$; b i o t i t e , 1 $ ; and about 1 $ of dark opaque f l a k e s , probably g r a p h i t e . F i g u r e 43 shows the i n t e n s e deformation and s t r a i n - s l i p - c l e a v a g e as seen i n the t h i n s e c t i o n . Some of the s e r i c i t e g r a i n s c o n t a i n minute t r a c e s o f f e a t h e r y b i o t i t e suggesting an a l t e r a t i o n . Many s e r i c i t e g r a i n s have zones of s l i p p a g e p a r a l l e l t o the cleavage, such zones o f t e n have brown m a t e r i a l along them. Along one s i d e of the s l i d e the s e r i c i t e has a l t e r e d to c h l o r i t e i n a band p a r a l l e l to the s c h i s t o s i t y . T h i s band has more of the opaque f l a k e s i n i t the r e s t of the s l i d e and i t corresponds to the dark band i n 7 9 the hand specimen. Many of the quartz g r a i n s are elongated p a r a l l e l t o the s c h i s t o s i t y . Gr - 2 i s an unusual s e r i c i t e s c h i s t from the west s i d e of K i t k i a t a Lake. In hand specimen i t i s a l i g h t g r e e n i s h -white w i t h many long narrow l e n s e s o f a dark micaceous m i n e r a l . (See F i g u r e 44). The rock i s s c h i s t o s e but does not break as e a s i l y along the s c h i s t o s i t y as do the other s e r i c i t e s c h i s t s . A t h i n s e c t i o n o f Or - 2 c o n t a i n s : p l a g i o c l a s e , 40$; ep i d o t e , 20$; b i o t i t e 15$; q u a r t z , 10$; s e r i c i t e , 15$; w i t h c o n s i d e r a b l e c h l o r i t e ; and some g a r n e t , magnetite and other opaques. The t h i n s e c t i o n shows the rock has a composition banding as w e l l as a s c h i s t o s i t y . S e r i c i t e and quartz form one set o f bands, f e l d s p a r and ep i d o t e form another, and the b i o -t i t e l e n s e s form a t h i r d but d i s c o n t i n u o u s set of bands. Augen shaped masses of quartz and some o f muscovite are d i s t r i b u t e d throughout the rock. The weak s c h i s t o s i t y i s due to the a l t e r n a t i n g bands of micas and f e l d s p a r and the g e n e r a l l y low content o f s e r i c i t e i n the rock. Much e a s i e r p a r t i n g i s obtained along the bands of s e r i c i t e . P l a g i o c l a s e , i n minute i r r e g u l a r l y angular g r a i n s , many showing evidences of s t r a i n and f r a c t u r e , i s the most abundant m i n e r a l . Most g r a i n s show zoned e x t i n c t i o n but r e l a t i v e l y few are twinned and p r a c t i c a l l y none show cleavage. T h e i r r e l i e f i s v e ry low to moderate p o s i t i v e a g a i n s t balsam and very low to moderate n e g a t i v e a g a i n s t quartz which i n d i c a t e s the p l a g i o -c l a s e Is somewhere between A n 2 Q and An^Q. Minute tab l i k e g r a i n s o f e p i d o t e , probably c l i n o z o i s i t e , a r e a s s o c i a t e d w i t h the p l a g i o c l a s e . Quartz forms much l a r g e r g r a i n s than the p l a g i o c l a s e . Most of i t shows undulatory e x t i n c t i o n . S m a l l p e r f e c t l y formed garnets are s c a t t e r e d through the s e c t i o n . The most unusual f e a t u r e s of the rock are the dark pod l i k e l e n s e s of b i o t i t e and c h l o r i t e . (See F i g u r e 44). B i o t i t e has grown out from both w a l l s o f the pods and i s s e p a r a t e d i n the c e n t r e by bands of epidote g r a i n s . Much of the b i o t i t e has a l t e r e d t o green c h l o r i t e . These lenses may have been hornblende c r y s t a l s which have been a l t e r e d to or r e p l a c e d by, b i o t i t e . However, none of the o r i g i n a l hornblende remains. F i g u r e 44. Photomicrograph of Or-2 plane p o l a r i z e d l i g h t X 15. Showing the b i o t i t e ^ p a r t l y a l t e r e d to c h l o r i t e ] i n the l e n s e s . Grey h i g h r e l i e f g r a i n s are c l i n o - z o l s i t e , white g r a i n s a r e mostly p l a g i o c l a s e . 81 B-40 i s one of the most unusual of the s e r i c i t e s c h i s t s . I t i s a l i g h t grey-brown rock w i t h a g r e e n i s h c a s t on f r e s h l y broken s u r f a c e s and c o n t a i n s l a r g e red-brown garnets along some c a l c a r e o u s bands. A t h i n s e c t i o n of B-40 c o n t a i n s : q u a r t z , 20$; p l a g i o -c l a s e 20$; s e r i c i t e 15$; c a l c i t e 15$; b i o t i t e 10$; g a r n e t , 8$; c l i n o z o i s i t e , 5$; hornblende, 5$; w i t h c h l o r i t e , magnetite, p y r i t e , and i r o n o x i d e s . P l a g i o c l a s e occurs as l a r g e and s m a l l mashed and de-formed g r a i n s showing z o n a l and undulatory e x t i n c t i o n . W e l l twinned g r a i n s are r a r e but one, o n l y approximately p e r p e n d i c u l a r to (010), gave an angle of 2 7 ° f o r X ' A (010) making the p l a g i o -c l a s e at l e a s t as c a l c i c as An 4g. A g a i n s t the quartz and the c a l c i t e , w i t h which i t i s o f t e n a s s o c i a t e d , the p l a g i o c l a s e has r e l i e f which i n d i c a t e s i t i s much more c a l c i c than An^Q. Probably i t i s at l e a s t a l a b r a d o r i t e , but, u n f o r t u n a t e l y , i t i s so deformed that no s e c t i o n could be found to g i v e proper i d e n t i f i c a t i o n . Quartz occurs as s m a l l i r r e g u l a r s t r a i n e d g r a i n s . About 10$ of the quartz occurs i n one augen o f s m a l l rounded and i r r e g u l a r g r a i n s a l l showing und u l a t o r y e x t i n c t i o n and i n pl a c e s sutured c o n t a c t s . C a l c i t e , i n a l l g r a i n s i z e s and shapes, i s u n u s u a l l y abundant throughout the s l i d e . Large g r a i n s occur i n bands p a r a l l e l t o the f o l i a t i o n and s m a l l i r r e g u l a r ones occur here and there elsewhere. The l a r g e r g r a i n s a r e i n t e n s e l y deformed and show twinning and bending of cleavage planes and twin l a m e l l a e . C a l c i t e i s a l s o present w i t h i n the garnet porphro-b l a s t s . ( F i g u r e 4 7 ) . T h i s c a l c i t e i s undoubtedly an o r i g i n a l sedimentary m i n e r a l as i t occurs s c a t t e r e d throughout the s l i d e as w e l l as concentrated along some bands, and because i t i s f r e s h and i s not a s s o c i a t e d w i t h any a l t e r a t i o n of the other m i n e r a l s . The severe deformation that i t has s u f f e r e d i n d i c a t e s i t has been i n the rock through the s h e a r i n g which accompanied the dynamic metamorphism. B i o t i t e s e r i c i t e and s m a l l amounts of c h l o r i t e are i n t i m a t e l y a s s o c i a t e d . Undoubtedly the b i o t i t e has a l t e r e d t o the other two. F i g u r e 4 5 shows a remnant of u n a l t e r e d b i o t i t e i n a l a t h of muscovite. F i g u r e 45. Photomicrograph of B-40 plane l i g h t X 40. S e r i c i t e l a t h w i t h remnant of b i o t i t e . C a l c i t e surrounds the end of the l a t h e c o n t a i n i n g the b i o t i t e . Garnet w i t h opaque m a t e r i a l forms a t h i r d of the p i c t u r e . Quartz and p l a g i o c l a s e are present. 8 3 A few l a r g e hornblende g r a i n s occupy the c e n t e r s of augens, (see F i g u r e 46). Such g r a i n s show signs of g l i d i n g and s h e a r i n g along cleavage t r a c e s . These g r a i n s may be o l d e r than the l a s t deformation and thus re p r e s e n t a few u n a l t e r e d remnants of an e a r l i e r stage of metamorphism. However, they are f r e s h and u n a l t e r e d suggesting they have grown d u r i n g the s h e a r i n g . S i m i l a r l a r g e sheared g r a i n s i n Z J - 3 0 and ZJ-24, F i g u r e s 3 7 and 83 ) are bleached and r e p l a c e d by a new growth of hornblende l a t h e s , i n d i c a t i n g they a r e a remnant of some previous metamorphic c o n d i t i o n of these r o c k s . F i g u r e 4$. Photomicrograph of B-40 plane p o l a r i z e d l i g h t X 15  P o i k i o b l a s t i c augen of hornblende surrounded by  s e r i c i t e . f e l d s p a r , quartz and e p i d o t e . Garnet i n  one c o r n e r . The hornblende i s the u s u a l deep blue-green type, the most common i n the rocks of the E c s t a l l septum. 84 Figure 47. Photomicrograph of a " r o l l e d " garnet i n B-40  Plane polarized l i g h t X 15. Magnetite and  p y r i t e . (black) are v i s i b l e within the garnet Figure 48. As above but crossed n i c o l s X 15. Large inclusions  i n the garnet are c a l c i t e . small white to grey ones  are quartz. S e r i c i t e , b i o t i t e , plagioclase and  c l i n o z o i s i t e form the bulk of the schist surround-ing the garnet. 85 A n u m b e r o f g a r n e t s , some n e a r l y 5 mm. a c r o s s , a r e p r e s e n t i n t h e s l i d e . Some a r e w e l l f o r m e d , ( S e e F i g u r e 4 8 ) s h o w i n g w e l l d e v e l o p e d c r y s t a l f a c e s , o t h e r s a r e i r r e g u l a r a n d s h o w l i t t l e s h a p e . A l l a r e h i g h l y f r a c t u r e d a n d p o i k i o -b l a s t i c . F i g u r e s 4 7 a n d 4 8 s h o w t r a i n s o f i n c l u s i o n s , q u a r t z , o p a q u e , a n d c a l c i t e , w h i c h g i v e t h e g a r n e t t h e a p p e a r a n c e o f h a v i n g b e e n r o l l e d . T h e s c h i s t a p p e a r s t o f l o w a r o u n d t h e g a r n e t p o r p h r o b l a s t s , a s i t d o e s a r o u n d t h e h o r n b l e n d e p o r p h r o b l a s t s . T h e t e x t u r e s i n t h e s e r i c i t e s c h i s t s d i s c u s s e d a b o v e i n d i c a t e t h e y h a v e b e e n s e v e r e l y d e f o r m e d , m u c h m o r e d e f o r m e d t h a n m o s t o f t h e r o c k s s u r r o u n d i n g t h e m . T h e a s s o c i a t i o n o f p y r i t e a n d m u s c o v i t e i s t y p i c a l o f m o s t o f t h e s e r o c k s , s u g g e s t i n g , b u t n o t p r o v i n g t h a t some t y p e o f h y d r o t h e r m a l p r o c e s s h a s p r o d u c e d t h e s e r i c i t e s c h i s t s . C h l o r i t e s c h i s t : C h l o r i t e s c h i s t i s r a r e s o u t h o f E c s t a l l L a k e b u t many o f t h e r o c k s c o n t a i n s m a l l a m o u n t s o f c h l o r i t e , g e n e r a l l y a n a l t e r a t i o n o f b i o t i t e o r h o r n b l e n d e . A f e w s c h i s t s w i t h s u f f i c i e n t c h l o r i t e t o w a r r a n t t h e name c h l o r i t e s c h i s t o c c u r i n t h e K i t k i a t a s c h i s t . B-16, a s p e c i m e n f r o m a m i l e n o r t h o f t h e m o u t h o f t h e Q u a a l r i v e r , i s a d a r k g r e e n s c h i s t c o m p o s e d p r e d o m i n a n t l y o f c h l o r i t e w i t h v e r y f i n e q u a r t z a n d f e l d s p a r . A t h i n s e c t i o n o f B - 1 6 c o n t a i n s ; q u a r t z , 2 0 $ ; c h l o r i t e , 25$; e p i d o t e , 1 0 $ ; o p a q u e l a t h e s , p r o b a b l y g r a p h i t e , 2 - 3 $ ; a f e w g r a i n s o f v e r y s m a l l g a r n e t s ; a n d a b o u t 4 0 $ o f very minute c o l o u r l e s s rounded fragments, probably f e l d s p a r . The quartz i s i n bands o f elongate g r a i n s . Each band i s enclosed i n green c h l o r i t e which separates i t from the other bands. Bands of m i l l e d out f e l d s p a r s , a l s o enclosed i n c h l o r i t e , occur at i r r e g u l a r i n t e r v a l s i n p l a c e o f quartz bands. A l l the bands show f o l d i n g , and the s e p a r a t e m i n e r a l g r a i n s show s t r a i n and deformation. The epidote which i s i n extremely s m a l l g r a i n s appears t o be c l i n o z o i s i t e . Most of the c h l o r i t e i s p l e o c h r o i c l i g h t t o dark green and has a low b i r e f r i n g e n c e but some i s p l e o c h r o i c f a i n t l i g h t - g r e e n t o brown and has a h i g h b i r e f r i n g e n c e . Such m a t e r i a l i s probably p a r t l y a l t e r e d b i o t i t e . Perhaps a l l the c h l o r i t e i n the rock i s a l t e r e d b i o t i t e . Or - 2 2 i s a dark green c h l o r i t e s c h i s t from the top of the r i d g e s between K i t k i a t a Lakes and the Quaal R i v e r . Augens of f e l d s p a r are abundant i n the r o c k but are w e l l shown only on a p o l i s h e d s u r f a c e cut across the s c h i s t o s i t y . A t h i n s e c t i o n of Or - 2 2 c o n t a i n s : c h l o r i t e , 40$; q u a r t z , 10$; p l a g i o c l a s e , 40$; sphene, 2-3$; w i t h some opaque g r a i n s , mostly p y r i t e . The t e x t u r e of the r ock, as shown i n F i g u r e 50 i n d i c a t e s extreme c a t a c l a s t i c deformation. Augens of broken p l a g i o c l a s e are s c a t t e r e d along the planes of s c h i s t o s i t y as are many s m a l l broken f e l d s p a r c r y s t a l fragments F e l d s p a r m y l o n i t e i s abundant a l o n g many of the f o l i a . A s e c t i o n of a zoned p l a g i o c l a s e , cut x t o X gave angles of 87 Z A ( O I O ) = 76 and 71° f o r A n ^ and An^g f o r the i n n e r and outer zones r e s p e c t i v e l y . i 2. mm- 1 F i g u r e 4 9 . S k e t c h of a number of f e l d s p a r fragments, some  appear t o be from the same g r a i n . Elongate quartz g r a i n s occur along some of the zones i n the s l i d e (see F i g u r e 50). Commonly they show u n d u l a t o r y e x t i n c t i o n and these are always enclosed i n c h l o r i t e . Sphene occurs as i r r e g u l a r aggregations o f minute rounded g r a i n s w i t h much hazy m a t e r i a l mixed throughout. A few opaque g r a i n s are a s s o c i a t e d w i t h the sphene, most of them are p y r i t e . 88 F i g u r e $0. Photomicrograph of Or-22 c r o s s e d N i c o l s X 40  shoving p l a g i o c l a s e augens between c h l o r i t e  l a y e r s . A few elongated quartz g r a i n s l i e along the planes of s c h i s t o s i t y . F i g u r e 5 1 . P h o t o g r a p h o f B-25 s h o w i n g t h e e x t r e m e f o l d i n g . L i g h t b a n d s a r e c a l c a r e o u s , d a r k b a n d s a r e  c h l o r l t i c . 8 9 B - 2 5 i s a c h l o r i t e - c a l c i t e s c h i s t from a m i l e n o r t h -west of Gertrude P o i n t . I t i s a dark green c o l o u r where c h l o r i t i c but has many creamy-brown l a y e r s of a c a l c a r e o u s m a t e r i a l . The specimen was taken from the c r e s t o f a t i g h t drag f o l d . F i g u r e 51 shows the c r o s s s e c t i o n of t h i s f o l d as seen on a p o l i s h e d end of the specimen. Besides t h i s main d i r e c t i o n of f o l d i n g the specimen has been f o l d e d i n another d i r e c t i o n ; i e t the a x i a l plane of the major drag f o l d has i t s e l f been f o l d e d . A t h i n s e c t i o n o f B - 2 5 c o n t a i n s : c a l c i t e , 30$; c h l o r i t e , 30$; q u a r t z , 30$; p l a g i o c l a s e , 18$; w i t h a few g r a i n s of b i o t i t e and opaque m a t e r i a l . C h l o r i t e occurs i n long t h i n blades and groups of blades a s s o c i a t e d w i t h f i n e quartz and f e l d s p a r , and separated from other s i m i l a r bands by bands of c a l c i t e . B o t h the quartz and f e l d s p a r are present p a r t l y i n moderate s i z e d g r a i n s (.1 mm.) and i n extremely minute g r a i n s 10 microns ot l e s s i n diameter. Most of the f i n e m a t e r i a l i s enmeshed i n the c h l o r -i t e bands or borders these bands. Elongated quartz g r a i n s l i e p a r a l l e l t o the c h l o r i t e leaves i n some bands. Quartz and p l a g i o c l a s e are a l s o present i n the c a l c i t e bands a l t h o u g h more s p a r i n g l y and as c o a r s e r g r a i n e d m a t e r i a l than i n the c h l o r i t e bands. P l a g i o c l a s e has a r e l i e f equal to and j u s t above balsam depending on the o r i e n t a t i o n , and r e l i e f w e l l below q u a r t s . A 90 s e c t i o n cut J L Z gave an angle o f 18.5° f o r X A ( 0 1 0 ) e q u i v a -l e n t t o An^, which seems a l i t t l e too s o d i c c o n s i d e r i n g the r e l i e f a g a i n s t balsam. O r i g i n a l l y the c h l o r i t e may have been b i o t i t e , f o r here and there i n the s l i d e remnants of u n a l t e r e d b i o t i t e are a s s o c i a t e d w i t h the c h l o r i t e , but, a l t e r a t i o n c o u l d have gone the other way and there i s l i t t l e evidence t o prove one over the o t h e r . Numerous s m a l l l a t h e s o f a b l a c k opaque, p r o b a b l y g r a p h i t e , are present along the planes of s c h i s t o s i t y . The m i n e r a l assemblage present i n t h i s rock f i t s none of the e q u i l i b r i u m s assemblages. T h i s , of course, i s common i n the rocks of the E c s t a l l septum. The c h l o r i t e undoubtedly r e p r e s e n t s a r e t r o g r e s s i o n towards the green s c h i s t f a c i e s . Garnet S c h i s t : Garnet s c h i s t i s a rock name which, i n the f i e l d , was r e s e r v e d f o r those s c h i s t s which c o n t a i n e d very l a r g e conspicuous garnets or those which contained many s m a l l garnets. Many of the other s c h i s t s c o n t a i n moderate amounts of l a r g e or sm a l l g a r n e t s . In the K i t k i a t a s c h i s t garnet s c h i s t crops out i n the creek d r a i n i n g Douglas Lake, about a m i l e n o r t h o f the l a k e , (B - 7 ), and even more abundantly along Douglas Channel, f o r the f i r s t three m i l e s n o r t h - e a s t of Gertrude P o i n t . B - 7 i s a specimen o f b i o t i t e - g a r n e t s c h i s t c o n t a i n i n g many l a r g e and s m a l l , i r r e g u l a r , h i g h l y f r a c t u r e d , r e d d i s h garnets which form about $0% of the rock. The specimen i s o v e r a l l a very dark brown w i t h a g r e e n i s h t i n t , p r obably a 91 r e s u l t o f the b i o t i t e a l t e r i n g to c h l o r i t e and s e r i c i t e . A t h i n s e c t i o n o f B-7 c o n t a i n s : garnet, 40$; p l a g i o -c l a s e , 20$; q u a r t z , 20$; b i o t i t e , 20$; opaque g r a i n s , % % w i t h minor c h l o r i t e . Many evidences of extreme deformation are presen t i n the s l i d e . Undulatory e x t i n c t i o n , i m b r i c a t e s t r u c t u r e , and extreme e l o n g a t i o n p a r a l l e l to the s c h i s t o s i t y are c h a r a c t e r -i s t i c of the q u a r t z . P l a g i o c l a s e g r a i n s show undu l a t o r y e x t i n c t i o n , bending of twin l a m e l l a e and cleavage p l a n e s , and i r r e g u l a r f r a c t u r i n g . One or two of the p l a g i o c l a s e g r a i n s have been broken i n t o a number of p i e c e s and the p i e c e s have been squeezed together to form sutured i r r e g u l a r c o n t a c t s . Each p i e c e i s j u s t out of o p t i c a l c o n t i n u i t y w i t h the next. M y l o n i t e , which occurs along some bands i n the rock has a h i g h r e l i e f and i s probably f e l d s p a r a l s o . A s e c t i o n of f e l d s p a r i t o Z gave X A(010) = — 8°, f o r A n ^ . B i o t i t e , the most abundant mica, has a l t e r e d t o c h l o r i t e i n some p a r t s o f the s l i d e . Many g r a i n s show evidence of s l i p p a g e along the cleavage. Opaque g r a i n s , some i r r e g u l a r , others i n micaceous p l a t e s , are s c a t t e r e d along the planes o f s c h i s t o s i t y and are p a r t i c u l a r l y abundant i n the g a r n e t s . The i r r e g u l a r g r a i n s a re magnetite w h i l e the micaceous ones are g r a p h i t e . ZJ-52 i s a specimen of garnet s e r i c i t e s c h i s t from the s t r e t c h o f g a r n e t i f e r o u s s c h i s t along the shore of Douglas Channel. I t i s a l i g h t grey rock w i t h l a r g e (1/4") red garnets weathered out on i t s s u r f a c e s . On a f r e s h l y broken s u r f a c e the r o c k has a g r e e n i s h t i n g e and i s covered w i t h nobs where the s c h i s t bends over g a r n e t s . A t h i n s e c t i o n o f Z J - 5 2 c o n t a i n s : garnet, 2 0 $ ; q u a r t z , 2 5 $ ; p l a g i o c l a s e , 1 0 $ ; opaque g r a i n s , 5$J s e r i c i t e , 2 5 $ ; b i o t i t e 1 2 $ ; c h l o r i t e , 3 $ « Two garnets about 5 mm and 3 mm. In diameter occur i n the s l i d e . Numerous s m a l l w e l l formed garnets . 1 mm. i n diameter are a l s o p r e s e n t . These s m a l l ones c o n t a i n dusty b l a c k m a t e r i a l a t t h e i r c e n t r e s but otherwise are f r e e o f i n c l u s i o n s . The l a r g e r garnets are f u l l o f q u a r t z , p l a g i o c l a s e and opaque i n c l u s i o n s and one has many embayments of impure f e l d s p a r extending i n t o the garnet from the surround-i n g rock. ( F i g u r e 5 2 ) . The quartz occurs i n bands o f s m a l l g r a i n s elongated w i t h the s c h i s t o s i t y . Micas a r e mixed i n w i t h the quartz bands and a l s o l i e between the quartz bands. P l a g i o c l a s e i s i n very f i n e untwinned g r a i n s . I t has low to moderate p o s i t i v e r e l i e f a g a i n s t balsam and n e g a t i v e r e l i e f a g a i n s t quartz making i t about o l i g o c l a s e i n composition. The s e r i c i t e i s probably an a l t e r a t i o n of b i o t i t e , f o r i n a l l p a r t s o f the s l i d e wisps and shreds of b i o t i t e r e -main i n the s e r i c i t e . In l a r g e b i o t i t e g r a i n s s m a l l areas along c l e a v a g e s , f r a c t u r e s and g r a i n boundaries have a l t e r e d to s e r i c i t e . 93 F i g u r e 52. Photomicrograph of ZJ - 5 2 c r o s s e d n i c o l s X 16  The b l a c k mass i s a garnet. Numerous c r y s t a l  f a c e s can be seen along the ragged edge. Im- pure f e l d s p a r f i l l s the spaces around the  garnet. S e r i c i t e and quartz makes up the  s c h i s t around the g a r n e t - f e l d s p a r augen. In a few areas l a r g e sheaves and r a d i a t i n g c l u s t e r s of green c h l o r i t e have developed i n the other micas. These are l a t e , f o r they cut across the s c h i s t o s i t y . ZJ - 5 5 i s a b i o t i t e garnet s c h i s t taken near ZJ - 5 2 . I t c o n s i s t s of f i n e b i o t i t e , 35$; r e d d i s h garnet averaging about 1/8" i n diameter, 50$; p l u s a l i t t l e quartz and f e l d s p a r . The garnets have weathered out to cover the s u r f a c e as shown i n F i g u r e 53. One quartz r i c h l e n s , f u l l o f s m a l l e r garnet than i n most of the specimens, cuts a c r o s s one corner of the rock. 9 4 F i g u r e 53* Photograph of ZJ-55 showing the innumerable  red-brown garnets weathered i n t o r e l i e f on  the s u r f a c e . The a s s o c i a t i o n o f q u a r t z , b i o t i t e , o l i g o c l a s e -andesine, w i t h a v a r i e t y o f almandine garnet does not f i t any s p e c i f i c assemblage of the metamorphic f a c i e s . The n e a r e s t f i t of any i s the almadine-diopside-hornblende s u b f a c i e s of the a m p h i b o l i t e s , but the two important members d i o p s i d e and hornblende are not r e p r e s e n t e d i n the garnet s c h i s t s d i s c u s s e d . Knotted S c h i s t : Along the south west s i d e o f K i t k i a t a Lake a group of b i o t i t e s c h i s t s w i t h l a r g e augens and p o r p h y r o b l a s t s of quartz & Turner and Verhoogen 1951. 