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Contributions to the geology of Bowen Island Leitch, Henry Cedric Browning 1947

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tU] ft) L b Ct CONTRIBUTIONS TO THE GEOLOGY OP BOWEN ISLAND, B.C. by H. C." B. LEITCH Thesis submitted 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 the degree of Master of^Science i n G e o l o g i c a l Engineer-i n g at t h e \ U n i v e r s i t y of B r i t i s h Columbia. A p r i l , 1947 TA3LE OF CONTENTS . Page f a r t I Acknowledgments • 1 A b s t r a c t 1 I n t r o d u c t i o n •••• 4 •Location and Access 4 H i s t o r y 5 Summary"of Methods Used and the work completed - 6 P a r t L I General Features , .8 Topography 8 General Geology .. 8 Table of Formations ( f o l l o w i n g pg. 1 0 ) . . . 10(a) Part I I I D e s c r i p t i o n of Rocks of the D e t a i l e d Area .. 11 P r e - B a t h o l i t h i c Rocks 11 V o l c a n i c s and Interbedded Sediments .... 11 Agglomerate 12 Megascopic C h a r a c t e r i s t i c s . . . 12 Microscopic C h a r a c t e r i s t i c s ......... 13 ' Conclusions 15 Amygdaloidal Flows .... 16 Megascopic C h a r a c t e r i s t i c s • •. 16 Microscopic C h a r a c t e r i s t i c s 17 Feldspars 1 7 Amphibole " 18 Conclusions 22 Tuffaceous Sediments 2 5 - Megascopic C h a r a c t e r i s t i c s 26 Microscopic C h a r a c t e r i s t i c s . 26 Feldspars 2 7 Conclusions . ... 29 Flow B r e c c i a s and Related types of Rocks 2 9 . Megascopic C h a r a c t e r i s t i c s (type 1 ) . 30 Megascopic C h a r a c t e r i s t i c s (type 2 ) . 31 Microscopic C h a r a c t e r i s t i c s (type 2 ) 32 Feldspars . ... 3 3 Amphiboles 3 4 Conclusions » •. ' 3 5 Schistose Greenstone and interbedded V a r i e t i e s 4 0 . Megascopic C h a r a c t e r i s t i c s 4 2 Microscopic C h a r a c t e r i s t i c s 4 2 Conclusions 4 3 i Page f a r t I I I (cont'd) P r e - B a t h o l i t h Dykes ...., . ' 4 6 Megascopic- C h a r a c t e r i s t i c s ....... 49 Microscopic C h a r a c t e r i s t i c s ..... 49 Feldspars 5 ° Amphiboles 51 Conclusions 51 B a t h o l i t h i c and Minor I n t r u s i v e s ....... 5 5 . Q u a r t z - D i o r i t e 5 5 Megascopic C h a r a c t e r i s t i c s 5 5 Microscopic C h a r a c t e r i s t i c s ...... 5 6 Feldspars 5 6 Unknown M i n e r a l ' 5 7 Amphibole 5 7 • B i o t i t e ' . , . . . . . . . ' 58 Quartz • 5 9 Minor I n t r u s i v e s 5 9 P o s t - B a t h o l i t h Rocks 5 9 Basic Dykes 5 9 Megascopic C h a r a c t e r i s t i c s 6 0 Microscopic C h a r a c t e r i s t i c s ...... 6 0 Feldspars 61 Quartz 6,1. Conclusions .• 6 2 P a r t . I V S t r u c t u r a l Geology ...'.• 63 P a r t V General Conclusions 68 B i b l i o g r a p h y 7 4 11 LIST OF ILLUSTRATIONS Key Map f o l l o w i n g page 3 Figure 1, Heulandite g r a i n , showing cleavage l i n e s page 19 Figure 2, Heulandite c r y s t a l , showing o r i e n t a t i o n . . . . . . . " 20 Figure 3 , Appearance of gr a i n s of a l t e r e d ferromagnesian i n t h i n - s e c t i o n , (diagrammatic)............ " 2ft Figure 4, Replacement of andesine? by a l b i t e (diagram, no s c a l e ) . . . . . . . . " 3 ^ P l a t e I f o l l o w i n g page 12 P l a t e I I opposite * 16 P l a t e I I I • f o l l o w i n g " 31 P l a t e IV ........ opposite " 60 P l a t e V f o l l o w i n g " 66 Maps Compilation Map D e t a i l Map envelope on back cover. P. A R T I ACKNOWLEDGEMENTS The author i s indebted to Dr. H.C. Gunning f o r d i r e c t i n g him to an extremely i n t e r e s t i n g problem and f o r h i s guidance, advice and a s s i s t a n c e f r e e l y given at a l l stages of the preparation of t h e . t h e s i s . Guidance and advice by Dr. K. Watson on matters of petrography and petrology were v a l u a b l e . The author appreciates a l s o the guidance and i n t e r e s t given him i n matters of paleontology by-Dr..M. Y. Wi l l i a m s and Dr. V. J . O k u l i t c h . ABSTRACT Bowen I s l a n d i s s i t u a t e d w i t h i n s i x and one-half miles of the U n i v e r s i t y of B r i t i s h Columbia and i s a c c e s s i b l e a t a l l seasons. The i s l a n d contains a great v a r i e t y of rocks and o f f e r s an e x c e l l e n t oppor-t u n i t y f o r the student g e o l o g i s t to study b a t h o l i t h i c and minor i n t r u s i v e s , a c i d i c to b a s i c e x t r u s i v e s , : p y r o c l a s t i c s and sediments. The w r i t e r studied the rocks and i s submitting 3 f o r a Master's degree i n G e o l o g i c a l E n g i n e e r i n g ^ t h i s paper encompassing the r e s u l t s of h i s study. Roughly two'-4thirds of the i s l a n d were v i s i t e d i n reconnaissance survey. Mapping was done by means of pacing, compass and barometer. A c o m p i l a t i o n map -2 showing the w r i t e r ' s observations and those of e a r l i e r observers i s presented. A small area, roughly h a l f a mile square, was studied i n d e t a i l and i s the main basis of the paper. The area studied i n d e t a i l was found to be composed of v o l c a n i c s , sediments, q u a r t z - d i o r i t e and minor i n t r u s i v e s . The e a r l i e s t rocks i n the d e t a i l e d area are a s e r i e s of v o l c a n i c s with some interbedded s e d i -ments. The v o l c a n i c s and interbedded sediments are h i g h l y metamorphosed and i n t r u d e d by basic porphyry dykes which are i n t u r n metamorphosed to a l e s s e r degree. A l l the above are cut by q u a r t z - d i o r i t e and minor a c i d i n t r u s i o n s . This places the basic porphyry dykes as l a t e r than the v o l c a n i c s and e a r l i e r than the quartz-d i o r i t e : . . and r e l a t e d r o c k s . Basic dykes of t r a c h y t i c t e x t u r e represent the c l o s i n g period of i n t r u s i o n . P l e i s t o c e n e and po s t - p l e i s t o c e n e sediments l i e unconformably on the e a r l i e r r o c k s . There are three types of metamorphism present: a) dynamic metamorphism; b) thermal metamorphism; c) contact metamorphism. I n . a d d i t i o n to these, paulopost j u v e n i l e a c t i o n and p r o p y l i t i z a t i o n have caused considerable a l t e r a t i o n of the v o l c a n i c s and r e l a t e d dykes. The age of the b a t h o l i t h i s accepted p r o v i s i o n a l l y as Upper J u r a s s i c . M a t e r i a l which i s b e l i e v e d to be from f o s s i l i z e d organisms but which has not yet proved i d e n t i f i a b l e , i s found i n limey i n c l u s i o n s i n the v o l c a n i c s of Wharf P o i n t . The i n c l u s i o n s may i n d i c a t e an e a r l i e r limestone formation or mud formation con-temporaneous wi t h the flow r o c k s . S t r u c t u r e s i n the p r e - b a t h o l i t h v o l c a n i c s are of questionable a s s i s t a n c e i n determining top from bottom of a formation. KEY MAP -4-I N T R O D U C T I O N I t i s the i n t e n t i o n of the w r i t e r to c o n t r i b u t e some g e o l o g i c a l observations and conclusions from a b r i e f study of port i o n s of Bowen I s l a n d . A d e t a i l e d study of a small area of Bowen I s l a n d was made i n the hope that i t would act as a key to the o v e r a l l geology of p r e - b a t h o l i t h formations and give some idea of the s t r a t i g r a p h i c succession of rock types, and of the ages and the s t r u c t u r a l r e l a t i o n s h i p of these e a r l i e r formations. I t was d e s i r e d , p r i m a r i l y , to di s c o v e r some of the older rocks i n a more or l e s s undisturbed c o n d i t i o n and i n a not too metamorphosed s t a t e . Because these c o n d i t i o n s were absent, the rocks encountered g e n e r a l l y showing a tendency to advanced stages of a l t e r a t i o n , p a r t i c u l a r a t t e n t i o n was paid to the e f f e c t s of meta-morphism. A study of the nature and degree of meta* morphism may i n d i c a t e the o r i g i n a l character of the roc k s . LOCATION_AND ACCESS Bowen I s l a n d i s on the west f l a n k of the Coast Range b a t h o l i t h of B r i t i s h Columbia, at the j u n c t i o n of Howe Sound and the Gulf of Georgia. Prom the U n i v e r s i t y of B r i t i s h Columbia, on P o i n t Grey, to Cowan Poin t on Bowen I s l a n d i s 6 1/4 m i l e s , • -5-but the route of Union Steamships l i n e , the normal means of t r a n s p o r t a t i o n , covers 1 2 to 1 3 miles from Vancouver Harbour to Snug Cove, the main centre of population on the i s l a n d . Union Steamships make d a i l y connection with Bowen I s l a n d throughout the year. An a l t e r n a t i v e means of- reaching Bowen I s l a n d i s by way of the Lions Gate Bridge and the North Shore Road to W h y t e c l i f f e on Horseshoe Bay, both about 22 miles from the U n i v e r s i t y , and thence by a d a i l y f e r r y s e r v i c e 2 miles to Snug Cove. There are numerous roads and t r a i l s on the i s l a n d which are passable the year around. The south shore and i n t e r i o r v a l l e y s can be reached by road. Only one-half mile of the west shore i s a c c e s s i b l e by way of the K i l l a r n e y V a l l e y Road. A road to the north end of the i s l a n d was being completed at the time of w r i t i n g . This road w i l l make the northern h a l f of the east coast a c c e s s i b l e . The southern h a l f of the east coast, f o r the greater p a r t , i s i n a c c e s s i b l e except by boat. HISTORY The e a r l i e s t published r e p o r t s on the geology of the i s l a n d are by 0. E. LeRoy of the G e o l o g i c a l Survey of Canada. He r e p o r t s that a survey of a reconnaissance nature was made i n the year 1906 i n which the s h o r e l i n e -6-geology was mapped. • A l l succeeding maps show the geology i n the same manner as that mapped by LeRoy. From 1 9 1 3 to 1 9 1 4 , Dr. .E. M. J . Burwash examined the area of Howe Sound and more p a r t i c u l a r l y the north shore of Burrard I n l e t . A number of mining engineers, among them V. Dolmage, N. W.- -Emmons and A. Sharp, examined p r o p e r t i e s on Bowen I s l a n d i n the years 1 9 1 3 to 1 9 2 2 . Reference i s made to t h e i r f i n d i n g s i n the Reports of the M i n i s t e r of Mines, B.C. The l a t e s t work of a g e o l o g i c a l nature on Bowen I s l a n d was done by T. ,C. Phemister during the years of h i s stay at the U n i v e r s i t y of B r i t i s h Columbia as Professor of Petrography, 1 9 2 6 to 1 9 3 3 . This i s the most comprehensive r e p o r t on the geology of Bowen I s l a n d e xtant. ' SUMMARY OF METHODS USED and the • WORK COMPLETED • The author was able to v i s i t the i s l a n d f o r f i e l d s work only on a few weekends and during the Christmas . h o l i d a y s i ' D i f f i c u l t i e s of t r a n s p o r t a t i o n , dense bush, short winter days w i t h poor l i g h t , treacherous snow c o n d i t i o n s and steep-walled shores and c l i f f s were a few of the - 7 -handicaps that had to be overcome i n u n r a v e l l i n g the geology. Because of these d i f f i c u l t i e s and l a c k of accomoda-t i o n i n o u t l y i n g areas, the w r i t e r decided to examine i n d e t a i l a r e p r e s e n t a t i v e area i n the immediate v i c i n i t y of Wharf and Lodge Coves. G-eological mapping was done by pace and compass methods w i t h a barometer for' v e r t i c a l c o n t r o l . An e x c e l l e n t topographic map, prepared by the Hydrographic S e r v i c e , Department of Mines and Resources, Canada, on a sc a l e of one i n c h equal to one-half m i l e , was used as a base . r f o r the w r i t e r ' s - c o m p i l a t i o n map. This map has been produced by compiling a l l the a v a i l a b l e i n f o r m a t i o n about the geology of the I s l a n d , but i s based l a r g e l y on work done by the w r i t e r and by T. C. Phemister. Reconnaissance t r a v e r s e s were made f i r s t to a l l coasts of t h e . i s l a n d and to every s e c t i o n that could be reached by road except the extreme southwest c o r n e r . The reconnaissance survey was intended to a i d i n f a m i l i a r i z i n g the w r i t e r w i t h the rock types and to i n d i c a t e to him t h e i r o v e r a l l d i s t r i b u t i o n , The area of Lodge and Wharf- Coves f o r one^quarter mile west of s h o r e l i n e has been mapped on a s c a l e of 100 f e e t to the i n c h . IS t h i n - s e c t i o n s were made from samples taken i n t h i s area. I A R T I I -8-GENERAL FEATURES TOPOGRAPHY The i s l a n d i s mountainous, with steep f l a n k e d h i l l s and peaks r i s i n g to 1400 f e e t , and i n the Instance of Mt. Gardiner to 2500 f e e t , from sea l e v e l . I t w i l l he observed from, the c o m p i l a t i o n map that the i s l a n d i s d i v i d e d by deep, ;comparatively_JL,ow, U-shaped v a l l e y s i n t o . t h r e e main d i v i s i o n s . Streams are numerous on the i s l a n d . In places they have cut small gorges to a depth of 20 f e e t i n t o hardpan and c l a y d e p o s i t s . Several small lakes occur i n the upper reaches of the v a l l e y s . The slopes of the h i l l s , are h e a v i l y wooded wi t h deciduous evergreen and .