95 and f e l d s p a r occur. They are l i g h t grey rocks w i t h a knotted appearance due to the many augen shaped masses weathered out on s u r f a c e o f the r o c k s . No specimen of t h i s rock type was taken. The m i n e r a l assemblages present i n the v a r i o u s types of K i t k i a t a s c h i s t , are i n g e n e r a l , those o f the a m p h i b o l i t e f a c i e s , w i t h , of course, the e x c e p t i o n o f the r e t r o g r a d e c h l o r i t e and s e r i c i t e . The a s s o c i a t i o n of o l i g o c l a s e -andesine w i t h c l i n o z o i s i t e , very common i n these r o c k s , i s not i n e q u i l i b r i u m f o r the a m p h i b o l i t e s . Other l e s s common assemblages, g a r n e t - c a l c i t e - p l a g i o c l a s e - h o r n b l e n d e (B-40) b i o t i t e - g a r n e t - c a l c i t e (B-41), are a l s o out o f e q u i l i b r i u m f o r the a m p h i b o l i t e s . B-25 appears to be i n the b i o t i t e - c h l o r i t e s u b f a c i e s of the g r e e n s c h i s t f a c i e s but even here the assemblage o f c a l c i t e - c h l o r i t e - q u a r t z - a l b i t e - b i o t l t e i n the rock i s not q u i t e an e q u i l i b r i u m assemblage f o r c a l c a r e o u s members of that f a c i e s . Johnson Lake S c h i s t s : A t h i c k group o f b i o t i t i c s c h i s t and impure micaceous q u a r t z i t e w i t h interbedded hornblende r i c h s c h i s t , c rops out i n the a r e a n o r t h and south o f Johnson Lake. (See G e o l o g i c a l Map, F i g u r e 9 2 ) . T h i s group o f r o c k s may be a northward ex-t e n s i o n o f the Douglas Channel g n e i s s as they s t r i k e i n t o one another and have s i m i l a r a t t i t u d e s . N o r t h o f Johnson Lake the ft Turner and Verhoogen, 1951. rocks are r e p o r t e d t o be q u a r t z i t e and impure q u a r t z i t e w i t h h o r n b l e n d i c rocks interbedded. A few specimens of rock from Johnson l a k e s c h i s t were obtained d u r i n g a t r a v e r s e along the shore of Johnson l a k e and over the r i d g e south of the l a k e . Or - 2 0 , a specimen from the shore of Johnson l a k e , i s unusual f o r the l a r g e knots of K - f e l d s p a r i t c o n t a i n s ( F i g u r e 54). Quartz, f e l d s p a r and b i o t i t e , are abundant i n the rock. S m a l l p e r f e c t l y c r y s t a l l i z e d red-brown garnets are s c a t t e r e d here and there i n the rock. F i g u r e 54. Photograph of a p o l i s h e d s u r f a c e on O r - 2 0 showing the l a r g e p r o p h y r o b l a s t s of o r t h o c l a s e . A t h i n s e c t i o n of O r - 2 0 c o n t a i n s : b i o t i t e , 2 5 $ ; q u a r t z , 3 0 $ ; p l a g i o c l a s e , 1 5 $ ; c l i n o z o i s i t e , 1 0 $ ; o r t h o c l a s e , 4 Holyk, W.J., 1952. 20$; hornblende and c h l o r i t e . O r t h o c l a s e forms very l a r g e angular p o r p h y r o b l a s t s which are f u l l o f c l i n o z o i s i t e and quartz i n c l u s i o n s , g i v i n g a marked s i e v e t e x t u r e . ( F i g u r e 55). B i o t i t e , quartz and f e l d s p a r make up the ground mass which In p a r t flows around the o r t h o c l a s e c r y s t a l s and i n p a r t b u t t s a g a i n s t them. ( F i g u r e 55) • F i g u r e 55. Photomicrograph of Or-20 cr o s s e d n i c o l s X 16  Pa r t s of two l a r g e o r t h o c l a s e p o r p h y r o b l a s t s  s i e v e d w i t h q u a r t z , e p i d o t e and some b i o t i t e , are surrounded by curved l a y e r s o f s c h i s t . The quartz occurs i n i r r e g u l a r g r a i n s and elongate tabs; many of the l a t t e r showing undulatory e x t i n c t i o n . The b i o t i t e i s very l i g h t c o l o u r e d ; much l i g h t e r than the b i o t i t e present i n most of the rocks s t u d i e d . In p l a c e s i t i s a l t e r -98 i n g t o c h l o r i t e , p a r t i c u l a r l y a l o n g c l e a v a g e s . P l a g i o c l a s e o c c u r s i n s m a l l w e l l t w i n n e d g r a i n s . S e c t i o n s x t o ( 0 1 0 ) g a v e m a x i m u m a n g l e s o f 2 8 ° f o r X 1 / ^ ( 0 1 0 ) g i v i n g A n ^ g a s a m i n i m u m v a l u e f o r t h e a n o r t h i t e c o n t e n t . T h e p l a g i o c l a s e h a s r e l i e f e q u a l t o q u a r t z i n o n e d i r e c t i o n a n d m u c h h i g h e r t h a n q u a r t z i n t h e o t h e r , t h u s t h e a n o r t h i t e v a l u e i s r e a s o n a b l y a c c u r a t e . F i g u r e 5 6 . P h o t o m i c r o g r a p h o f O r - 2 0 p l a n e p o l a r i z e d l i g h t  X~5o. One e d g e o f a l a r g e o r t h o c l a s e p o r p h y r o -b l a s t s i e v e d w i t h q u a r t z a n d c l i n o z o i s i t e a p p e a r s  o n t h e l e f t , s c h i s t a p p e a r s o n t h e r i g h t . T h e  l a r g e g r a i n o f b i o t i t e i n t h e c e n t e r i s a l m o s t  c o m p l e t e l y a l t e r e d t o c h l o r i t e . A f e w l a t h e s o f l i g h t g r e e n - b l u e h o r n b l e n d e a r e p r e s e n t . T h e y a r e a l i g h t e r c o l o u r e d v a r i e t y t h a n t h a t p r e s e n t i n m o s t o f t h e o t h e r m e t a m o r p h i c r o c k s ; t h u s a r e p o s s i b l y 99 - a F i g u r e 57. Sketch of B-92 shoving l a r g e r a d i a t i n g l a t h e s of  b i o t i t e flakes*. The groundmass i s q u a r t z w i t h  a few c r y s t a l s o f b i o t i t e and minor amounts of  p l a g i o c l a s e . The l a r g e red g r a i n s are g a r n e t r 100 hornblende, but i t i s a very l i g h t green c o l o u r , has moderate b i r e f r i n g e n c e and a p p a r e n t l y low to moderate e x t i n c t i o n angles; suggesting i t i s a t r e m o l i t i c hornblende, but i t i s a l i t t l e dark f o r t r e m o l i t e . T h i s rock i s probably a low s t r e s s e q u i v a l e n t o f the c l i n o z o i s i t e - s o d i c - p l a g i o c l a s e types abundant i n the septum. The low s t r e s s , as evidenced by the l a c k o f s t r a i n i n the quartz and the p o o r l y developed s c h i s t o s i t y , has p e r m i t t e d the GaO to remain f i x e d i n l a b r a d o r i t e . •B-93 i s a knotted b i o t i t e s c h i s t s i m i l a r t o Or - 2 0 . B i o t i t e quartz s c h i s t appears to flow around the augen shaped p o r p h y r o b l a s t s . The rock i s s t r i p e d by a l t e r n a t i n g bands o f dark, b i o t i t e r i c h , m a t e r i a l and grey-white q u a r t z - f e l d s p a t h i c m a t e r i a l . A t h i n s e c t i o n of B - 9 3 c o n t a i n s : q u a r t z , 70$; b i o t i t e , 10$; muscovite, 15$; garnet, 10$| w i t h a n d a l u s i t e , magnetite and p y r i t e . Quartz i n bands of tab shaped g r a i n s between l a y e r s o f mica, gives the rock i t s w e l l developed s c h i s t o s i t y . The muscovite appears to be an a l t e r a t i o n of b i o t i t e (See F i g u r e 58). Garnet i n ve r y s m a l l subhedral g r a i n s , many w i t h minute i n -c l u s i o n s and some completely f u l l o f I n c l u s i o n s , are s c a t t e r e d along the planes of s c h i s t o s i t y . A n d a l u s i t e occurs w i t h quartz i n augen shaped masses around which the other m i n e r a l s flow. One l a y e r i n the s e c t i o n 101 i s r i c h i n such augens. A p o l i s h e d s u r f a c e of the rock i t -s e l f shows three separate l a y e r s of them. (See F i g u r e 59). F i g u r e 58. Photomicrograph of B-93 plane p o l a r i z e d l i g h t X^Bo. B i o t i t e , grey l a t h e s , i s a l t e r e d to  s e r i c i t e . c o l o u r l e s s l a t h e s . Subhedral garnets  w i t h s m a l l c e n t r a l i n c l u s i o n s are p r e s e n t . Most  of the l i g h t areas are quartz g r a i n s , many of  them o u t l i n e d by s m a l l amounts o f mica and i r o n  o x i d e s . F i g u r e 59* P o l i s h e d s u r f a c e of B-93 shoving dark bands  and augens of q u a r t z - a n d a l u s i t e X - l The a n d a l u s i t e i s present as l a r g e i r r e g u l a r s i e v e t e x t u r e d g r a i n s . I t i s c o l o u r l e s s , has h i g h r e l i e f , v e r y low b i r e f r i n g e n c e and i s o p t i c a l l y n e g a t i v e w i t h a h i g h 2v. The assemblage, q u a r t z , b i o t i t e , muscovite, a n d a l u s i t e and garnet f i t s none of the f a c i e s as g i v e n by Turner and V e r -hoogen. Probably the assemblage r e p r e s e n t s the a m p h i b o l i t e f a c i e s . Specimens of the amphibole r i c h rock or " h o r n b l e n d i t e " interbedded w i t h the Johnson l a k e s c h i s t were c o l l e c t e d along the upper E c s t a l l r i v e r . Two specimens of these r o c k s P - l l and P-12 are d i s c u s s e d under the meta-igneous r o c k s . Other S c h i s t s : S c h i s t s occur interbedded w i t h most of the other rock types i n the E c s t a l l septum. A few examples of these s c h i s t s w i l l be d i s c u s s e d below i n the same order as the K i t k i a t a s c h i s t s were d i s c u s s e d . B i o t i t e s c h i s t ; W-41 i s a p o o r l y f o l i a t e d b i o t i t e - f e l d s p a r s c h i s t from the Barbara Lake q u a r t z i t e s . I t i s l i g h t grey i n c o l o u r w i t h numerous f l a k e s of b l a c k b i o t i t e and l a r g e g r a i n s of p y r r h o t i t e . A t h i n s e c t i o n c o n t a i n s : p l a g i o c l a s e , 60$; b i o t i t e , 25$; q u a r t z , 5$; c h l o r i t e , 5$; p y r r h o t i t e , 2 - 3 $ ; hornblende, 0 . 5 $ ; and a few g r a i n s of a p a t i t e and magnetite. The p l a g i o c l a s e i s i n v e r y s m a l l , equant, a n h e d r a l g r a i n s , some w e l l twinned, and many showing z o n a l e x t i n c t i o n . One s e c t i o n x to (010) gave values of A n 2 5 i An33> a n d An42» and Ancjo, from the c e n t e r out as shown i n F i g u r e 60. 1 0 3 F i g u r e 6 0 . P l a g i o c l a s e g r a i n cut to ( 0 1 0 ) . X ' A ( O I O ) = A, 8 . 5 ° B, 1 5 ° C, 2 2 A n 2 ^ An-,-, An 3 3 4 2 D , 2 7 .5 C An 50 B i o t i t e occurs as s m a l l f l a k e s more or l e s s a l i g n e d w i t h the s c h i s t o s i t y . In a number of p l a c e s i t has a l t e r e d to green c h l o r i t e w i t h sm a l l amounts o f magnetite. The horn-blende i s present as a few l a r g e , deep blue-green g r a i n s . Some of the l a r g e r c h l o r i t e areas may be a l t e r a t i o n s o f horn-blende. The p y r r h o t i t e occurs as q u i t e l a r g e g r a i n s , some an e i g h t h of an Inch i n diameter. I t i s opaque, s l i g h t l y bronze y e l l o w under r e f l e c t e d l i g h t , and magnetic. A few u n s t r a i n e d quartz g r a i n s a r e s c a t t e r e d randomly through the r o c k . 104 ¥ -45 i s a specimen of g r e e n i s h brown coarse g r a i n e d b i o t i t e s c h i s t taken i n the creek emptying Gordon Lake. A few augens of quartz and some p y r i t e cubes can be seen on a p o l i s h e d s u r f a c e cut a c r o s s the f o l i a t i o n . The t h i n s e c t i o n c o n t a i n s : b i o t i t e , 15$; b i o t i t e a l t e r e d to c h l o r i t e , 15$; p l a g i o c l a s e , 40$; q u a r t z , 2 5 $ ; w i t h garnet, e p i d o t e , s e r i c i t e , and c h l o r i t i z e d hornblende. Both b i o t i t e and c h l o r i t e are concentrated along narrow bands, but b i o t i t e i s present a l s o throughout the rock. Much of the b i o t i t e and the few g r a i n s of hornblende have been o b v i o u s l y p a r t l y a l t e r e d to c h l o r i t e i n t h i s s e c t i o n . T h i s c h l o r i t e i s the reason f o r the marked g r e e n i s h t i n g e i n the hand specimen. A few b i o t i t e g r a i n s c o n t a i n minute c r y s t a l - i n c l u s i o n s of epidote around which a p l e o c h r o i c h a l o has developed. The rfepidote" may be a l l a n i t e . A s e c t i o n of p l a g i o c l a s e cut j _ to a gave an angle o f X ' A ( O I O ) = 21°, An^g. Another c u t x t o a was zoned, g i v i n g from the c e n t e r A n 4 ^ and A n 3 2 ; (X' A (010) » 24° and 14.5°). Both the quartz and the p l a g i o c l a s e are f r e e of the s i g n s o f deformation commonly seen i n many of the r o c k s . Probably the s t r a i n was concentrated along the b i o t i t e r i c h bands. R a d i a t i n g c l u s t e r s of c h l o r i t e have developed along the b i o t i t e r i c h zones and i r r e g u l a r , complexly twinned, p y r i t e c r y s t a l s are s c a t t e r e d about i n the rock. Both these m i n e r a l s are l a t e r than the deformation which produced the s c h i s t o s i t y . 105 B i o t i t e - h o r n b l e n d e s c h i s t s W-34 i s a s p e c i m e n o f b i o t i t e - h o r n b l e n d e s c h i s t f r o m t h e B a r b a r a L a k e q u a r t z i t e . I t c o n t a i n s l a r g e f l a k e s o f g o l d e n - b r o w n b i o t i t e , a n d g r e e n h o r n b l e n d e , a n d h a s a n o v e r a l l p u r p l i s h c a s t . T h e b i o t i t e a n d h o r n b l e n d e a r e o r i e n t e d t o g i v e a p l a n e o f s c h i s t o s i t y w h i c h , h o w e v e r , i s p o o r l y d e v e l o p e d b e c a u s e o f t h e h i g h c o n -t e n t o f q u a r t z a n d p l a g i o c l a s e . A t h i n s e c t i o n o f W-34 c o n t a i n s : h o r n b l e n d e , 25$; b i o t i t e , 20$; p l a g i o c l a s e , 4 0 $ ; q u a r t z , 5$; e p i d o t e , 1 - 2 $ , w i t h m u s c o v i t e , c h l o r i t e , s p h e n e , a n d o p a q u e g r a i n s . P l a g i o c l a s e , t h e m o s t a b u n d a n t m i n e r a l , o c c u r s i n a n h e d r a l g r a i n s a b o u t . 1 mm. i n d i a m e t e r . M a n y g r a i n s a r e u n t w i n n e d , a n d f e w s h o w a n y c l e a v a g e . R e v e r s e d z o n i n g i s common i n m a n y o f t h e g r a i n s . S e c t i o n s j _ t o (010) g a v e m a x -imum a n g l e s o f 2 7 ° f o r X ' / \ (010), = t o A n 4 Q , w h i c h i s a n a v e r a g e m i n i m u m v a l u e f o r t h e a n o r t h i t e c o n t e n t . T h r e e z o n e d s e c t i o n s c u t JL t o (010) g a v e a n a v e r a g e v a l u e o f A n ^ f o r t h e i n n e r z o n e a n d A n 3 2 f ° r t h e o u t e r z o n e . F i g u r e 61 b e l o w s h o w s t h e d e t a i l s o f t h e z o n i n g a n d t h e d e t e r m i n e d a n g l e s . M a n y s m a l l a n h e d r a l g r a i n s o f q u a r t z o c c u r i n s m a l l g r o u p s h e r e a n d t h e r e i n t h e s l i d e , w h i l e s e p a r a t e g r a i n s a r e o c c a s i o n a l l y m i x e d i n w i t h t h e f e l d s p a r . -1 m rr\ A B C F i g u r e 6 1 . S k e t c h o f thr e e p l a g i o c l a s e g r a i n s cut to ( 0 1 0 ) and a l l showing re v e r s e d z o n i n g . T a b l e of "angles X ' A C O I O ) and a n o r t h i t e content G r a i n : A B C Zone: angle ka% angle angle a 1 5 ° 3 2 14° 3 1 1 2 . 5 ° b 2 7 ° 46 2 5 ° 44 2 3 ° 3 0 42 The b i o t i t e i s an unusual reddish-brown c o l o u r . Many-gr a i n s are almost c o l o u r l e s s p a r a l l e l t o the E-W cross h a i r , but deeply c o l o u r e d p a r a l l e l t o the N-S cross h a i r . Horn-blende, o c c u r r i n g i n long blades and stubby c r y s t a l s , shows w e l l developed s i e v e t e x t u r e due to p l a g i o c l a s e i n c l u s i o n s . Some very l a r g e elongate g r a i n s a r e s u b d i v i d e d along t h e i r l e n g t h by i r r e g u l a r f r a c t u r e s i n t o f o u r or f i v e fragments. Some of the g r a i n s have a s l i g h t c u r v a t u r e which causes each fragment to have a s l i g h t l y d i f f e r e n t o r i e n t a t i o n than the next one. In other cases t h e r e has been s l i g h t movement along the f r a c t u r e s , a g a i n g i v i n g each fragment a s l i g h t v a r i a t i o n i n o r i e n t a t i o n . T h i s hornblende i s the t y p i c a l deep blue-green v a r -i e t y w i t h i n t e r m e d i a t e e x t i n c t i o n angles of Z A C , t h a t i s found i n most of the E c s t a l l metamorphis r o c k s . In one or two areas of the s l i d e the f e l d s p a r s are s a u s s u r i t i z e d and nearby hornblendes are p a r t l y a l t e r e d to c h l o r i t e . Both e p i d o t e and s e r i c i t e occurs i n these s a u s s u r i t i z e d areas but o n l y v e r y s m a l l amounts of low r e l i e f f e l d s p a r are p r e s e n t . Many of these areas of a l t e r a t i o n are a s s o c i a t e d w i t h a long t h i n f r a c t u r e which c r o s s e s the s l i d e c u t t i n g through a l l the min-e r a l s . In the p l a g i o c l a s e the f r a c t u r e i s f i l l e d w i t h e p i d o t e , but where the f r a c t u r e c rosses hornblende t h e r e i s o n l y a b l e a c h i n g of the green hornblende to a c o l o u r l e s s v e r y h i g h b i r e f r i n g e n t amphibole. ( F i g u r e 6 2 ) . T h i s a l t e r a t i o n appears t o be r e l a t e d to the i n -t r u s i v e g r a n o d i o r i t e , (see the d e s c r i p t i o n of specimens Or -5 and W-14), as i t i s found almost e x c l u s i v e l y near the con-t a c t s w i t h the b a t h o l i t h i c r o c k s . 108 F i g u r e 62. Photomicrograph of W-34 plane p o l a r i z e d l i g h t X 16  Shoving a l t e r a t i o n of hornblende, dark grey, along  an epidote f i l l e d f r a c t u r e . B l a c k g r a i n s are  magnetite. W-44 i s a specimen of b i o t i t e - a n t h o p h y l l i t e s c h i s t from the creek d r a i n i n g Gordon Lake. I t i s s i l v e r y - g r e e n v i t h brovn i r o n s t a i n s along a l l the veathered s u r f a c e s . I t has a prominent s c h i s t o s i t y and a good f r a c t u r e at r i g h t angle to the s c h i s t o s i t y both due t o the p a r a l l e l alignment of innumerable a n t h o p h y l l i t e n e e d l e s . A t h i n s e c t i o n cut across the l e n g t h of the antho-p h y l l i t e g r a i n s c o n t a i n s : a n t h o p h y l l i t e , 35$; p l a g i o c l a s e , 45$; q u a r t z , 5$; b i o t i t e , 5$; v i t h c h l o r i t e and a f e v g r a i n s of opaque m a t e r i a l , probably magnetite. Most of the a n t h o p h y l l i t e appears i n the t h i n s e c t i o n as diamond shaped c r o s s s e c t i o n s showing two cleavages at 60 and 1 2 0 ° . A few s e c t i o n s cut p a r a l l e l to the C a x i s are pre s e n t . These have h i g h b i r e f r i n g e n c e , (2nd order b l u e ) , and p a r a l l e l e x t i n c t i o n . The amphibole i s o p t i c a l l y p o s i t i v e w i t h a 2V of about 7 0 ° . The p l a g i o c l a s e i s i n sm a l l w e l l twinned g r a i n s , three o f which, cut j . t o a gave angles of 19, 19.5 and 20° f o r X'A (010), f o r an average v a l u e o f A1135. B i o t i t e occurs i n p l a t e s which appear t o be l a r g e r than any of the other m i n e r a l s . Many of the b i o t i t e g r a i n s have been a l t e r e d to c h l o r i t e along cleavages and g r a i n boundaries. Quartz g r a i n s are s c a t t e r e d randomly through the p l a g i o c l a s e . B-86 i s a specimen of h o r n b l e n d e - b i o t i t e s c h i s t from the Quaal R i v e r gneiss about two m i l e s south-west of E c s t a l l Lake. I t i s a coarse g r a i n e d rock w i t h l a r g e stubby c r y s t a l s of hornblende and p o r p h y r o b l a s t s of p l a g i o c l a s e weathered out on one s u r f a c e . Large p l a t e s of brown b i o t i t e cover the f r e s h l y f r a c t u r e d s u r f a c e s . A t h i n s e c t i o n o f B-86 c o n t a i n s : hornblende, 50$; b i o t i t e , 20$; p l a g i o c l a s e , 20$; e p i d o t e , 2-3$; w i t h q u a r t z , sphene, s e r i c i t e , and c h l o r i t e . The hornblende i s s i m i l a r to that i n many other rocks of the a r e a , a deep blue-green v a r i e t y . I t occurs as l a r g e and s m a l l anhedral g r a i n s , many showing de-forma t i o n and s l i g h t amounts of a l t e r a t i o n . The l a r g e r g r a i n s are f r a c t u r e d and movement of one p a r t o f the g r a i n past the other has oc c u r r e d . B i o t i t e and hornblende blades appear t o 110 have grown through these l a r g e f r a c t u r e d hornblende g r a i n s . T h i s growth must have o c c u r r e d at a l a t e r stage than t h a t which produced the l a r g e g r a i n s . B i o t i t e occurs i n bands of t h i n b l a d e s . S h e a r i n g has o c c u r r e d along these bands and c l i n o z o i s i t e and sphene c r y s t a l s have formed along them. S m a l l amounts of c h l o r i t e have developed i n some of the b i o t i t e g r a i n s . Only s m a l l g r a i n s o f p o o r l y twinned p l a g i o c l a s e occur i n the s e c t i o n . Many are a l t e r e d at t h e i r c e n t e r s where they c o n t a i n many f i n e wisps o f s e r i c i t e . Two s e c t i o n s t o J - X gave Z A(010) = 71° and 70.5° g i v i n g a v a l u e o f A n ^ f o r the a n o r t h i t e content o f the p l a g i o c l a s e . A few groups of s m a l l s t r a i n e d quartz g r a i n s occur here and there i n the s e c t i o n . The m i n e r a l assemblages present i n the above rocks w i l l f i t i n t o the s t a u r o l i t e - k y a n i t e or the c o r d i e r i t e -a n t h o p h y l l i t e s u b f a c i e s of the amp h i b o l i t e f a c i e s , p r o v i d e d the absence of K - f e l d s p a r i s ig n o r e d . The presence of ep i d o t e would put the rocks i n the s t a u r o l i t e - k y a n i t e group t o which there i s g e n e r a l l y a more p e r f e c t comparison. C h l o r i t e and muscovite i n these rocks r e p r e s e n t s r e t r o -g r e s s i v e metamorphism, as i t does i n the K i t k i a t a s c h i s t s and the other rock t y p e s . S e r i c i t e S c h i s t s B-85 i s a specimen of s e r i c i t e s c h i s t from a r i d g e top about 3 m i l e s west-south-west of E c s t a l l l a k e . The rock i s I l l s i l v e r y - w h i t e on planes of f o l i a t i o n and grey white w i t h b l a c k and brown s t r e a k s of micas o u t l i n i n g the f o l i a t i o n on a s e c t i o n cut a c r o s s the f o l i a t i o n . Many p a r t s of the rock a r e s t a i n e d brown by i r o n o x i d e s , micas being p a r t i c u l a r l y s u s c e p t i b l e to such s t a i n i n g . Quartz and f e l d s p a r i n augen shaped masses occur between the planes of mica and make up about 70$ o f the rock. A t h i n s e c t i o n of B - 8 5 c o n t a i n s : q u a r t z , 40$; p l a g i o c l a s e , 30$; b i o t i t e , 15$; s e r i c i t e , 6$; c h l o r i t e , 3$; w i t h p y r i t e , hematite, i r o n hydroxides and e p i d o t e . About h a l f the quartz occurs i n very l a r g e g r a i n s and aggregates of three or f o u r l a r g e r g r a i n s . A l l show extreme undulatory e x t i n c t i o n , o f t e n banded s i m i l a r t o the i m b r i c a t e s t r u c t u r e ( F i g u r e s 7 and 8 ) . A l l the l a r g e compound g r a i n s have sutured c o n t a c t s and ragged embayed edges. The r e s t of the quartz occurs as s m a l l equant shaped anhedral g r a i n s showing on l y s l i g h t amounts of s t r a i n . A few tab shaped g r a i n s l i e i n the mica bands and are elongated p a r a l l e l t o the bands. The f e l d s p a r i s i n anhedral g r a i n s g e n e r a l l y elongate p a r a l l e l to the s c h i s t o s i t y . I t i s p o o r l y twinned, r a r e l y shows cleavag e , and has a r e l i e f above and below t h a t of q u a r t z . Some g r a i n s have a few f l e c k s of s e r i c i t e i n them. A s e c t i o n ± to X gave Z A ( 0 1 0 ) = 84° f o r An25, another s e c t i o n X X gave Z A ( O Q l ) = -5° f o r A n ? A . 