•./ t r e e s . Dense undergrowth prevents easy t r a v e l even i n autumn and wi n t e r . GENERAL GEOLOGY The rocks of the i s l a n d are c h i e f l y of igneous o r i g i n , both of an e x t r u s i v e and i n t r u s i v e nature. They range from a c i d i c to b a s i c i n composition; from volcanic' surface flows to p l u t o n i c rocks; from minor d y k e - l i k e i n t r u s i o n s to i n t r u s i o n s greater than a square mi l e i n area; from p y r o c l a s t i c s to normal sediments. I n the main the rocks c o n s i s t of a v o l c a n i c assemblage of greats.thickness, probably measured i n thousands of f e e t , made up of flows , b r e c c i a s , agglomerates and tuffaceous sediments cut "by b a s i c porphyry dykes which may have been feeders f o r f l o w s . The v o l c a n i c s and b a s i c dykes are intruded and meta-morphosed by the coast b a t h o l l t h , which i n t u r n i s cut by l a t e r aplite,,pegmatite and basic dykes. Metamorphism has been s u f f i c i e n t l y strong to obscure the o r i g i n a l composition of the v o l c a n i c s and the p r e - b a t h o l i t h dykes. I d e n t i f i a b l e f o s s i l s have not (^re^ been found. .One area on Wharf P o i n t I s known i n which fragments i n a l a v a show a s t r u c t u r e that may be derived from organic remains. The calcareous fragments may i n d i c a t e e i t h e r a formation of limestone e a r l i e r than the l a v a or a mud formation contemporaneous with the l a v a . The age of the v o l c a n i c s . and other p r e - b a t h o l i t h i c rocks i s not known. They resemble rocks of the Vancouver group as developed on Vancouver I s l a n d and other parts of the west coast. This group contains rocks that range i n age from Permian or o l d e r to J u r a s s i c * but i t i s dominantly T r i a s s i c . -The b a t h o l i t h i s g e n e r a l l y accepted as being Upper J u r a s s i c i n age. P r i o r to i t s . emplacement there was a widespread i n t r u s i o n of b a s i c dykes. Only one period of i n t r u s i o n of these dykes was determined by the w r i t e r . No rocks of d e f i n i t e Cretaceous or T e r t i a r y age were determined, but i t i s very l i k e l y that p o s t - b a t h o l l t h b a s i c dykes belong somewhere i n t h i s . i n t e r v a l . Fresh - 1 0 * t u f f s found i n the i n t e r i o r of the i s l a n d may be T e r t i a r y i n age. Gabbroic rocks, probably p r e - b a t h o l i t h i n age, were found at the south end of Seymour Bay. (See com p i l a t i o n map). Large areas of g r a n o d i o r i t e and " h y b r i d " i n t r u s i o n s are known to outcrop on the i s l a n d . The general s t r i k e of the s t r a t a ranges 15° on e i t h e r side of east. Dips are g e n e r a l l y steep.' - 1 0 ( a ) -Table o'f Formationa Recent . . . . . Beach and v a l l e y a l l u v i u m P l e i s t o c e n e T i l l T e r t i a r y ? Fresh t u f f s Upper J u r a s s i c to T e r t i a r y ? Basic dykes Upper J u r a s s i c (to p o s s i b l y L. Cretaceous?) . . . . . . . Q u a r t z - d l o r i t e Carboniferous to J u r a s s i c ? . Andesite-porphyry? dykes Carboniferous to J u r a s s i c ? Metamorphosed f l o w s , p y r o c l a s t l c s and probably some i n t e r -bedded sediments F A R T I I I DESCRIPTION OF ROCKS OF THE DETAILED AREA PRE-BATHOLITHIC ROCKS V o l c a n i c s and Interbedded Sediments From a study of the c o m p i l a t i o n map, i t w i l l be seen that perhaps 10% or more of the i s l a n d i s made up of p r e - b a t h o l i t h i c r o c k s . The w r i t e r has i n d i c a t e d i n h i s c o m p i l a t i o n map that the b a t h o l i t h i n t r u s i v e rocks are probably the f l o o r of most of K i l l a r n e y V a l l e y . The bulk of evidence suggests that there i s an a r e a l trend to the s t r i k e of the p r e - b a t h o l i t h rocks, ranging around 10° to 15° oh e i t h e r side of east and g e n e r a l l y about 15° south of east. The rocks are p r a c t i c a l l y a l l s t e e p l y d i p p i n g when d i p can be observed but notable v a r i a t i o n s do occur. A l l the v o l c a n i c rocks examined show some e f f e c t s of metamorphism. Due west of the west shore of Lodge Cove there are some occurrences which appear f r e s h e r than most of t h i s p r e - b a t h o l l t h type. A l l of the v o l c a n i c s have a f i n e - g r a i n e d groundmass The p r e - b a t h o l i t h rocks examined i n d e t a i l i n the area around Lodge and Wharf Coves are, so f a r as could be determined, n e a r l y a l l of v o l c a n i c o r i g i n . Beginning on the south shore of Wharf P o i n t , the rock v a r i e t i e s w i l l be described i n the order of t h e i r -12 -occurrence from that point northwards to the north shore of Lodge Cove. The f i r s t v a r i e t y to be described i s the agglomerate. AGGLOMERATE The one occurrence l o c a t e d f l a n k s the south shore of Wharf Poi n t from the end of the Po i n t west f o r 400 f e e t and l i e s l a r g e l y below high water. I t forms a b e l t of rock 10 to 40 f e e t wide, p a r a l l e l to the shore. The northern contact of the agglomerate w i t h the ex t r u s i v e rock s t r i k e s roughly N.E.-S.W. Megascopic, C h a r a c t e r i s t i c s I t i s as though l a r g e bomb-like pieces of rock up to 2 1/2 f e e t i n diameter had been caught up wit h a mass of smaller fragments i n a scoriaceous l a v a . Closer observation r e v e a l s that the formation i s a mass of fragments ranging from rounded and elongated chunks of rock to t i n y a s h - l i k e p a r t i c l e s . The colour of the rock formation i s r u s t y brown and i n places , the appearance i s l i k e that of an i r o n gossan. The l a r g e r fragments show rounded white spots. Some of the white spots are almond-shaped and are undoubtedly amygdules. The hand specimen shows the porous nature of the rock and the prevalent brownish green colour on a f r e s h f a c e . Between the l a r g e fragments, the m a t e r i a l i s c l i n k e r - l i k e . This i n t e r s t i t i a l m a t e r i a l gives a FLA TE I Agglomerate. L o c a l i t y : Wharf Point ..acrophotograph of T.S. L ~ i 4 i l l u s t r a t i n g amygdaloidal character of agglomerate. - 1 > m e t a l l i c r i n g when rubbed l i g h t l y . M icroscopic C h a r a c t e r i s t i c s T.S. L-34 Is a s e c t i o n made from a l a r g e fragment of the rock. The s l i d e i s r i d d l e d w i t h s m a l l , g e n e r a l l y s p h e r i c a l but commonly hour-glass or almond-3haped, white areas. The s i z e of these amygdules ranges from .04 mms. to 4 mms. Phenocrysts of f e l d s p a r up to 2 mms. i n s i z e are v i s i b l e i n a d d i t i o n to many smaller fragments. The i n t e r f r a g m e n t a l cementing m a t e r i a l i s a coarse-grained carbonate. The composition of the f e l d s p a r phenocrysts i s b e l i e v e d to be a l b i c l a s e . They show the f o l l o w i n g o p t i c a l p r o p e r t i e s : B i a x i a l (+) Indices a l l lower than balsam. A l b i t e and Carlsbad twinning. Maximum e x t i n c t i o n angle i s -12°. The round areas are amygdules, the i n t e r i o r f i l l i n g being c h i e f l y carbonate or f e l d s p a r . ' In the l a r g e r amygdules, the f i l l i n g i s mainly carbonate. In the smaller ones, the f i l l i n g may be q u a r t z , f e l d s p a r or carbonate, o f t e n having next to the w a l l an outer r i n g of c l e a r grey m a t e r i a l of undetermined composition. The f e l d s p a r s of the amygdules have been replaced by carbonate, which i s present i n well-formed rounded or polygonal g r a i n s . By f a r the greater p r o p o r t i o n of the f e l d s p a r s of the amygdules are of one composition. The f o l l o w i n g are o p t i c a l data, obtained from t h i s c h i e f c o n s t i t u e n t : -14-Indices lower than balsam. P i n k i s h shade when viewed aga i n s t quartz or balsam. .2 sets of cleavage l i n e s at 90° (approx.) B i a x i a l (-) 2V l a r g e , about 85°. Optic plane perpendicular to 010. The data seem to i n d i c a t e a potash f e l d s p a r , since the two sets of cleavage t r a c e s , the s i g n and l a r g e 2V e l i m i n a t e h e u l a n d i t e and the l a c k of m u l t i p l e twinning combined with the angle between the cleavages t r a c e s appears to e l i m i n a t e microclin©. The o p t i c a l data w i l l f i t f o r ort h o c l a s e w i t h the exception that the o p t i c a l angle i s r a t h e r l a r g e , 69°-72° being the accepted value. In a d d i t i o n to t h i s f e l d s p a r , there i s at l e a s t one d e f i n i t e instance where a g r a i n of p l a g i o c l a s e was found i n s i d e an amygdule. The g r a i n showed higher i n d i c e s than the f e l d s p a r , a l b i t e and car l s b a d twinning, and was b i a x i a l p o s i t i v e . A mineral w i t h 2V l e s s than 60° and wit h no v i s i b l e cleavage, i s a l s o present i n a few amygdules. I t may be h e u l a n d i t e . D i f f i c u l t y i n d i s c e r n i n g t h i s m i n e r a l , i n d i f f e r e n t i a t i n g i t from the untwinned low index f e l d s p a r mentioned above, and i n s u f f i c i e n t time to make observations, f o r c e the w r i t e r to leave i t s i d e n t i f i c a t i o n i n the questionable category. Some of the amygdules have a centre composed of black m a t e r i a l which i s mainly magnetite. The i n t e r s t i t i a l groundmass of the amygdules and phenoerysts i s composed c h i e f l y of magnetite w i t h abundant epidote and c h l o r i t e . Some l a t h - l i k e m i c r o l i t e s -15-of f e l d s p a r occur In the groundmass. Aside from the black specks of magnetite and the f e l d s p a r m i c r o l i t e s , the groundmass Is c r y p t o c r y s t a l l i n e . A few phenocryst-l i k e areas remain o u t l i n e d by magnetite or hematite w i t h q u a r t z , magnetite, f e l d s p a r and carbonate c e n t r e s . V e i n l e t s of epidote t r a v e r s e the s l i d e . Conclusions The c o n c l u s i o n reached from f i e l d evidence and microscopic work i s that t h i s rock was formed by the explosive a c t i o n of a volcano. The fragmentary m a t e r i a l s , f i n e and coarse, have formed a l a y e r measured In tens of f e e t . The predominance of coarse m a t e r i a l and the s i z e of some fragments i n d i c a t e s the p r o x i m i t y of the v o l c a n i c source. The fragments have features i n common wit h the a d j o i n i n g p o r p h y r i t i c andesite which i s considered to be a flow rock. The o r i g i n a l f e l d s p a r of the formation i s b e l i e v e d to have been completely replaced by a l b i t e . The amygdules conceivably were f i l l e d o r i g i n a l l y w i t h z e o l i t e and l a t e r converted by the a c t i o n of contact metamorphism to f e l d s p a r s . Supporting evidence f o r t h i s i s presented i n the conclusions of amygdaloidal rock v a r i e t y . The q u a r t z - d i o r i t e i n t r u s i v e can be observed about 1000 f e e t west of the formation but i t i s q u i t e p o s s i b l e that i t i s (only 100 f e e t d i s t a n t ) v e r t i c a l l y . PLATE JL A 60 LIT? /CK Structures i n the limestone i n c l u s i o n s found i n the amygdalotdal flow. Enlarged view of a p o r t i o n of the above showingLaemblance" o f \ I n t e r n a l s t r u c t u r e i n bud-like" i n d i v i d u a l s . -16-AMYG-DALOI DAL FLOWS On Wharf "Point there are outcrops of rocks which have a pronounced p o r p h y r i t i c t e x t u r e and c o n t a i n infrequent amygdules. Present as entrapped m a t e r i a l are l a r g e r e d d i s h and p u r p l i s h fragments, up to 30 f e e t broad, probably of tuffaceous m a t e r i a l . Short s e c t i o n s of rocks a l s o occur which resemble the streaked, e l l i p s o i d a l v a r i e t i e s except that they are composed of f i n e - g r a i n e d s i l i c e o u s m a t e r i a l w i t h a hard, dense chalcedonic or cherty appearance. 10 to 20 f o o t sections of t h i s banded rock appear i n the massive dark green to b l a c k i s h amygdaloidal v a r i e t y of rock. S t r i k e and d i p can be obtained from them but they are discontinuous, g i v i n g place r a p i d l y to reddish brown types of the amygdaloidal rocks. At some p o i n t s they appear to merge i n t o the dark . type without any d i s c e r n a b l e boundary being crossed. Flow banding i s present at s e v e r a l p o i n t s along the south shore of the p o i n t . The s t r i k e and d i p vary w i d e l y . F a r t h e r to the east at the extreme t i p of Wharf P o i n t , which i s marked by a pole s i g n a l , are rocks which c o n t a i n i n c l u s i o n s of very limey m a t e r i a l . The i n c l u s i o n s are b e l i e v e d to be fragments of a limestone formation caught up i n the l a v a f l o w . The i n c l u s i o n s c o n t a i n rounded and odd-^shaped areas not u n l i k e o o l i t e s , and o c c a s i o n a l l y shov; c o n c e n t r i c i n t e r n a l s t r u c t u r e . Megascopic C h a r a c t e r i s t i c s Megascopically the rock i s c h a r a c t e r i z e d by white f e l d s p a r phenocrysts i n a f i n e - g r a i n e d , dense, dark green groundmass. The phenocrysts are very i r r e g u l a r i n shape but show some sharp c r y s t a l edges. Some g r a i n s show - 1 7 -rounded corners suggestive of r e s o r p t i o n . They are - numerous, making up perhaps 4 0 $ of the rock, and they The rock i s hard, tough and weathers brown on the surfac e . I t \ i s observed to have weathered evenly to a depth of s l i g h t l y over 1 / 1 6 i n c h . In addition t© phenocrysts, some round and e l l i p t i c a l white spots about 1/2 to 1 nun., i n s i z e can be observed i n the hand specimen. In some specimens, these are numerous, but i n general only a few can be seen per specimen. Microscopic C h a r a c t e r i s t i c s Two thin-sections.were examined, L - 1 0 9 and L - 6 6 . The overallt,.appearance i s that of a porphyry; the phenocrysts which are present appear as r e c t a n g u l a r to lath-shaped g r a i n s of grey f e l d s p a r i n a f i n e - g r a i n e d groundmass. The groundmass c o n s i s t s mainly of minute n e e d l e - l i k e m i c r o l i t e s of f e l d s p a r and a green amphibole.. In T.§. L i - 1 0 9 , about f i v e elongate almond-shaped to hour-g l a s s shaped areas are noted. The f o l l o w i n g I s a d e s c r i p -t i o n based on the misroscoplc examination of T.S. L - 1 0 9 . FELDSPARS; Determination of the l a r g e r f e l d s p a r phenocrysts r e v e a l s that they c o n s i s t of andesine w i t h the f o l l o w i n g o p t i c p r o p e r t i e s : range i n s i z e from 1/2 to 3 mms. on the average. -18-The p r o p e r t i e s conform best to those of a f e l d s p a r of composition AD55 to Abc;Q. The groundmass f e l d s p a r s have more or l e s s the same composition as the phenocrysts but there are many g r a i n s of a l b i t e present. Twinning, when present, i s c h i e f l y broad and i r r e g u l a r . A few f e l d s p a r g r a i n s show good twinning. A l t e r a t i o n i s l a r g e l y to s e r i c i t e with some c l i n o z o i s i t e and q u a r t z . AMPHIBOLE: There are some euhedral phenocrysts but the amphibole occurs mainly as minute shreds or f l a k e s l i b e r a l l y d i s t r i b u t e d throughout the s l i d e . Optic p r o p e r t i e s are: Greenish c o l o u r x = pale yellow P l e o c h r o i c , y s greenish yellow . z - yellow green B i a x i a l (-) B i r e f r i n g e n c e orange to blue-grey of f i r s t order 3 . O i l to . O 1 3 Length slow ( p o s i t i v e elongation) Index above 1.64, probably about 1.68 2V around 70 to 80° Maximum e x t i n c t i o n about 13° The l a r g e r phenocrysts are q u i t e e v i d e n t l y an amphibole as shown by the c h a r a c t e r i s t i c 56° and 124° angles between the cleavage l i n e s . The o p t i c a l p r o p e r t i e s do not i n d i c a t e hornblende, but r a t h e r a t r e m o l i t e h i g h i n i r o n , c o n t a i n i n g say 55% to 56% of f e r r o t r e m o l i t e molecule. I t might be termed a high i r o n a c t i n o l i t e . In a d d i t i o n to f e l d s p a r and amphibole, the rock contains the secondary mineral c l i n o z o i s i t e . I t i s de r i v e d , i n p a r t , from f e l d s p a r a l t e r a t i o n . A small but d i s t i n c t v e i n l e t crosses s l i d e L - t 0 9 , c u t t i n g the f e l d s p a r phenocrysts and amygdules. The v e i n l e t Is f i l l e d w ith c l i n o z o i s i t e , q u a r t z , a -19-c o l o u r l e s s mineral which i s probably h e u l a n d i t e and an unknown mineral with good cleavage. The c l i n o z o i s i t e appears c h i e f l y i n the c e n t r a l p o r t i o n of the v e i n l e t . Quartz, heulandite? and the unknown mineral show as w e l l developed g r a i n s along the w a l l s and i n the centre of the v e i n l e t . The amygdules co n t a i n the same minerals as the'".', v e i n l e t . Quartz tends to form rounded to angular g r a i n s i n a groundmass of h e u l a n d i t e ? . In a d d i t i o n to these minerals, a c t i n o l i t e g r a i n s appear i n the c e n t r a l p o r t i o n s of the amygdules wi t h no evident connection with the w a l l s or main groundmass of the rock. The v e i n l e t minerals are coarser and have b e t t e r formed and l a r g e r grains than the minerals i n the amygdules. The f o l l o w i n g are the o p t i c a l p r o p e r t i e s obtained on the mineral b e l i e v e d to be he u l a n d i t e : C o l o u r l e s s to f a i n t pink Indices lower than balsam or qua r t z , y i e l d i n g a p i n k i s h tone against e i t h e r . The becke l i n e i s d i s t i n c t and suggests i n d i c e s below 1.52. B i r e f r i n g e n c e about .008 B i a x i a l (+) One d i s t i n c t cleavage (shows only i n few g r a i n s of h i g h e r , b i r e f r i n g e n c e ) P i g . 1.--Heulandite g r a i n . One set of cleavage l i n e s i n g r a i n of higher b i r e f r i n g e n c e which shows some c r y s t a l o u t l i n e . - 20-E x t i n c t i o n p a r a l l e l Oapprox.) or a t r i g h t angles to cleavage. Cleavage traces p a r a l l e l to the f a s t e r ray. c A y = -7° X 9 P i g . 2 . - - I l l u s t r a t i n g o r i e n t a t i o n i n a c t u a l c r y s t a l of h e u l a n d i t e observed i n t h i n s e c t i o n . The unknown c o l o u r l e s s mineral has very low b i r e -f r i n g e n c e , perhaps .002 to .004, and appear/s~rdentical to the above except that i t shoy/s a f a i n t Becke l i n e against the h e u l a n d i t e , i n d i c a t i n g s l i g h t l y higher i n d i c e s . I t has two sets of cleavage traces p r a c t i c a l l y perpendicular to each other. Figures are very i n d i s t i n c t but the mineral i s apparently b i a x i a l and probably negative i n s i g n . The above data suggest potash f e l d s p a r to the w r i t e r . In the l a r g e s t amygdule, a curious s t r u c t u r e was noted. This s t r u c t u r e appears i n the c e n t r a l area of the amygdule where there i s an area of t i n y s p h e r i c a l grains about .002 mms. i n s i z e . Some of the gr a i n s are arranged i n co n c e n t r i c bands which, due to d i f f e r e n c e s i n b i r e f r i n g e n c e i n one band when compared to another, give the impression of conc e n t r i c l a y e r i n g . The concentric p a t t e r n i s r e a d i l y seen when viewed under - 2 1 -crossed n i c o l s , but disappears when viewed wi t h the upper n i c o l out. The t i n y g r a i n s are made up of at l e a s t two m i n e r a l s , as i n d i c a t e d by a d i f f e r e n c e i n index. The mineral showing the higher index of the two i s thought to be q u a r t z . T. S. L-109 shows a l a r g e bleb of magnetite with a l t e r a t i o n to hematite around the edges. Another s e c t i o n , T.S. L-66, was made from a rock sample taken from the north c e n t r a l p o r t i o n of Wharf ' P o i n t . As i n L-109, l a r g e phenoerysts of f e l d s p a r are present but the composition seems c l o s e r to a l b i c l a s e . A l l the minerals and i n p a r t i c u l a r the f e l d s p a r s are h i g h l y a l t e r e d . This makes i d e n t i f i c a t i o n d i f f i c u l t , i f not i m p o s s i b l e . The f o l l o w i n g o p t i c a l p r o p e r t i e s of the f e l d s p a r phenoerysts are noted: B i r e f r i n g e n c e .009 Indices l e s s than balsam, about 1.53 + (one index may be equal to balsam) Maximum e x t i n c t i o n angle x> />. 010 (twinning) = -6 1/2° B i a x i a l ( + ) (?) A few of the smaller g r a i n s seem to have an index greater than balsam or q u a r t z . A negative s i g n was obtained i n a few cases on these g r a i n s . They are b e l i e v e d to be the o r i g i n a l f e l d s p a r or p a r t i a l l y a l b i t i z e d o r i g i n a l f e l d s p a r and to have a composition of about andesine or o l i g o c l a s e - a n d e s i n e . The a l t e r a t i o n of the phenoerysts of f e l d s p a r i s c h i e f l y to carbonate and s e r i c i t e with some c l i n o z o i s i t e , c h l o r i t e and quartz. Where the a l t e r a t i o n i s i n t e n s e , l a r g e f l a k e s of s e r i c i t e have been produced. -22-The ferromagnesians have been e n t i r e l y converted to c h l o r i t e (pennine), magnetite, carbonate and epidote, but from the c r y s t a l o u t l i n e s remaining, i t i s l i k e l y that the ferromagnesians were c h i e f l y amphibole. P i g . 3.--Diagram i l l u s t r a t i n g a c t u a l appearance of g r a i n s of a l t e r e d ferromagneslan seen i n t h i n -s e c t i o n . Centre clouded except f o r t i n y r e s i d u a l areas of amphibole ( ? ) . Epidote i s evenly d i s t r i b u t e d through the s l i d e as small g r a i n s . A p a t i t e i s a common-mineral o c c u r r i n g as euhedral gr a i n s throughout. Quartz i s common but i s i n t e r s t i t i a l and, t h e r e f o r e , may have been a l a t e r a d d i t i o n . Conclusions The rock o r i g i n a t e d as a f l o w . This i s i n d i c a t e d by the flow l i n e s , some s t r e a k i n g and the broken f e l d s p a r •grains. The amygdules support t h i s i n that they would most l i k e l y have r e s u l t e d from trapped gases i n a f a i r l y r a p i d l y cooled rock such as a ^ s u r f i c l a ^ f l o w . The f i n e - g r a i n e d nature of the groundmass suggests r a p i d c o o l i n g . Amphibole i s present i n the c e n t r a l parts of the amygdules and t h i s i n d i c a t e s that i t i s a l a t e r and introduced mineral or i s due to a l t e r a t i o n of an e a r l i e r m i n e r a l . -23-Two types of a l t e r a t i o n , a l b i t i z a t i o n and propy-l i t i z a t i o n , are present. A l b i t i z a t i o n i s r e s p o n s i b l e f o r the r e p l a c i n g of the o r i g i n a l p l a g i o c l a s e , of composition about andesine, by f e l d s p a r w i t h a high sodic content. This would be an e a r l y a l t e r a t i o n due to paulapost j u v e n i l e a c t i o n or d e u t e r i c a c t i o n . The term paulapost j u v e n i l e a c t i o n i s a general one, "applied to changes suffered by igneous rocks immediately a f t e r t h e i r formation as a d i r e c t consequence of the c o n s o l i d a t i o n of the magma."— The numerous f r a c t u r e s , f i l l e d w i t h epidote, may have r e s u l t e d from f r a c t u r i n g during c o n s o l i d a t i o n w i t h subsequent f i l l i n g by r e s i d u a l l i q u o r s or by gases. S i x - i n c h wide but 40 or 50 f o o t long v e i n - l i k e bodies of greenish epidote were noted i n the flows and the rock had been bleached f o r as much as 2 inches on e i t h e r side of the v e i n - l i k e bodies. Examination of t h i s f eature showed that the fl o w rock had been a l t e r e d to epidote r e g a r d l e s s of amygdules, phenoerysts or ground-mass. P r o p y l i t i z a t i o n i s the second type of a l t e r a t i o n present. I t i s c h a r a c t e r i z e d m i c r o s c o p i c a l l y by the presence c h i e f l y of c h l o r i t e , epidote, carbonate, some quartz and some a l b i t e . The ferromagnesians are con-verted to c a l c i t e , c h l o r i t e (pennine), epidote and magnetite. Although the p l a g i o c l a s e g r a i n s sometimes show 60fo a l t e r a t i o n to c a l c i t e 'and c l i n o z o i s i t e , they are c h i e f l y a l t e r e d to s e r i c i t e and where the a l t e r a t i o n has been intense as on the north side of the Point, 1— R i c e , C M.: " D i c t i o n a r y of G e o l o g i c a l Terms", 1946, pg. 295. -24-they are 80$ converted to l a r g e f l a k e s of s e r i c i t e . The a l t e r a t i o n of the p l a g i o c l a s e to s e r i c i t e and the baked p u r p l i s h - r e d appearance of rock where the a l t e r a t i o n has been intense would seem to i n d i c a t e a l a t e r a l t e r a t i o n superimposed on the already p r o p y l i t i z e d rock. The presence of quartz and potash f e l d s p a r i n v e i n l e t s and amygdules and the presence of l a t e (?) i n t e r s t i t i a l quartz i n some po r t i o n s of the rock on the north side of Wharf poin t i s suggestive of hydrothermal a c t i v i t y . A l l of the a l t e r a t i o n might be due to hydrothermal a c t i v i t y . The ( p e c u l i a r j a s s o c l a t i o n of minerals c l i n o z o i s i t e , q uartz, h e u l a n d i t e , potash f e l d s p a r a n d - a c t i n o l i t e i n the v e i n l e t s and amygdules i s unusual. I t may have r e s u l t e d i n a manner s i m i l a r to th a t described by Harker: lavas of Skye by p l u t o n i c masses of gabbro and granophyre are f i r s t shown i n the amygdules where z e o l i t e s have been converted to f e l d s p a r s along with epidote, z o i s i t e and a c t i n o l i t e . In the body of the rock the augite has been converted i n t o f i b r o u s hornblende and c h l o r i t e i n t o b i o t i t e a t some dis t a n c e from the contact."— The amphibole i n the rock i s a c t i n o l i t e and i s e i t h e r an introduced mineral or may be due to a l t e r a t i o n of some e a r l i e r ferromagnesians. I t s occurrence i n s i d e II The e f f e c t s of the contact metamorphism of the b a s a l t 2 T y r r e l l ^ " f r i n c i p l e s of P e t r o l o g y " Pg. J01, 1926^ Methuen. 2 5 -the amygdules suggests l a t e r I n t r o d u c t i o n . The composition of the rock i s c l o s e s t to that of an andesite and since i t . i s metamorphosed and a l b i t i z e d , the term meta-andesite might serve as a d e s c r i p t i v e term. Another p o s s i b l e name f o r the rock might be p o r p h y r i t i c a n d e s i t e . The calcareous fragments are b e l i e v e d to be f r a g -ments of an e a r l i e r .or p o s s i b l y contemporaneous limestone^or mud) formation. TUFFACEOUS SEDIMENTS Under t h i s heading rocks of more than one o r i g i n may i n a d v e r t e n t l y ' b e i n c l u d e d ; u n t i l more d e t a i l e d observa-t i o n s can be made on them, they are i n a d o u b t f u l category. Some specimens of. these rocks were obtained, which c o n t a i n fragments up to 1/2 i n c h i n s i z e . This type of rock was not studied i n s u f f i c i e n t d e t a i l to determine whether b r e c c i a beds and sedimentary beds were interbedded with the tuffaceous sediments. The main occurrences are those shown on the compila-t i o n map as outcropping along both sides of Trout Lake V a l l e y . In the d e t a i l e d area, -the l a r g e s t outcrops of these rocks occur around the western and southern borders at the highest e l e v a t i o n s but there are a l s o minor occurrences at sea l e v e l . Outcrops marked "4" on the map i n d i c a t e the extent of these r o c k s . -- 2 6 -At one poin t i n a cutbank along the Trout Lake road j u s t outside the boundaries of the d e t a i l e d area, these rocks show an i r r e g u l a r lensey bedded character of i n t e r s t r a t i f i e d l i g h t and dark m a t e r i a l . P r e - b a t h o l i t h dykes e n t e r i n g these rocks show l i t t l e shearing. Fragments of the tuffaceous sediments are found i n the dykes. • Megascopic C h a r a c t e r i s t i c s W i thin the d e t a i l e d area these rocks are observed to be very dark, p u r p l i s h to black , very f i n e - g r a i n e d and c h e r t - l i k e with a conchoidal f r a c t u r e . Commonly they show, under c l o s e observation, a wavy banding, grading from black to l i g h t coloured bands wi t h i n t e r -mediate mottled bands. Two prominent features of t h i s v a r i e t y of rock are: abundant very f i n e - g r a i n e d p y r i t e d i s t r i b u t e d throughout the rock and the broken nature of the rocks from the multitude of t i n y shear planes d i s p e r s e d . i n a l l d i r e c t i o n s . Microscopic C h a r a c t e r i s t i c s In the s l i d e s t u d i e d , L - 1 , a crude bedded nature i s noted with l a r g e r f e l d s p a r fragments tending to congregate i n c e r t a i n bands. The boundaries between "beds" are i n d e f i n i t e and i r r e g u l a r . C e r t a i n bands tend to show l a r g e r development of carbonate. The mottled character imparted by darker fragments i n a l i g h t e r grey m a t e r i a l i s due c h i e f l y to an increase of b l a c k , very f i n e - g r a i n e d m a t e r i a l . The black m a t e r i a l -27-resembles minute gr a i n s of magnetite. Where these black areas are concentrated, the fragments of f e l d s p a r and quartz are much f i n e r . Many fragments of the f e l d s p a r are twinned and are angular. There are numerous long wedge-shaped, angular pieces such as would be expected i n a t u f f , but there are a l s o many rounded fragments. The i n t e r v e n i n g m a t e r i a l surrounding the l a r g e r f e l d s p a r fragments c o n s i s t s of minute g r a i n s , 90% of which are l e s s than .01 mms. i n diameter. About 75% of t h i s groundmass i s presumably f e l d s p a r and q u a r t z , judging only by the b i r e f r i n g e n c e . The remainder c o n s i s t s of carbonate, black m a t e r i a l , p y r i t e and epidote. FELDSPARS: On g r a i n s that a r e . l a r g e enough to be s t u d i e d , most have i n d i c e s higher than balsam and higher g e n e r a l l y than much of the groundmass, say > 1 . 