112 B i o t i t e occurs i n bands and as separate g r a i n s s c a t t e r e d through the other m i n e r a l s . A l l o f i t i s f a i r l y -w e l l a l i g n e d p a r a l l e l t o the s c h i s t o s i t y . In the b i o t i t e bands much of the m i n e r a l i s a l t e r e d to s e r i c i t e and some has a l t e r e d to c h l o r i t e . Often a l l three m i n e r a l s are i n c o n t a c t . Wisps of u n a l t e r e d b i o t i t e a re present i n most of the l a r g e s e r i c i t e g r a i n s . S m a l l subhedral epidote c r y s t a l s surrounded by p l e o -c h r o i c halos occur here and there enclosed i n b i o t i t e . Perhaps the " e p i d o t e " i s a l l a n i t e . A few g r a i n s of p y r i t e , a l l o f them more or l e s s a l t e r e d to i r o n o x i d e s , a re s c a t t e r e d throughout the rock. The a l t e r a t i o n occurs as red and brown rims around the remnants of the p y r i t e g r a i n s . The extreme deformation that t h i s rock has undergone, and the p y r i t e i n i t , i s t y p i c a l o f the s e r i c i t e s c h i s t s . The specimen came from a narrow zone of s e r i c i t e r i c h rock which has been l o c a t e d here and there along s t r i k e f o r n e a r l y t e n m i l e s . They may re p r e s e n t one zone, or a group of zones, along which s h e a r i n g and perhaps hydrothermal a l t e r a t i o n has been c o n c e n t r a t e d . 0 r - l 6 i s an unusual specimen of s e r i c i t e - c a r b o n a t e s c h i s t from the Quaal R i v e r g n e i s s , about two m i l e s west of K i t k i a t a i n l e t . I t i s a very l i g h t c o l o u r e d rock, f r e s h s u r f a c e s being almost white w i t h many s i l v e r y - g r e e n t i n t e d mica p l a t e s . On weathered s u r f a c e s i t has been s t a i n e d brown by i r o n o x i d e s . 113 Quartz i s the most abundant m i n e r a l but s l i g h t e f f e r -vescence i n HC1 i n d i c a t e s c a l c i t e i s a l s o p r e s e n t . A t h i n s e c t i o n o f Or-16 c o n t a i n s : q u a r t z , 60$; s e r i c i t e 15$; c a l c i t e , 15$; z o i s i t e , 10$; and some amorphous white m a t e r i a l . The quartz occurs as s m a l l ( .1 mm) anh e d r a l u n s t r a i n e d g r a i n s . Most of the g r a i n s a re equant shaped but a few are i n elongate tab shaped g r a i n s p a r a l l e l t o the s c h i s t o s i t y , these l a t t e r are u s u a l l y sandwiched between g r a i n s o f mica. C a l c i t e i n elongated h i g h l y sheared g r a i n s l y i n g p a r a l l e l to the s c h i s t o s i t y , i s a s s o c i a t e d and intergrown w i t h the mica. The z o i s i t e i s i n q u i t e l a r g e subhedral g r a i n s which are n e a r l y always h i g h l y f r a c t u r e d and a l t e r e d to a micaceous m i n e r a l along the f r a c t u r e s and along the g r a i n boundaries. These a l t e r e d corroded g r a i n s l o o k v e r y much l i k e g r a i n s of o l i v i n e a l t e r e d t o s e r p e n t i n e . Some of the z o i s i t e g r a i n s have s m a l l amounts of a white amorophous m i n e r a l a s s o c i a t e d w i t h them. The z o i s i t e has an anomolously low b i r e f r i n g e n c e , the u s u a l h i g h r e l i e f of ep i d o t e , an o p t i c angle o f about 6 0 ° , and i s o p t i c a l l y p o s i t i v e . I t i s p l e o c h r o i c b r i g h t l i g h t y e l l o w , cleavage N-S, almost c o l o u r l e s s cleavage E-W, and has p a r a l l e l e x t i n c t i o n i n a l l s e c t i o n s viewed. 114 F i g u r e 63. Photomicrograph of 0 r - l 6 plane p o l a r i z e d l i g h t  X 40. F r a c t u r e d z o i s i t e g r a i n s r e p l a c e d by mi- caceous m i n e r a l s along the f r a c t u r e s and around  g r a i n boundaries. Compare w i t h F i g . 63 below. C o l o u r l e s s low r e l i e f m a t e r i a l i s q u a r t z . F i g u r e 64. Photomicrograph of 0 r - l 6 c r o s s e d n l c o l s X 40  Same area as i n F i g . 63. White h i g h r e l i e f  shreds are micaceous m i n e r a l s , low r e l i e f b l a c k and white gra i n s a r e q u a r t z . 115 Micaceous m i n e r a l s have formed as an a l t e r a t i o n of the z o i s i t e but a l s o i n separate w e l l formed g r a i n s . The l a t t e r are probably s e r i c i t e , but the former may be a l l or i n p a r t , t a l c , s e r i c i t e , or a n t i g o r i t e and c h r y s o t i l e , w h i c h i t resembles c l o s e l y . S h e a r i n g of the c a l c i t e and micas, and the b r e c c i a t i o n of the z o i s i t e suggest c o n s i d e r a b l e d e formation. The a l t e r -a t i o n of the z o i s i t e may correspond to the r e t r o g r e s s i o n of b i o t i t e and hornblende to s e r i c i t e and c h l o r i t e as seen i n other r o c k s . C h l o r i t e S c h i s t : B-88 i s a specimen of t h i n banded f i n e g r a i n e d c h l o r -i t e s c h i s t taken a m i l e e a s t of E c s t a l l Lake. Quartz i s the most abundant m i n e r a l i n the rock but green c h l o r i t e coats a l l the c l o s e l y spaced planes of s c h i s t o s i t y g i v i n g a green, micaceous look to the rock. A few cubes of p y r i t e are v i s i b l e on the f r e s h l y broken s u r f a c e s . A t h i n s e c t i o n of B-88 c o n t a i n s : q u a r t z , 45$; p l a g i o -c l a s e , 30$; c h l o r i t e , 15$; c l i n o z o i s i t e , 10$; s e r i c i t e , 10$; and a few g r a i n s of p a r t l y o x i d i z e d p y r i t e . Three types o f bands are seen i n the t h i n s e c t i o n . Elongate quartz g r a i n s .1 mm. by . 0 5 mm form one set of bands, c h l o r i t e l a t h e s s e p a r a t i n g each l a y e r of quartz g r a i n s form the second set o f bands and minute rounded and i r r e g u l a r g r a i n s of low r e l i e f , ( a g a i n s t q u a r t z ) , f e l d s p a r forms a t h i r d d i s c o n t i n u o u s s e t between the quartz and mica bands. Most of the c h l o r i t e 116 g r a i n s , which are very elongate, bend back and f o r t h along t h e i r l e n g t h . S e r i c i t e f l a k e s , i n t i m a t e l y mixed w i t h the c h l o r i t e , are probably an a l t e r a t i o n of the c h l o r i t e . The c l i n o z o i s i t e i s present as t r a i n s of i r r e g u l a r broken g r a i n s which have a s l i g h t g r e e n i s h - y e l l o w c o l o u r , h i g h r e l i e f , and h i g h b i r e f r i n g e n c e . The t e x t u r e s i n the rock, the d i s c o n t i n u o u s bands of p l a g i o c l a s e m y l o n i t e , elongate quartz g r a i n s and a l i g n e d mica f l a k e s , i n d i c a t e extreme c a t a c l a s t i c metamorphism. The c h l o r i t e and s e r i c i t e may r e p r e s e n t r e t r o g r e s s i v e metamor-phism of an o r i g i n a l l y b i o t i t e r i c h rock. Garnet S c h i s t : B-53 i s a g a r n e t - b i o t i t e hornblende s c h i s t taken from the Douglas Channel g n e i s s . I t i s a dark grey rock c o n t a i n i n g about 40$ b i o t i t e and hornblende and 20$ l a r g e ( . 5 inches i n diameter) rounded red g a r n e t s . The remainder of the rock i s mostly f e l d s p a r . The b i o t i t e s c h i s t appears to flow around the garnets as do a few t e n t h - i n c h t h i c k l e n s e s of w h i t i s h q u a r t z . A t h i n s e c t i o n of B - 5 3 c o n t a i n s : b i o t i t e , 20$; horn-blende, 25$; p l a g i o c l a s e 20$; q u a r t z , 15$; garnet, 10$; e p i d o t e , 5$; sphene, 5$; and a few opaque g r a i n s . The garnet o c c u r s , i n the t h i n s e c t i o n , as two l a r g e anhedral rounded c r y s t a l s which make up about 15$ of the a r e a of the s l i d e , but they are so f u l l o f quartz sphene and c l i n -o z o i s i t e i n c l u s i o n s t h a t o n l y about h a l f of the g r a i n i s 117 a c t u a l l y garnet. About 2 or 3$ of ve r y s m a l l subhedral gar-nets are s c a t t e r e d through the r e s t o f the s l i d e . Thus t h e r e i s a c t u a l l y much l e s s garnet i n the rock than there appears t o be from a study o f the hand specimen. A l s o the garnets i n the hand specimen are concentrated along one s i d e and a r e p r a c t i c a l l y absent elsewhere. T h i s c o n c e n t r a t i o n i s not r e -l a t e d to the s c h i s t o s i t y f o r the garnet r i c h band cuts across the s c h i s t o s i t y . A p p a r e n t l y because the garnets are r e s i s t a n t to weathering they have formed the s u r f a c e o f the r o c k . In the outcrop from which B-53 was obtained the l a r g e garnets were developed only along one narrow zone which appeared to p a r a l l e l the s c h i s t o s i t y . The t r a i n o f i n c l u s i o n s p r e s e n t i n the l a r g e garnets are g e n e r a l l y p a r a l l e l to the s c h i s t o s i t y but some evidence of movement of the garnet or development around an S shaped f o l d are present i n the bending of these t r a i n s of i n c l u s i o n s . Many s m a l l g r a i n s of c l i n o z o i s i t e and diamond shaped c r y s t a l s of sphene are s c a t t e r e d along narrowly spaced bands p a r a l l e l i n g the s c h i s t o s i t y . Both sphene and c l i n o z o i s i t e are abnormally abundant along the edges of the l a r g e r garnets and one or two l a r g e patches o f sphene c r y s t a l s occur i n em-bayments i n the borders o f the garnet. A l l of the c l i n o -z o i s i t e g r a i n s are c o l o u r l e s s , f r e s h and c r i s p l o o k i n g . Many have a w e l l developed p a r t i n g as w e l l as the p e r f e c t (001) cleavage. Such c l i n o z o i s i t e i s t y p i c a l of many of the meta-morphic rocks o f the E c s t a l l septum and p a r t i c u l a r l y the Douglas Channel g n e i s s . 1 1 8 Hornblende, the u s u a l deep blue-green v a r i e t y , and b i o t i t e occur i n anhedral g r a i n s elongate p a r a l l e l w i t h the s c h i s t o s i t y . P l a g i o c l a s e and quartz occur i n i r r e g u l a r bands i n t e r -s t i t i a l t o the hornblende and mica. Quartz g r a i n s a r e s m a l l e r than the p l a g i o c l a s e g r a i n s , and both are elongate p a r a l l e l to the s c h i s t o s i t y . A s e c t i o n of p l a g i o c l a s e c u t _ L to X gave an angle of 7 7 ° f o r Z A ( O I O ) making the p l a g i o c l a s e a c a l c i c o l i g o c l a s e , An^g. Two other specimens of s c h i s t c o n t a i n i n g v e r y l a r g e garnets were c o l l e c t e d . B-44 from Douglas Channel i s a b i o t i t e - g a r n e t s c h i s t . The garnets are l a r g e deep-red eu-h e d r a l c r y s t a l s up to .75 i n c h i n diameter, which are inbedded i n a s c h i s t composed of l a r g e p l a t e s of dark g r e e n i s h - b l a c k b i o t i t e . The b i o t i t e has weathered away l e a v i n g the garnet dodecahedrons s t a n d i n g i n r e l i e f on the s u r f a c e . Garnets, surrounded by b i o t i t e , occur on two s i d e s of the specimen, separated, or r a t h e r h e l d t o g e t h e r , by a q u a r t z - f e l d s p a r r i c h l a y e r of b i o t i t e - v / h i t e mica s c h i s t . The white mica may be muscovite or perhaps weathered b i o t i t e . Some of the b i o t i t e i n the r o c k has a green t i n t and i s q u i t e s o f t , probably i t has a l t e r e d to c h l o r i t e . The three l a r g e s t garnets are o u t l i n e d by a narrow band of g r e e n i s h -white m a t e r i a l which appears t o be a mixture of quartz and c h l o r i t e . 1 1 9 B - 9 5 i s a g a r n e t - s e r i c i t e s c h i s t from the n o r t h end of Prospect H i l l where the Johnson Lake s c h i s t crops out. Three l a r g e red garnets showing the t y p i c a l garnet dodecahedron make up about a h a l f of the specimen. Many much s m a l l e r brown garnets are a l s o p r e s e n t . The r e s t of the specimen i s p r a c t -i c a l l y a l l s i l v e r y - w h i t e muscovite w i t h a few f l a k e s o f dark green mica and a few l e n s e s of q u a r t z , two of them along the edges of garnet c r y s t a l s . '1'. I]! III w Ill l|ll|l [Mi 4 5 6 1 '7 F i g u r e 6 5 . Photograph of B - 9 5 . g a r n e t - s e r i c i t e s c h i s t , The garnets i n specimen B - 9 5 are a v a r i e t y o f almadine. 120 S i l t s t o n e and P h y l l i t e s : S i l t s t o n e s and P h y l l i t e s a r e r a r e south o f E c s t a l l l a k e , or perhaps they are so s t r o n g l y metamorphosed they cannot o f t e n be r e c o g n i z e d i n that a r e a . North of the l a k e they occur i n many p l a c e s . Some p h y l l i t e beds have been tr a c e d f o r a m i l e or more i n the Johnson l a k e and E c s t a l l mine areas where they occupy topographic depressions which form prominent lineaments e a s i l y seen on a e r i a l photographs. S e v e r a l zones of s i l t s t o n e and p h y l l i t e were found near the top and on the west s i d e of Prospect H i l l , but due to heavy timber cover and the presence o f pre-metamorphic i n t r u s i o n s along t h i s r i d g e the rocks c o u l d not be t r a c e d f a r . S i l t s t o n e , or at l e a s t rock c o n s i s t i n g o f s i l t s i z e g r a i n s , occur i n bedded l a y e r s j u s t n o r t h east of the mouth of the Quaal r i v e r . Z-J-28 i s a specimen of a s i l t s t o n e from t h i s a r e a . I t i s a f i n e - g r a i n e d , t h i n banded, green i s h - w h i t e rock. There i s a p a r t i n g p a r a l l e l to the banding along l a y e r s of greenish-white mica. A t h i n s e c t i o n of Z-J-28 c o n t a i n s ; q u a r t z , 35$; p l a g i o c l a s e , 25$; s e r i c i t e , 30$; c a l c i t e , 10$; and some e p i d o t e . Most of the m a t e r i a l i s v e r y f i n e ( . 3 mm to .02 mm. i n diameter. F i g u r e 66 on the f o l l o w i n g page shows the t e x t u r e and g r a i n s i z e of the rock. Quartz and c a l c i t e are the l a r g e r g r a i n s , both occur as f r e s h u n s t r a i n e d angular g r a i n s . The quartz i s i n bands o f elongated or tab shaped g r a i n s w i t h bands of muscovite and bands of p l a g i o c l a s e s e p a r a t i n g the v a r i o u s quartz bands. 121 F i g u r e 6 6 . Photomicrographs o f Z-J-28 X 1 6 Plane l i g h t above, c r o s s e d n i c o l s below. High r e l i e f m a t e r i a l i s muscovite. Coarse grained m a t e r i a l under c r o s s e d n i c o l s  i s q u a r t z f The banding of the rock shows  up i n both photos. 122 Muscovite occurs as s m a l l l a t h e s and i n some p l a c e s as l a r g e r embayed ragged g r a i n s , a l l a l i g n e d p a r a l l e l w i t h the quartz bands. The p l a g i o c l a s e i s i n extremely s m a l l rounded g r a i n s u s u a l l y l e s s than . 0 1 mm. i n diameter many l e s s than . 0 0 1 mm. Bands of t h i s f i n e g r a i n e d untwinned f e l d s p a r occur between the l a r g e r quartz t a b l s . The f e l d s p a r has a low r e l i e f a g a i n s t the balsam. E p i d o t e i s strun g out as bands of s i n g l e minute g r a i n s one or two of which are l a r g e enough t o show the u s u a l h i g h b i r e f r i n g e n c e and g r e e n i s h y e l l o w t i n t of the ep i d o t e common i n the rocks of the a r e a . T h i s rock has undergone severe c a t a c l a s t i c meta-morphism t o produce the banding cf coarse q u a r t z , muscovite.-..arid f i n e p l a g i o c l a s e . The assemblage of a l b i t e s o d i c o l i g o c l a s e , q u a r t z , muscovite and epidote f i t s none of the metamorphic f a c i e s . 0 r - 1 7 i s another f i n e - g r a i n e d rock, taken about a m i l e east of ZJ-18. In hand specimen i t i s f i n e - g r a i n e d , t h i n banded and has a cleavage p a r a l l e l t o the banding. G l i s t e n i n g p l a t e s o f g r e e n i s h mica are v i s i b l e on the cleavage p l a n e s . H a l f of the bands i n the rock are green due to f i n e l y d i v i d e d c h l o r i t e and g r e e n i s h muscovite, the other h a l f o f the bands are white w i t h many brown i r o n s t a i n s , and many v o i d s produced by weathering and removal of s o l u b l e m a t e r i a l . A t h i n s e c t i o n o f 0 r - 1 7 c o n t a i n s : q u a r t z , 60%; 123 f e l d s p a r , 25$; c h l o r i t e , 10$; w i t h y e l l o w i r o n o x i d e s , muscovite, b i o t i t e , and some opaque g r a i n s . The quartz occurs mostly as very f i n e m a t e r i a l w i t h even f i n e r f e l d s p a r s , m y l o n i t e between the g r a i n s . A few bands and l e n s e s of coarse quartz g r a i n s are p r e s e n t . Some of these coarse quartz bands are surrounded by bands o f coarse c h l o r i t e g r a i n s . The rounded specks of f e l d s p a r are too f i n e t o show twinning but they have a s l i g h t l y p o s i t i v e r e l i e f a g a i n s t balsam hence must be a p l a g i o c l a s e , p o s s i b l y o l i g o c l a s e . C h l o r i t e occurs i n bands of rods and blades a l l a l i g n e d w i t h the banding of the rock. One or two of the c h l o r i t e bands have remnants of b i o t i t e g r a i n s i n them. Muscovite g r a i n s are ragged and embayed, and are more or l e s s p a r a l l e l to the s c h i s t o s i t y . Red opaque i r o n oxides and s o l u t i o n p i t s formed by weathering occur abundantly i n one h a l f of the s l i d e . Such areas of the s l i d e c o n t a i n much l e s s c h l o r i t e than other a r e a s . The extremely f i n e g r a i n of these two rocks may be an o r i g i n a l sedimentary t e x t u r e , that i s , the parent rock may have been a s i l t s t o n e o r , on the other hand, the f i n e g r a i n may be a r e s u l t of extreme c a t a c l a s t i c deformation. C e r t a i n l y both the rocks have been deformed and r e c r y s t a l l i z e d . S i m i l a r t e x t u r e s , but on a l a r g e r s c a l e , occur i n the g n e i s s , where they are undoubtedly r e l a t e d to deformation. 124 Prospect H i l l Group T h i s group of rocks c o n s i s t s of q u a r t z i t e , s c h i s t , p h y l l i t e , c a l c a r e o u s beds, and some ve r y f i n e g r a i n e d rocks termed s i l t s t o n e . Outcrops of these rocks are thin-bedded w i t h a prominent j o i n t i n g p a r a l l e l to the bedding. Most o f them are extremely f i n e g r a i n e d , and a r e commonly of dark c o l o u r . U s u a l l y they show two and sometimes three d i r e c t i o n s of crumpling on the bedding p l a n e s . A number of specimens of these rocks were s t u d i e d . P-2 i s a f i n e g r a i n e d hard b l a c k rock w i t h an im-p e r f e c t s l a t y cleavage. Cleavage planes are covered by ex-tremely s m a l l , g l i s t e n i n g , g r e y - b l a c k p l a t e s of mica. One s i d e of the rock i s coated w i t h c a l c i t e c o n t a i n i n g a few p y r i t e g r a i n s . A t h i n s e c t i o n o f P-2 c o n t a i n s : q u a r t z , 35$; s e r i c i t e , 20$; b i o t i t e , 10$; magnetic m a t e r i a l , 4$; c h l o r i t e , 10$; f l a k e s of b l a c k opaque m a t e r i a l , probably g r a p h i t e , 20$. Intense f o l d i n g on a s m a l l s c a l e has crumpled the rock, as shown i n F i g u r e 67. The quartz i s i n g r a i n s o f .1 to 0.1 mm. i n l e n g t h , by about one h a l f the l e n g t h i n w i d t h . These quartz tabs are a l i g n e d i n bands, w i t h bands of micaceous material'. A l l of the quartz g r a i n s are more or l e s s a ngular. 125 F i g u r e 6 7 . Photomicrograph of P-2 c r o s s e d n i c o l s X - 1 6  The crumpling of the rock and the elongate  quartz tabs are c l e a r l y shown. The s e c t i o n  shown i s normal to the f o l d a x i s . Most of the micas occur as minute s c a l e s between the quartz bands, w i t h here and there some l a r g e r g r a i n s t h a t can be i d e n t i f i e d as b i o t i t e , s e r i c i t e , or c h l o r i t e . A few l a r g e c h l o r i t e g r a i n s seem to be the beginning of augens, as the g r a i n of the rock flows around them as i f i t has been f o r c e d a s i d e . Opaque black g r a i n s occur mixed w i t h the mica, making the i d e n t i f i c a t i o n of the v a r i o u s micas even more d i f f i c u l t . T h i s opaque m a t e r i a l i s probably g r a p h i t e as i t i s not magnetic and i s f a i r l y s o f t . G rains of an opaque magnetic m a t e r i a l occur f a i r l y abundantly i n the s l i d e . They have a s l i g h t bronze t i n g e under r e f l e c t e d l i g h t and are probably p y r r h o t i t e , perhaps, w i t h some g r a i n s of magnetite, as some of the m a t e r i a l i s v e r y h i g h l y magnetic. T h i s rock i s a p h y l l i t e . P - 3 i s a f i n e - g r a i n e d , g r e y - b l a c k , t h i n banded p h y l l i t e w i t h a pronounced s l a t y cleavage. Green, brown, and b l a c k micaceous p a r t i c l e s are v i s i b l e on the bedding p l a n e s . On one s i d e , which c r o s s cuts the bedding, minute g r a i n s of p y r i t e can be seen s c a t t e r e d through the rock. Two d i r e c t i o n s o f crumples are v i s i b l e on the bedding p l a n e s . A t h i n s e c t i o n of P - 3 c o n t a i n s : q u a r t z , 50$; p l a g i o -c l a s e , 10$; mica, 20$; c a l c i t e , 3$; c h l o r i t e , 2$; g r a p h i t e , 10$; p y r i t e , 5$. The rock i s , a g a i n , extremely f i n e - g r a i n e d , and con-s i s t s o f elongate and rounded g r a i n s o f quartz i n bands set o f f by bands of mica. P l a g i o c l a s e i s i n minute rounded g r a i n s which are abundant a l o n g a few zones i n the rock. The micas are b i o t i t e and s e r i c i t e , but they are'so f i n e t h a t i t i s i m p o s s i b l e to say where one begins and the other ends. Flakes and s c a l e s of b l a c k opaque m a t e r i a l occurs along some of the f o l i a . T h i s i s probably g r a p h i t e as i t i s not magnetic. C a l c i t e occurs s p a r i n g l y as i r r e g u l a r g r a i n s s c a t t e r e d through the rock, and i s l o c a l l y abundant as elongate g r a i n s i n c a l c a r e o u s bands, f o r p a r t i n g s . Large g r a i n s o f p y r i t e are present here and there i n the rock. The f o l i a t i o n passes 127 through the g r a i n s which, t h e r e f o r e , must be l a t e m i n e r a l s . (See F i g u r e 68). F i g u r e 6 8 . Photomicrograph of P - 3 plane p o l a r i z e d l i g h t X 8 0  A l a r g e g r a i n of p y r i t e . b l a c k , has grown across  the f o l i a t i o n which i n p l a c e s p r o j e c t s i n t o the  g r a i n . A cross f r a c t u r e c r o s s e s the s l i d e but  passes through the g r a i n s without d i s t u r b i n g i t . The extremely f i n e - g r a i n e d nature of P - 3 i s a l s o  shown by t h i s photo. Bands of a murky-yellow, h i g h r e l i e f , h i g h b i r e -f r i n g e n t m a t e r i a l occur along a number o f zones; u s u a l l y a s s o c i a t e d w i t h c a l c i t e . Such m a t e r i a l may be e p i d o t e . P-5 i s a b l a c k p h y l l i t i c , i n t e n s e l y drag f o l d e d specimen of rock. F i g u r e 69 shows t h i s i n t e n s e f o l d i n g and the l a r g e amounts of opaque m a t e r i a l i n the rock. Some mica can be seen i n the hand specimen but the great amount of b l a c k opaque m a t e r i a l masks most of the mica and a l l the other m i n e r a l s . F i g u r e 69. Microphotograph o f P-5 plane p o l a r i z e d l i g h t X 15  Intense drag f o l d i n g w i t h a s t r a i n s l i p c leavage, impressed across the f o l i a t i o n . The b l a c k mater-i a l Is opaque, probably g r a p h i t e , the white  m a t e r i a l i s extremely f i n e - g r a i n e d q u a r t z . T h i n s e c t i o n shows P-5 to c o n t a i n : quartz 60$; g r a p h i t e , 25$; mica, 15$; w i t h minor amounts of c h l o r i t e and i r o n oxide. The quartz i n the specimen i s i n s i l t s i z e t a b s , many of them ten times as long as they are wide. (See f i g u r e 69). The micas are i n extremely f i n e l a t h e s , w i t h s e r i c i t e probably predominant, as most of the m a t e r i a l i s c o l o u r l e s s and has a h i g h b i r e f r i n g e n c e . So much opaque m a t e r i a l i s mixed w i t h the micas that any i d e n t i f i c a t i o n i s d i f f i c u l t . Red brown i r o n oxides are conc e n t r a t e d along one s i d e of the s l i d e . Along t h i s zone the micas have a l t e r e d to c h l o r i t e , p o s s i b l y as a r e s u l t of weathering. Textures present i n the rocks d i s c u s s e d above i n d i c a t e extreme dynamic metamorphism, but the m i n e r a l s p r e s e n t suggest that a v e r y low r a t e of thermal metamorphism accompanied the deformation. C h l o r i t e s c h i s t s , q u a r t z i t e , and s e r i c i t e s c h i s t are a l s o present i n the Prospect H i l l group but only a specimen o f extremely f i n e - g r a i n e d q u a r t z i t e was taken. B - 9 9 i s an extremely f i n e - g r a i n e d q u a r t z i t e w i t h a l t e r n a t i n g cream and grey b l a c k bands. The dark bands appear to owe t h e i r c o l o u r to f i n e l y d i v i d e d g r a p h i t i c m a t e r i a l . They are much s o f t e r than the cream c o l o u r e d bands. The band-i n g , sketched i n F i g u r e 7 0 , appears to be an o r i g i n a l s e d i -mentary f e a t u r e . F i g u r e 7 0 . Sketch of B - 9 9 showing sedimentary banding. I v h i t e - p i n k i s h f i n e - g r a i n e d q u a r t z i t e , b l a c k f i n e - g r a i n e d b l a c k g r a p h i t i c m a t e r i a l 130 Calcareous Rocks Calcareous rocks are r e l a t i v e l y r a r e i n the E c s t a l l septum. The t h i c k e s t s e c t i o n o f such rocks so f a r found crops out i n a steep g u l l y on the west side' o f a n o r t h - s o u t h t r e n d i n g r i d g e about a m i l e and a h a l f south o f Barbara l a k e . These rocks c o n s i s t o f : blue grey c r y s t a l l i n e l i m e s t o n e , which co n t a i n s narrow quartz r i c h bands; s i l i c e o u s l i m e s t o n e ; g a r n e t i f e r o u s limestone; b i o t i t e s c h i s t ; b i o t i t e f e l d s p a r s c h i s t ; b i o t i t e - h o r n b l e n d e s c h i s t ; and q u a r t z i t e ; a l l s t r i k i n g due n o r t h and d i p p i n g about 35° west, more or l e s s p a r a l l e l w i t h the h i l l s i d e . An a c c u r a t e estimate of the t h i c k n e s s o f the limy beds could not be made because they have been r e -peated by s m a l l s c a l e f o l d i n g , but limestone and l i m y rocks appear i n the g u l l y w a l l between e l e v a t i o n s o f 775 and 960 f e e t and again between 1290 and 1400 f e e t . These are e i t h e r two separate c a l c a r e o u s l a y e r s o r , perhaps, one l a y e r repeated by l a r g e s c a l e f o l d i n g or f a u l t i n g . As w e l l as the s m a l l s c a l e f o l d i n g , which i s i n the order o f 10 to 20 f e e t from c r e s t t o c r e s t , the rocks are s t r o n g l y drag f o l d e d and some have a l s o c r e n u l a t i o n s on the bedding planes (see F i g u r e 73) . G r a n i t e dykes, o f f shoots o f the B a r b a r a l a k e g r a n o d i o r i t e which i s onl y 30 or 40 f e e t n o r t h o f the creek bed, have i n t r u d e d the limestone (see F i g u r e 71). 