5 6 . There are, however, v a r i a t i o n s ; some fragments' show a lower index than balsam. Those of higher index show! 2V, about 7 5 ° or greater B i a x i a l ( T) D i s t i n c t a l b i t e twinning Maximum e x t i n c t i o n angle about + 2 7 ° I t would seem safe to suppose that t h i s f e l d s p a r i s of a composition about Ab^^ and i s andesine. No f i g u r e s were obtained on the f e l d s p a r s of low index but they had a p i n k i s h appearance against balsam and the groundmass. These low index g r a i n s have maximum e x t i n c t i o n angles of - 1 5 ° i n d i c a t i n g a l b i t e . - 2 8 -Quartz i s present as gra i n s of .2 mm. s i z e and i s sp a r s e l y d i s t r i b u t e d . Carbonate i s common and d i s t r i b u t e d throughout the . s l i d e . I t i s observed to be more abundant, i n c e r t a i n bands. Epidote g r a i n s which can be i d e n t i f i e d as such are • rare but a good deal of the groundmass i s b e l i e v e d to be epidote. A mineral with a s l i g h t b l u i s h t i n g e when viewed wi t h upper n i c o l out, i s present. I t shows the f o l l o w i n g . o p t i c a l f e a t u r e s : Low b i r e f r i n g e n c e , .005 No pleochroism Cleavage \ P a r a l l e l , e x t i n c t i o n Index about 1.60 . Apparently b i a x i a l -I t may belong i n the c h l o r i t e f a m i l y . J T h e s l i g h t c o l o u r i n the extremely f i n e - g r a i n e d groundmass i s probably due to a great p r o p o r t i o n of t h i s m i n e r a l . The f e l d s p a r "fragments are l a r g e l y c l e a r , o f t e n w i t h sharp edges; sometimes they.do show ragged edges. With the exception of one band i n which there i s . a greater abundance of the l a r g e r f e l d s p a r fragments, the l a r g e r f e l d s p a r fragments are evenly d i s t r i b u t e d through-out the rock. The quartz which i s present is' d u l l and contains many i n c l u s i o n s . There i s a l t e r a t i o n . t o epidote and c l i n o z o i s i t e i n the groundmass. Carbonate i s secondary and i s apparently introduced. Much of the epidote and c l i n o z o i s i t e i s b e l i e v e d to be the product -29-of o r i g i n a l amphiboles. In a d d i t i o n to p y r i t e , two other m e t a l l i c minerals are noted i n the s l i d e . One, a brown t r a n s l u c e n t m i n e r a l , might be'hematite or s p h a l e r i t e ; i t i s noted as o c c u r r i n g p r i n c i p a l l y i n a l i t t l e v e i n l e t . In,the second i n s t a n c e , the m e t a l l i c mineral i s opaque and i s p y r r h o t i t e . Conclusions This rock i s b e l i e v e d to be derived from p y r o c l a s t i c fragments, some of which were of extremely f i n e nature and others composed of g l a s s . P o s s i b l y some mud was inc l u d e d . The banding i s very i r r e g u l a r and wavy and suggests r a t h e r a haphazard d e p o s i t i o n i n t e r f e r e d w i t h by slumping and s e t t l i n g . I t i s notable that what i s thought to have been o r i g i n a l l y g l a s s y m a t e r i a l i s l a r g e l y confined to separate bands,.as though a greater p r o p o r t i o n of gl a s s was deposited at c e r t a i n p e r i o d s . , The rough s o r t i n g suggests some s l i g h t reworking--, by water. FLOW BRECCIAS AND RELATED TYPES OF ROCK The rocks" described below outcrop n o r t h of the pr e v i o u s l y described rocks along the n o r t h shore of Lodge Cove and i n the general v i c i n i t y of the northern-most creek e n t e r i n g Lodge Cove. Two types occur i n these rocks. The f i r s t , type 1, which w i l l be described only megascopically, has d e f i n i t e l i n e a r features which give : i t a banded or streaked appearance. The s t r i k e and d i p -30-of these f e a t u r e s conform to the r e g i o n a l trend of s t r i k e and d i p . The second type (type 2) a d j o i n s type 1 and grades northward somewhat sharply i n t o i t . Type 2 contains sc a t t e r e d l a r g e , s quarish white fragments i n a l i g h t to dark-green .matrix;. The best outcrop of these two types which i l l u s t r a t e s t h e i r r e l a t i o n to each other i s 600 by 300 f e e t ; the northern boundary i s a porphyry dyke, the western, eastern and southern boundaries are over-burden. As I l l u s t r a t e d on the d e t a i l map, type. 1 i s hot continuous westward along i t s s t r i k e a f t e r the dyke i s crossed, but areas do occur, on the west side of the dyke, of type 2 i n which there i s some semblance of alignment i n the fragments. These areas are not f a r from being i n l i n e with type 1. Megascopic C h a r a c t e r i s t i c s (type 1) Type 1 represents the streaked rock. This s t r e a k i n g i s observed to be due to very elongated e l l i p s o i d s of dense l i g h t coloured minerals i n a dark green to black matrix of s i m i l a r t e x t u r e . The white e l l i p s o i d s vary g r e a t l y i n s i z e from 1/4 to 2 inches i n width and from 1/2 i n c h to 2 f e e t i n l e n g t h . I t i s common to have 7 or 8 of them about the width of, a f i n g e r i n a foot-wide s e c t i o n across the s t r i k e . The e l l i p s o i d s have t h e i r longest axes' p a r a l l e l , producing a s t r u c t u r e which conforms to the general s t r i k e . The ( l i g h t ' and dark) sharp d i s t i n c t i o n between the two components/is due to d i f f e r e n c e s of c o l o u r r a t h e r than t e x t u r e , To use T. C. Phemister's d e s c r i p t i o n of the rock,; which the w r i t e r has . v e r i f i e d i n every d e t a i l and which he f e e l s he cannot express any b e t t e r : "The p r i n c i p a l c o n s t i t u e n t of the rock as a whole i s d u l l white f e l d s p a r i n well-shaped c r y s t a l s and some of the l i g h t e r e l l i p s o i d s appear to c o n s i s t of t h i s e n t i r e l y , whereas the rock contains i n a d d i t i o n a black base i n which these p l a g i o c l a s e prisms are s e t . A constant component of both parts of the rock i s pyroxene i n black c r y s t a l s about 2 mm. i n diameter and t h i s mineral sometimes occurs with part of the c r y s t a l i n the l i g h t , part i n the dark p o r t i o n s of the rock, i n d i c a t i n g that these two are probably but d i f f e r e n t phases of one l a v a type."2 Megascopic C h a r a c t e r i s t i c s (type 2) Type 2 of the same rock v a r i e t y i s a dark to l i g h t green rock w i t h squarish white fragments dispersed unevenly through i t . The s i z e of these fragments v a r i e s g r e a t l y but does not appear to exceed 3 inches i n diameter. When the edges of these fragments are observed c l o s e l y , many smaller fragments can be found rimming the l a r g e r ones.. The cores of the l a r g e r fragments are ; grained coarser/than the outer p o r t i o n s . . ' The white areas' i n the dark green groundmass c o n s i s t mainly of white f e l d s p a r w i t h amphibole g r a i n s dispersed through the f e l d s p a r . Some of the- white fragments appear to have an outer Phemister, T.C., "coast Range B a t h o l i t h near Vancouver, B.C." Q.J. G-.S. of London. Oct. 1945,Pg. 5 1 . PLATE m Flow b r e c c i a v a r i e t y of rock (type 2 ) , showing white f r a g -ments scattered through the rock. P r e - b a t h o l i t h dyke c u t t i n g through flow b r e c c i a v a r i e t y of rock. -32-g h o s t - l i k e area surrounding them i n which the dark minerals are reduced. I t as though the white fragments were a d j u s t i n g themselves around the borders to a magma higher i n ferromagnesian mi n e r a l s . In these outer zones, the white g r a i n s of f e l d s p a r are elongate and show a somewhat s u b - p a r a l l e l arrangement in. a l i g h t e r coloured green area, the whole being enclosed i n a d u l l dark green base.". : '• Many of the gr a i n s of f e l d s p a r measure from 1 to 3 mms• The main body of rock which forms a dark base f o r the fragments appears somewhat granular with f i n e - g r a i n e d green i n t e r s t i t i a l m a t e r i a l . Examination shows that white f e l d s p a r of the same type as that i n the white fragments la s c a t t e r e d throughout the dark green base, the only apparent d i f f e r e n c e between the fragments and the dark base being the p r o p o r t i o n of f e l d s p a r to amphibole. Microscopic G h a r a c t e r i s t l c s (Type 2) The main c o n s t i t u e n t s of the rock are p l a g i o c l a s e and green hornblende. The amphibole occurs as green clumps which transgress the boundaries of the f e l d s p a r s . Accessory c o n s t i t u e n t s are p y r r h o t i t e , epidote and a mineral b e l i e v e d to be z o i s i t e , with the f o l l o w i n g o p t i c a l p r o p e r t i e s : 2V not over 70° C o l o r l e s s L i g h t grey-blue b i r e f r i n g e n c e : .004 B i a x i a l (probably +) Index below that of epidote - 3 3 -Secondary c o n s t i t u e n t s are carbonate, epidote and s e r i c i t e . Minute v e i n l e t s which c o n t a i n epidote, z o i s i t e , p y r r h o t i t e and secondary hematite are confined l a r g e l y to the white fragments. ? FELDSPARS: The l a r g e phenoerysts apparently have a considerable range. One v a r i e t y has the f o l l o w i n g c h a r a c t e r i s t i c s : L i g h t p e a r l y grey b i r e f r i n g e n c e - .008 - .009 Indices lower than balsam or very close to balsam. B i a x i a l ( O 2V ^ 75° I E x t i n c t i o n angle j_x= +82° t T h i s v a r i e t y i s be l i e v e d to be a l b i t e with a composition of about Abg.5 to AbgQ. The most c h a r a c t e r i s t i c f e a t u r e about t h i s f e l d s p a r i s the size' of 2V. The second v a r i e t y seems to have a lower b i r e -f r i n g e n c e , i s ' b i a x i a l negative ( ? ) , w i t h the l a r g e r 2V and i n d i c e s greater than balsam. I t shows some i n d i c a t i o n s of twinning. T h i s f e l d s p a r apparently belongs i n the andesine range. Twinning of the f e l d s p a r s i s not common and when evident, i s of a ragged, i l l - d e f i n e d nature. The twinning l a m e l l a e are broad and coarse. . Something very much a k i n to twinning can be observed i n a few of the l a r g e r phenoerysts of f e l d s p a r . Close observation of one of these g r a i n s shows that the supposed twinning i s i n r e a l i t y a l t e r a t i o n of a f e l d s p a r of low b i r e f r i n g e n c e to a f e l d s p a r of seemingly higher b i r e f r i n g e n c e . There are d i f f e r e n c e s i n the o p t i c p r o p e r t i e s of the two mine r a l s . - 3 4 -The f e l d s p a r showing the lower b i r e f r i n g e n c e has the f o l l o w i n g o p t i c a l p r o p e r t i e s : R e l a t i v e l y c l e a r B i r e f r i n g e n c e about .006 - .007 No d i s c e r n i b l e cleavage B i a x i a l (-)? Large 2V Index higher than high b i r e f r i n g e n c e f e l d s p a r (?) This f e l d s p a r i s b e l i e v e d to be i n the andesine range, i . e . , Ab 6 5 - . The f o l l o w i n g i s data f o r the f e l d s p a r showing the higher b i r e f r i n g e n c e : B i a x i a l (+)? B i r e f r i n g e n c e about .009 - .010 Smaller 2V(?) F u l l of i n c l u s i o n s This f e l d s p a r i s b e l i e v e d to be a l b i t e , i . e . , Abo^ to AbgQ. Figur e 4 , below, i s presented as evidence of the observation: F i g . 4 . — D i a g r a m (no scale) i l l u s t r a t i n g replacement of andesine? by a l b i t e ( l i g h t p e a r l g r e y ) . There i s no true zoning evident. I n c l u s i o n s mask the f e l d s p a r s to such an extent that few observations can be made on them. AMPHIBOLES: Green hornblende i s the only amphibole d e f i n i t e l y i d e n t i f i e d . I t i s b i a x i a l (-)• Some g r a i n s of amphibole o c c u r r i n g i n the f e l d s p a r s are n e e d l e - l i k e ai;nd p r a c t i c a l l y c o l o r l e s s . They have the outward appearance of a c t i n o l i t e but the grains are too small to o b t a i n adequate o p t i c a l data on them. Some gr a i n s of amphibole of 1 mm. s i z e are to be observed but i n the main, the g r a i n s range i n s i z e from »Q2 to .08 mms- wide and .04 to .14 mms. long. The green hornblende tends to a glomero-porphyritic t e x t u r e i n the white fragments. Much of the green hornblende shows good c r y s t a l l i n e o u t l i n e . Z o i s i t e and epidote are secondary m i n e r a l s . They are abundantly developed i n the white fragments, g i v i n g a brown dusty appearance to them. The epidote occurs as c l u s t e r s of very t i n y g r a i n s i n the f e l d s p a r s . In some areas there are g r a i n s up to .04 mms. i n s i z e . The z o i s i t e g r a i n s tend to be much l a r g e r . The best develop-ment of epidote, ( c l i n o z o i s i t e ? ) , and z o i s i t e i s i n the v e i n l e t s which cross the white fragments i n s e v e r a l d i f f e r e n t d i r e c t i o n s . Conclusions The microscopic study i n d i c a t e s a h i s t o r y of b r e c c i a t i o n and a l b i t i z a t i o n . The e l l i p s o i d a l f e a t u r e s of the type 1 rock a r e ' developed p r i m a r i l y by e l o n g a t i o n of fragments during consolida_M^h Joi^the-^f.l.ojL. The fragments seen as separate l i g h t e r coloured areas i n the dark green back-ground of the main body of the type 2 rock are b e l i e v e d to have been derived from the b r e c c i a t i o n of the c o o l i n g surface of a viscous flow. The only d i f f e r e n c e s evident. -36-i n the fragmental areas i n the type 2 rock as compared to the base.; surrounding them are the proportions of amphibole and the greater development of z o i s i t e and epidote i n the f e l d s p a r s and v e i n l e t s of the white fragments. I t seems that some of the e l o n g a t i o n of the white fragments arose from d i f f e r e n t i a l movement,of c r u s t i f i e d l a y e r s of the f l o w . L a t e r shearing s t r e s s , so evident i n other adjacent rocks, may have g r e a t l y MQs» emphasized the e l o n g a t i o n . The rock showing the elongated, e l l i p s o i d s can be seen grading r a t h e r sharply i n t o s e c tions where the rock contains squarish or only s l i g h t l y e l l i p t i c a l fragments of the same composition, v i z . type 2 rocks. The compositon of the e l l i p s o i d a l v a r i e t y of rock, i . e . type 1, was not'examined m i c r o s c o p i c a l l y by the- w r i t e r but h i s megascopic examination of i t and the microscopic work done by T. C. Phemister on t h i s same type, i n d i c a t e s t r i k i n g s i m i l a r i t i e s , i f not i d e n t i c a l c h a r a c t e r i s t i c s , i n both type 1 and type 2. Phemister, i n h i s study of the coarser e l l i p s o i d a l v a r i e t i e s of the streaked r o c k s , type 1 of the w r i t e r , makes the f o l l o w i n g observations from h i s microscopic study: "Thin s e c t i o n s show that these rocks ( e l l i p s o i d a l v a r i e t i e s ) have had a very v a r i e d h i s t o r y . The o r i g i n a l p l a g i o c l a s e has been c a l c i c l a b r a d o r i t e , but p r i o r to the r e c r y s t a l -l i z a t i o n which i s everywhere present, a l b i t i z a t i o n has a l t e r e d these c r y s t a l s i n part to more sodic m a t e r i a l . The e l l i p s o i d a l s t r u c t u r e of the rock i s a primary f e a t u r e and i s due to the accumulation of the f e l d s p a r c r y s t a l s i n c l o t s which have been drawn out i n the flow of the. l a v a -37-i n t o elongated e l l i p s o i d s and s t r e a k s . The l a t e r shearing s t r e s s e s , however, have emphasized t h i s s t r u c t u r e and i n the completely r e c o n s t i t u t e d product the dark p o r t i o n c o n s i s t s of p l a g i o c l a s e amphibolite and the l i g h t e r p o r t i o n mainly of c l i n o z o i s i t e and c l e a r c r y s t a l s of c a l c i c andesine...- The darker p o r t i o n g e n e r a l l y resembles the main greenstone formation, though i t i s , on the whole, somewhat more b a s i c . The l i g h t e r p o r t i o n i s of a n d e s i t i c composition but the microscopic evidence suggests that i t c o n s i s t e d o r i g i n a l l y of c a l c i c p l a g i o -c l a s e c r y s t a l s which were l a t e r a l b i t i z e d . — The w r i t e r ' s type 2 rock grades i n t o t h i s v a r i e t y j u s t described and i s part of the same rock formation. The types d i f f e r only w i t h regard to number of fragments and s t r u c t u r a l arrangements of the fragments. In h i s d i s c u s s i o n of type 2 rock, the w r i t e r has i n d i c a t e d h i s d i f f i c u l t y i n determining the composition of the f e l d s p a r s and i n determining s i g n . There are two f e l d s p a r s present. One of these i s s o d i c , a l b i t e or a l b i t e - o l i g o c l a s e ; the other i s known to be of higher index than balsam, s u f f i c i e n t l y high to suggest andesine or even c a l c i c andesine, but not to suggest c a l c i c l a b r a d o r i t e as Phemister b e l i e v e s the o r i g i n a l f e l d s p a r to be. The i l l u s t r a t i o n on page 34 ( P i g . 