131 PI a n F i g . 71 Sketch of limestone outcrops i n creek bed on t h e west edge of the Barbara Lake q u a r t z i t e . 132 T h i n s e c t i o n s of two of the limestones from t h i s area were s t u d i e d . Or- 1 2 i s a specimen of b l u i s h grey c o a r s e l y c r y s t a l l i n e limestone showing bands of r e s i s t a n t quartz r i c h m a t e r i a l which have weathered out t o form r i d g e s on i t s s u r f a c e . A t h i n s e c t i o n of Or- 1 2 c o n t a i n s : c a l c i t e , 80$; q u a r t z , 15$; w i t h muscovite, c h l o r i t e t r e m o l i t e , d i o p s i d e , c l i n o z o i s i t e , and some opaque m a t e r i a l i n c l u d i n g a few g r a i n s of p y r i t e . C a l c i t e occurs as l a r g e s t r a i n e d and twinned anhedral c r y s t a l s w i t h rounded q u a r t z - g r a i n - i n c l u s i o n s . ( F i g u r e 73). The r e s i s t a n t zones c o n t a i n a h i g h percentage of these rounded quartz g r a i n s , up to 50$ or more. These rounded g r a i n s are o b v i o u s l y of sedimentary o r i g i n . Some gr a i n s of q u a r t z i t e , rounded l i k e the other quartz sand g r a i n s a r e a l s o p r e s e n t . Rounded g r a i n s of c h l o r i t e are f a i r l y abundant, they c o n s i s t of sheaves of l i g h t green t i n t e d , low b i r e f r i n g e n t , l a t h e s . A few blades of f r e s h muscovite, and a few g r a i n s of b i r e f r i n g e n t almost c o l o u r l e s s mica are p r e s e n t . T r e m o l i t e , i n almost c o l o u r l e s s l a t h e s and diamond-shaped c r o s s s e c t i o n s which show t y p i c a l amphibole cleava g e , occurs w i t h i n c r y s t a l s of c a l c i t e and i n one or two p l a c e s along the edges of c a l c i t e c r y s t a l s . In one p l a c e there i s a c o n c e n t r a t i o n o f h a l f a dozen of these g r a i n s . 1 3 3 F i g u r e 72. Photomicrograph o f Or-12 plane p o l a r i z e d l i g h t  X-16. The l a r g e g r a i n s o f h i g h r e l i e f "material  shoving t y p i c a l carbonate cleavage i s c a l c i t e . The rounded c l e a r g r a i n s a r e q u a r t z . Note the  abundance of quartz over c a l c i t e i n one end of  the photo, t h i s i s a r e s i s t a n t quartz r i c h band. The b l a c k spots are opaque g r a i n s o f p y r i t e and  magnetite. Minute c o l o u r l e s s h i g h b i r e f r i n g e n t g r a i n s shoving two cleavages at r i g h t angles occur i n t e r s t i t i a l l y to the c a l c i t e g r a i n s . T h i s m a t e r i a l i s a pyroxene, probably d i o p s i d e . A f e v f a i r l y l a r g e g r a i n s of c o l o u r l e s s c l i n o z o i s i t e are present along quartz r i c h zones i n the s e c t i o n . These gr a i n s d i f f e r from t r e m o l i t e i n being completely c o l o u r l e s s , having o n l y one cleavage, and because they are i n much l a r g e r i n t e r s t i t i a l g r a i n s v h i c h are not as a c c i c u l a r as the amphi-b o l e . They d i f f e r from the pyroxene i n being much l a r g e r , 134 having a greyer colour, lower birefringence and p a r a l l e l or near p a r a l l e l extinction i n a l l grains showing cleavage. Or-13 i s th i n bedded blue grey limestone si m i l a r to Or-12, but f i n e r i n grain s i z e . Folded quartz r i c h bands have weathered out on the surface as shown i n Figure 73. P y r i t e , present i n the quartz bands, has weathered and the iron oxide produced has stained the bands brown. A th i n section of Or-13 contains the same minerals as did Or-12 but there i s more c l i n o z o i s i t e , tremolite, and diopside, and the c h l o r i t e i s a green rather than a grey colour. Figure 73. Sketch of Or-13 shows crumpled beds of quartz-r i c h material between thicker beds of limestone. C a l c i t e the main mineral occurs as large strained and twinned anhedral c r y s t a l s with again, many rounded quartz-sand-grain inclusions. The other minerals are the same as i n Or-12. The diopside, which occurs along c a l c i t e grain 135 boundaries has i r r e g u l a r corroded boundaries and one or two of these d i o p s i d e g r a i n s c o n t a i n b i t s o f m a t e r i a l showing amphibole cleavage s u g g e s t i n g a l t e r a t i o n from one m i n e r a l t o the o t h e r . S t r a i n e d c a l c i t e and s t r o n g l y crumpled quartzoee bands i n d i c a t e t h i s rock has been i n t e n s e l y deformed. Larger s c a l e f o l d i n g and drag f o l d i n g a re present i n the outcrops o f both Or-12 and Or - 1 3 . The m i n e r a l o g i c a l a s s o c i a t i o n o f q u a r t z , c a l c i t e , ( c l i n o z o i s i t e ( ? ) , ) d i o p s i d e and t r e m o l i t e suggest the rocks have passed step 3 but not step 4 i n Bowen 1s 13 steps o f p r o g r e s s i v e metamorphism of a s i l i c e o u s d o l o m i t e . Thus these rocks have never been subjected t o a h i g h temperature, and the stage o f metamorphism reached corresponds to t h a t present i n the g n e i s s , q u a r t z i t e , and s c h i s t s ; some of which are hundreds of times f a r t h e r from the igneous contact than these l i m e s t o n e s . O r i g i n a l l y the limestone was v e r y low i n magnesium, -assuming none was removed by metasomatic e f f e c t s , - or there would be much more t r e m o l i t e and d i o p s i d e p r e s e n t . The brown p o r p h y r o b l a s t s of garnet present i n some of the l i m y beds may be products of the same metamorphism that produce the d i o p s i d e and t r e m o l i t e ; or the garnet may be a product o f c o n t a c t metamorphism by the g r a n o d i o r i t e . S e r i c i t e and c h l o r i t e i n the rocks r e p r e s e n t s r e -t r o g r e s s i v e metamorphism p a r a l l e l i n g t h a t observed i n the & Bowen, N.L. P r o g r e s s i v e Metamorphism o f a S i l i c e o u s Lime-stone and Dolomite. 136 other rock groups. Perhaps t h i s i s r e l a t e d to the i n t r u s i o n of g r a n o d i o r i t e . T h i n beds of limestone and impure limestone have been noted i n v a r i o u s p l a c e s i n the E c s t a l l septum. Such beds are p a r t i c u l a r l y abundant i n the K i t k i a t a s c h i s t , where they crop out along the Douglas Channel shore. In many outcrops l e n s e s of limy m a t e r i a l have become segregated at the c r e s t of f o l d s . F i g u r e 74 below i s a s k e t c h of one such occurrence t h a t i s p a r t i c u l a r l y w e l l developed. F i g u r e 74. S k e t c h of f o l d e d rocks v i t h limestone segregated  at the c r e s t s of the f o l d s . ZJ-29 Is a specimen of b l a c k carbonaceous l i m e s t o n e from the K i t k i a t a s c h i s t s on Douglas Channel. One s i d e o f the specimen has a l a y e r of g r a p h i t e along i t . Carbonaceous 137 matter i s probably r e s p o n s i b l e f o r the b l a c k c o l o u r of the rock. Numerous narrow white i n t e r s e c t i n g v e i n l e t s cut the specimen. A t h i n s e c t i o n of ZJ-28 c o n t a i n s : c a l c i t e , 70$; q u a r t z , 20$; carbonaceous matter, 10$; w i t h a few l a t h e s of muscovite. The c a l c i t e occurs as s m a l l cloudy g r a i n s , except along the v e i n l e t s where i t occurs as l a r g e c l e a n a n h e d r a l c r y s t a l s . The v e i n l e t s c o n t a i n about 60$ quartz and 40$ c a l c i t e . Undoubtedly the c a l c i t e i n the v e i n s r e p r e s e n t s o r i g i n a l sedimentary c a l c i t e r e c r y s t a l l i z e d and cleaned by the s o l u t i o n s that brought i n the q u a r t z . The dark m a t e r i a l c l o u d i n g the c a l c i t e i n the main r o c k mass i s probably f i n e l y d i v i d e d g r a p h i t e . Quartz i s a l s o present.: i n the main p a r t of the rock where i t occurs s e p a r a t e l y as s m a l l rounded g r a i n s i n s m a l l groups, and a l s o i n one or two t h i n bands. T h i s m a t e r i a l i s o r i g i n a l quartz sand g r a i n s . B-54, a specimen of sugary t e x t u r e d b r i g h t green d i o p s i d e - q u a r t z rock which c o n t a i n s a few l a r g e brown g a r n e t s , i s v i s i b l e from the shore of Douglas Channel. A t h i n s e c t i o n shows the rock i s composed of: d i o p s i d e , 55$; q u a r t z , 30$; and garnet, 15$; The d i o p s i d e i s i n s l i g h t l y g r e e n i s h - t i n t e d , equant shaped, hi g h r e l i e f , subhedral c r y s t a l s which show: 2 cleavages at r i g h t angles; one cleavage to which the e x t i n c t -i o n i s moderate to h i g h l y i n c l i n e d ; or no cleavage a t a l l . 1 3 8 N e i t h e r quartz nor garnet g r a i n s show any s i g n s o f s t r a i n or f r a c t u r e . T h i s rock may o r i g i n a l l y have been s i l i c e o u s d o l o mite. F i g u r e 7 5 . Photomicrograph o f B - 5 4 plane p o l a r i z e d l i g h t , X 8 0 . The h i g h r e l i e f g r a i n s showing; i n some  g r a i n s two cleavages at r i g h t angles are  d i o p s i d e ; the c o l o u r l e s s m a t e r i a l i s q u a r t z . A few t h i n limestone beds and many l i m y - p h y l l i t e beds were found i n the Prospect H i l l group on the west s i d e o f the h i l l . S i m i l a r beds occur f a r t h e r west i n the Mine S e r i e s . Perhaps limestone i s much more common i n the area than i t appears to be but i t weathers r a p i d l y and thus does form good outcrops. Beds and le n s e s o f c l i n o z o i s i t e r i c h rocks are common 1 3 9 i n both q u a r t z i t e and g n e i s s . Such beds may r e p r e s e n t sediments o r i g i n a l l y r i c h i n l i m e s t o n e . B-79 i s a specimen o f q u a r t z - c l i n o z o i s i t e rock from near the top o f the r i d g e j u s t west of E c s t a l l Lake. T h i s rock was interbedded w i t h the Quaal g n e i s s . The specimen i s h a l f green e p i d o t e r i c h bands w i t h quartz r i c h i n t e r b a n d s and h a l f grey b l a c k quartz w i t h o n l y a few green e p i d o t e r i c h bands. A t h i n s e c t i o n cut normal t o the banding c o n t a i n s : q u a r t z , 40$; c l i n o z o i s i t e , 35$; p l a g i o c l a s e , 15$; s e r i c i t e , 8$; b i o t i t e , s e r i c i t e , p y r i t e , and i r o n o x i d e s . C l i n o z o i s i t e occurs i n bands of y e l l o w t i n t e d , weakly p l e o c h r o i c g r a i n s and aggregates of g r a i n s w i t h l a r g e quartz g r a i n s between the bands. Many of the quartz bands c o n t a i n bands showing un-d u l a t o r y e x t i n c t i o n . A l l the micas are a l i g n e d p a r a l l e l t o the quartz epidote bands. A l s o present are a few g r a i n s of p y r i t e which are o x i d i z e d to l i m o n i t e a l o n g the f r a c t u r e s and g r a i n boundaries. Most of the f e l d s p a r i s i n minute rounded g r a i n s w i t h hazy boundaries. S i m i l a r m a t e r i a l i s common i n a l l the i n -t e n s e l y deformed rocks o f the E c s t a l l septum. Large c o l o u r -l e s s irregular-embayed g r a i n s of muscovite are present as are sm a l l e r l a t h l i k e g r a i n s of s e r i c i t e which has a much lower b i r e f r i n g e n c e . Some of the l a t t e r g r a i n s have b i t s o f b i o t i t e i n them suggesting they are an a l t e r a t i o n o f b i o t i t e . Z J - 1 7 i s a specimen of e p i d o t e - q u a r t z rock from a 140 l e n s e i n the Quaal R i v e r gneiss near Sporran Lake. The hand specimen i s a sugary t e x t u r e d , even green c o l o u r e d rock. Numerous b i o t i t e f l a k e s along two p a r a l l e l s i d e s may re p r e s e n t planes o f f o l i a t i o n or bedding. In t h i n s e c t i o n ZJ-17 c o n s i s t s o f : c l i n o z o i s i t e , 85$; q u a r t z , 10-12$; and some b i o t i t e . The c l i n o z o i s i t e i s present as elongate g r a i n s showing p a r a l l e l or near p a r a l l e l ex-t i n c t i o n a g a i n s t the u s u a l l y w e l l developed (001) cle a v a g e , and as end s e c t i o n s which o f t e n show a p a r t i n g as w e l l as a cleavage. Some equant g r a i n s show l i t t l e cleavage or p a r t i n g . Some s e c t i o n s showing good cleavage are twinned. Quartz i s present i n s m a l l i r r e g u l a r g r a i n s , some i n bands, o t h e r s s e p a r a t e l y . The b i o t i t e occurs as s m a l l i r r e g u l a r g r a i n s showing deep green c o l o u r and marked pleochroism. Many other types of rocks s l i g h t l y h i g h e r i n CaO are present i n the E c s t a l l Septum. Some of these have been d i s c u s s e d under the Douglas Channel g n e i s s , others under K i t k i a t a s c h i s t . A group o f rocks that are abnormally h i g h i n CaO are interbedded w i t h the K i t k i a t a Lake g n e i s s . Two unusual specimens of these rocks w i l l be d i s c u s s e d below. W-10 was taken from a zone i n the K i t k i a t a Lake gneiss very near the contact w i t h the K i t k i a t a lake stock. The hand specimen has a marked g r e e n i s h cast induced by the numerous l a r g e needles and l a t h e s of dark green hornblende and the much f i n e r g rained and l i g h t e r green c l i n o z o i s i t e . ( F i g u r e ? 6 ) . A gew g r a i n s o f f e l d s p a r and q u a r t z a re presen t forming bands 1 4 1 and s m a l l c l o t s i n the rock. Two forms of hornblende occur, one forms broad l a t h e s which l i e i n a plane g i v i n g a crude f o l i a t i o n , the other form i s a c i c u l a r and these g r a i n s are more or l e s s p e r p e n d i c u l a r to the f o l i a t i o n . F i g u r e 7 6 . Photograph o f p o l i s h e d s u r f a c e of W-10 showing  r a d i a t i n g needles of hornblende and l i g h t  f e l d s p a r bands i n a predominantly c l i n o z o i s i t e  ground mass. A t h i n s e c t i o n o f W - 1 0 c o n t a i n s the f o l l o w i n g m i n e r a l s : c l i n o z o i s i t e , 5 5 to 6 0 $ ; hornblende, 25$; p l a g i o c l a s e , 1 0 $ ; q u a r t z , 5 $ ; spene, 3 $ ; and a few scraps of b i o t i t e . Horn-blende, deep blue-green cleavage, N-S, yellow-green cleavage E-W, i s s i m i l a r t o the hornblende i n the K i t k i a t a s c h i s t and the Douglas Channel g n e i s s . Probably i t i s a low aluminum h i g h c a l c i u m member. I t occurs as long a c i c u l a r and p r i s m a t i c 142 c r y s t a l s , some an i n c h long by a q u a r t e r i n c h wide. A l l are subhedral showing a t y p i c a l hornblende c r y s t a l form but no r e g u l a r f a c e s , f o r t h e i r c o n t a c t s w i t h other m i n e r a l s are ragged, and embayed. Most of the hornblende c o n t a i n s i n c l u s -ions o f c l i n o z o i s i t e , and some g r a i n s have long t r a i n s o f c l i n o z o i s i t e which may form up to 10% of the a r e a enclosed w i t h i n the g r a i n boundaries. (See F i g u r e 7 7 ) . F i g u r e 7 7 * Photomicrograph of W-10 plane p o l a r i z e d l i g h t  X 40. Lar> e hornblende l a t h e s , one w i t h a  t r a i n of c l i n o z o i s i t e g r a i n s along i t s c e n t e r  and surrounded by h i g h r e l i e f , grey m a t e r i a l , c l i n o z o i s i t e , and c o l o u r l e s s white m a t e r i a l  f e l d s p a r . C l i n o z o i s i t e i s i n s m a l l a n h e d r a l , h i g h r e l i e f , almost c o l o u r -l e s s g r a i n s . Small diamond-shaped p o i k i l o b l a s t i c sphene c r y s t a l s (see F i g u r e 7 8 ) are abundant i n the c l i n o z o i s i t e . Quartz 143 occurs as s m a l l , u n s t r a i n e d , i r r e g u l a r g r a i n s , i n t e r s t i t i a l to the hornblende and c l i n o z o i s i t e . Together w i t h the p l a g i o -c l a s e , which i s i n l a r g e , w e l l twinned p o r p h y r o b l a s t s and groups of p o r p h y r o b l a s t s , the quartz forms i r r e g u l a r bands more or l e s s p a r a l l e l to the f o l i a t i o n . F i g u r e 78. Photo micrograph of W-10 plane p o l a r i z e d l i g h t  showing a l a r g e diamond-shaped p o i k i l o b l a s t  c r y s t a l of sphene surrounded by hornblende  blades and s m a l l g r a i n s of c l i n o z o i s i t e . P l a g i o c l a s e s e c t i o n s x to (010) gave maximum angles of 18° f o r X ' A (010), f o r An^cj ( a n d e s i n e ) . The r e l i e f i s n e g a t i v e or p o s i t i v e a g a i n s t quartz depending on the o r i e n t a t i o n . The m i n e r a l content of t h i s rock i n d i c a t e s i t may c o n t a i n up to 20 or 2% CaO. The c l i n o z o i s i t e i t s e l f would 144 c o n t a i n about 1% of the mass of the rock as CaO. CaO i s abundant i n the sphene, hornblende and andesine. The h i g h content of CaO suggests the rock was o r i g -i n a l l y a c a l c a r e o u s sediment. The m i n e r a l s present c o r r -espond to the amphibolite f a c i e s about the same l e v e l of metamorphism as the s c h i s t s and g n e i s s e s . Specimen Or-25 was obtained two m i l e s south o f W-10, on the east s i d e o f K i t k i a t a Lake. V e r y l a r g e p l a t e l i k e hornblende p o r p h y r o b l a s t s are v i s i b l e i n the hand specimen. Some of them are inches long and up to an i n c h t h i c k . One very l a r g e hornblende c r y s t a l cut by f r a c t u r e s and a l t e r e d t o c h l o r i t e and s e r i c i t e i s v i s i b l e on a p o l i s h e d f a c e o f Or-25, (see F i g u r e 79). F i g u r e 79. Photograph of Or-25. One very l a r g e hornblende  g r a i n forms a c o n s i d e r a b l e part of the s e c t i o n  shown. B l a c k areas are hornblende, grey areas  c h l o r i t e - s e r i c i t e - q u a r t z which i n pa r t i s an a l t e r a t i o n o f the l a r g e hornblende g r a i n . 1 4 5 P o r p h y r o b l a s t s of garnet and magnetite and a few c r y s t a l s o f p y r i t e can be seen on the p o l i s h e d s u r f a c e . A t h i n s e c t i o n o f O r - 2 5 c o n t a i n s J q u a r t z , 3 0 $ ; p l a g i o c l a s e , 3 0 $ ; hornblende, 1 5 $ ; muscovite, 1 0 $ ; c h l o r i t e , 5 $ ; c l i n o z o i s i t e , 5 $ ; garnet, 3 $ ; magnetite, 2 $ ; w i t h a few g r a i n s of p y r i t e and b i o t i t e . Hornblende i s present i n g i g a n t i c s i e v e t e x t u r e d p o r p h y r o b l a s t s . I t shows the blue green c o l o u r t y p i c a l o f most of the hornblendes i n the E c s t a l l r o c k s . A l t e r a t i o n to c h l o r i t e and perhaps b i o t i t e and s e r i c i t e i s common (see f i g u r e s 7 9 , 8 0 , 8 1 ) . Quartz forms most of the i n c l u s i o n s i n the hornblende. F i g u r e 8 0 . Photomicrograph of O r - 2 5 plane p o l a r i z e d l i g h t X 16 showing one s m a l l p a r t of a'very l a r g e s i e v e  t e x t u r e d hornblende g r a i n . S m a l l areas of c h l o r - i t e a l t e r a t i o n are v i s i b l e along some edges of the  g r a i n . Quartz forms most of the i n c l u d e d m a t e r i a l but magnetite i s a l s o p r e s e n t . 