4) represents what i s b e l i e v e d to be the r e l a t i o n s h i p of the two f e l d -spars, i . e . , the sodic f e l d s p a r r e p l a c i n g the o r i g i n a l andesine or c a l c i c andesine?. The glomero-porphyritic texture of the amphibole i n Phemister, T.C.: op. c i t . , pg. 51. -38-type 2 rocks i n d i c a t e s segregation, as pointed out by Phemister. The w r i t e r could not make out any d e f i n i t e signs of segregation i n the f e l d s p a r s but i f there were segregation of amphiboles, i t i s q u i t e p o s s i b l e t h a t there was a l s o segregation i n the f e l d s p a r s . The f a c t that the fragments are 75 to 90% f e l d s p a r may be an i n d i c a t i o n of t h i s . The f o l l o w i n g i s an attempt to p i c t u r e the sequence of events which brought about the features c h a r a c t e r i s i n g the rocks. V o l c a n i c a c t i v i t y r e s u l t e d In a r a t h e r t h i c k flow of l a v a which during slower than usual c o o l i n g enabled i t s "> c o n s t i t u e n t minerals to segregate to some extent. The segregation conceivably r e s u l t e d i n a con c e n t r a t i o n of s i l i c e o u s m a t e r i a l , due p o s s i b l y to l i g h t e r s p e c i f i c g r a v i t y , i n the top of the flow. More r a p i d c o o l i n g at the surface formed a c r u s t which during s o l i d i f i c a t i o n f r a c t u r e d i n t o p l a t e y fragments. These fragments remained s u f f i c i e n t l y p l a s t i c to be stretched out by the now viscous flow. The more f l u i d m a t e r i a l c o n s t a n t l y replaced the surface areas and the fragments were r o l l e d i n t o the lower p o r t i o n s of the flow as l a r g e clumps of fragments or as s i n g l e fragments. Many fragments reached the i n t e r i o r of the flow before being elongated. This i s shown by the squarish forms of the fragments i n type 2 rock. As the flow became more viscous and moved more slo w l y , the fragments remained only i n the upper p o r t i o n s and were subject to greater s t r e t c h i n g . The base of the flow tended to l a g and the upper l a y e r s moved over i t . - 3 9 -The above hypothesis regarding the s t r e t c h i n g of the fragments could only be supported by a c t u a l evidence of such a t h i n g i n an undeformed flow. Such evidence i s l a c k i n g . L a t e r , shearing f o r c e s set up by dynamic metamorphism accentuated the elongated, e l l i p s o i d a l character of the fragments. The white fragments and f e l d s p a r s i n p a r t i c u l a r show a l t e r a t i o n to epidote and s e r i c i t e but the f a c t that the t i n y v e i n l e t s of epidote and z o i s i t e w ith p y r r h o t i t e are confined l a r g e l y to the fragments seems to r e q u i r e another explanation than simply a l t e r a t i o n . P o s s i b l y these minerals were concentrated i n the r e s i d u a l l i q u o r or gases of the flow during c r y s t a l l i z a t i o n and p r e c i p i t a t e d i n the e a r l y f r a c t u r e s . They might be due a l s o to l a t e r i n t r o d u c t i o n of m a t e r i a l . I f the l a t t e r were so.,, i t i s d i f f i c u l t to imagine why they developed as v e i n f i l l i n g s to such an extent i n the white f r a g -ments only. I f . s h e a r i n g s t r e s s alone was the cause of the e l l i p s o i d a l s t r u c t u r e , then the type 2 rock should a l s o show signs of t h i s shearing a c t i o n . There i s l i t t l e evidence of shearing a c t i o n i n the type 2 rock. One of the odd features of t h i s p a r t i c u l a r area (North shore of Lodge Cove) i s t h a t shearing a c t i o n i s very prominent i n a l l rocks to the north of t h i s v a r i e t y . The e l l i p s o i d a l type of rock b u t t s up a g a i n s t a porphyry dyke and a continuance of the type cannot be found on the f a r (western) s i d e . Only clumps of f r a g --mo-ments with s l i g h t alignment and elongation can be lo c a t e d on the west side of the dyke. In other words, there has been displacement of the east-west trending e l l i p s o i d a l v a r i e t y of rock along the dyke so that type 2 rock can now be observed only on the west s i d e . This i s taken to i n d i c a t e that the west side moved northward with respect to the east s i d e . Flow b r e c c i a s which o r i g i n a t e from c r u s t s are mentioned i n the g e o l o g i c a l l i t e r a t u r e ^though there i s some controversy over t h i s concept. Grout, one who supports t h i s i d e a , s t a t e s t h a t : "they may r e s u l t from the c o l l a p s e of t h i n surface c r u s t s of s o l i d i f i e d m a t e r i a l on a flow."5- I t i s r e a l i z e d that t h i s i s but a s i n g l e instance where a p o r t i o n of a flow i s apparently l e s s deformed than usual and that the evidence presented i s s l i m . This d i s c u s s i o n i s only an attempt to e x p l a i n some odd f e a t u r e s . A l b i t i z a t i o n or a general tendency f o r the f e l d s p a r s to a l t e r , i n p a r t , to more sodic m a t e r i a l i s the reason f o r some of the anomalous -optical p r o p e r t i e s of the fe l d s p a r s i n what probably was o r i g i n a l l y a rock c o n t a i n -ing andesine or more c a l c i c f e l d s p a r s . A l a t e r period of r e c r y s t a l l i z a t i o n , i n p a r t due to dynamic metamorphism and i n part due to thermal meta-morphism, has brought about the abundant development of epidote and s e r i c i t e i n the f e l d s p a r s . ^ . uv ^ M J ' ^ Sx*Jc SCHISTOSE GREENSTONE AND INTERBEDDED VARIETIES ^ These v a r i e t i e s of rocks outcrop along the north ^ Grout, F.F.: "Petrography and Petrology", McGraw-Hill, 1932, pg. 119 -41-shore of Lodge Gove and are interbedded w i t h the flow b r e c c i a s . They are outstanding because of t h e i r repeated occurrence along with the flow b r e c c i a s i n a b e l t at l e a s t a quarter mile wide by 2 miles long, g e n e r a l l y s t r i k -i n g south 80°E. and d i p p i n g very s t e e p l y to the n o r t h . The word "schistose" i s used f o r want of a b e t t e r term. I t i s not to be a p p l i e d i n the s t r i c t e s t sense as these rocks do not show f o l i a t i o n i n the hand specimen. In the s c h i s t o s e greenstone rocks the s c h i s t o s i t y i s i n c l i n e d to be discontinuous along the s t r i k e or across the s t r i k e . There are sections of these greenstones which O are d i s t i n c t l y p o r p h y r i t i c . . These s e c t i o n s appear on passing along the s t r i k e or across the s t r i k e from a s e c t i o n of rock having a l i n e a t e d appearance. There i s a change i n c o l o u r w i t h the change i n t e x t u r e , the l i n e a t e d s e c t i o n being c h a r a c t e r i z e d by a darker green or g r e y i s h colour w i t h p u r p l i s h hues when f r e s h l y broken. These sec t i o n s a l s o show commonly a considerable development of p y r i t e which p a r a l l e l s the t i n y black l i n e a r f e a t u r e s . The l i n e a t e d appearance r e s u l t s from traces of inch-long p a r a l l e l planes on the s u r f a c e . The p o r p h y r i t i c sections are of a l i g h t e r green co l o u r , showing p l a g i o c l a s e phenoerysts i n a f i n e - g r a i n e d , l e s s than 1/4 mm. groundmass. These s e c t i o n s can occur as f a i n t p o d - l i k e areas i n the l i n e a t e s e c t i o n . I t i s p o s s i b l e to get a change from p o r p h y r i t i c through l i n e a t e d s ections to streaked or laminated s e c t i o n s i n a 100-feet s e c t i o n across the s t r i k e . Another type of rock interbedded w i t h the above described rocks and having the same s t r i k e and d i p i s -42-laminated i n appearance. I t w i l l be described mega-s c o p i c a l l y and m i c r o s c o p i c a l l y . Megascopic C h a r a c t e r i s t i c s The appearance of the rock i s due to streaks of dark minerals i n t e r l a m i n a t e d w i t h l i g h t e r coloured minerals on a small s c a l e . Pour or f i v e lensey l i g h t and dark areas commonly occur i n one i n c h . Close observation shows l i g h t e r coloured s e c t i o n s l i k e a narrowed eye s l i t i n darker minerals. The l i g h t e r minerals are c h i e f l y a p l a g i o c l a s e f e l d s p a r ; the darker are ferromagnesians. The rock shows many j o i n t planes, g e n e r a l l y at a low angle to the planes of l a m i n a t i o n . Many f i n e t i n y f r a c t u r e s cross the s t r i k e of the planes of s t r e a k i n g or l a m i n a t i o n at n e a r l y n i n e t y degrees. Microscopic . Examination T.S. L-21, the only s l i d e made of rocks of t h i s v a r i e t y , was made from a sample of the laminated or streaked type. Low power examination reveals a discontinuous banding. Bands of l i g h t coloured minerals pass around small l s n s e - l i k e g rains of green hornblende and greenish epidote. Some bands of the greenish minerals almost manage to cross the s l i d e before s p l i t t i n g up and t a i l i n g out. There are other l e n s e - l i k e p o r t i o n s of mainly f e l d s p a r and quartz surrounded by amphibole and epidote. A streak of green amphibole and epidote with very l i t t l e f e l d s p a r and quartz crosses the s l i d e , c u t t i n g the -4> lam i n a t i o n at a low angle. A d e f i n i t e l i n e l i k e a l i n e of p a r t i n g can be seen weaving along the centre, more or l e s s , of the amphibole str e a k s . The l i n e s l i c e s through grains and f l a k e s of amphibole but o f t e n the f l a k e s seem to have taken shape on e i t h e r side of the l i n e . Some of the f l a k e s of amphibole are bent. The l i n e , when observed c l o s e l y , r e v e als i t s e l f as a v e i n l e t .002 mms. wide, f i l l e d w ith a c l e a r grey m i n e r a l , probably q u a r t z . The rock c o n s i s t s of quartz, a l b i t e (twinned and lower index than q u a r t z ) , z o i s i t e , c a l c i t e , c l i n o z o i s i t e ( ? ) , epidote, c h l o r i t e ( ? ) , hornblende, augite and p y r i t e . The main c o n s t i t u e n t s are quartz, a l b i t e , c h l o r i t e , epidote and green hornblende. What i s be l i e v e d to be f e r r i f e r o u s a u g i t e , i d e n t i f i e d mainly by high e x t i n c t i o n angles, z A cleavage = 35°-57° and by the higher b i r e f r i n g e n c e than'the hornblende, gives evidence of a l t e r a t i o n at i t s edges to hornblende. The c h l o r l t e ( ? ) i s a green-grey v a r i e t y with b i r e f r i n g e n c e - .011 and i s apparently grains b i a x i a l (-) wi t h very small 2V. A few :. of p y r i t e present i n a l e n s e - l i k e area i n the s l i d e have been almost e n t i r e l y a l t e r e d to hematite. The- rock i s very f i n e - g r a i n e d , the grains ranging from .01 to .04 mms-. wide by .08 to .17 mms. long on the average. There are some gra i n s s e v e r a l times these measurements. Conclusions That metamorphism and a l t e r a t i o n have played an -44-iraportant part i n these rocks i s q u i t e evident. I t i s , however, d i f f i c u l t to he sure of the type of metamorphism. The p u r p l i s h , indurated, almost cherty appearance of the sheared greenstone rock3 with the l a r g e development of p y r i t e suggests a h i g h degree of metamorphism i n which h i g h temperature i s one of the c h i e f f a c t o r s causing a l t e r a t i o n . The heat from a nearby igneous body might be the cause of the a l t e r a t i o n . The igneous body i n t h i s i n s t a n c e would be that of the Coast Range b a t h o l i t h , p o r t i o n s of which outcrop about 1700 f e e t to the southwest. I t may be that the g r a n o d i o r i t e (from T. C. Phemister's map) outcropping 1/2 mile to the north i s much c l o s e r v e r t i c a l l y . The wavy " p a r t i n g l i n e s " through the streaks of amphibole, which are f i l l e d at times by what seems to be quartz, are taken as evidence of movement. This movement along the streaks i s betrayed a l s o by the bending of twinning lamellae i n the amphibole f l a k e s . The beginning of development of s c h i s t o s i t y from shearing i s i n d i c a t e d by alignment of the amphibole so that the p r e f e r r e d o r i e n t a t i o n i s with the long a x i s p a r a l l e l to the d i r e c t i o n of movement. A f u r t h e r i n d i c a -t i o n of t h i s i s the f a c t that a l l the amphibole g r a i n s , almost u n i f o r m l y , show maximum absorption (dark green c o l o u r ) , p a r a l l e l to the s c h i s t o s i t y . S t i l l f u r t h e r i n d i c a t i o n s of rock flowage are f l a t t e n e d , f r a c t u r e d p l a g i o c l a s e g r a i n s , small " s " patterns i n the s o - c a l l e d p a r t i n g l i n e s , and twinning i n the amphibole f l a k e s . The plane c r o s s i n g the s t r e a k i n g at a low angle w i t h coarser development of amphibole, quartz and f e l d s p a r -45-i n d i c a t e s a s l i g h t change i n d i r e c t i o n of s t r e s s . The above noted features could have r e s u l t e d from dynamic metamorphism. The rock does not s p l i t r e a d i l y along the shear planes i n s p i t e of the e f f e c t s of dynamic metamorphism, hence i t i s p o s s i b l e that the streaky, laminated appearance of the rock i s due fundamentally to the manner of d e p o s i t i o n and dynamic metamorphism has.found these d e p o s i t i o n a l c h a r a c t e r i s t i c s most favourable on which to impress i t s e f f e c t s . In h i s d i s c u s s i o n of r e g i o n a l metamorphism, Harker shows albite-epidote-hornblende s c h i s t s develop by stages due to the a c t i o n of r e g i o n a l metamorphism on b a s i c rocks. The stages are c a l c i t e - a l b i t e - e h l o r i t e - s c h i s t to an a l b i t e - e p i d o t e - c h l o r i t e s c h i s t w i t h greater or l e s s e r amounts of c a l c i t e and then "with progressive development of hornblende and succeeding b i o t i t e zone, coming now from the r e a c t i o n of c h l o r i t e with c a l c i t e or epidote, the c h l o r i t e r a p i d l y dwindles and epidote i s somewhat reduced i n amount.. We have thus a d i s t i n c t i v e type of albite-epidote-hornblende s c h i s t i n which horn-it 6 blende g r a d u a l l y becomes the p r i n c i p a l c o n s t i t u e n t . " — Harker, A.: "Metamorphism" (1932), pg. 280. -46-The streaky laminated character could he i n d i c a t i v e of some d e p o s i t i o n by water of tuffaceous m a t e r i a l before the e f f e c t s of dynamic metamorphism increased the streaky c h a r a c t e r i s t i c s . The c o n c l u s i o n i s that t h i s p a r t i c u l a r type of r o c t could represent f i n e - g r a i n e d tuffaceous m a t e r i a l which to some extent has been reworked by water. The l a r g e r grains of p l a g i o c l a s e and hornblende might represent fragments that o r i g i n a l l y were p l a g i o c l a s e and pyroxene. The pyroxene a l t e r e d to amphibole during the r e c r y s t a l -l i z a t i o n of the f i n e - g r a i n e d m a t e r i a l s to mainly a l b i t e epidote and green hornblende. This v a r i e t y of rock i s interbedded with other v o l c a n i c s having flow c h a r a c t e r i s t i c s and a n d e s i t i c composition. Pre-3ath.olith Dykes The i d e n t i f i c a t i o n of the dykes about to be described as p r e - b a t h o l i t h dykes r e s t s l a r g e l y on the f i n d i n g s of T. C. Phemister, on c o r r e l a t i o n s w i t h s i m i l a r , i f not i d e n t i c a l , bodies at C a u l f e i l d , and on some observations by the w r i t e r . These dykes occur as concordant__and d i s - uJ~U^jL. cordant bodies. There i s unquestionable evidence that they are l a t e r than the tuffaceous sediments, flow b r e c c i a s , s c h i s t o s e greenstone and interbedded rocks which have been des c r i b e d . With regard to t h e i r r e l a t i o n s h i p t o the b a t h o l i t h , Phemister s t a t e s , when d e s c r i b i n g h i s p r e - b a t h o l i t h dykes which are i d e n t i c a l to dykes described by the w r i t e r , -47-that " b e t t e r evidence w i l l be seen when the area to the east ( C a u l f e i l d ) i s studied but there i s l i t t l e doubt that the group i s p r e - b a t h o l i t h i c , as both i n the v i c i n i t y of P o i n t Cowan and Deep (Lodge)Cove i n d i v i d u a l occurrences are cut by the i n t r u s i v e rocks."2. Only i n one instance d i d the w r i t e r f i n d the Coast Range b a t h o l i t h i c rock c o n t a c t i n g a p r e - b a t h o l i t h dyke. In t h i s instance there was 3 f e e t of contact exposed and p r a c t i c a l l y no evidence other than a r e d u c t i o n i n g r a i n • s i z e i n the l a s t s i x inches of the b a t h o l i t h i c rock. Granite occurs above and below the dyke which forms a f a l l s i n the stream from K i l l a r n e y Lake. The contact rocks, f o r the most p a r t , are black tuffaceous sediments. There i s a profound change i n the s t r i k e of the dyke a t t h i s p o i n t . In one instance a porphyry dyke cuts d i s c o r d a n t l y across the streaked and r e l a t e d rocks i n the northwest corner of the area of Lodge Cove and then turns to f o l l o w concordantly the o v e r a l l s t r i k e of the formation. Both lea d s , one c r o s s i n g the s t r i k e , the other f o l l o w i n g the s t r i k e , are only 5 to 6 feet. In width and j o i n a much l a r g e r body i n a manner suggestive of pipes w i t h feeder dykes. The d i s c o r d a n t body i n t h i s case c a r r i e s small pieces of b r e c c i a from the a d j o i n i n g formation along i t s s i d e s . S l i g h t c h i l l i n g i s evident along the dyke borders. Several other occurrences are worthy of mention. Two of these outcrop on the west shore of Lodge Cove, one i n Phemister, T.C.: op. c i t . , pg. 53. -48-p a r t i c u l a r i n f r o n t of Bowen H o t e l . Examination of these dyke rocks r e v e a l s that the only d i f f e r e n c e from the f i r s t mentioned occurrence i s that the percentage of f e l d s p a r phenoerysts i s much reduced and i n place of them, black l a t h s of hornblende, smaller than i n the dyke c u t t i n g the streaked rocks, make up a greater p r o p o r t i o n of the rock. The dykes at t h i s p o i n t show a marked columnar s t r u c t u r e below tide-water. The dyke outcropping i n f r o n t of the h o t e l has a 2-foot apophysis running i n the same general d i r e c t i o n as.the main body. At t h i s p o i n t the dykes cut the dark to l i g h t coloured tuffaceous sediment r o c k s . Another l a r g e occurrence outcrops on the beach at Scarborough Head. The dyke i s concordant w i t h the ad-j o i n i n g streaked rocks. Phenoerysts of f e l d s p a r of t2 mms. s i z e were noted near the contact, the s i z e of the phenoerysts decreasing r a p i d l y w i t h distance from the contact u n t i l a t a p o i n t 10 f e e t from i t , the phenoerysts were about 2 mms. i n s i z e and l e s s numerous. T. G. Phemister reports that two p r i n c i p a l d i r e c t i o n s are favoured by the i n t r u d i n g dykes, "one about 10° W. of N. and the other about 1'5-20° E. of N. but as there i s no s i g n of one c u t t i n g across the other, the two sets of ft dykes have probably developed about the same time."— The w r i t e r ' s own observations bear t h i s out and, as p r e v i o u s l y pointed out, one dyke observed i s both concord-Phemister, T.G.: op c i t . , pg. 53. -49-ant and d i s c o r d a n t , f o l l o w i n g paths widely v a r i a n t , i . e . , east-west and 10° E. of N. Thus i t i s very l i k e l y that what appears to be two sets of dykes of two d i f f e r e n t periods of i n t r u s i o n are the r e s u l t of only one period of i n t r u s i o n . The greater number of p r e - b a t h o l i t h i c dykes observed occur concordantly or s i l l - l i k e and these have a tendency to be broader than the dis c o r d a n t bodies. S l i d e L-210 was made from the dyke showing c r o s s -c u t t i n g r e l a t i o n s h i p with the streaked v o l c a n i c b r e c c i a s . Megascopic Examination The dyke c u t t i n g the flow b r e c c i a s i s taken as an example of the p r e - b a t h o l i t h dykes of the d e t a i l e d area. The dyke Is markedly p o r p h y r i t i c with both f e l d s p a r and hornblende being present as phenoerysts. The f e l d s p a r phenoerysts range from microscopic s i z e up to 5 mms. S i m i l a r l y , some of the amphibole phenoerysts reach 5 mms. Feldspar phenoerysts make up 25% and amphibole make up 20% of the t o t a l rock. The remainder of rock c o n s i s t s of a d u l l grey groundmass. Microscopic C h a r a c t e r i s t i c s ,; Microscopic study revealed that the rock c o n s i s t e d of about 60% of f e l d s p a r phenoerysts. The phenoerysts range from 2 mms. to 2 .6 mms. i n l e n g t h . Large l a t h - l i k e greenish and brownish areas up to 3.5 mms. i n leng t h and the t y p i c a l diamond-'shaped areas with blunt ends and angles of 5 6 0 and 124° between sides i n d i c a t e s hornblende - 5 0 -r a t h e r than pyroxene. The whole rock, as i n d i c a t e d by the s l i d e , shows a high degree of a l t e r a t i o n ; s c a r c e l y a s i n g l e fragment of f e l d s p a r or amphibole mineral as groundmass or phenocryst remains which does not show almost complete breakdown. Only the o u t l i n e s of the f e l d s p a r phenocrysts remain with the odd r e s i d u a l of f e l d s p a r I n a mass of a l t e r a t i o n products. The groundmass i s not e x c e s s i v e l y dark i n colour but r a t h e r i ntermediate, say grey on the average. FELDSPARS: On the average, these appear to have the composition of l a b r a d o r i t e , although some sodic f e l d s p a r i s present as small c l e a r areas g e n e r a l l y about .2 mms- i n s i z e . Minor amounts of the f e l d s p a r have o p t i c a l p r o p e r t i e s denoting o l i g o c l a s e . O p t i c a l p r o p e r t i e s obtained on some of the l a r g e r phenocrysts, p a r t i c u l a r l y one l a r g e c l e a r 2.5 mm. c r y s t a l , w ith e x c e l l e n t twinning, are as f o l l o w s : Index decidedly higher than balsam and q u a r i z but considerably lower than Pennine, approx. 1.56 B i a x i a l (+) 2V = 80°+ Maximum e x t i n c t i o n = +32 E x t i n c t i o n angles j _ Z, x /\ 010 a -t9 (?) Composition considered to be about Ab45± A l t e r a t i o n i s n e a r l y complete* i n many instances the main products are muscovite up to .08 mms. i n g r a i n s i z e and carbonate w i t h very minor amounts of q u a r t z , c l i n o z o i s i t e and a l b i t e . - 5 1 -AMPHIBOLES: These are b e l i e v e d to be amphiboles, mainly on the b a s i s of t h e i r long l a t h - l i k e appearance as phenoerysts. In a d d i t i o n , many small r e s i d u a l portions of the phenoerysts have a maximum e x t i n c t i o n angle of around 1 5 ° . The l a r g e s t phenoerysts are completely a l t e r e d --except f o r what are b e l i e v e d to be t i n y r e s i d u a l f l a k e s (see above) of amphibole — to coarse .4 mm. g r a i n s of c l i n o z o i s i t e , p i s t a c i t e , magnetite, pennine and l a r g e areas of carbonate. There are minor amounts of quartz and a l b i t e . Apparently the groundmass was made up o r i g i n a l l y of 80% f e l d s p a r m i c r o l i t e s . . The remainder c o n s i s t e d of amphibole and p o s s i b l y q u artz. I t i s q u i t e l i k e l y that the quartz i s secondary as no l a r g e g r a i n s were observed. The groundmass now shows considerable c h l o r i t e , a l b i t e and quartz w i t h r e s i d u a l l a b r a d o r i t e f e l d s p a r , a l s o much carbonate and dusty magnetite, both derived from the breakdown of the other m i n e r a l s . Conclusions The above described dykes are placed as p r e - b a t h o l i t h i n age by reason t h a t : ( 1 ) T. C. Phemister has noted dykes of i d e n t i c a l composition and character i n the v i c i n t y of Po i n t Cowan and Deep Cove which are cut by i n t r u s i v e rocks. Phemister, T.C.: op. c i t . , pg. 5 3 * -52-(2) A contact of i n t r u s i v e and dyke i n the area of the B r i d a l F a l l s shows a r e d u c t i o n i n g r a i n s i z e of the d i o r i t e next to the dyke. (3) Dykes i d e n t i c a l i n composition and c h a r a c t e r , with the same development of hornblende and f e l d s p a r phenocrysts, i n the C a u l f e i l d area were observed by the w r i t e r t o show r e l a t i o n -ships i n d i c a t i n g that the d i o r i t e was l a t e r than the dykes. These r e l a t i o n s h i p s were: (a) B r e c c i a of the dyke included i n the d i o r i t e at contact. (b) Small i n t r u s i o n s of d i o r i t e i n t o the dyke body. I t should be noted t h a t i n the study of the pre-b a t h o l i t h dykes of Bowen I s l a n d , the w r i t e r has been able to present only one item of evidence f o r p r e - b a t h o l i t h age. This i s due l a r g e l y to l a c k of opportunity to widen h i s observations. Observations of the C a u l f e i l d pre-b a t h o l i t h dykes i n d i c a t e s to him that they are i d e n t i c a l w ith those of Bowen I s l a n d . The evidence from observations on the dyke outcrop j u s t west of the northwest corner of Lodge Cove suggest to the w r i t e r that the p r e ~ b a t h o l i t h dykes were emplaced a f t e r metamorphism of the v o l c a n i c s had taken p l a c e . The p r e - b a t h o l i t h porphyry dyke there cuts across the streaked and r e l a t e d rocks but i s not a f f e c t e d by the dynamic metamorphism so e v i d e n t . i n these r o c k s . -53 I t lias been pointed out p r e v i o u s l y that the streaked rocks w i t h t h e i r pronounced l i n e a r f e a t u r e s contact the dyke a t an angle but are not found on the west s i d e as a c o n t i n u a t i o n of the same s t r i k e . A displacement of some so r t previous t o the emplacement of the dyke would e x p l a i n t h i s . This i n tu r n bears out the contention that the i n t r u s i o n of dyke post-dates the metamorphism which accentuated the l i n e a r f eatures of the streaked rocks and the s c h i s t e d appearance of the tuffaceous r o c k s . On t h i s same theme, T. C. Phemister s t a t e s : "The next question regarding t h e i r h i s t o r y (the.dykes) I s whether or not they have been i n v o l v e d i n the metamorphism which we have seen a f f e c t e d a l l of the other r o c k s . . . . . . . . . . A l l of the t e x t u r a l f eatures are c l e a r l y t o be r e f e r r e d to primary c r y s t a l l i z a t i o n . . . . . These dykes t h e r e f o r e probably post-date the f o l d i n g and metamorphism " — The f a c t t h a t a great many of the l a r g e r bodies of p r e - b a t h o l i t h i n t r u s i v e s are concordant with the^ s t r i k e of the l i n e a r f e a t u r e s suggests that the f r a c t u r e or opening f o r the dyke f i l l i n g was evolved during l a t e r stages of dynamic metamorphism. Since the dykes j u s t described are p r e - b a t h o l i t h , some i n d i c a t i o n s of the e f f e c t s of the i n t r u s i o n of the b a t h o l i t h on the dykes were looked f o r i n t h i n -s e c t i o n work. Phemister, T. C.: op. c i t . , pg. 54 _ 54-9 Decomposition i n the dykes has developed white mica, mainly i n the f e l d s p a r phenoerysts, a l s o some c h l o r i t e and c a l c i t e . In the hornblendes the a l t e r a t i o n was l a r g e l y to carbonate and c h l o r i t e with minor amounts of epidote and quartz. Any l a r g e c l o t of carbonate or c h l o r i t e could g e n e r a l l y be observed to be w i t h i n a p h e n o c r y s t - l i k e area r e s i d u a l from the breakdown of the amphibole. Smaller c l o t s of some minerals could be observed as in. t h e ground-mass. Quartz and a l b i t e occur i n the groundmass as secondary minerals. No v e i n l e t s of carbonate or epidote occurred i n the s l i d e s examined nor were v e i n l e t s of these minerals observed i n f i e l d examination of the dykes. The s l i d e s were made from as f r e s h rocks as p o s s i b l e , although weathering of a nature to cause a change i n colour had i n most cases reached a depth of 1/8". The p o s s i b i l i t i e s f o r the medium to h i g h degree of a l t e r a t i o n are shearing or dynamic metamorphism, thermal metamorphism or to a l a t e - s t a g e hydro-thermal a c t i o n . There i s no evidence i n the dykes f o r the f i r s t p o s s i b i l i t y . Of the remaining two p o s s i b i l i t i e s , e i t h e r might be s u i t a b l e but the proximity of the b a t h o l i t h lends stre n g t h to the ide a of thermal metamorphism being the dominant process. A l b i t i z a t i o n from d e u t e r i c a l t e r a t i o n during the c r y s t a l l i z a t i o n of the dyke accounts f o r the presence of the high sodium f e l d s p a r s . In the adjacent flow and b r e c c i a s , there are v e i n l e t s of epidote. They are nowhere observed as o c c u r r i n g i n -55-t h e dykes. Phemister reaches the concl u s i o n that l a t e - s t a g e hydrothermal a c t i o n causes the development of carbonate and c h l o r i t e i n some of the p r e - b a t h o l i t h dykes. B a t h o l i t h l c and Minor I n t r u s i v e s  QUARTZ-DIORITE This rock i s of widespread occurrence and makes up the only I n t r u s i v e rock from the d e t a i l e d area which was m i c r o s c o p i c a l l y examined. The q u a r t z - d i o r i t e outcrops i n the d e t a i l e d area at B r i d a l F a l l s and on the south side of the Lagoon. Large i n c l u s i o n s are common i n the q u a r t z - d i o r i t e , v a r y i n g i n s i z e from massive great pieces w i t h undetermin-able boundaries to fragments 1 i n c h or so i n s i z e . Some fragments are decidedly angular and una l t e r e d and others are rounded w i t h a l t e r e d borders. Megascopic C h a r a c t e r i s t i c s When f r e s h , the appearance i s l i k e that of a l i g h t coloured rock w i t h abundant l a t h s of black hornblende. Hornblende forms as clumps or c l o t s of 5 mm. s i z e . In general, the g r a i n s i z e ranges around 1/2 to 2 mms., medium grained. The f e l d s p a r s make up between 50% to 65% of the t o t a l . Quartz i s seldom d i s t i n g u i s h a b l e with the hand l e n s . -56-Microscopic C h a r a c t e r i s t i c s • FELDSPARS; The average composition of the p l a g i o c l a s e of the rock i s about A b ^ A n ^ . By f a r the greater percentage, perhaps 85%, i s d e f i n i t e l y andesine. O p t i c a l p r o p e r t i e s -of the andesine are: B i a x i a l (+/) 2V l a r g e (80°) Indices higher than 1*55 Maximum e x t i n c t i o n angle - +27° Birefringence.