146 C h l o r i t e , s e r i c i t e and a few scraps of b i o t i t e occur i n a l t e r e d zones along the cleavage of the hornblende g r a i n s and i n areas s e p a r a t i n g l a r g e p i e c e s o f o p t i c a l l y continuous hornblende which may have been one continuous c r y s t a l , or at l e a s t grey i n the same c r y s t a l l o g r a p h i c o r i e n t a t i o n . F i g u r e 81. Photomicrograph of Or-25 plane p o l a r i z e d l i g h t X16 Pa r t o f same g r a i n as shown i n F i g u r e 80, but here  much more a l t e r e d to c h l o r i t e . Most of the opaque  g r a i n s a r e magnetite. The low r e l i e f c o l o u r l e s s  bands c u t t i n g through the hornblende are s e r i c i t e , the l i g h t grey c h l o r i t e , probably both are an  a l t e r a t i o n o f the hornblende. The p l a g i o c l a s e has a r e l i e f above and below t h a t of qu a r t z , dependong on the r e l a t i v e o r i e n t a t i o n , and g i v e s max-imum angles o f X' A (010) = 21° f o r s e c t i o n j- to (010) - and perhaps J - to a, but th e r e i s no cleavage v i s i b l e - f o r An^Qj andesine. I t occurs as w e l l twinned s l i g h t l y zoned anhedral 147 g r a i n s . Q u a r t z i s p r e s e n t a s s m a l l i r r e g u l a r g r a i n s some s h o w i n g e x t r e m e u n d u l a t o r y e x t i n c t i o n . M o s t o f t h e c l i n o -z o i s i t e i s i n m i n u t e i r r e g u l a r g r a i n s b u t some g r a i n s a r e d i a m o n d s h a p e d c r y s t a l s . M a g n e t i t e i n i r r e g u l a r g r a i n s , c u b i c c r y s t a l s , a n d i n i r r e g u l a r c u b i c s h a p e s , a s s h o w n i n F i g u r e 8 2 o c c u r i n t h e q u a r t z r i c h a r e a s , a n d a l o n g t h e p l a n e s o f a l t e r a t i o n i n h o r n -b l e n d e c r y s t a l s . C r y s t a l s h a p e s a s s h o w n i n F i g u r e 8 2 i n d i c a t e t h e m a g n e t i t e i s a l a t e m i n e r a l . S u c h s h a p e s w o u l d b e d e s t r o y e d b y s t r e s s s u f f i c i e n t t o s t r a i n t h e q u a r t z a n d f r a c t u r e t h e h o r n b l e n d e . T h e g a r n e t s a r e p r e s e n t a s r o u n d e d s h a t t e r e d g r a i n s w i t h c h l o r i t e a n d m u s c o v i t e a l o n g t h e f r a c t u r e s . M o s t g r a i n s o f g a r n e t c o n t a i n i n c l u s i o n s o f q u a r t z a n d e p i d o t e . T h e c o m p o s i t i o n o f t h i s r o c k a s r e v e a l e d b y t h e m i n e r a l s p r e s e n t i s p r o b a b l y n o h i g h e r i n CaO t h a n t h e t y p i c a l K i t k i a t a L a k e g n e i s s , o r f o r t h a t m a t t e r m a n y o f t h e s p e c i m e n s o f D o u g l a s C h a n n e l g n e i s s , b u t i t i s h i g h i n r e l a t i o n t o t h e a v e r a g e c o m p o s i t i o n o f t h e b u l k o f t h e r o c k s , q u a r t z i t e , g n e i s s a n d s c h i s t . T h e m i n e r a l a s s e m b l a g e p r e s e n t i s t h a t o f t h e a m p h i -b o l i t e f a c i e s , s t a u r o l i t e - k y a n i t e s u b - f a c i e s , f o r r o c k s h i g h i n K 2 0 . T h e c h l o r i t e - s e r i c i t e a l t e r a t i o n i s d e f i n i t e l y a l a t e r a l t e r a t i o n , r e p r e s e n t i n g r e t r o g r e s s i v e m e t a m o r p h i s m . T h e b i o t i t e may a l s o b e a l a t e m i n e r a l b u t t h e r e i s n o t e n o u g h o f i t t o b e s u r e . 148 F i g u r e 82. S k e t c h of g r a i n s of magnetite X 200 shoving i r r e g u l a r c u b i c o u t l i n e s s u g g e s t i v e of l a t e  o r i g i n . The m a t e r i a l i n the i n c l u s i o n s , quartz and epidote i s the same as that  surrounding the g r a i n s . Or-21, taken j u s t west of the west arm of B a r b a r a Lake, i s a c a l c - s i l i c a t e g n e i s s . Bands of l i g h t green e p i d o t e are i n t e r l a m i n a t e d w i t h bands of dark-green hornblende. (See F i g u r e 8 3 ) . The rock i s very f i n e g r a i n e d and a l l the 1 4 9 m i n e r a l s are a l i g n e d to produce a s c h i s t o s i t y p a r a l l e l to the g n e i s s i c banding. A few grain s o f f e l d s p a r occur along the c e n t e r of some of the wider epidote bands. F i g u r e 8 3 . Photo of a p o l i s h e d s u r f a c e across the banding  of C T - 2 1 . Dark bands are mostly hornblende. grey bands e p i d o t e , white m a t e r i a l i s probably  f e l d s p a r . A t h i n s e c t i o n o f Or-21 c o n t a i n s : e p i d o t e , 50$; blue-green hornblende, 35$; sphene, 10$; w i t h s m a l l amounts of t r e m o l i t e , f e l d s p a r , and a corroded pyroxene. One or two bands i n the t h i n s e c t i o n have a c o l o u r l e s s corroded and embayed m i n e r a l along them. I t looks v e r y much l i k e the e p i d o t e but i t has a s m a l l e r o p t i c angle, i s opt-i c a l l y p o s i t i v e , and does not show anomalous b i r e f r i n g e n c e . Some of these g r a i n s have two cleavages c l o s e to r i g h t angle 150 to one another. T h i s m a t e r i a l i s probably d i o p s i d e . T h i s rock has probably reached h i g h e r stage i n the metamorphic f a c i e s than most. The m i n e r a l s present suggest i t has undergone r e t r o g r e s s i v e metamorphism from the upper part of the amphibolite f a c i e s to a lower stage i n the same f a c i e s . E p i d o t e i s present i n bands of almost c o l o u r l e s s very i r r e g u l a r g r a i n s . I t shows b r i l l i a n t b e r l i n - b l u e i n t e r -f e r a n c e c o l o u r s and i s o p t i c a l l y n e g a t i v e w i t h a h i g h 2V making i t the v a r i e t y p i s t a c i t e . The hornblende i s i n bands of elongated g r a i n s showing the t y p i c a l c o l o u r s and p l e o -chroism of t r e m o l i t i c hornblende. A few blades of c o l o u r l e s s amphibole are s c a t t e r e d here and t h e r e i n the rock. T h i s m a t e r i a l , most abundant i n the a l t e r e d pyroxene, i s undoubtedly t r e m o l i t e . Some of the t r e m o l i t e needles are h a l f c o l o u r l e s s h a l f blue-green suggesting an a l t e r a t i o n has taken p l a c e . C o l o u r l e s s s p o t s , are present i n many of the l a r g e hornblende g r a i n s . These grade i n t o the blue green p a r t s of the g r a i n s as shown i n F i g u r e 84. Minute rounded diamond shaped c r y s t a l s of sphene are very abundant i n t h i n bands or zones a l l through the rock. Some of these bands pass r i g h t through the i n t e r v e n i n g horn-blende g r a i n s as i n F i g u r e 84. 151 F i g u r e 8 4 . S k e t c h shoving; t r a i n s o f sphene c r y s t a l s c u t t i n g hornblende. A l t e r a t i o n of hornblende  to t r e m o l i t e . Meta-igneous Rocks H o r n b l e n d e - d i o r i t e masses of g r a n i t o i d r o c k i n t r u d e the sedimentary rocks along Prospect H i l l . Most o f these appear to be s i l l s conforming to the f o l i a t i o n o f the meta-sedimentary r o c k s , but some of the l a r g e r bodies appear to be s t o c k - l i k e . No bedding i s evident i n these rocks but many outcrops show an alignment of the hornblende g r a i n s . The con t a c t s of some of the b o d i e s , p a r t i c u l a r l y the s t o c k - l i k e ones, are h i g h l y sheared and c h l o r i t i z e d and resemble the c h l o r i t e s c h i s t s o f the meta-sedimentary r o c k s . These c o n t a c t -shear zones may be the r e s u l t of deformation accompanying the i n t r u s i o n of the h o r n b l e n d e - d i o r i t e masses, or a l t e r n a t i v e l y , the r e s u l t o f deformation accompanying the f o l d i n g and a l t e r -a t i o n o f the a d j o i n i n g sedimentary r o c k s . 152 The h o r n b l e n d e - d i o r i t e has been s t r o n g l y meta-morphosed. A l l o f the o r i g i n a l f e l d s p a r has a l t e r e d t o a mass of e p i d o t e , s e r i c i t e , some c h l o r i t e , and low r e l i e f f e l d s p a r , (probably a l b i t e ) . T h i s a l t e r a t i o n p robably occurred contemporaneously w i t h the metamorphism of the surrounding Prospect H i l l group. T h i n s e c t i o n s of the hornblende d i o r i t e from the Prospect H i l l area ( P - l , B - 9 6 , B-100) a l l show l a r g e , p a r t l y c h l o r i t i z e d , green-brown hornblende g r a i n s surrounded by a mass of s a u s s e r i t i z e d p l a g i o c l a s e . E p i d o t e , s e r i c i t e , and c h l o r i t e i n a groundmass of a l b i t e surround and extend i n t o the corroded and p a r t l y a l t e r e d hornblende g r a i n s i n a manner s u g g e s t i v e o f o p h i t i c t e x t u r e , (See F i g u r e 8 5 ) . F i g u r e 85. Photomicrograph of a t h i n s e c t i o n of hornblende-d i o r i t e showing hornblende, c o l o u r l e s s i n a mass  of s a u s s e r i t i z e d p l a g i o c l a s e . The embayments i n  the hornblende are probably a r e l i c t o p h i t i c  t e x t u r e ^ Plane p o l a r i z e d l i g h t X 16. 153 A h o r n b l e n d e - d i o r i t e rock s i m i l a r t o the Prospect H i l l type occurs south of the Quaal R i v e r . Most outcrops c o n t a i n many rounded i n c l u s i o n s o f metamorphosed sedimentary rock surrounded and veined by hornblende d i o r i t e . In some cases the outcrops are predominately meta-sedimentary rock w i t h many narrow i n t e r s e c t i n g v e i n l e t s of f i n e - g r a i n e d horn-blende d i o r i t e . Such rocks are very s i m i l a r i n many r e s p e c t s to the coarse vent agglomerates found i n some v o l c a n i c areas. W-71 i s a specimen of the hornblende d i o r i t e from the Quaal r i v e r mass. I t i s a medium g r a i n e d , g r a n i t i c t e x t u r e d rock w i t h a v e r y poor f o l i a t i o n . Hornblende, i n v a r y i n g s i z e d g r a i n s , some of them 3/10 of an i n c h l o n g , and f e l d s p a r make up most of the rock which i s dark grey on f r e s h s u r f a c e s , but weathers white. Large b l a c k hornblende c r y s t a l s have weathered out on the s u r f a c e . A l a y e r of bleached rock extends inwards about a q u a r t e r o f an i n c h from the weathered s u r f a c e s . A t h i n s e c t i o n of W-71 c o n t a i n s : p l a g i o c l a s e , 55$; hornblende, 35$; b i o t i t e , 2-3$; e p i d o t e , 1-2$; magnetite, 1-2$; quartz 2-3$; The p l a g i o c l a s e i s i n l a r g e , a n h e d r a l , w e l l twinned c r y s t a l s w i t h i r r e g u l a r l y sutured c o n t a c t s between each other. Some of the g r a i n s show bent twin l a m e l l a e , many have been broken, and two or three appear crushed. Most o f the p l a g i o c l a s e shows normal zoning; a few s e c t i o n s cut more or l e s s p e r p e n d i c u l a r to t h e i r l e n g t h show complex, o s c i l l a t o r y z o n i n g . S e c t i o n s JL to a gave angles o f X'A(OIO) v a r y i n g from 154 20° t o 25° f o r An^g to A n ^ . A s e c t i o n p e r p e n d i c u l a r to X gave ZA ( 0 1 0 ) = 7 3 ° f o r A n 3 4 . The hornblende i s s i m i l a r i n type to that found i n most of the other types o f metamorphis rock but i t has a s l i g h t brownish t i n g e i n some s e c t i o n s . Most g r a i n s show evidence o f s t r a i n . Some are twinned; many bent or broken. Quite a number of hornblende g r a i n s have numerous s m a l l i n -c l u s i o n s of magnetite and most others have some g r a i n s o f magnetite along the co n t a c t s or nearby i n the p l a g i o c l a s e . Evidence o f deformation i s a l s o seen i n the b i o t i t e . S h e a r i n g appears to have taken p l a c e along the cleavage o f many of the g r a i n s and some other g r a i n s have areas o f i r r e g u l a r e x t i n c t i o n . Most of the epidote g r a i n s are much s m a l l e r than the other m i n e r a l g r a i n s . H o r n b l e n d i t e Hornblende r i c h metamorphic rocks occur abundantly i n n e a r l y every one of the major rock u n i t s of the E c s t a l l septum. Two d i s t i n c t i v e types can be r e c o g n i z e d : hornblende g r a n u l i t e , the r a r e r o f the two, i s composed of l a r g e equant c r y s t a l s or g r a i n s o f hornblende w i t h s m a l l amounts of f e l d s p a r and f i n e - g r a i n e d hornblende cement; hornblende s c h i s t , much commoner than g r a n u l i t e , c o n s i s t s of two v a r i a t i o n s ; one made up of a c i c u l a r hornblende g r a i n s a l i g n e d t o give the rock a poor s c h i s t o s i t y , but a p e r f e c t l i n e a t i o n ; the other made up of broad f l a t p l a t e s of hornblende a l i g n e d t o gi v e a p e r f e c t s c h i s t o s i t y , but l i t t l e or no l i n e a t i o n . 155 Hornblende g r a n u l i t e : Rocks made up of l a r g e hornblende g r a i n s s e t i n f i n e r m a t e r i a l and having l i t t l e or no d i r e c t i v e t e x t u r e were found i n two areas of the septum; along Douglas Channel where they are interbedded w i t h the K i t k i a t a s c h i s t s , ( Z J - 4 8 and 4 9 ) ; and near Gordon Lake, where they are interbedded w i t h the Quaal R i v e r g n e i s s , ( W - 6 2 ) . W - 6 2 i s a coarse grained g r e e n i s h rock cut by a band of f e l d s p a r and quartz which spreads out along one s i d e of the specimen i n t o an i r r e g u l a r mass surrounding some o f the hornblende g r a i n s . About 95$ of the rock i s dark green horn-blende, h a l f of i t i n g r a i n s 2 cm. or so i n diameter; the other h a l f as f i n e broken fragments o f hornblende g r a i n s . Most of the l a r g e g r a i n s have rounded c o r n e r s , sutured c o n t a c t s w i t h the cement, and are surrounded by f i n e g r a i n e d m a t e r i a l . On a p o l i s h e d s u r f a c e the l a r g e c r y s t a l s can be seen t o have a l i g h t green c e n t r a l a r e a surrounded by a v e r y dark-green outer rim. S m a l l amounts of p l a g i o c l a s e occur i n t e r s t i t i a l l y t o the hornblende g r a i n s . On one f a c e of the specimen a few of the hornblende g r a i n s have a l t e r e d t o a l i g h t green s o f t micaceous m a t e r i a l , p r o b a b l y c h l o r i t e . Brown b i o t i t e g r a i n s are s c a t t e r e d through the hornblende on one f a c e of the specimen. The rounded c o r n e r s , sutured c o n t a c t s , numerous f r a c t u r e s of the hornblende m e t a c r y s t s , and the zones of f i n e r g r a i n e d m a t e r i a l c u t t i n g through the rock a t t e s t to the extreme 156 m e t a m o r p h i s m t h a t h a s t a k e n p l a c e s i n c e t h e l a r g e c r y s t a l s g r e w . A t h i n s e c t i o n o f W - 6 2 c o n t a i n s ; h o r n b l e n d e , 85$; p l a g i o c l a s e , 10$; e p i d o t e , 5$; a n d a f e w f l a k e s o f b i o t i t e . T h e t h i n s e c t i o n c o n f i r m s t h e e v i d e n c e s e e n i n t h e h a n d s p e c i m e n : t h a t t h e r o c k i s c o m p o s e d o f l a r g e b r o k e n a n d r o u n d e d g r a i n s o f h o r n b l e n d e c e m e n t e d b y s m a l l f r a g m e n t s o f h o r n b l e n d e a n d p l a g i o c l a s e g r a i n s . T h e l a r g e h o r n b l e n d e g r a i n s h a v e l a r g e c e n t r a l a r e a s d a r k e n e d b y s m a l l a m o u n t s o f d u s t y m a t e r i a l a n d s u r r o u n d e d b y c l e a r g r e e n a r e a s a t t h e b o r d e r s o f t h e g r a i n s . T h e p l a g i o c l a s e i s i n l a r g e a n h e d r a l g r a i n s i n t e r -s t i c i a t o t h e h o r n b l e n d e . M a n y o f t h e s e g r a i n s h a v e i r -r e g u l a r a n d s u b h e d r a l c r y s t a l s o f e p i d o t e i n t h e m , a p p a r e n t l y a n a l t e r a t i o n o f t h e p l a g i o c l a s e . A s e c t i o n o f p l a g i o c l a s e J _ t o X ( Z A ( 0 0 1 ) = 2 8 ° ) g a v e a v a l u e o f A n 4 2 f o r t h e a n o r t h i t e c o n t e n t . Z J - 4 8 a n d 4 9 a r e s p e c i m e n s o f c o a r s e g r a i n e d h o r n -b l e n d e g r a n u l i t e f r o m D o u g l a s C h a n n e l . N o . 4 9 i s a f r e s h u n w e a t h e r e d p i e c e c o m p o s e d o f s u b h e d r a l g r e e n y - b l a c k h o r n -b l e n d e c r y s t a l s , some o f t h e m 2 c m . l o n g b y a b o u t 1 c m . i n d i a m e t e r , s e t i n a c e m e n t o f p l a g i o c l a s e , b i o t i t e , a n d f i n e g r e e n m a t e r i a l . N o . 4 8 i s a s i m i l a r s p e c i m e n b u t i t h a s m a n y w e l l f o r m e d h o r n b l e n d e g r a i n s w e a t h e r e d o u t i n t o r e l i e f o n t h e s u r f a c e . A p p a r e n t l y t h e c e m e n t i n g m a t e r i a l i s m o r e e a s i l y w e a t h e r e d a w a y t h a n t h e l a r g e c r y s t a l s . T h e c r y s t a l f a c e s 1 5 7 h a v e a n u n e v e n s t e p p e d a p p e a r a n c e d u e t o t h e v e r y c l o s e l y s p a c e d c l e a v a g e p l a n e s i n t h e c r y s t a l s . M a n y o f t h e c r y s t a l s a p p e a r t o b e i n t e r p e n e t r a t i n g t w i n s . One s i d e o f t h i s s p e c i m e n i s c o v e r e d b y f a u l t g o u g e a n d m u s l i o n s t r u c t u r e . A t h i n s e c t i o n o f Z J - 4 9 c o n t a i n s : h o r n b l e n d e , 85$; p l a g i o c l a s e , 12$; c l i n o z o i s i t e , 5$; c a l c i t e , 2$; b i o t i t e , 1$. T h e h o r n b l e n d e i s m o s t l y i n v e r y l a r g e s u b h e d r a l p o i k i l o b l a s t i c c r y s t a l s , some o f t h e m a r e b r o k e n a n d t h e p a r t s h a v e m o v e d i n r e l a t i o n t o o n e a n o t h e r . A l l o f t h e m a r e s u r r o u n d e d a n d c e m e n t e d t o g e t h e r b y m a n y s m a l l g r a i n s o f c l i n o z o i s i t e , b i o -t i t e , p l a g i o c l a s e , a n d c a l c i t e , w h i c h i n p l a c e s p r o j e c t i n t o t h e h o r n b l e n d e g r a i n s g i v i n g t h e m v e r y r a g g e d b o r d e r s . F r e s h a n h e d r a l g r a i n s o f c l i n o z o i s i t e , c a l c i t e , b i o t i t e a n d a f e w g r a i n s o f p l a g i o c l a s e o c c u r w i t h i n t h e h o r n b l e n d e c r y s t a l s . Some o f t h e s e i n c l u s i o n s h a v e s h a p e s w h i c h h a v e b e e n c o n t r o l l e d b y t h e c l e a v a g e p l a n e s o f t h e h o r n b l e n d e . T h e p l a g i o c l a s e i s p r e s e n t a s v e r y s m a l l a n g u l a r a n h e d r a l g r a i n s . M o s t o f t h e m a r e w e l l t w i n n e d a n d s h o w s l i g h t z o n a l e x t i n c t i o n . A s e c t i o n X t o Z g a v e X A ( O I O ) - 1 3 . 5 ° f o r A n ^ . W-46 i s a r o c k t h a t h a s a t e x t u r e i n t e r m e d i a t e b e t w e e n t h e r o c k d i s c u s s e d a b o v e a n d t h e g r o u p t o f o l l o w , t h e p l a t y h o r n b l e n d e s c h i s t s . I n h a n d s p e c i m e n W-46 i s c o m p o s e d o f 9 0 $ h o r n b l e n d e w i t h 10$ p l a g i o c l a s e a n d t r a c e s o f b i o t i t e . Two s i z e s a n d s h a p e s o f h o r n b l e n d e g r a i n s a r e p r e s e n t . L a r g e 158 stubby metacrysts are enclosed i n much f i n e r elongate blades which bend around and i n p l a c e s p i e r c e the m e t a c r y s t s . A t h i n s e c t i o n of W-46 c o n t a i n s : hornblende 80$; p l a g i o c l a s e , 12$; b i o t i t e , 5$; w i t h sphene, magnetite, and garnet. In the t h i n s e c t i o n the hornblende aga i n appears i n two s i z e s , the l a r g e r g r a i n s are a n h e d r a l , f r a c t u r e d , and surrounded by the much s m a l l e r , s u bhedral to e u h e d r a l , elongate c r y s t a l s which o f t e n p i e r c e the l a r g e r g r a i n s . The s e c t i o n i s cut p e r p e n d i c u l a r to the s c h i s t o s i t y . Hence, t h e r e i s l i t t l e v i s i b l e " f l o w i n g " of the s c h i s t o s e m a t e r i a l around the l a r g e g r a i n s , as i s so w e l l shown on a p o l i s h e d s l i d e of the hand specimen, p a r a l l e l t o the banding. Many of the l a r g e hornblende g r a i n s are r e p l a c e d or a l t e r e d to b i o t i t e along f r a c t u r e s and cleavage p l a n e s . Both s i z e s of hornblende appear e x a c t l y I d e n t i c a l as f a r as o p t i c a l p r o p e r t i e s and c o l o u r are concerned. The p l a g i o c l a s e shows s t r o n g r e v e r s e d z o n i n g . A s e c t i o n cut 1 t o X gave angles of Z A (001) - 1 2 ° ; 1 7 ° ; and 24°; from the c e n t e r outwards, f o r A n 2 2 , An^ 2, and An^g. There i s good evidence, p a r t i c u l a r l y i n the hand specimen, t h a t t h i s rock has undergone two stages of meta-morphism; f i r s t , a p e r i o d of thermal metamorphisn d u r i n g which the l a r g e hornblende metacrysts were formed; and l a t e r , a p e r i o d of s t r o n g dynamic metamorphism when many of the meta-c r y s t s were broken down i n t o f i n e r m a t e r i a l . 159 In g e n e r a l , these coarse g r a i n e d , g r a n u l i t i c t e x t u r e d , hornblende r i c h rocks must have s u f f e r e d much l e s s d e f o r -mation than the s c h i s t s and gneisses t h a t surround them. The t e x t u r e i n d i c a t e s they were c r y s t a l l i z e d i n a low s t r e s s en-vironment and l a t e r deformed. Hornblende s c h i s t : As mentioned above the hornblende s c h i s t i s of two types. The l e a s t common of the two i s the v a r i e t y c o n s i s t i n g of l a r g e elongate p l a t e s g i v i n g the rocks a very good s c h i s t o s i t y . ¥ - 1 7 i s a dark green hornblende s c h i s t taken from the east s i d e of K i t k i a t a Lake. I t i s composed of elongate p l a t e s of hornblende w i t h s m a l l amounts of p l a g i o c l a s e and a few f l a k e s of b i o t i t e . The hornblende i s very s h a r p l y bent i n t o chevron f o l d s , (see F i g u r e 86) w i t h a s t r o n g s t r a i n s l i p cleavage which shows up even i n the hand specimen'. A t h i n s e c t i o n cut p e r p e n d i c u l a r t o the s c h i s t o s i t y of W-17 c o n t a i n s : hornblende, 60$; p l a g i o c l a s e , 30$; b i o t i t e , 5 $ ; q u a r t z , 5 $ ; e p i d o t e , 3$; w i t h opaque p l a t e - l i k e g r a i n s and a few f l a k e s of c h l o r i t e . About a t h i r d of the hornblende appears i n the t h i n s e c t i o n as extremely l o n g b l a d e s , many of them s l i g h t l y bent and f r a c t u r e d . These g r a i n s l i e a t r i g h t angles to the planes of the f o l d axes. The r e s t of the hornblende occurs i n s e c t i o n showing 2 cleavages and hence cut c l o s e to p e r p e n d i c u l a r to the C a x i s . These g r a i n s l i e more or l e s s p a r a l l e l to the f o l d axes, (see F i g u r e 8 6 ) . 160 Many o f the long hornblende blades c o n t a i n a few i n c l u s i o n s of p l a g i o c l a s e and ep i d o t e . A l l the hornblende i s a deep bl u e green v a r i e t y . F i g u r e 86. Photomicrograph of W-17. Plane p o l a r i z e d l i g h t X-16. The p i c t u r e shows the a x i a l r e g i o n of one  of the chevron f o l d s as seen i n t h i n s e & t i o n . Hornblende c r y s t a l s w i t h h i g h r e l i e f l i e i n two  main o r i e n t a t i o n s . Opaque m a t e r i a l i s magnetite. some c o l o u r l e s s quartz and p l a g i o c l a s e . The p l a g i o c l a s e appears as equant g r a i n s and as g r a i n s elongated p a r a l l e l t o the a c i c u l a r hornblende. B i o t i t e , q u a r t z , and opaque l a t h e s are i n a s i m i l a r form. There i s a d e f i n i t e tendency f o r the quartz and p l a g i o c l a s e to be con-c e n t r a t e d towards the a x i a l regions of the c r e n u l a t i o n s . A s e c t i o n o f p l a g i o c l a s e cut J - t o Z gave X A ( 0 1 0 ) = 11.5° f o r An 42« 161 The b i o t i t e l a t h e s are l a t e r than the hornblende as i t has developed along f r a c t u r e s i n the hornblende. A few b i o t i t e g r a i n s a re p a r t i a l l y a l t e r e d t o c h l o r i t e . B-56 i s a hornblende s c h i s t from the Douglas Channel g n e i s s . I t i s almost i d e n t i c a l w i t h ¥ - 1 7 but the hornblende p l a t e s a r e much l a r g e r and the f o l d i n g i s g e n t l e r . S m a l l amounts of b i o t i t e and f e l d s p a r are v i s i b l e i n the hand specimen which i s about 90$ hornblende. A t h i n s e c t i o n cut normal t o the s c h i s t o s i t y and the f o l d axes c o n t a i n s : hornblende, 80$; p l a g i o c l a s e , 10$; q u a r t z , 5 $ ; b i o t i t e , 2$; w i t h t r a c e s o f c l i n o z o i s i t e and s e r i c i t e . Two p r e f e r r e d o r i e n t a t i o n s o f the hornblende g r a i n s are v i s i b l e i n the t h i n s e c t i o n . One s e t of hornblende g r a i n s l i e a l i g n e d p a r a l l e l to the f o l d a x i e s and hence are cut approx-i m a t e l y normal t o t h e i r l e n g t h . The other set l i e s perpen-d i c u l a r t o the f o l d a x i s and appear i n the t h i n s e c t i o n as long b l a d e s . T h i s i s e x a c t l y the same r e l a t i o n s h i p as i n ¥ - 1 7 . The hornblende i s the same deep blue-green v a r i e t y noted i n the other r o c k s . Other m i n e r a l s l i e between the l a r g e hornblende c r y s t a l s , except f o r a few which are enclosed i n the hornblende g r a i n s . A s e c t i o n of p l a g i o c l a s e cut 4 . t o X gave a v a l u e of An 2 5 f o r the a n o r t h i t e content of the: p l a g i o c l a s e , ( Z A ( 0 1 0 ) = 8 1 ° ) . 162 ZJ-24, i s a v e r y f i n e grained v a r i e t y o f hornblende s c h i s t , i t was obtained a m i l e e a s t o f Sporr a n Lake. Very long narrow blades o f hornblende can be seen l y i n g i n p a r a l l e l alignment on the planes o f s c h i s t o s i t y but the bulk o f the m a t e r i a l i s so f i n e t h a t i n d i v i d u a l g r a i n s cannot be seen. The planes o f s c h i s t o s i t y have many bulges on them where the s c h i s t has bent around l a r g e equant g r a i n s of hornblende, (see F i g u r e 8 7 ) . The rock has a p e r f e c t s l a t y cleavage p a r a l l e l to the s c h i s t o s i t y . A t h i n s e c t i o n o f Zj-24 c o n t a i n s : hornblende, 68$, p l a g i o c l a s e , 20$; q u a r t z , 10$; opaque, 2$; w i t h a few b i r e -f r i n g e n t g a r n e t s . Two types o f hornblende g r a i n s a re v i s i b l e i n the t h i n s e c t i o n o f ZJ-24. One i s i n l a r g e h i g h l y deformed equant g r a i n s , ( F i g u r e 87) and shows s i g n s o f c o r r o s i o n , a l t e r a t i o n p a r t i a l b l e a c h i n g and extreme deformation. The oth e r type, although the same c o l o u r (both are a deep bl u e green) i s i n long narrow blades which bend around, or i n one or two p l a c e s , p i e r c e the l a r g e equant g r a i n s . These long blades o f horn-blende make up about 65$ of the rock. Quartz and p l a g i o c l a s e occur as elongated g r a i n s between the hornblende c r y s t a l s . The p l a g i o c l a s e i s s t r o n g l y zoned, c o n s i s t i n g o f a s o d i c c e n t r a l a r e a and a c a l c i c outer rim. A s e c t i o n i t o Z gave X A ( 0 1 0 ) = 3 . 5 ° f o r A n ^ . A zoned s e c t i o n J_ to Z gave angles o f - . 5 ° and - 1 5 . 5 ° f o r X/v(010) f o r i n n e r and outer zones r e s p e c t i v e l y f o r a n o r t h i t e contents of A n 3 o a n d A n ^ . F i g u r e 87. Photomicrograph of ZJ-24. Plane p o l a r i z e d Tight X 16. A l a r g e metacryst o f hornblende  surrounded by much f i n e r elongate hornblende  c r y s t a l s w i t h p l a g i o c l a s e and q u a r t z , both  c o l o u r l e s s . A few p i e c e s o f the l a r g e horn-blende g r a i n are s t r u n g out p a r a l l e l t o the  s c h i s t o s i t y . Many s m a l l opaque g r a i n s and a few equant, h i g h r e -l i e f , c o l o u r l e s s g r a i n s , some of which have a s l i g h t b i r e -f r i n g e n c e , are s c a t t e r e d through the t h i n s e c t i o n . Some of the opaque g r a i n s are magnetite and some are g r a p h i t e . The equant g r a i n s are garnet. The l a r g e hornblende g r a i n s i n the rock e i t h e r grew f a s t e r f o r some reason and hence became l a r g e r than the r e -maining m a t e r i a l or they are a remnant of an e a r l i e r phase o f c r y s t a l l i z a t i o n . In some ways the rock resembles the coarse grained hornblende g r a n u l i t e where l a r g e hornblende c r y s t a l s have f i n e r g r a i n e d hornblende and f e l d s p a r between them. The 164 l a r g e hornblende g r a i n s i n the g r a n u l i t e s however are much more a l t e r e d and corroded than those i n ZJ-24. The second type of hornblende s c h i s t , the more common type, i s that composed of a c i c u l a r c r y s t a l s of hornblende a l i g n e d t o g i v e a v e r y p e r f e c t l i n e a t i o n but o n l y a v e r y poor f o l i a t i o n . Or - 1 0 from the Quaal R i v e r g n e i s s , a m i l e west of Douglas Lake, i s a t y p i c a l specimen of the hornblende s c h i s t composed of a c i c u l a r c r y s t a l s which g i v e the rock an e x c e l l e n t l i n e a t i o n . I t i s a very dark, almost b l a c k rock and appears to be about 95$ hornblende on f r e s h s u r f a c e s , but where the rock i s weathered c o n s i d e r a b l e amounts of f e l d s p a r and quartz can be seen. A . 2 5 i n c h quartz v e i n l e t forms one end of the specimen, i t cuts across the s c h i s t o s i t y at r i g h t a n g l e s . A t h i n s e c t i o n of Or - 1 0 c o n t a i n s : hornblende, 75$; p l a g i o c l a s e , 15$; q u a r t z , 10$; w i t h s m a l l amounts o f garnet, e p i d o t e , magnetite, and t r a c e s of b i o t i t e . N e a r l y a l l the hornblende g r a i n s present i n the s l i d e have been cut almost normal to the C a x i s . They are the u s u a l blue-green v a r i e t y so common i n the metamorphic r o c k s . Both quartz and p l a g i o c l a s e are present i n g r a i n s u s u a l l y s m a l l e r than the hornblende. The quartz i s u n s t r a i n e d , and the p l a g i o -c l a s e i s w e l l twinned and shows s t r o n g r e v e r s e z o n i n g . A s e c t i o n j_ to X gave Z A(010) = - 3 ° f o r i n n e r zone and - 5 « 5 ° f o r the outer zone f o r An3Q and An 34. Another s e c t i o n x. to 165 (010) gave angles o f X'A (010) = 8 . 5 ° , and 19° making the in n e r zone An 2(j and the outer zone A n ^ . An unzoned s e c t i o n _Lto a gave X'A (010) = 24° f o r A n 4 2 . The c e n t r a l s o d i c zones are g e n e r a l l y much broader than the outer c a l c i c ones. Traces of b i o t i t e and e p i d o t e , probably c l i n o z o i s i t e , are s c a t t e r e d throughout the s l i d e . Minute equant garnets are a l s o p r e s e n t , perhaps forming .01$ of the s l i d e . W - l l i s a f i n e g r a i n e d h o r n b l e n d e - f e l d s p a r s c h i s t from the e a s t s i d e of K i t k i a t a Lake. I t i s dark grey on f r e s h s u r -f a c e s , weathering brownish-black. A c i c u l a r c r y s t a l s o f horn-blende form about 50$ of the rock. They are a l i g n e d t o g i v e the rock a p e r f e c t l i n e a t i o n but p r a c t i c a l l y no f o l i a t i o n . A t h i n s e c t i o n o f W - l l c o n t a i n s : hornblende, 50$; p l a g i o c l a s e , 40$; q u a r t z , 5$; e p i d o t e , 1$; sphene, 1$; b i o t i t e , mostly a l t e r e d to c h l o r i t e , 1$; w i t h s e r i c i t e , opaque b l a c k g r a i n s , and some brown i r o n o x i d e s . Blue-green hornblende i n elongate blades and i r r e g u l a r diamond shaped cross s e c t i o n s forms most of the s l i d e . Many gr a i n s have embayed c o n t a c t s , p a r t i c u l a r l y a g a i n s t sphene, epidote and q u a r t z . Whereas a g a i n s t p l a g i o c l a s e the hornblende tends to have smooth c o n t a c t s . Some hornblende g r a i n s c o n t a i n i n c l u s i o n s o f sphene, g e n e r a l l y as w e l l formed diamond-shaped c r y s t a l s , and occas-i o n a l l y subhedral g r a i n s of e p i d o t e , and rounded g r a i n s o f qu a r t z . C o n c e n t r a t i o n s of sphene and ep i d o t e occur s p o r a d i c a l l y throughout the s l i d e . Much of the e p i d o t e , (probably c l i n o -z o i s i t e ) , i s a s s o c i a t e d w i t h a l t e r e d dust f i l l e d p l a g i o c l a s e . In some of these a l t e r e d p l a g i o c l a s e g r a i n s s c a l e l i k e f l a k e s of a c o l o u r l e s s m i n e r a l , resembling s e r i c i t e , are a l s o p r e s e n t . B i o t i t e , completely or p a r t i a l l y a l t e r e d to c h l o r i t e occurs here and there i n c o n c e n t r a t i o n s o f three or fou r g r a i n s . Most o f the quartz and a l l o f the p l a g i o c l a s e occur as v e r y s m a l l g r a i n s i n t e r s t i t i a l l y t o hornblende c r y s t a l s . Both m i n e r a l s are o f t e n elongated p a r a l l e l to the l i n e a t i o n of the rock. Many p l a g i o c l a s e g r a i n s a r e w e l l twinned and show re v e r s e d zoning. S e c t i o n s J _ to (010) gave maximum e x t i n c t i o n angles o f XA(010) = 20° f o r A n 4 Q . W-61 i s a f i n e g r a i n e d rock composed o f t h i n dark bands of hornblende, l i g h t bands of f e l d s p a r and w i t h a good s c h i s t o s i t y p a r a l l e l to the banding. The rock has a good l i n e a t i o n of hornblende c r y s t a l s . A t h i n s e c t i o n c o n t a i n s 70% hornblende, the u s u a l blue green v a r i e t y , mostly as diamond shaped s e c t i o n s showing two cleavages at 60° and 1 2 0 ° , and 30$ p l a g i o c l a s e as s m a l l g r a i n s I n t e r s t i t i a l to the hornblende. Most o f the p l a g i o c l a s e i s untwinned and shows l i t t l e cleavage. One s e c t i o n normal t o (010) was found, (no cleavage v i s i b l e ) . I t gave a v a l u e o f 33° f o r X ' A ( 0 1 0 ) f o r An^Q- A few of the f e l d s p a r g r a i n s a re clouded by dark m a t e r i a l and have wisps of a h i g h b i r e f r i n g e n t m i n e r a l i n them. The l a c k o f epidote i n t h i s rock may be because a l l the CaO i s f i x e d i n the l a b r a d o r i t e . 167 P-6 i s a dark green hornblende s c h i s t obtained near the c o n t a c t of a hornblende d i o r i t e i n t r u s i v e mass on Pros -pect H i l l . I t i s a v e r y dense, heavy rock which c o n t a i n s a c o n s i d e r a b l e amount of magnetite. A t h i n s e c t i o n o f P-6 c o n t a i n s : hornblende 85$; p l a g i o c l a s e , m y l o n i t e , 10$; magnetite, 5$; and s m a l l amounts of e p i d o t e . The hornblende i s i n l a r g e , broken and deformed equant g r a i n s and elongate fragments which enclose the l a r g e g r a i n s . P l a g i o c l a s e mylonite l i e s i n bands between the elongate hornblende g r a i n s . The f e l d s p a r has an almost i m p e r c e p t i b l e r e l i e f a g a i n s t balsam. T h i s m a t e r i a l has an average diameter of 1 or 2 microns. Magnetite occurs as l a r g e i r r e g u l a r g r a i n s , some en-t i r e l y surrounding hornblende g r a i n s . These rocks have under-gone extreme metamorphism which has broken and s t r u n g out some of the hornblende g r a i n s and a l l of the p l a g i o c l a s e . In one or two p l a c e s the m y l o n i t e has g r a i n s of h i g h r e l i e f m a t e r i a l i n i t ; t h i s may be e p i d o t e . P - l l i s a very dark hornblende s c h i s t from the upper E c s t a l l R i v e r . I t c o n t a i n s , besides l o n g s l e n d e r blades of hornblende, about 5$ f e l d s p a r . A t h i n s e c t i o n o f P - l l c o n t a i n s ; hornblende, 90$; quartz and f e l d s p a r 4$; sphene, 1$; and about 5$ of b l a c k opaque g r a i n s . The hornblende i s i n s m a l l p o i k i l o b l a s t i c g r a i n s , many showing the e f f e c t s of deformation and minor amounts of 168 a l t e r a t i o n . Sphene and i l m e n i t e occur together; the sphene as rims around i l m e n i t e or as sm a l l i n c l u s i o n s w i t h i n the i l m e n i t e g r a i n s . P l a g i o c l a s e and quarts occur together as very s m a l l equant g r a i n s . P r a c t i c a l l y none of the p l a g i o c l a s e i s twinned but i t has a h i g h r e l i e f a g a i n s t q u a r t z and hence i s a c a l c i c v a r i e t y . P-12, outwardly very s i m i l a r t o P - l l , was c o l l e c t e d from v e r y near P - l l . P-12 has i r r e g u l a r bands of e p i d o t e r i c h m a t e r i a l c u t t i n g through i t , has l e s s hornblende than P - l l , and i s covered by a t h i c k c o a t i n g of brown i r o n oxide. A t h i n s e c t i o n shows the r o c k c o n t a i n s : hornblende, 75$; e p i d o t e , 10$; p l a g i o c l a s e ; 10$, s e r i c i t e , 3$; w i t h opaque g r a i n s and sphene about 1$ each; and brown i r o n o x i d e s . Hornblende, i n subhedral g r a i n s , w i t h the other miner-a l s as i r r e g u l a r i n t e r s t i t i a l g r a i n s , i s much l e s s deformed than P - l l . Grains of ep i d o t e are very common i n the p l a g i o -c l a s e , o f t e n they are surrounded by f i n e g r a i n e d , h i g h r e l i e f , c o l o u r l e s s wisps, probably s e r i c i t e . S e c t i o n s of u n a l t e r e d p l a g i o c l a s e cut j . to (010) gave maximum angles o f X'A (010) = 40° f o r A n r j Q , l a b r a d o r i t e . Where the p l a g i o c l a s e i s f u l l of epidote and s e r i c i t e i t has a much lower r e l i e f than the u n a l t e r e d m a t e r i a l . Sphene, i n l a r g e g r a i n s , i s u s u a l l y a s s o c i a t e d w i t h b l a c k opaque g r a i n s , probably i l m e n i t e . The epidote i s i n s m a l l , equant, subhedral g r a i n s . I t i s c o l o u r l e s s , has h i g h b i r e f r i n g e n c e and i s o p t i c a l l y n e g a t i v e . 169 The m i n e r a l assemblage i n these hornblende r i c h r o c k s ; blue-green hornblende, i n t e r m e d i a t e p l a g i o c l a s e , b i o t i t e , us-u a l l y w i t h epidote and quartz f i t s the s t a u r o l i t e - k y a n i t e sub-f a c i e s o f the a m p h i b o l i t e s . Garnets are a l s o common i n these rocks and probably r e p r e s e n t a n o n - e q u i l i b r i u m assemblage. The c a l c i t e of ZJ - 4 9 i s probably an o r i g i n a l sedimentary m i n e r a l as t h i s r o c k comes from a group w i t h many limy beds i n i t . The a l b i t e , ( P - 6 ) , the c h l o r i t e , s e r i c i t e , and some of the epidote i n the other rocks may represent products of r e t r o g r e s s i v e metamorphism. O r i g i n a l l y these h o r n b l e n d i c rocks may have been impure c a l c a r e o u s or d o l o m i t i c sediments, or rocks of igneous o r i g i n ; dykes, s i l l s , f l o w s , or perhaps, f l u v i a l - v o l c a n i c d e p o s i t s . I I . Igneous Rocks Coast I n t r u s i o n s G r a n o d i o r i t e Large b a t h o l i t h i c masses of i n t r u s i v e rock border both s i d e s of the E c s t a l l Septum. Two s m a l l stocks of v e r y s i m i l a r rocks l i e w i t h i n the septum. One of these, the K i t k i a t a Lake stoc k , i s completely cut o f f In p l a n from the r e s t of the batho-l i t h , w h i l e the o t h e r , the Barbara Lake sto c k , i s bounded by metamorphic rocks on t h r e e s i d e s and Douglas Channel on the other. (See F i g u r e 9 2 ) . I t may however be c o e x t e n s i v e w i t h the i n t r u s i v e rocks cropping out across the channel on Hawkesbury I s l a n d . Specimens of the i n t r u s i v e rock on the west s i d e of the E c s t a l l septum were obtained along the shore of Agnes Lake. 170 This rock has hypidiomorphic-granular texture and i s com-posed of quartz, hornblende, K-feldspar, minor b i o t i t e and sphene, with a large percentage of plagioclase feldspar. A poorly developed l i n e a t i o n of the hornblende c r y s t a l s i s apparent i n some outcrops p a r t i c u l a r l y near the contact with the metamorphic rocks. The amount of b i o t i t e increases while the amount of hornblende decreases towards the contact. Near the contact, where b i o t i t e i s abundant, the rock i s strongly f o l i a t e d . A l l along the shores of Agnes lake narrow white bands are seen i n the g r a n i t i c rocks. These bands consist of ridges of weathered feldspars along narrow stringers of epidote. In fre s h l y broken specimens such feldspar bands are white on weathered surfaces but except for the narrow ve i n l e t s of green epidote, appear no d i f f e r e n t than the rest of the rock on fresh surfaces. A thin, section cut through one of the bands shows that a l l the plagioclase along the band i s altered to sausserite. The hornblende i n this section i s strongly sheared and p a r t l y altered to c h l o r i t e . Large grains of epidote occur along fracture zones cutting through the other minerals. A specimen of t y p i c a l Agnes Lake granodiorite, ¥-14, contains: plagioclase, 65$; quartz, 15$; microcline, 10$; hornblende, 10$; with minor amounts of b i o t i t e , sphene, apatite, and c h l o r i t e . The rock has hypidiomorphic granular texture, i s quite 171 coarse g r a i n e d , and has no v i s i b l e l i n e a t i o n . A combined c a r l s b a d - a l b i t e twin c u t normal t o (010) gave angles o f X ' A (010) = 6 . 5 and 1 6 . 5 ° f o r A n ^ . In g e n e r a l the mi n e r a l s are f r e s h and very l i t t l e a l t e r e d . Evidences of minor amounts of s t r a i n and deform-a t i o n a re apparent i n the t h i n s e c t i o n . T h i s could have r e -s u l t e d from l a t e movement i n the almost completely s o l i d i f i e d rock, or i t co u l d have r e s u l t e d from deformation much l a t e r than the s o l i d i f i c a t i o n . The Barbara Lake stock i s composed of rock o f v e r y s i m i l a r composition but there i s no l i n e a t i o n or f o l i a t i o n i n i t and l a r g e subhedral c r y s t a l s of m i c r o c l i n e and zoned p l a g i o c l a s e a r e q u i t e abundant to give the rock a p o r p h y r i t i c t e x t u r e . ¥-21 i s a t y p i c a l specimen of Barbara Lake grano-d i o r i t e . In hand specimen i t i s a v e r y l i g h t c o l o u r e d rock composed mostly of f e l d s p a r and qua r t z w i t h s m a l l amounts of b i o t i t e and hornblende. Large phenocrysts o f l i g h t c o l o u r e d f e l d s p a r s are v i s i b l e i n the rock. A t h i n s e c t i o n of ¥-21 c o n t a i n s ; p l a g i o c l a s e , 60$; q u a r t z , 20$; m i c r o c l i n e , 10$; b i o t i t e , 3$; hornblende, 2$; c l i n o z o i s i t e 2$; w i t h sphene, s e r i c i t e , c h l o r i t e and magnetite. The p l a g i o c l a s e occurs i n l a r g e subhedral complexly zoned g r a i n s . Many c o n t a i n c o n s i d e r a b l e amounts of dark hazy opaque d u s t . Some have t h i s i n i r r e g u l a r l i n e s p a r a l l e l i n g one or more of the narrow zones. These l i n e s probably r e p r e s e n t zones of c o r r o s i o n produced when c r y s t a l l i z a t i o n was 172 i n t e r r u p t e d and the c r y s t a l was a t t a c k e d by the melt. S e c t i o n s cut normal to X gave angles of Z A ( 0 1 0 ) = 85° f o r An 2^, and X Z X A ( O I O ) = 0°+2°+5° A n 3 Q A n 2 7 and A n ^ . Most o f the quartz g r a i n s a re about the same s i z e as the p l a g i o c l a s e g r a i n s , although a few are c o n s i d e r a b l y l a r g e r . A l l o f the quartz g r a i n s show many narrow bands o f v a r i a b l e e x t i n c t i o n i n d i c a t i n g the m i n e r a l has s u f f e r e d extreme deformation. Anhedral g r a i n s of m i c r o c l i n e occur i n t e r s t i t i a l l y to the other m i n e r a l s . Both b i o t i t e and hornblende show si g n s of a l t e r a t i o n to c h l o r i t e . The b i o t i t e i s a n h e d r a l but the hornblende euhedral. S m a l l g r a i n s of c l i n o z o i s i t e are q u i t e abundant i n the s l i d e . They occur w i t h shreds o f s e r i -c i t e i n a l t e r e d p l a g i o c l a s e , but t h e r e does not appear to be any a l b i t e w i t h i t . The t e x t u r e of the rock suggests i t has undergone c o n s i d e r a b l e more s t r a i n than have the Agnes Lake i n t r u s i v e s . I n c l u s i o n s a re abundant i n the i n t r u s i v e rocks on the west s i d e of the septum. Numerous dark grey elongated l e n s e s , probably drawn-out i n c l u s i o n s of the w a l l r o c k s , were noted along the shores o f Agnes Lake. These l e n s e s plunge northwards many a t o n l y a few degrees from the h o r i z o n t a l , o t h e r s q u i t e s t e e p l y . A few dark bands were a l s o seen to occur but they are r a r e r than the l e n s e - l i k e b o d i e s . An i n c r e a s e i n the amount of hornblende and a darkening of the groundmass f e l d s p a r s seems to be the reason f o r the darker c o l o u r of the i n c l u s i o n s . As no work was done more than a m i l e w i t h i n the b a t h o l i t h i t i s not known whether or not these are contact phenomenon. In the s e c t i o n i n v e s t i g a t e d there seemed to be no v a r i a t i o n i n the numbers of i n c l u s i o n s as the c o n t a c t was approached. Larger i n c l u s i o n s of dark h o r n b l e n d e - r i c h rock were observed east of Gordon Lakes. Some of these were strongly-banded, the banding seemingly p a r a l l e l i n g the nearby c o n t a c t . A specimen of one such i n c l u s i o n , W-55» i s a v e r y dark rock composed of hornblende w i t h euhedral c r y s t a l s of p l a g i o c l a s e which have white rims and c l e a r watery c e n t e r s . In t h i n s e c t i o n the rimmed p l a g i o c l a s e i s normally zoned and the white rim i s seen to be a band of s a u s s e r i t i z e d p l a g i o -c l a s e a few tenths of a m i l l i m e t e r wide completely surrounding the g r a i n . A s e c t i o n of p l a g i o c l a s e cut normal to a gave angles of X'A ( 0 1 0 ) = 24 . 