= .008 Twinning of a l b i t e type i s seldom absent and carlsbad-twinning i s common. The rock a l s o contains g r a i n s of untwinned p l a g i o c l a s e or qu a r t z . These grains give i n t e r f e r e n c e f i g u r e s that may be e i t h e r b i s e c t r i x f i g u r e s or f l a s h f i g u r e s . Zoning of the p l a g i o c l a s e s i s common, but i t i s seldom very d i s t i n c t and i t does not i n t e r f e r e with the e x t i n c t i o n of the twin l a t h s . The p l a g i o c l a s e s , on the whole, appear comparatively some f r e s h but a l t e r a t i o n of the cores and/bands of the zoned gra i n s i s very common. In 70% of the occurrences the a l t e r a t i o n product i s almost e n t i r e l y s e r i c i t e , but some la r g e grains, of p l a g i o c l a s e a l t e r to s e r i c i t e , z o i s i t e , c h l o r i t e (pennine) and epidote; others show a ; r e t i c u l a t e p a t t e r n of t i n y l i g h t - g r e y b i r e f r i n g e n c e f l a k e s (a c h l o r i t e ? ) , as the sol e a l t e r a t i o n product. I n c l u s i o n s are not p l e n t i f u l but gr a i n s of b i o t i t e , a p a t i t e and an unknown mineral are present i n t h i s manner. UNKNOWN MINERAL # 1 ; This mineral i s an acces sory. I t i s present as blebs, o f t e n crescent or worm-shaped, or as rhombic g r a i n s , i n quartz and r a r e l y i n p l a g i o c l a s e , otherwise i t i s i n t e r s t i t i a l . O r d i n a r i l y , the blebs are t i n y , . 2 mms. on the average. This mineral does not make up more than 2 $ of the e n t i r e s l i d e . I t s intergrowth with quartz resembles micropegmatite. The f o l l o w i n g are some o p t i c data obtained on t h i s mineral". 90% of the f i g u r e s obtained are c l e a r , b i s e c t r i x f i g u r e s , and give a p o s i t i v e s i g h . No twinning 2 V about 7 0 ° Indices d i s t i n c t l y lower than balsam, quartz or andesine. » Decidedly p i n k i s h tone against e i t h e r balsam, quartz or andesine. 2 d i s t i n c t cleavages X A 0 0 1 cleavage-4° B i r e f r i n g e n c e = . 0 1 0 The data would seem to i n d i c a t e a l b i t e . UNKNOWN MINERAL if2: O p t i c a l data are: B i r e f r i n g e n c e = . 0 0 6 B i a x i a l (-) 2 V <. 3 0 ° , probably 1 5 - 2 0 ° + Indices <f quartz, probably 1 . 5 2 -Intergrown with q u a r t z . AMPHIBOLE: Green hornblende i s e s t a b l i s h e d as being present. E x t i n c t i o n angle Z A c, reaches as high as 2 i ° but i n most instances i s about 1 7 ° . O p t i c a l p r o p e r t i e s : B i a x i a l (-) o o E x t i n c t i o n angle Z A C = 1 7 - 2 8 Higher index, on r o t a t i o n , than b i o t i t e > 1.64 Pleochroism not strong except i n c r o s s - s e c t i o n s , then l i g h t green to greenish brown. - 5 8 -B i o t i t e - i s an a l t e r a t i o n product of hornblende. Hornblende grades o f f i n t o spots of brown, b i o t i t e . w i t h i n d e f i n i t e borders. There i s l i t t l e i n d i c a t i o n of a l t e r a t i o n to c h l o r i t e . One instance occurs where the' hornblende has a l t e r e d to a green c h l o r i t e and i s surrounded by a rim of p y r i t e which i n tu r n i s l a r g e l y a l t e r e d to hematite. P y r i t e and hematite Occur as i n c l u slons i n the hornblende. In a l l cases where the p y r i t e occurs i n , and i s a s s o c i a t e d w i t h , green hornblende, the p y r i t e has a t h i c k rim of hematite or l i m o n i t e . ' BIOTITE: A dark brown b i o t i t e makes up about 15% of the s l i d e , a percentage equal to or a l i t t l e g r e ater than that of hornblende.' I t i s s t r o n g l y p l e o c h r o i c , changing from a fawn colour when absorption i s l e a s t to a r i c h brown when, the absorption i s greatest.' I t has a tendency to segregate and group i t s e l f - -with hornblende f l a k e s and i s In close a s s o c i a t i o n with the l a t t e r . , Quartz penetrates along the cleavage l i n e s of the b i o t i t e i n elongate g r a i n s of e n t i r e l y d i f f e r e n t o r i e n t a t i o n to surrounding q u a r t z , suggesting i n t e r -growth. > A l t e r a t i o n i s mainly to c h l o r i t e (green) with d e f i n i t e ult'rablue b l r e f r i n g e n c e c o l o u r s . A l t e r a t i o n i s from i n n e r cleavage areas outward. . I n c l u s i o n s are magnetite, r u t i l e and a p a t i t e . -59-2V i s p r a c t i c a l l y zero and the f i g u r e i s s e n s i b l y u n i a x i a l w i t h v i s i b l e r i n g s . Average l a t h s i z e i s about .3 mms. x .8 mms. Q.UARTZ: The percentage of quartz i n the rock would appear to be >5% to <8%. I t i s not observed to cross g r a i n boundaries but i s observed only as an i n t e r s t i t i a l mineral or as an intergrowth with e i t h e r the unknown minerals or i n ra r e i n s t a n c e s , with p l a g i o c l a s e . The intergrowth suggests, micropegmatite. G e n e r a l l y , the quartz i s c l e a r but there are many minute i n c l u s i o n s . A p a t i t e i s one of the included minerals. A few quartz g r a i n s are l a r g e , about 2 mms. MINOR INTRUSIVES Minor i n t r u s i v e s of g r a n i t i c , a p l i t i c and pegmatitic nature which are b e l i e v e d to be l a t e r than the quartz d i o r i t e , occur at many p o i n t s outside the d e t a i l e d area. Since they do not occur i n s i d e the d e t a i l e d area, they were not st u d i e d m i c r o s c o p i c a l l y and therefore only t h i s b r i e f reference w i l l be made to them. POST-BATHOLITH ROCKS BASIC DYKES There are only two occurrences of t h i s type of dyke i n s i d e the d e t a i l e d area. They outcrop on the shore i n f r o n t of the H o t e l . These dykes cut only the tuffaceous sediments a t t h i s p o i n t , but on the b a s i s of t h e i r PLATE: M P o s t - b a t h o l i t h dyke c u t t i n g v o l c a n i c f r a g -ments and a p l i t e . Fragments are not d i s p l a c e d by dyke. L o c a l i t y : K i l l a r n e y Lake o u t l e t . T r a c h y t i c texture of a p o s t - b a t h o l i t h dyke. -60-s i m i l a r i t i e s w i t h the C a u l f e i l d . p o s t - b a t h o l i t h dykes and w i t h a dyke at the o u t l e t of Lake K i l l a r n e y which i s known to be l a t e r than the b a t h o l i t h rocks, they are placed as p o s t - b a t h o l i t h i n age. (See P l a t e IV o p p o s i t e ) . Thin-sections were made of the Lake K i l l a r n e y occurrence and of the l a r g e r dyke i n f r o n t of the Bowen H o t e l . Only the l a t t e r , which i s i n s i d e the d e t a i l e d area, w i l l be d e s c r i b e d . The study of t h i s dyke was not very d e t a i l e d . Megascopic C h a r a c t e r i s t i c s A dark to l i g h t brown weathered surface i s t y p i c a l of the outcrop of these dykes. The f r e s h rock has a l i g h t s l a t e - g r e e n c o l o u r , i s dense and very f i n e - g r a i n e d i n the smaller dykes. The smaller dykes have a stoney appearance. Only an o c c a s i o n a l white phenocryst can be discerned. The rock i s apparently hard and only moderately a l t e r e d , though the green appearance suggests an abundance of c h l o r i t e . Microscopic C h a r a c t e r i s t i c s The t e x t u r e i n the l a r g e dyke of from 4 to 10 f e e t breadth, can be termed t r a c h i t o i d . ( I n g e n e r a l , the smaller dykes show very f i n e [.02 x .13 mms.] lath-shaped m i c r o l i t e s of p l a g i o c l a s e of about andesine composition, making up about 70%> of the rock. These have a sub-p a r a l l e l arrangement l i k e a shoal of minnows swimming around o b s t a c l e s . The obstacles are the few l a r g e phenocrysts, 1/4 to 1/2 mm. i n s i z e , and the very f i n e l y grained, almost i s o t r o p i c , c h l o r i t i c i n t e r s t i t i a l m a t e r i a l . ) -61-FELDSPARS: The m i c r o l i t e s of T.S. L-20 are s o d i c , probably about a l b i t e - o l i g o c l a s e i n composition. The maximum e x t i n c t i o n angle i s -14°. The m i c r o l i t e s are g e n e r a l l y clouded, showing a l t e r a t i o n to carbonate and s e r i c i t e mainly and r a r e l y to z o i s i t e . Where they are not clouded, they show a pearly-grey b i r e f r i n g e n c e . The phenocrysts of T.S. L-20 are a l b i t e , Ab^oAniQ. The f o l l o w i n g are a few o p t i c a l p r o p e r t i e s : The i n d i c e s are everywhere lower than balsam. Carlsbad twinning and not I n f r e q u e n t l y a l b i t e twinning can be observed. B i a x i a l (+). 2V about equal to 70°, maximum e x t i n c t i o n = -16°. In the small dykes there i s some i n d i c a t i o n of zoning i n the phenocrysts. The f r e s h e s t p o r t i o n s of these phenocrysts are the outer zones. QUARTZ: This was the only other mineral of primary o r i g i n that was d e f i n i t e l y e s t a b l i s h e d as being present. I t does not appear to be more than an accessory m i n e r a l . I t occurs only i n t e r s t i t i a l l y and i n small g r a i n s . I n the s l i d e the gra i n s are e a s i l y i d e n t i f i e d but they do not appear to be i n excess of Qfo of the t o t a l . T?/o other minerals are p o s s i b l y primary; they are u n i d e n t i f i e d . One has a worm-like form, i s b i a x i a l (O, c o l o r l e s s , creamy-yellow b i r e f r i n g e n c e ( t h i c k ? ) and I s not u n l i k e quartz i n general appearance.. The other i s lath-shaped, w i t h r e l i e f approximately the same as the f e l d s p a r s , a s l i g h t yellow tinge under crossed n l c o l s -62-and i s u n i a x i a l negative. Only about two g r a i n s of each mineral could be l o c a t e d and the g r a i n s are too small to e s t a b l i s h i d e n t i t y . Secondary minerals are c h l o r i t e , epidote and carbonate. C h l o r i t e f i l l s 90$ of the i n t e r s t i t i a l space of the dyke f e l d s p a r s . I t i s l i g h t to dark-green i n c o l o u r , moderately p l e o c h r o i c and shows anomalous blue colours under crossed n i c o l s . Centres c o n s i s t i n g mainly of aggregates of t h i s c h l o r i t e , plus epidote, carbonate and quartz are present i n the l a r g e r dykes. Oarbonate i s abundant i n the l a r g e r dykes. Conclusions The age of the dyke described i s open to question u n t i l more d e t a i l e d work can be done. A l b i t i z a t i o n may be l a r g e l y r e s p o n s i b l e f o r the high sodium content of the f e l d s p a r s . P A R T IV -63-STRUCTURAL G-EOLOGY Study of the d e t a i l e d area gives l i t t l e i n f o r m a t i o n regarding the s t r u c t u r e of the rocks except to i n d i c a t e that i t i s very complex. The b e l t of sheared rocks north of Lodge Cove agrees q u i t e w e l l w i t h the r e g i o n a l trend as observed i n areas outside the d e t a i l e d area. There are, however, notable v a r i a t i o n s from the r e g i o n a l trend w i t h i n the d e t a i l e d area. Reference to the d e t a i l map w i l l show that an abrupt change i n d i p and s t r i k e takes place i n c r o s s i n g a small creek e n t e r i n g the northwest corner of Lodge Cove. The change i s from the general east-west trend on the north side to 50° south of east on the southern s i d e of the creek. At the water's edge, an area i s shown where the rocks, streaked i n t h i s i n s t a n c e , apparently form a s y n c l i n e plunging northwest. However, very l i t t l e s i g n of a north limb of the s y n c l i n e i s v i s i b l e and the d i r e c t i o n i n which the s t r a t a are s t r i k i n g i n that limb, i n d i c a t e s that they could not continue f o r more than 200 f e e t without being truncated. These observations might be taken as I n d i c a t i o n s of a f a u l t occupying the stream bed. The nose of the " s y n c l i n a l " s t r u c t u r e would then be due to dragging of the s t r a t a , as i f the s t r a t a on the southwest side of the stream moved so u t h e a s t e r l y . The l i n e a r appearance of the stream bed could then be due to a s t r a i g h t f a u l t l i n e . - 6 4 -The presence of an outcrop of a s i l i c e o u s dyke (?) rock, c o n t a i n i n g b r e c c i a of the v o l c a n i c s , which a d j o i n s a post-b a t h o l i t h dyke of t r a c h y t i c t e x t u r e might be taken as f u r t h e r evidence of movement i n the general area of the stream bed. This occurrence i s i n the area 100 f e e t south of the l a r g e s t bridge c r o s s i n g the stream. The s i l i c e o u s rock shows something i n the nature of banding. About a 6 - i n c h width of b r e c c i a i s observed i n the s i l i c e o u s m a t r i x . Some of the b r e c c i a i s poorly cemented and the cementing m a t e r i a l i s drusy. The druses are s m a l l , about 1/4 i n c h g e n e r a l l y and encrusted w i t h quartz c r y s t a l s . The b r e c c i a c o n s i s t s of angular fragments of v o l c a n i c rock, sharply o u t l i n e d In'white q u a r t z . The b r e c c i a has probably r e s u l t e d from f a u l t i n g and the s i l i c e o u s m a t e r i a l has f i l l e d the f r a c t u r e . . Taking the banding i n the ' s i l i c e o u s rock as, i n d i c a t i v e of s t r i k e , t h i s .hypothetical f a u l t l i n e would be at. an angle of about 4 5 ° to the stream bed. Evidence of the d i s t o r t i o n of the s t r a t a i s i l l u s t r a t e d on the shore below the creek mouth where the rock i s drag^ f o l d e d , crumpled and highly, sheared. The dis c o r d a n t s t r i k e s i l l u s t r a t e t h i s . F arther to the south In the d e t a i l e d area, s t r i k e and d i p are almost o b l i t e r a t e d . Some very low dip s occur i n i s o l a t e d p o r t i o n s of the rock showing a l i t t l e s t r e a k i n g or flow s t r u c t u r e . .At the high t i d e mark i n f r o n t of #6 cabin, there are banded rocks showing unusual s t r i k e and d i p . The, tuffaceous rocks which o v e r l y the banded rocks suggest an unconformity but since the d i p and s t r i k e i s p r a c t i c a l l y undefinable i n these rocks, the evidence i s only s u f f i c i e n t to make one suspicous that an i n t e r e s t i n g p o s s i b i l i t y might be developed to a c e r t a i n t y w i t h a d d i t i o n a l d e t a i l e d observa-t i o n . -65-Tn no instance could the top of a formation be d e f i n i t e l y d i s t i n g u i s h e d from the bottom. There i s only one instance that would be of p o s s i b l e use i n d i s c e r n i n g (flow b r e c c i a ) , top from bottom. The streaked r o c k s / shown i n the top c e n t r a l area of the 100 f e e t - 1 i n c h s c a l e map as out-cropping along a creek and d i p p i n g s t e e p l y northward, might i n d i c a t e a p o s s i b l e top. These streaked rocks, which are one and the same with the a