5 ° 16.5°, and 9 ° , f o r normal zoning of A n ^ , An^ 2 and A n ^ . The other m i n e r a l s present i n the rock a r e : hornblende, 50$; b i o t i t e , 15$; sphene, 5$; and a p a t i t e , 2-2$; Hornblende occurs as l a r g e f r e s h blades which have the same deep b l u e -green c o l o u r o f the hornblende i n the metamorphic r o c k s . The sphene occurs as l a r g e euhedral honey y e l l o w g r a i n s . A p a t i t e i s i n minute rods and i s o t r o p i c end s e c t i o n s . G r a n i t e Dykes and S i l l s A number of g r a n i t e - t e x t u r e d dykes and s i l l s were found c u t t i n g the metamorphic rocks at and near the c o n t a c t s of the 174 main i n t r u s i v e . Except f o r a v e r y t h i c k s i l l - l i k e body l y i n g j u s t east of Agnes Lake, a l l of these a r e v e r y narrow i r r e g u l a r bodies which f o l l o w j o i n t s and bedding planes o f t e n making sharp r i g h t angled t u r n s . These dykes and s i l l s have c h i l l e d margins which are r i c h e r i n b i o t i t e than the c o a r s e r c e n t r a l p a r t s . They a r e very s i m i l a r i n composition to the main g r a n o d i o r i t e r o c k s . Quartz and f e l d s p a r form about 90$ w i t h 10$ b i o t i t e and a few g r a i n s of p y r i t e . The l a r g e s i l l - l i k e mass east of Agnes Lake seems to be a h y b r i d rock. Specimens from i t c o n t a i n s 20$ or more hornblende w i t h as much as 10$ b i o t i t e and 3$ or more sphene i n v ery l a r g e c r y s t a l s . P l a g i o c l a s e seems to be the p r e -dominant m i n e r a l , forming 65$ of the rock. S m a l l g r a i n s of quartz are present but form no more than 5$. The mafic m i n e r a l s are commonly a l i g n e d to g i v e a f o l i a t i o n or l i n e a t i o n which p a r a l l e l s the c o n t a c t s of the s i l l . Many mafic i n c l u s i o n s , elongate p a r a l l e l t o the f o l -i a t i o n , a r e p r e s e n t . These a r e o b v i o u s l y not e q u i v a l e n t to the contiquous metamorphic rocks as they are composed of hornblende and b i o t i t e and p r a c t i c a l l y no f e l d s p a r . Nearer the c o n t a c t , however, t h e r e a r e i n c l u s i o n s which by t h e i r angular n a t u r e , t e x t u r e and m i n e r a l o g i c a l composition are o b v i o u s l y broken o f f p i e c e s of the nearby w a l l r o c k s . Contacts between the s i l l and the metamorphic rocks are o v e r a l l conformable, but i n many p l a c e s the dyke c u t s a c r o s s the bedding, sometimes at r i g h t a n g l e s . As shown i n the G e o l o g i c Map ( F i g u r e 92) the s i l l p a r a l l e l s the c o n t a c t of the main i n t r u s i o n and the metamorphic rocks f o r most of i t s o l e n g t h , even to the p o i n t of t u r n i n g almost 90 as the main co n t a c t swings east south of Agnes Lake. East of Gordon Lakes a s i m i l a r s i l l crops out i n a creek; t h i s may be a con-t i n u a t i o n of the l a r g e s i l l , but heavy timber and v a l l e y f i l l obscures most of the geology of the a r e a . A p l i t e s and Pegmatites Dykes and s i l l s of a p l i t e occur s p a r i n g l y i n both the i n t r u s i v e and metamorphic r o c k s . They are very l i g h t c o l o u r e d and c o n t a i n quartz and f e l d s p a r w i t h a few f l a k e s o f g r e e n i s h mica. Pegmatites are very common a t the con t a c t s o f the coast i n t r u s i o n s and the metamorphic r o c k s . Only simple pegmatites occur i n the area. B e s i d e s coarse c r y s t a l masses of K ^ f e l d s p a r and i r r e g u l a r c r y s t a l s o f q u a r t z , a c c e s s o r y g r a i n s of g r e e n i s h mica, b i o t i t e , p y r i t e , and r a d i o a c t i v e a l l a n i t e are o f t e n p r e s e n t . L a t e I n t r u s i o n s Lamprophyre dykes: B a s i c dykes are found i n a l l p a r t s o f the E c s t a l l - Q u a a l a r e a , both i n the metamorphic and i n the igneous complexes. One dyke was t r a c e d from the g r a n o d i o r i t e i n t o the metamorphic rock. At the con t a c t i t was o f f s e t some tens o f f e e t , p robably by l a t e movement of the igneous mass. Most of these b a s i c dykes are dark grey 176 or g r e e n i s h b l a c k , one or two a r e reddish-brown. They vary from a few inches to a few f e e t i n width and o c c a s i o n a l l y are 3 0 or more f e e t wide. Many of the dykes send apopyses i n t o the w a l l r o c k s , some s p l i t i n t o a s e t of p a r a l l e l dykes which may r e j o i n i n a few tens of f e e t . Phenocrysts of b l a c k l u s t r o u s hornblende were seen i n a l l the dykes, one or two of them contained b i o t i t e as w e l l . About h a l f of the dykes, u s u a l l y the f i n e r g r a i n e d examples, c o n t a i n rounded white blebs which look l i k e amygdules. (See F i g u r e 88). A l l of the dykes have c h i l l e d margins where the groundmass i s f i n e g r a i n e d , but the phenocrysts are the same s i z e as those i n the cen t e r of the dyke. F i g u r e 88. Photomicrograph, plane p o l a r i z e d l i g h t X 16  A white amygdule i n a hornblende lamprophyre. C a l c i t e i s grey, (high r e l i e f ) a n a l c i t e i s  white, (low r e l i e f and i s o t r o p i c ) . 1 7 7 A number of t h i n s e c t i o n s of the dykes were s t u d i e d . In a l l s e c t i o n s , where the groundmass i s coarse enough to i d e n t i f y , i t i s a h i g h l y a l t e r e d , c l o u d y p l a g i o c l a s e w i t h n e g a t i v e r e l i e f a g a i n s t balsam. Probably i t i s a l b i t e . In some s e c t i o n s the p l a g i o c l a s e i s o b v i o u s l y s a u s s u r i t i z e d as there are numerous shreds of epidote w i t h i n i t . Large zoned c r y s t a l s o f brownish hornblende occur i n a l l the s e c t i o n s , forming from 20 to 40% o f the rock. In some examples the hornblende occurs as s h o r t , stubby broken prisms showing v e r y prominent growth banding, (See F i g u r e 89) • i n others i t occurs as long p r i s m a t i c to a c i c u l a r forms. (See F i g u r e 9D. In one or two s e c t i o n s both c r y s t a l shapes are present. B i o t i t e i s present as s m a l l amounts i n only one of the s e c t i o n s s t u d i e d . F i g u r e 8 9 . Photomicrograph of l a r g e broken zoned hornblende phenocrysts i n a hornblende lamprophyre. Plane  p o l a r i z e d l i g h t . X 16. 178 A very few grains of pyroxene, one or two of them rimmed with hornblende, were seen i n one section. (See Figure 90). One other section contains grains which may be pyroxene but no grains could be found showing cleavages at right angles to give a p o s i t i v e i d e n t i f i c a t i o n . Apatite and mag-ne t i t e are common accessories forming up to % of most sections. Sphene i s present i n one section and there i s one grain of r u t i l e i n another. Figure ^0* Photomicrograph of pyroxene grain, r i g h t angled  cleavage surrounded by hornblende phenocrysts  and rimmed on one side by a thin layer of horn-blende. Plane polarized l i g h t X 80 Thin sections of the fin e grained dykes show many of the hornblende grains are par t l y altered from a brownish hornblende to long curving needles of the bright green a c t i n o l i t e amphibole. (See Figure 91). This a l t e r a t i o n seems to begin at one end of the hornblende g r a i n , the other end i s not a f f e c t e d . C a l c i t e and a n a l c i t e form the round white blebs common i n these r o c k s . (See F i g u r e 88). C a l c i t e a l s o occurs as s c a t t e r e d g r a i n s , and narrow v e i n s on bands. F i g u r e 91. Photomicrograph of lamprophyre dyke. Plane  p o l a r i z e d l i g h t ' X 40. Elongate prisms oT~~ hornblende are p a r t l y a l t e r e d to a c t i n o l i t e . The composition, t e x t u r e , and extreme a l t e r a t i o n , of these dyke rocks are a l l t y p i c a l of the lamprophyre dykes. In composition they are most c l o s e l y r e l a t e d to the spess-a r t i t e s . CHAPTER 17 STRUCTURAL GEOLOGY I n t r o d u c t i o n The s t r u c t u r e of the E c s t a l l - Q u a a l r i v e r s a r e a i s v e r y complicated. Added to the o b v i o u s . s t r u c t u r a l complexity i n the metamorphic t e r r a i n e a r e the.great masses of i n t r u s i v e s which surround i t on three and perhaps a l l s i d e s . I n t e r -p r e t a t i o n i s hampered by heavy bush, scanty outcrop, and the extreme metamorphism which has destroyed n e a r l y a l l of the primary sedimentary f e a t u r e s . Observations on s c h i s t o s i t y , bedding, l i n e a r s t r u c t u r e s , and the r e l a t i o n s h i p s between metamorphic and i n t r u s i v e rocks suggest there has been more than one phase of deformation. Steep to v e r t i c a l d i p s , w i t h v a r i a t i o n s about the v e r t i c a l , s u g g e s t i v e of o v e r t u r n i n g s , and the s t r u c t u r a l d i s c o n t i n u i t i e s i n the a r e a r u l e out any simple e x p l a n a t i o n of the s t r u c t u r e . The s t r u c t u r e of t h i s s m a l l a r e a i s p a r t of the much l a r g e r Coast Range s t r u c t u r e , which i s i t s e l f but a s m a l l p a r t of the C o r d i l l e r a n s t r u c t u r e . J u s t as s t r u c t u r e s i n the Coast Range are r e f l e c t i o n s of the much l a r g e r s t r u c t u r a l p i c t u r e , so the E c s t a l l - Q u a a l s t r u c t u r e i s r e l a t e d to the same over a l l f o r c e s and c o n d i t i o n s . Thus the n o r t h - n o r t h -west trend of most of the major s t r u c t u r e s i n the s m a l l e r a r e a i s p a r a l l e l to the main o u t l i n e s of the Coast Range complex and p a r a l l e l to the main lineaments of the C o r d i l l e r a . The e a s t e r l y to n o r t h e a s t e r l y d i p s of much of the bedding and/or f o l i a t i o n , i n t r u s i v e c o n t a c t s , and lineaments i n the i n t r u s i v e rocks appear to repr e s e n t a g e n e r a l t r e n d through much of the Coast Range. Perhaps i t i s a r e s u l t of the t h r u s t i n g of the c o n t i n e n t a l masses over the rocks of the P a c i f i c b a s i n . At l e a s t , i t seems to i n d i c a t e s t r o n g compressive f o r c e s acted i n a d i r e c t i o n approximately at r i g h t angles t o these s t r u c t u r e s , w i t h the adjustments to such f o r c e s t a k i n g p l a c e a l o n g the c o n t i n e n t a l margins and on the c o n t i n e n t a l s i d e of the zone of adjustment r a t h e r than on the deep sea s i d e . Large S c a l e S t r u c t u r e s i n the Metamorphic Rocks Between Douglas Channel and the Skeena R i v e r the E c s t a l l Septum s t r i k e s N 1 5 ° W but the bedding and f o l i a t i o n of the rocks i n the septum s t r i k e s N 5 ° W to N 1 0 ° W. Thus the i n t r u s i v e rock c u t a c u t e l y a c r o s s the f o l i a t i o n and the bedding of the septum. In the southern p a r t of the septum three major s t r u c t -u r a l trends are e v i d e n t . Along the E c s t a l l - Q u a a l V a l l e y the r e g i o n a l s t r i k e i s N 5 ° ¥ to H 1 0 ° ¥, wh i l e i n a zone 3 to 5 m i l e s wide along the east c o n t a c t o f the septum the r e g i o n a l s t r i k e i s R 4 5 ° W. The rocks at the con t a c t between these two regions have been s t u d i e d i n few p l a c e s and nowhere c o u l d the exact nature or l o c a t i o n of the con t a c t between the two rocks groups be e s t a b l i s h e d . A l l o b s e r v a t i o n s i n d i c a t e the contact i s abrupt and sharp (See F i g u r e 9 4 ) . Masses of i n t r u s i v e rock 182 occur along the zone of c o n t a c t of these two " t r e n d s " . In the n o r t h are the Prospect H i l l hornblende d i o r i t e s , and east of K i t k i a t a Lake i s the K i t k i a t a Lake g r a n o d i o r i t e s t o c k . The d i f f e r e n c e i n a t t i t u d e between these two r o c k groups might be e x p l a i n e d e i t h e r by an unconformity, by a major s t r u c t u r a l d i s l o c a t i o n such as f a u l t i n g , or a combin-a t i o n of f a u l t i n g and f o l d i n g . The presence of i n t r u s i v e s of d i v e r s e age along t h i s s t r u c t u r a l "break" suggests t h a t i t was a major zone of weakness f o r a great l e n g t h of time. A second major s t r u c t u r a l f e a t u r e i s f o l d i n g of the n o r t h - s o u t h t r e n d i n g K i t k i a t a s c h i s t s along the Agnes Lake-K i t k i a t a I n l e t t r a n s v e r s e v a l l e y . T h i s f o l d has a h o r i z o n t a l r a d i u s of curvature of 3 to 5 m i l e s . I t i s not a smooth even f o l d , f o r i t appears to be broken on t h e e a s t e r n s i d e . Along K i t k i a t a l a k e the K i t k i a t a s c h i s t s d i p west between 55 and 75 degrees. Southward the d i p steepens to v e r t i c a l then changes to 7 0 ° northward. T h i s f o l d seems to be r e l a t e d to the i n t r u s i v e rocks n o r t h and south of i t . The K i t k i a t a Stock seems to f i l l the core of the f o l d . I t s c o n t a c t s more or l e s s p a r a l l e l s the c u r v i n g trend of the s c h i s t s . F o l d i n g , s i m i l a r t o that d e s c r i b e d above, occurs i n the metamorphic rocks a l l along the southern c o n t a c t s w i t h the b a t h o l i t h . These f o l d s are more o b v i o u s l y g e n e t i c a l l y r e l a t e d t o the i n t r u s i o n ; or more p r o p e r l y to the f o r c e s which brought the i n t r u s i v e rocks to t h e i r present p o s i t i o n . 183 The t h i r d major f e a t u r e i n the metamorphic rocks i s the change i n d i p across the Q u a a l - E c s t a l l v a l l e y . (See Geologic C r o s s - s e c t i o n s , F i g u r e 9 3 ) . On the east s i d e the K i t k i a t a s c h i s t dips 55 to 7 0 ° west, on the west s i d e the Quaal R i v e r gneiss and Agnes Lake q u a r t z i t e d i p s 65 to 7 5 ° e a s t . In two places outcrops i n the zone of changing d i p were i n v e s t i g a t e d . Going west, j u s t east of E c s t a l l Lake, dips g r a d u a l l y i n c r e a s e to v e r t i c a l then d i p eastward. Many of the rocks c o l l e c t e d from t h i s a r e a show evidences of extreme m y l o n i t i z a t i o n . S i m i l a r c o n d i t i o n s were found at Sporran Lake above the Quaal R i v e r e s t u a r y . In n e i t h e r case was any major d i s l o c a t i o n r e c o g n i z e d , but i n the l a t t e r a r e a great v a r i a t i o n s i n a t t i t u d e were noted i n the g n e i s s . A l l o b s e r v a t i o n s made i n d i c a t e the change i n d i p i s a s s o c i a t e d w i t h the change from Quaal gneiss to K i t k i a t a s c h i s t . Southeast of Sporran Lake f o l d i n g a s s o c i a t e d w i t h the i n t r u s i v e r o c k s , has destroyed evidence of any change i n p o s s i b l e p r e - e x i s t i n g r e g i o n a l d i p . N o r t h of E c s t a l l Lake a s i m i l a r change i n d i p i s apparent, but the e a s t e r n segment of rocks i n t h i s area i s p r a c t i c a l l y unmapped. S m a l l S c a l e S t r u c t u r e s i n the Metamorphic Rocks The metamorphic rocks of the E c s t a l l Septum c o n t a i n numerous s m a l l s c a l e s t r u c t u r a l f e a t u r e s such as c a t a c l a s t i c banding, g n e i s s i o s i t y , s c h i s t o s i t y , drag f o l d s , minor crumples ( c r e n u l a t i o n s ) , and l i n e a t i o n s of m i n e r a l s . Two major rock t y p e s , gneisses and s c h i s t s , have been recognized on the b a s i s of mineralogy and t e x t u r e . The gneisses c o n t a i n many f e a t u r e s s u g g e s t i v e of extreme dynamic metamorphism. A l l show bands of g r a n u l a t e d f e l d s p a r s crushed between r e s i s t a n t masses of s t r a i n e d q u a r t z . In some gneiss m i c r o c l i n e may form p a r t of the coarse grained phase. In the Douglas Channel g n e i s s e s augens and porphyro-b l a s t s o f K - f e l d s p a r are common. P l a g i o c l a s e and garnet p o r p h y r o b l a s t s are l o c a l l y abundant i n some beds. Zones of myl o n i t e are present i n these rocks a l s o , but they are l e s s common and not as prominently developed as i n the Quaal R i v e r g n e i s s . Perhaps the deformation was not as i n t e n s e i n these r o c k s . In the q u a r t z i t e s the same t e x t u r e s are present but here a g a i n , because of the g r e a t e r s t r e n g t h of q u a r t z and the l o c a l i z a t i o n of s h e a r i n g along mica or hornblende r i c h i n t e r b e d s i t i s not as w e l l developed. Undoubtedly the m i n e r a l f o l i a t i o n c h a r a c t e r i z i n g the g n e i s s i c rocks has been produced i n p a r t (perhaps i n t o t a l ) by the dynamic metamorphism impressed on these r o c k s . Quartz and K - f e l d s p a r s are more r e s i s t a n t to g r a n u l a t i o n than p l a g i o -c l a s e , mica, or amphibole, hence tend to be strung out i n coarse grained bands between which the other m i n e r a l s are found as f i n e rounded g r a i n s and t a b u l a r c r y s t a l s o r i e n t e d w i t h long axes p a r a l l e l to the banding. E p i d o t e ( c l i n o z o i s i t e ) and garnet are found i n the f i n e - g r a i n e d bands. They appear to have formed l a t e r than the other m i n e r a l s f o r they are only s l i g h t l y broken, probably by l a t e phase of the deformation. 185 C a t a c l a s t i c t e x t u r e s are a l s o present i n the s c h i s t s p a r t i c u l a r l y the quartz and f e l d s p a r r i c h v a r i e t i e s . In many of these, bands and l e n s e s of coarse quartz g r a i n s are surrounded by bands of m i l l e d p l a g i o c l a s e and f o l i a of b i o -t i t e and hornblende. Most of the micas and hornblendes show bending, s h e a r i n g and f r a c t u r i n g . In some of these rocks p o r p h y r o b l a s t s of garnet and f e l d s p a r occur. Large garnets show s i g n s of r o l l i n g , w h i l e the f e l d s p a r p o r p h y r o b l a s t s have u s u a l l y been broken and drawn out i n t o augen shapes. In the rocks however, a w e l l developed s c h i s t o s i t y i s more prominent than c a t a c l a s t i c t e x t u r e s . Because o f t h e i r h i g h content of mica or amphibole the s c h i s t s deformed more by s l i p p i n g and bending than by b r e a k i n g and c r u s h i n g . Hence i t i s i n these rocks that drag f o l d s and c r e n u l a t i o n s are abundant. M i n e r a l l i n e a t i o n s a r e common but g e n e r a l l y d i f f i c u l t to measure a c c u r a t e l y . Observations of drag f o l d s , crumples and m i n e r a l l i n e a t i o n s were made throughout the a r e a , though not enough to permit s t a t i s t i c a l a n a l y s i s of them. No d e f i n i t e p a t t e r n o f drag f o l d s t h a t might a i d i n the s t r u c t u r a l i n t e r p r e t a t i o n as yet has been found. G e n e r a l l y one d i r e c t i o n of l a r g e - s c a l e drag f o l d i n g i s r e c o g n i z a b l e i n any s i n g l e outcrop but along w i t h i t , two, and p o s s i b l y t h r e e , d i r e c t i o n s of s m a l l e r crumples or c r e n u l a t i o n s occur. M i n e r a l l i n e a t i o n s may occur w i t h the drag f o l d i n g . In some cases two d i r e c t i o n s of major drag f o l d i n g were found i n the same outcrop. 9 Stereograms of the p o l e s of s c h i s t o s i t y , f o l i a t i o n , and/or bedding i n v a r i o u s p a r t s of the area were p l o t t e d and contoured. Of the seven diagrams so obtained one shows three g i r d l e s , three others show two s t r o n g g i r d l e s and the l a s t three show one w e l l d e f i n e d g i r d l e w i t h a p o o r l y developed secondary g i r d l e . These diagrams have been drawn on the s t r u c t u r a l map, F i g u r e 94, where they are r e f e r r e d to the area from which the b a s i c data was d e r i v e d . P l u n g e s f o f f o l d s , c r e n u l a t i o n s , and m i n e r a l l i n e a t i o n s p l o t t e d on the same diagrams f a l l over a f a i r l y wide a r e a centered about the poles of the g i r d l e s . Not enough readings on such l i n e a t i o n s are a v a i l a b l e to give a complete p i c t u r e . Taken t o g e t h e r , w i t h the divergence of the plunges of drag f o l d s , and other l i n e a t i o n s the e x i s t e n c e of two g i r d l e s i n the stereograms of l i n e a t i o n s i n the area suggest two d i r e c t i o n s of f o l d i n g . These could have formed s i m u l t a n e o u s l y d u r i n g one p e r i o d of deformation or they c o u l d r e p r e s e n t two separate f o l d s one impressed on the other at some l a t e r date. In view of the numerous c o m p l i c a t i o n s i n the major s t r u c t u r a l t r e n d s , the second e x p l a n a t i o n i s p r e f e r r e d . S t r u c t u r e of the Igneous Rocks Those areas of the igneous rocks which were mapped are composed of coarse g r a i n e d , g r a n i t i c t e x t u r e d rock. F o l i a t i o n s or l i n e a t i o n s are present i n some ar e a s , but they are never w e l l developed. In the Agnes Lake a r e a , the b i o t i t e r i c h rock next to the c o n t a c t was f a i r l y s t r o n g l y f o l i a t e d . Away from the contact as hornblende takes the place of bio-t i t e , the f o l i a t i o n weakens and disappears. In some of the rocks a poor l i n e a t i o n of hornblende grains can be made out but i t i s usually too weak and i n d e f i n i t e to measure accur-ately. The general attitude of the f o l i a t i o n and l i n e a t i o n i s K 1 0 ° ¥ 78°E, more or less p a r a l l e l to the contact. Lenticular inclusions plunge moderately to steeply northwards. F o l i a t i o n was not apparent i n the Barbara Lake stock and no other masses of the Coast Intrusions were c l o s e l y investigated so the presence or absence of banding can only be guessed at from a e r i a l observations. In f l y i n g along the eastern contact of the granite numerous areas of strongly f o l i a t e d rocks were noted within the i n t r u s i v e rocks. Several of these were stained brown or red by iron oxides. The same f o l i a t e d zones are v i s i b l e on the a e r i a l photographs of the area. The rocks of some of these areas may be f o l i a t e d inclusions of older metamorphic rocks caught up i n the i n -trusion. Much of the f o l i a t i o n , however, seems to be p a r a l l e l to the dip and s t r i k e of the contact and thus p a r a l l e l to the dip and s t r i k e of the Douglas Channel metamorphic gneiss. Lineations within the igneous rocks of the east and south sides of the septum seem much more common than on the west. The most prominent of these lineaments are shown on Figure 94, the S t r u c t u r a l Map. The major joints and/or f a u l t s appear to s t r i k e north or east and dip east and north. There are many that have other attitudes but the o v e r a l l impression i s as above. A study of a e r i a l photographs of the contact regions 1 8 8 of the septum i n d i c a t e the same g e n e r a l s t r i k e s and di p s f o r the s t r o n g e r and more abundant f r a c t u r e s . Wherever the a t t i t u d e of a con t a c t c o u l d be e s t a b -l i s h e d e i t h e r by d i r e c t o b s e r v a t i o n s i n the f i e l d , or by topographic r e l a t i o n s on a e r i a l photographs, the d i p was to the e a s t , n o r t h - e a s t , or n o r t h . Thus the co n t a c t s and the other lineaments i n the i n t r u s i v e g e n e r a l l y have s i m i l a r a t t i t u d e s . They bear a s i m i l a r r e l a t i o n s h i p to the bedding and/or f o l i a t i o n i n the metamorphic complex. Besides the many examples of p a r a l l e l and sub p a r a l l e l igneous contacts and bedding i n the metamorphic rocks there are examples of sharp, i n some p l a c e s r i g h t angle, cross c u t t i n g . The best example i s on the h i g h r i d g e s south-east of Barbara Lake. Here a group of li m e s t o n e , s c h i s t and q u a r t z i t e s t r i k e s at r i g h t angles i n t o the i n t r u s i v e rock. Other s i m i l a r occurrences a r e : j u s t s o u t h o f Agnes Lake, f i v e m i l e s n o r t h o f Amoeba Lake, and a c r o s s Johnson Lake. In these p l a c e s there Is str o n g f o l d i n g t o b r i n g the metamorphic rocks around w i t h the i n t r u s i v e c o n t a c t but there i s , i n each case, vast amounts of m i s s i n g metamorphic rock to account f o r . A set of f r a c t u r e s i s v i s i b l e on photographs of the southern p a r t of the Foch Lagoon a r e a . North-west-trending f r a c t u r e s are o f f s e t some hundreds of f e e t by a n o r t h e a s t -t r e n d i n g s e t . (See F i g u r e 94). Movement i s n o r t h s i d e south-west. These l a t t e r are f a u l t s t h a t p a r a l l e l the shore o f Douglas Channel, as does a set of minor v a l l e y s , which may occupy s i m i l a r f a u l t zones. Perhaps t h i s s e t of f a u l t s i s the c o n t r o l on Douglas Channel i t s e l f . CHAPTER V: GEOLOGIC HISTORY O r i g i n o f the Metamorphic Rocks The great t h i c k n e s s e s of q u a r t z i t e along the western edge of the septum rep r e s e n t a sediment, probably marine, l a i d down i n a shallow water s t a b l e s h e l f environment. I n t e r -beds of more s h a l y m a t e r i a l , now r e p r e s e n t e d by hornblende-b i o t i t e s c h i s t s , were l a i d down du r i n g p e r i o d s of calm water, or d u r i n g p e r i o d s when so much sediment was a v a i l a b l e that a l l of i t c o u l d not be washed c l e a n . In common w i t h a l l the rocks s t u d i e d i n the septum, the q u a r t z i t e s have i n s i g n i f i c a n t amounts o f the heavy m i n e r a l s that are found i n mature sediments or i n sediment d e r i v e d from sedimentary or metamorphic r o c k s . T h i s suggests a p r e -dominance of igneous rocks i n the a r e a of provenance. Lenses of q u a r t z - c l i n o z o i s i t e s c h i s t s , s p a r i n g l y present i n these r o c k s , r e p r e s e n t l o c a l accumulations of l i m e . The next s e t of rocks to the e a s t , the Quaal R i v e r Gneisses, could have o r i g i n a t e d i n a number of ways. F i r s t they could have been a t h i c k sequence o f a r k o s i c sandstones. T h i s would r e q u i r e c o n d i t i o n s of r e f i n e d e r o s i o n and t r a n s -p o r t a t i o n , w i t h a minimum of chemical weathering. Most t h i c k sequences of arkose are a s s o c i a t e d w i t h c o n t i n e n t a l d e p o s i t s and o f t e n w i t h a r i d or c o l d c l i m a t e s which i n h i b i t chemical 190 decay and permit quick d e p o s i t i o n . A problem i n t h i s o r i g i n i s that zones of K - f e l d s p a r - r i c h g n e i s s are interbedded w i t h zones h a l f K - f e l d s p a r and h a l f p l a g i o c l a s e , and other zones w i t h a l l p l a g i o c l a s e . Such v a r i a t i o n s i n composition would r e q u i r e sudden changes i n the composition o f the source rocks or some method of s o r t i n g one f e l d s p a r from the o t h e r . N e i t h e r of these are very probable. Another e x p l a n a t i o n i s that these rocks were d e r i v e d from a s e r i e s of a r g i l l a c e o u s s i l t s t o n e s which were a l t e r e d by profound r e g i o n a l metamorphism w i t h c o n s i d e r a b l e movement of elements w i t h i n the r o c k s . The average gneiss i s q u i t e low i n c a l c i u m , and p a r t i c u l a r l y low i r o n , and magnesium. What c a l c i u m i s present occurs i n p l a g i o c l a s e and c l i n o z o i s i t e . The i r o n i s i n the b i o t i t e , which averages between 5 and 10% of the K - f e l d s p a r v a r i e t y of g n e i s s , and s l i g h t l y more i n the p l a g i o c l a s e r i c h v a r i e t i e s . As the amount o f p l a g i o c l a s e i n c r e a s e s the amounts of b i o t i t e , e p i d o t e , and garnet i n -crease and hornblende appears. Potassium may have been added, along c e r t a i n zones much as i t has been added to the s e r i c i t e s c h i s t shear zones. Any excess c a l c i u m , i r o n , and magnesium, could be removed by the same pr o c e s s . Such a process would e x p l a i n the K - f e l d s p a r r i c h zones. Quartz-epidote l e n s e s and e p i d o t e r i c h - z o n e s are f a i r l y abundant i n the g n e i s s e s , p a r t i c u l a r l y the Douglas Channel Gneisses. They suggest areas i n which l i m e - s e c r e t i n g organisms l i v e d . T h i s i s f u r t h e r evidence f o r a marine en-vironment of d e p o s i t i o n . 1 9 1 K - f e l d s p a r i n the Douglas Channel rocks occurs as po r p h y r o b l a s t s i n a p l a g i o c l a s e groundmass. T h i s potassium could have been added t o the rock or i t co u l d be o r i g i n a l sedimentary m a t e r i a l . For some reason the s i l t s t o n e and a r g i l l i t e s do not seem to have undergone the same degree of metamorphism as the r e s t of the r o c k s . Most of these rocks are found i n the no r t h e r n part of the area where the grade of metamorphism appears to be s l i g h t l y lower than that to the south. Meta-morphism of rocks such as the s i l t s t o n e s c ould g i v e com-p o s i t i o n s f a i r l y c l o s e to the gneisses which appear to be on s t r i k e w i t h these rocks t o the south. Limestones are important f o r they i n d i c a t e an abundance of c a l c i u m carbonate i n the water and l i m e - s e c r e t i n g organisms. In many areas limestone i s a s s o c i a t e d w i t h q u a r t -z i t e s , or the limestone i t s e l f may c o n t a i n c o n s i d e r a b l e q u a r t z . T h i s suggests a shallow water marine s h e l f f a c i e s i n the zone of c u r r e n t and wave a c t i o n . The s c h i s t s must have had o r i g i n a l l y a much high e r p r o p o r t i o n of c l a y m i n e r a l s than the q u a r t z i t e s and g n e i s s e s . They have a high e r content o f i r o n , c a l c i u m , sodium, and magnesium as evidenced by the h i g h p r o p o r t i o n of b i o t i t e , hornblende, g a r n e t , c l i n o z o i s i t e , and p l a g i o c l a s e . Magnetite, p y r i t e , sphene, a p a t i t e , and c a l c i t e are more commonly present i n these r o c k s . Such rocks are a product o f deeper, q u i e t e r , water, where the f i n e c l a y m a t e r i a l s would s e t t l e out. 1 9 2 Some of the s c h i s t s a re very r i c h i n q u a r t z , but poor i n alumina. They g e n e r a l l y c o n t a i n much b i o t i t e . Most of the alumina would be l i n e d i n t h i s m i n e r a l . Hornblende s c h i s t s may r e p r e s e n t beds formed i n even q u i e t e r water than the other s c h i s t s , or perhaps they r e -present sediments d e r i v e d from a d i f f e r e n t source. The high e r content o f i r o n , c a l c i u m , and magnesium i n these rocks suggests that the o r i g i n a l r o c k was e i t h e r an impure dolomite sediment or a b a s i c igneous rock. The h o r n b l e n d i t e s are s t i l l more b a s i c . They c o n t a i n l i t t l e other than hornblende and c a l c i c f e l d s p a r . Such rocks o r i g i n a l l y could have been b a s i c f l o w s , dykes, or s i l l s . In the f i e l d many of these "beds" appear to be conformably w i t h the e n c l o s i n g rocks but the l i m i t e d o utcrop, the heavy bush, and the many l o c a l s t r u c t u r a l i r -r e g u l a r i t i e s obscure the exact r e l a t i o n s h i p . Metamorphism i n the Septum I t i s d i f f i c u l t i f not i m p o s s i b l e t o f i t the rocks of the area i n t o any of the metamorphic f a c i e s . Most of them appear t o f a l l i n the amp h i b o l i t e f a c i e s , predominately the s t a u r o l i t e - k y a n i t e s u b f a c i e s . In a l l but a few cas e s , however, the rocks c o n t a i n so many m i n e r a l s t h a t they cannot p o s s i b l y r e p r e s e n t e q u i l i b r i u m assemblages. In most cases the m i n e r a l s present could not e x i s t together i n any f a c i e s , i f e q u i l i b r i u m had been reached. The a s s o c i a t i o n of a blue green hornblende w i t h c l i n o z o i s i t e and o l i g o c l a s e - a n d e s i n e could be c o n s i d e r e d a phase j u s t past the a l b i t e - e p i d o t e - a m p h i b o l i t e f a c i e s . T h i s assemblage i s the most common i n the r o c k s . I t occurs i n q u a r t z i t e s , g n e i s s e s , s c h i s t s , and h o r n b l e n d i t e s and i s probably e q u i v a l e n t to the s t a u r o l i t e - k y a n i t e s u b f a c i e s . Another common a s s o c i a t i o n i s K - f e l d s p a r w i t h c l i n o z o i s i t e , minor garnet, b i o t i t e , q u a r t z , a n d w i t h or without p l a g i o -c l a s e and hornblende. T h i s type would a l s o be i n the s t a u r o l i t e - k y a n i t e s u b f a c i e s . Many of the rocks s t u d i e d c o n t a i n s m a l l amounts of c h l o r i t e and s e r i c i t e . T h i s m a t e r i a l i s g e n e r a l l y an a l t e r -a t i o n of b i o t i t e or more r a r e l y f e l d s p a r and hornblende. A broad zone of such rocks appears t o p a r a l l e l the main band of s c h i s t s through the middle of the a r e a . N o r t h o f E c s t a l l Lake i t i s much wider and the r e t r o g r e s s i v e e f f e c t s are much more pronounced. The a r e a mapped i s so l a r g e , and the number of rocks c o l l e c t e d and s e c t i o n e d so s m a l l i n p r o p o r t i o n , that exact boundaries of t h i s zone cannot be e s t a b l i s h e d . Areas i n the g n e i s s e s and q u a r t z i t e s a l s o c o n t a i n rocks w i t h c h l o r -i t e and s e r i c i t e . Probably a l l the rocks have undergone t h i s r e t r o g r e s s i v e metamorphism. In some rocks a l b i t e i s present as an a l t e r a t i o n of more c a l c i c p l a g i o c l a s e , t h i s may be e q u i v a l e n t to c h l o r i t e and s e r i c i t e . The e f f e c t of t h i s metamorphism has been to reduce the rocks towards the green-s c h i s t f a c i e s , but m i n e r a l s unstable i n t h i s f a c i e s s t i l l predominate. 1 9 4 The s a u s s e r i t i z e d hornblende d i o r i t e s of t h e area do not appear to f i t w i t h the l e v e l of metamorphism of the surrounding r o c k s . Probably these rocks were r e s i s t a n t to s h e a r i n g s t r e s s e s and to chemical r e c o n s t i t u t i o n because of t h e i r c oarse g r a i n and m i n e r a l composition. Thus they were l e s s a f f e c t e d by the r e g i o n a l metamorphism, except at t h e i r c o n t a c t s where they became c h l o r i t e s c h i s t s . S a u s s e r i t i z -a t i o n may have occ u r r e d w i t h the metamorphism of the surrounding r o c k s , or p o s s i b l y d u r i n g the l a t e r s t a g es. S e r i c i t e shear zones appear to be a l a t e r hydro-thermal a l t e r a t i o n , perhaps r e l a t e d t o the hydrothermal a l t e r a t i o n of the hornblende d i o r i t e s . The occurrence of s t r o n g l y sheared s e r i c i t e r i c h rocks i n d e f i n i t e zones suggests that some s t r u c t u r a l f e a t u r e has c o n t r o l l e d t h e i r f o r m a t i o n . I f they are a c t u a l l y l a t e r than the r e g i o n a l metamorphism, then they cannot be l o c a l i z e d along a p a r t i c u l a r sedimentary l a y e r , f o r the metamorphism would probably d e s t r o y any o r i g i n -a l f e a t u r e s that would favour such l o c a l i z a t i o n . The presence of p y r i t e i n p r a c t i c a l l y a l l the s e r i c i t e s c h i s t s suggests that the f l u i d s which e f f e c t e d the metasomatism c a r r i e d s u l -phur. Such f l u i d s c ould be r e l a t e d to the coast range i n -t r u s i o n s . P o s s i b l y to a l a t e post c r y s t a l l i z a t i o n phase. The E f f e c t s of the I n t r u s i v e Rock on the Metamorphic Rocks: One important f a c t i s apparent from a study of the contact o f the i n t r u s i v e and metamorphic r o c k s ; t h e r e i s no sudden i n c r e a s e i n metamorphism as the c o n t a c t i s approached. The o n l y evidence of any change i n the rocks i s a zone more r e s i s t a n t to e r o s i o n along the c o n t a c t and the displacement of the d e p r e s s i o n which commonly p a r a l l e l s the c o n t a c t t o -wards the metamorphic s i d e . T h i s r e s i s t a n t zone which may be 50 to 100 f e e t wide, i s not present everywhere. A p l i t e s , pegmatites, and g r a n i t e dykes a r e common along the margins of the i n t r u s i v e bodies both i n the igneous rock and i n the metamorphic rock . In some p l a c e s t h e r e i s a narrow zone marked by innumerable c r i s s c r o s s e d dykes and s i l l s . Because these minor i n t r u s i v e s are c l e a r l y younger than the b a t h o l i t h i t s e l f , they cannot be considered an advancing f r o n t of m i g m a t i z a t i o n . I f the E c s t a l l septum represented p a r t of a g r a n i t i z e d t e r r a i n e there would be a v a s t a r e a of migmatized r o c k s , perhaps c o v e r i n g the whole of the septum, r a t h e r than an i n s i g n i f i c a n t s t r i p a long the c o n t a c t s . Great t h i c k n e s s e s of l i m e s t o n e , s c h i s t , and q u a r t z i t e have been cut approximately at r i g h t angles by the Barbara Lake s t o c k . T h i n s e c t i o n s of the massive s i l i c e o u s l i m e -stones from t h i s area show the r o c k has r e c r y s t a l l i z e d to a marble c o n t a i n i n g s m a l l amounts of d i o p s i d e , t r e m o l i t e , and c l i n o z o i s i t e . Rounded g r a i n s , o b v i o u s l y o r i g i n a l quartz sand, are s c a t t e r e d throughout the rock. Even though t h i s rock i s w i t h i n 50 f e e t or l e s s of the c o n t a c t , and i s cut by a g r a n i t i c dyke over a f o o t wide, the l e v e l of metamorphism i s q u i t e low, c e r t a i n l y not above the f o u r t h r e a c t i o n of Bowens s e r i e s , f o r the metamorphism o f a s i l i c e o u s d o l o m i t e , or c o n s i d e r i n g the rock as a s i l i c e o u s l i m e s t o n e , the assemblage i s s t i l l below the f i r s t r e a c t i o n o f Bowens s e r i e s f o r t h a t rock. One s e c t i o n o f the limestone has numerous, l a r g e , a n h e d r a l , rounded, brown garnets i n a c a l c i t e - e p i d o t e - q u a r t z groundmass. T h i s rock looks l i k e a t y p i c a l product o f c o n t a c t metamorphism, but i t may have r e s u l t e d from the same meta-morphism that produced the r e s t o f the metamorphic r o c k s . The g r a n i t i c dykes which cut the Barbara Lake rocks have t h i n c h i l l e d selvedges which i n d i c a t e t h a t the meta-morphic rocks were q u i t e c o l d when the dykes were i n j e c t e d . Perhaps the metamorphic rocks were so c o l d when the main i n -t r u s i o n o c c u r r e d that they cooled the magma before i t c o u l d heat the metamorphic rocks s u f f i c i e n t l y to cause any change i n t h e i r s t a t e . The r e g i o n a l metamorphism which o c c u r r e d b e f o r e the i n t r u s i o n of the g r a n i t i c rocks probably drove o f f a l l the connate water and completely r e c r y s t a l l i z e d the r o c k s , so that when the i n t r u s i v e rocks were emplaced c o n d i t i o n s no longer favoured metamorphism. The r e l a t i v e l y u n a l t e r e d s i l i c e o u s limestone i n the Barbara Lake rocks i n d i c a t e s t h at the Barbara Lake s t o c k must have i n t r u d e d at a low temperature, c o n s i d e r a b l y l e s s than 1000° C, f o r i f the temperature had been g r e a t e r than t h i s & Bowen, N.L. 1940 197 the c a l c i t e would have d i s s o c i a t e d i n t o CaO and C 0 2 . ^ Probably the temperature of the rocks along the c o n t a c t o f the B a r b a r a Lake stock never reached more than 700° C, f o r above t h a t temperature w o l l a s t o n i t e and c a l c i t e are s t a b l e even i n the presence o f excess C 0 2 . ^ O r i g i n o f the I n t r u s i v e Rocks The evidence c i t e d above i n d i c a t e s t hat the magma must not have been v e r y hot when i t was emplaced and without a great d e a l of super heat i t could not p o s s i b l y have melted i t s way to reach i t s present p o s i t i o n . The f a c t t h at the f o l i a t i o n o f the s c h i s t , g n e i s s , and q u a r t z i t e i s n e a r l y everywhere conformable to the marked l o c a l i r r e g u l a r i t i e s i n the co n t a c t suggests t h a t some t r e -mendous f o r c e was a c t i v e d u r i n g i n t r u s i o n . The e f f e c t s o f such a f o r c e are evident i n the numerous f a u l t s and f r a c t u r e s that p a r a l l e l the con t a c t i n both rock types. Many of these are l a t e f e a t u r e s . They may r e p r e s e n t , however, the r e s u l t of f o r c e s r e s p o n s i b l e f o r the i n t r u s i o n c o n t i n u i n g and grad-u a l l y s u b s i d i n g long a f t e r the igneous rocks had been emplaced. A number of p o i n t s are a g a i n s t a f o r c e f u l i n t r u s i o n of a magma. F i r s t , the i n t r u s i v e rocks are not s t r o n g l y f o l i a t e d as might be expected i f there was motion i n a p a r t l y c r y s t a l l i z e d mass. Second, as noted above, the i n t r u s i v e A Ingerson, E. (1955) £ 2 Turner and Verhoogen (195D does not appear to have come i n at an e x c e s s i v e temperature. T h i s would suggest i n t r u s i o n as a predominantly c r y s t a l l i n e mass but the l i m i t e d amount o f s t r a i n and b r e c c i a t i o n i n the i n t r u s i v e rock does not i n d i c a t e t h i s o c c u r r e d . Other workers i n the n o r t h e r n Coast Range have noted ft pronounced banding or g n e i s s o s i t y p a r a l l e l i n g the c o n t a c t s . Such banding may be common along the margins o f the E c s t a l l septum, but as yet not enough of the i n t r u s i v e rock has been i n v e s t i g a t e d to be sure . That which has been seen i s not s t r o n g l y banded. The evidence so f a r obtained i n d i c a t e s the i n t r u s i v e rock has reached i t s present p o s i t i o n by f o r c e f u l i n t r u s i o n along l o n g p a r a l l e l b e l t s of weakness which were prepared by st r o n g orogenic deformation. Such an i n t r u s i o n might be. very s i m i l a r to a l a r g e t h r u s t sheet coming t o the s u r f a c e , from the ea s t , along a l i n e of f a u l t i n g . The rocks on e i t h e r s i d e might be l i t t l e e f f e c t e d by the t h r u s t i n g . A l l evidence suggests the i n t r u s i v e rock or magma o r i g i n a t e d not at i t s present l e v e l , but at some much deeper l e v e l i n the c r u s t . ft McConnell, R.G. (1912). CHAPTER V I CONCLUSIONS The sedimentary rocks i n the E c s t a l l septum were l a i d down i n an uns t a b l e s h e l f environment. A p e r i o d of r e g i o n a l metamorphism preceded the i n -t r u s i o n o f the Coast Range Complex B a t h o l i t h . T h i s p e r i o d may have been connected w i t h the f o r m a t i o n of the hornblende d i o r i t e i n t r u s i o n s . The l e v e l of metamorphism was not ex-c e s s i v e , the m i n e r a l assemblages are those o f the lower stages o f the amp h i b o l i t e f a c i e s . The g r a n o d i o r i t e s of the i n t r u s i v e complex d i d not evolve at t h e i r present l e v e l . I t appears that they a r r i v e d at t h e i r present p o s i t i o n by f o r c e f u l i n t r u s i o n , perhaps through low angle t h r u s t f a u l t i n g . Motion would be from east t o west. R e t r o g r e s s i v e metamorphism has reduced the grade of some of the rocks towards the g r e e n s c h i s t f a c i e s . T h i s meta-morphism could be connected w i t h the i n t r u s i o n of the batho-l i t h . U p l i f t and long continued e r o s i o n has exposed the rocks at a low l e v e l . P l e i s t o c e n e g l a c i a t i o n has been an important f o r c e i n the shaping of the topography of the r e g i o n . 200 BIBLIOGRAPHY Bacon, W.R., (1957), Geology of Lower J e r v i s I n l e t B r i t i s h Columbia, B.C. Dept. of Mines B u l l . No. 39. Bostock, H.S. (194-8), Physiography of the Canadian C o r d i l l e r a w i t h S p e c i a l Reference t o the Area N o r t h of the F i f t y - f i f t h P a r a l l e l , Geol. Surv. Canada, Mem. 247. Bowen, N.L. (1940), P r o g r e s s i v e Metamorphism of S i l i c e o u s Limestone and Dolomite. Jour. Geol., 48, 225-274. B r e s s l e r , C.T. (1950), Garnet Deposits near Wrangell South-e a s t e r n A l a s k a , U.S.G.S. B u l l . 963-C. Buddington, A.F., and Chapin, T. (1929), Geology and M i n e r a l Deposits of So u t h e a s t e r n A l a s k a , U.S.G.S. B u l l . 800. Dolmage, V. (1921), Coast and I s l a n d s of B r i t i s h Columbia Between Burke I n l e t and Douglas Channel, Canada Dept. of Mines, Geol. Surv. Sum. Rept., P t . A, pp. 22-49. (1922), Coast and Is l a n d s of B r i t i s h Columbia Between Douglas Channel and the Alaskan Boundary, Geol. Surv. Sum, Rept., P t . A. pp. 9-34. Dana, S.A. (1932), A Textbook of Min e r a l o g y , ( r e v i s e d by F o r d ) , John W i l e y and Sons, New York. G i l l , J .E., and Byers, A.R. (1948), S u r f I n l e t and Pugsley Mines, S t r u c t u r a l Geology of Canadian Ore D e p o s i t s , C.I.M.M., J u b i l e e V o l . pp. 99-104. Hanson, G. (1922), Reconnaissance Between K i t s a u l t R i v e r and Skeena R i v e r B.C., Geol. Surv. Sum. Rept. P t . A. pp. 35A-50A. (1923), Reconnaissance Between Skeena R i v e r and Stewart; Geol. Surv. Canada, Sum. Rpt. P t . A. pp. 29-45. (1935), P o r t l a n d Canal Area, B r i t i s h Columbia, Geol. Surv., Canada, Mem. 175. Holyk, W. (1952), Geology of E c s t a l l R i v e r Mine Area, Unpublished Report, E c s t a l l Mining Company. 201 Ingerson, E. (1955), Geologic Thermometry; Crust of the Earth, Geol. Soc. America S p e c i a l Paper 62. Irvine, W.T. (194-8), Britannia Mine, S t r u c t u r a l Geology of Canadian Ore Deposits, C.I.M.M., Jubilee Vol. pp. 105-109. James, H.T. (1929), B r i t a n n i a Beach Map-area, B r i t i s h Columbia, Geol. Surv., Canada, Mem. 158. Kindle, E.D. (1937), Mineral Resources of Terrace Area, Coast D i s t r i c t , B r i t i s h Columbia, Geol. Surv. Canada, Mem. 205. Mineral Resources, Usk to Cedarvale, Terrace Area, Coast D i s t r i c t , B r i t i s h Columbia, Geol. Surv. of Canada. Mem. 212. Lahee, F.H. (1952), F i e l d Geology, F i f t h E d i t i o n , McGraw-H i l l Book Co. Inc. Larsen, E.S. (1948), Bat h o l i t h of Southern C a l i f o r n i a , Geol. Soc. Am., Mem. 29. Le Roy, O.E. (1908), Preliminary Report on a Portion of the Main Coast of B r i t i s h Columbia and Adjacent Islands Included i n New Westminster and Nanaimo D i s t r i c t s Canada Dept of Mines, Geol. Surv. Branch. Lord, C.S., Hage, CO., and Stewart, J.S. (1947), The Cor d i l l e r a n Region, Geology and Economic Minerals of Canada, Third E d i t i o n , Canada Dept. of Mines, Geol. Surv., Ec. Geol. S e r i e s , No. 1. Mayo, E.B. (1941), Deformation i n the Interval Mt. Lyell-Mt. Whitney, C a l i f o r n i a , 1 G e o l . Soc. Am. B u l l . V o l . 52 pp. 1001-1084. McConnell, R.G. (1912), Geological Section along the Grand Trunk P a c i f i c Railway from Prince Rupert to Aldermere, B.C., Geol. Surv., Canada, Sum. Rept. pp. 55-62. Nelson, N.E. (1948), Hidden Creek Mine, St r u c t u r a l Geology of Canadian Ore Deposits, C.I.M.M. Jubilee, V o l . pp. 125-128. Rogers, A.F.,Kerr, P.F. (1942), Optical Mineralogy, Second E d i t i o n , McGraw-Hill Book Co. Inc. 202 Peacock, M.A. (1935), The F i o r d - l a n d of B r i t i s h Columbia Geol. Soc. Am. B u l l . , V o l . 46, pp. 633-696. P e t t i j o h n , F . J . (1957), Sedimentary Rocks, second e d i t . Harper and B r o t h e r s . Phemister, T.C. (1945), The Coast Range B a t h o l i t h near Vancouver, B.C.,. Quart. Journ. Geol. S o c , London, V o l . CI, P t s . lan d 2 pp. 37-88. Thornbury, W.D. (1954), P r i n c i p l e s of Geomorphology, John Wiley and Sons, Inc., T y r r e l l , G.W. (1926), The P r i n c i p l e s of P e t r o l o g y , Tenth E d i t . 1946, Methuen and Co. L t d . , Turner, F . J . and Verhoogen, J . (195D, Igneous and Meta-morphic P e t r o l o g y , McGraw-Hill Book Co. Inc., W i l l i a m , H. Turner, F . J . G i l b e r t , C M . (1955), Petrography W.H. Freeman and Co. W i n c h e l l , A.N., W i n c h e l l , H. ( 1 9 5 D , Elements of O p t i c a l Mineralogy P a r t I I , D e s c r i p t i o n s of M i n e r a l s , John W i l e y and Sons, Inc. 

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