d j o i n i n g rocks to the south that c o n t a i n l a r g e fragments, could be considered the top of a b r e c c i a t e d f l o w . A h y p o t h e t i c a l considera-t i o n of how t h i s could come about has been developed i n the s e c t i o n on "pibow B r e c c i a s " . Another hypothesis could be advanced to account f o r the fragments, v i z . that they r e s u l t e d from the flow of l a v a p i c k i n g up e a r l i e r fragments of the saiae e r u p t i o n and r o l l i n g them i n t o the present p o s i t i o n , which could them represent top, bottom or middle of the fl o w . A s i m i l a r c o n c l u s i o n as to v a r i a b i l i t y of p o s s i b l e p o s i t i o n s i n the flow would be reached i f the fragments o r i g i n a t e d as p y r o c l a s t i c fragments and s e t t l e d on the flow. They could then be r o l l e d i n t o any p o s i t i o n . Study of the fragments does not i n d i c a t e that they c o n s i s t of f o r e i g n m a t e r i a l . .The only d i f f e r e n c e i n composition i n the fragments and matrix i s the la r g e p r o p o r t i o n of amphibole i n the l a t t e r . These observations are made i n the hope that f u t u r e i n v e s t i g a t i o n may uncover unquestionable evidence to bear out the reasoning. -66-The c o n c l u s i o n must remain that i n s u f f i c i e n t evidence i s presented to decide which i s top or "bottom i n t h i s i n s t a n c e . Both contacts of the flow are not i n view, hence any other c o n c l u s i o n would he unwarranted. Again, t h i s instance i s isolated> study of a few such occurrences might lend weight to the idea that the elongated b r e c c i a f r a g -ments are from a surface c r u s t and concentrated i n the top. One other f e a t u r e a s c e r t a i n e d from casual observation i s a prominent b e l t of sheared and a l t e r e d r o c k s . This b e l t i s at l e a s t 1/4 mile wide, shows the east-west regional trend, and crosses the i s l a n d from Scarborough Head to the north end of K i l l a r n e y Lake. The b e l t contains the s c h i s t o s e rocks already d e s c r i b e d , as w e l l as other sheared v o l c a n i c s and what appear to be amphibolite bands. The shearing i s not confined to p r e - b a t h o l i t h rocks but i s very evident i n the i n t r u s i v e q u a r t z - d i o r i t e ( ? ) rock on the north side of Grafton Bay. These l a t t e r have been termed "hy b r i d " 11 rocks by Dr. Phemister." In general, they are observed to c ontain a great number of i n c l u s i o n s of e a r l i e r r o c k s . These b a t h o l i t h i c rocks show a s t r u c t u r e caused by a multitude of c l o s e l y spaced shear planes which are g e n e r a l l y about 1/8 i n c h apart and are coated .with c h l o r i t e and carbonate. The o v e r a l l s t r i k e of t h i s shearing appears to f o l l o w the h i l l contours. (See c o m p i l a t i o n map). The shearing i n the "hybrid" or q u a r t z _ d i o r l t e ( ? ) rock apparently took place a f t e r i t s emplacement. Since Phemister, T.C.: op. c i t . , P i g . 3, Pg• 49. PLATE JZ I l l u s t r a t i n g the effects* of dynamic metamorphism on tuffaceous sediments(?) Enlarged s e c t i o n of above: broken f e l d s p a r l a t h showing d i s p l a c e d twinning. Grafton Bay area. -67-the b e l t of the p r e - b a t h o l i t h rocks a d j o i n s the "hybr i d " ( q u a r t z - d i o r i t e ? ) rock on the west side of the i s l a n d and, the d i r e c t i o n of the shear planes i s continuous from the "hybrid" i n t o the b e l t of p r e - b a t h o l i t h rocks, i t i s very probable that shearing i n both r e s u l t e d at the same time and i s p ost-"hybrid" ( q u a r t z - d i o r i t e ? ) emplacement. The f a c t that i n t r u s i v e s occur on both side s of the long b e l t of sheared p r e - b a t h o l i t h rocks may have some bearing on the o r i g i n of the dynamic e f f e c t s . I A R T V -68-GENERAL CONCLUSIONS The nature of- the rocks described, t h e i r apparent sequence, t h e i r composition, texture and s t r u c t u r e , and t h e i r metamorphism show many s i m i l a r i t i e s to the rocks described by C. H. Clapp i n study of the V i c t o r i a and 19 Saanich a r e a s . — In h i s Vancouver group he describes flows, amygdaloidal v a r i e t i e s , t u f f s , agglomerates, i n t r u s i v e dykes and s i l l s of b a s a l t and andesite por-p h y r i a s . The w r i t e r has discussed v a r i e t i e s s i m i l a r to some of these. Another s i m i l a r i t y i s noted between the calcareous (probably limestone) i n c l u s i o n s i n the amygdaloidal flow of the w r i t e r ' s d e s c r i p t i o n and the l e n t i l s of c r y s t a l l i n e limestone (Sutton formation) i n the Vancouver v o l c a n i c s as 1P described by C l a p p . — There are notable d i f f e r e n c e s i n the composition of the Vancouver v o l c a n i c s as described by Clapp and s i m i l a r v o l c a n i c s as described by the w r i t e r . The main d i f f e r e n c e s are i n the composition of the f e l d s p a r s and i n the f a c t that augite i s reported by Clapp as present i n some of h i s v o l c a n i c s . The f e l d s p a r s of the amygdaloidal flow as described by the w r i t e r are placed as andesine. C. H. Clapp mentions that the f e l d s p a r s i n h i s andesite flows are andesine. He a l s o mentions phenoerysts of hornblende which have a l t e r e d i n some instances to a c t i n o l i t e and u r a l i t e . This would Clapp, C.H.: "Geology of the V i c t o r i a and Saanich Map areas, V.I., B.C., G.S.C, Mem. 36. -69-agree somewhat with the f i n d i n g s of the w r i t e r w i t h regard to h i s amygdaloidal f l o w s . The a l t e r a t i o n products are the same i n both cases-Many other p a r a l l e l s e x i s t between the w r i t e r ' s s e r i e s of rocks and those described by Clapp. The w r i t e r has described rocks which i n c l u d e s c h i s t o s e v o l c a n i c v a r i e t i e s and interbedded sedimentary v a r i e t i e s . (Amphibolite bands were observed about 3000 f e e t n o r t h -west of the above v a r i e t i e s i n the b e l t of sheared rocks on the n o r t h side of K i l l a r n e y v a l l e y . ) S i m i l a r v a r i e t i e s of rock are described by C. H. Clapp i n h i s Vancouver group. S c h i s t s d e r i v e d from v o l c a n i c and sedimentary rocks are described i n h i s " S i c k e r s c h i s t s " . Because of the s i m i l a r i t i e s noted, the w r i t e r would suggest that the v o l c a n i c s and interbedded sediments described by him be placed p r o v i s i o n a l l y i n the Vancouver Group. Clapp has placed the age of t h i s group as J u r a s s i c to T r i a s s i c on the b a s i s of f o s s i l s i n the Sutton forma-t i o n . D i l i g e n t search f o r f o s s i l s i n the limey bands and i n c l u s i o n s of Wharf P o i n t , Bowen I s l a n d , might l o c a t e f o s s i l s to bear out the p r o v i s i o n a l age c l a s s i f i c a -t i o n . The present sequence as shown on the map agrees wi t h the hypothesis that the f l o w - b r e c c i a v a r i e t y of rock has streaky, elongated e l l i p s o i d a l fragments at the top of the flow. The f a c t that so l i t t l e can be a s c e r t a i n e d regarding the s t r u c t u r e makes the observations of l i t t l e v a lue. I f the sequence were as shown, south to n o r t h , - 7 0 -the odd a t t i t u d e and appearance of the rocks at a point on the shore 5 0 0 f e e t south of the (Lodge Cove) creek mouth might i n d i c a t e an unconformity. I t should he noted that some of the d i s c r e p a n c i e s i n composition between the v o l c a n i c s described by the w r i t e r and those described by Clapp may be l a r g e l y due to greater a l t e r a t i o n and a l b i t i z a t i o n of the Bowen Isla n d r o c k s . The v o l c a n i c s and p r e - b a t h o l i t h rocks as a whole are h i g h l y metamorphosed but not so h i g h l y that some of the o r i g i n a l c h a r a c t e r i s t i c s of the rock cannot be discerned. Two types of metamorphism at l e a s t are present J (a) dynamic metamorphism (b) thermal metamorphism In a d d i t i o n , paulopost j u v e n i l e a c t i o n or d e u t e r i c a l t e r a t i o n and p r o p y l i t i c a l t e r a t i o n accounts f o r con-s i d e r a b l e a l t e r a t i o n of the flows and p r e - b a t h o l i t h r o c k s . Dynamic metamorphism has caused the s c h i s t o s e and sheared s t r u c t u r e of the 1/4 mile or greater band of rocks to the north of Lodge Cove. Consequent on i t s a c t i o n i s the development of hornblende, a l b i t e , c h l o r i t e and epidote i n the s c h i s t e d r o c k s . Thermal metamorphism must have had some hand i n causing a l t e r a t i o n of the v o l c a n i c s and i n t e r r e l a t e d rocks. The p u r p l i s h appearance, the development of -71-l a r g e amounts of p y r i t e and. p y r r h o t i t e i n ...many of the v o l c a n i c s i s probably due to a l a r g e extent t o heat, as from a-contact aureole. This could be supplied by the b a t h o l i t h . Metasomatism may have played s.ome part i n the development of the p y r i t e and p y r r h o t i t e . , .The most pronounced development i s n o t i c e d where the v o l c a n i c s and sediments are w i t h i n 100 f e e t of the i n t r u s i v e . The l a r g e amounts of hornblende so c h a r a c t e r i s t i c of the v o l c a n i c s could be due to thermal metamorphism. Harker states that basic rocks show an a l t e r a t i o n of . augite "to hornblende commonly of a l i g h t green v a r i e t y . . ..Hornblende may a r i s e too from decompositional products of augite and t h i s can of t e n be distinguished, by i t s manner of occurrence, e.g. as slender, s t r i n g s occupying cracks i n the f e l d s p a r . . . . C l o s e l y a s s o c i a t e d w i t h hornblende, as i f t a k i n g i t s p l a c e , patches of deep brovm b i o t i t e are not i n f r e q u e n t l y seen and they u s u a l l y occur about c r y s t a l s of primary magnetite. " "Magnetite and i l m e n i t e of primary o r i g i n have o f t e n f u r n i s h e d a c e r t a i n amount of i r o n and t i t a n t i u m f o r the formation of b i o t i t e a t a somewhat e a r l y stage.""^ Paulopost j u v e n i l e a c t i o n or d e u t e r i c a l t e r a t i o n e f f e c t s are widespread i n the. flow and dyke r o c k s . A l b i t i z a t i o n or the .replacement of- p l a g i o c l a s e by a l b i t e i s a t t r i b u t e d to t h i s type of a l t e r a t i o n . The veins of epidote so common i n the v o l c a n i c flows as l a r g e 4- inch to 12 inch wide f i l l i n g s are a t t r i b u t e d to changes made Harker, A.: "Metamorphism", Metheun, 1939 ed. \ v -72-i n the j u v e n i l e l i q u o r as a consequence of the c o n s o l i d a -t i o n of the magma. F r a c t u r i n g during c r y s t a l l i z a t i o n and f i l l i n g of the f r a c t u r e s by r e s i d u a l l i q u o r s seems best to f i t the occurrence. The v e i n l e t s of carbonate, potash, f e l d s p a r , heulan-d i t e and quartz which cut the agglomerate and amygdaloidal flow rocks and which are the channels f o r the m a t e r i a l f i l l i n g the amygdules, might owe t h e i r o r i g i n to introduced m a t e r i a l which was p o s s i b l y d e r i v e d from the und e r l y i n g b a t h o l i t h . Some of the above e f f e c t s may be the r e s u l t of contact metamorphism, as suggested e a r l i e r (see page 24). Another p o s s i b l e manner of i n t r o d u c t i o n would be when the amygdaloidal flow rock, o r i g i n a l l y probably a v e s i c u l a r b a s a l t i c (?) or a n d e s i t i c flow, f r a c t u r e d during c r y s t a l l i z a t i o n and r e s i d u a l s o l u t i o n s , gaseous or l i q u i d , passed up the f r a c t u r e s to reach the amygdules, f i l l i n g both them and the veins w i t h the same m i n e r a l s . The agglomerate fragments have been subjected to somewhat the same type of m i n e r a l i z a t i o n . The agglomer-ates are b e l i e v e d to be part of the same e x t r u s i o n as the amygdaloidal flow rocks, but e a r l i e r than the f l o w s . Thermal metamorphism by the nearby b a t h o l i t h i n t r u s i v e would cause some r e c r y s t a l l i z a t i o n . In the agglomerate there are no v i s i b l e e f f e c t s of dynamic metamorphism, i n f a c t the agglomerate has a porous appearance. No doubt t h i s i s due i n part to the smaller fragments being protected i n the interspaces of the l a r g e r fragments and i n part to the weathering out of carbonate. -73-F o s s i l organic remains are present on the i s l a n d . This i s the c o n v i c t i o n of the w r i t e r and i s s u b s t a n t i a t e d to a l i m i t e d degree by Dr. V. Okulitch.. Dr. O k u l i t c h b e l i e v e s that there i s some p o s s i b i l i t y of the s t r u c t u r e s , poor as they ar.e, being algae. Examination of one of the i n c l u s i o n s found i n a limey band i n the amygdaloidal flow rocks, shows i t to c o n s i s t of a l a c e - l i k e network of pores; only on the weathered surface can the true porous as nature of the spedimen be s e e n , / r e c r y s t a l l i z e d carbonate o r d i n a r i l y f i l l s the pores and o b l i t e r a t e s the s t r u c t u r e . An i n t e n s i v e search f o r f o s s i l s may y i e l d r e s u l t s which would be of- utmost importance i n e s t a b l i s h i n g the age of the v o l c a n i c s . BIBLIOGRAPHY Clapp, C. H.i " Geology of the V i c t o r i a and Saa'nich Map Areas, V.I., B.C." G.S.C., Memoir 36, t913 -Clapp, C.H.: "Southern Vancouver I s l a n d " , Summary Report of the G e o l o g i c a l Survey Branch, 1908-1909. Clarke, P. ¥.: The Data of Geochemistry, U.S.G.S. B u l l . 770. Grout, P. P.: "Petrography and Petrology", McGraw-Hill, 1932. Harker,, A.- "Metamorphism", Metheun, 1939 e d i t i o n . J Johannsen, A.: "A D e s c r i p t i v e Petrography of the Igneous Rocks", 1945 . Johnston, W. A.: Geology of Fraser R i v e r D e l t a Map-Area, G.S.C., Mem. -135, 1923. LeRoy, O.E., G.S.C, Report, 1906. ^ Phemister, T. C.: "Coast Range B a t h o l i t h near Vancouver, B.C." Q u a r t e r l y Journal of G e o l o g i c a l S o c i e t y of London, 0ct_ober 1945. R i c e , CM.' " D i c t i o n a r y of G e o l o g i c a l Terms", Edward Bros. I n c . 1946. J Swanson, C 0..: "Flow Cleavage i n Folded Beds", B u l l , of the G.S, America, August 1941 . W i n c h e l l , A. N.: "Elements of O p t i c a l Mineralogy", Part I I , J . Wiley & Sons, 3 r d Ed., 1945, y « — in <r i ( V . a: L C G E /VO — G - c r &6 f~C>'C //7~6/~U^/ l^G — L//?c/fv/c/ed l^o/carptcs -~ 7~a./ c-f<zceot.c£ /x'ocAis Uni Cr/~a 7^4or? Hood -cites -3«y 3C* 0 V; T£C? o r e r . o / ? e v. 4 5 ' 0 0> MTGarcther r r o i 4^  rVa crc/ . T P * J_ Ofeerr<a-<L C?*>a£cic£ YAssufnccf Con-6crc-£ EN •\5"OQ O ISLAND Gc/. / _ 6crop • fooo-So' Zoo1 JCowan Point Corr?f>//a 4/on M ap /r? -for-m a. 4/or? bui M<7/n/y Based or? IVor/c Done by 77C. Phem/s4er <3/7c/ /-/. C /Le/4of> ySca/e / " ~ '/JZ. rr? / / e 

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