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Thermal drilling and deep ice-temperature measurements on the Fox Glacier, Yukon Classen, David Farley 1970

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THERMAL DRILLING AND DEEP ICE-TEMPERATURE MEASUREMENTS ON THE POX GLACIER, YUKON by DAVID PARLEY CLASSEN B . S c , S t . L o u i s U n i v e r s i t y , 1 9 ^ 7 THESIS SUBMITTED IN PARTIAL FULFILMENT OP THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of GEOPHYSICS We a c c e p t t h i s t h e s i s a s . c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OP BRITISH COLUMBIA A p r i l , 1 9 7 0 In presenting th i s thes i s in pa r t i a l f u l f i lment of the requirements fo r an advanced degree at the Un ivers i ty of B r i t i s h Columbia, I agree that the L ibrary sha l l make i t f r ee l y ava i l ab le for reference and study. I fur ther agree tha permission for extensive copying of th i s thes i s for scho lar ly purposes may be granted by the Head of my Department or by his representat ives. It is understood that copying or pub l i ca t ion o f th is thes is f o r f inanc ia l gain sha l l not be allowed without my wr i t ten permission. Depa rtment The Univers i ty of B r i t i s h Columbia Vancouver 8, Canada i ABSTRACT D u r i n g the summer o f 1 9 6 9 a t h e r m a l d r i l l i n g and deep i c e - t e m p e r a t u r e measurement program was c a r r i e d out on the Pox G l a c i e r , Yukon T e r r i t o r y . The t h e r m a l d r i l l i n g r e s u l t e d i n seven i n s t r u m e n t e d h o l e s a t s i x l o c a t i o n s on the g l a c i e r . , t h r e e r e a c h i n g b e d r o c k . Temperature measurements i n d i c a t e d t h a t the g l a c i e r was below the p r e s s u r e - m e l t i n g p o i n t t h r o u g h o u t and t h a t memory of a d i s t u r b e d t h e r m a l regime e x i s t e d . E s t i m a t e s o f g e o t h e r m a l heat f l o w were d e t e r m i n e d and an anomalous v a l u e o f 4.73 ^ c a l / c m sec o b t a i n e d . Bottom t e m p e r a t u r e models were d e v e l o p e d which i n d i c a t e the p o s s -i b i l i t y of b a s a l m e l t i n g . i i TABLE OP CONTENTS Page 1. INTRODUCTION 1 1 . 1 S u r g i n g G l a c i e r s 1 1 . 2 Surge Mechanisms ~ 2 1 . 3 Purpose of the Program 3 1 . 4 Fox G l a c i e r 3 2. INSTRUMENTATION 6 2 . 1 Thermal Probe 6 2 . 2 D e s i g n D e s c r i p t i o n 6 2. 3 F i e l d O p e r a t i o n s 9 2 . 4 S t a c e y - t y p e P r o b e s 1 0 2.5 T h e r m i s t o r s 1 2 2 . 6 C a l i b r a t i o n 1 2 2 . 7 R e d u c t i o n of C a l i b r a t i o n Data 1 3 2 . 8 P r e p a r a t i o n o f T h e r m i s t o r C a b l e s 1 5 2 . 9 F i e l d Measurements 1 6 2 . 1 0 S e l f - h e a t i n g C o n s i d e r a t i o n s 1 6 3 . EXPERIMENTAL RESULTS 1 9 3 . 1 D r i l l i n g R e s u l t s 1 9 3 . 2 Probe A n a l y s i s 2 2 3 . 3 T h e r m i s t o r D i s t r i b u t i o n 2 3 3 . 4 C o o l i n g Curve 24 3 . 5 Temperature R e s u l t s 2 7 3 . 6 A d d i t i o n a l R e s u l t s 3 7 4. DISCUSSION 3 8 4 . 1 Geothermal Heat Flow 3 8 4 . 2 Lapse Rate 4 l 4 . 3 Bottom Temperature Models 4 4 4 . 4 C o n c l u s i o n 4 9 BIBLIOGRAPHY 5 0 APPENDIX 56 i i i LIST OP FIGURES Page FIGURE NUMBER 1 Fox G l a c i e r l o c a t i o n map. 4 2 Thermal probe d e s i g n . ~ 7 3 L i n e h e a t i n g - 240 v o l t o p e r a t i o n . 11 4 Thermistor c a l i b r a t i o n c i r c u i t . 14 5 F i e l d measurement c i r c u i t . 1 7 6 L o c a t i o n map of Fox G l a c i e r thermal d r i l l i n g s i t e s . " 20 7 Contour map of c a l c u l a t e d g r a v i t y depths f o r Fox G l a c i e r . 21 8 T h e r m i s t o r d i s t r i b u t i o n along the l o n g i -t u d i n a l a x i s of the g l a c i e r . V e r t i c a l e x a g g e r a t i o n 4x. 2 5 9 C o o l i n g curve taken at Hole 4. 2 6 10 F i f t y - d a y c o o l i n g curve. 2 8 11 Temperature p r o f i l e , Hole 1. 31 12 Temperature p r o f i l e , Hole 2. 3 2 1 3 Temperature p r o f i l e , Hole 3. 33 1 4 Temperature p r o f i l e , Hole 4. 34 15 Temperature p r o f i l e , Hole 5 . 35 1 6 Temperature p r o f i l e , Hole 6. 3 6 1 7 V a r i a t i o n of temperature w i t h s u r f a c e e l e v a t i o n . 4 2 1 8 Fox G l a c i e r , dry a d i a b a t i c , and U.S. Standard l a p s e r a t e s . 43 1 9 Fox G l a c i e r bottom temperature map, Model A. ' 4 6 20 Fox G l a c i e r bottom temperature map, Model B. 47 i v LIST OP TABLES Page TABLE NUMBER 1 C a l i b r a t i o n d a t a . 58 2 T h e r m i s t o r d i s t r i b u t i o n . • 60 3 C o o l i n g c u r v e d a t a . 6 l 4 R e s i s t a n c e and te m p e r a t u r e d a t a . 62 5 P i n a l Pox G l a c i e r t e m p e r a t u r e s . 64 6 Bottom t e m p e r a t u r e d a t a . 6 65 V ACKNOWLEDGEMENTS I wish to express my sincere a p p r e c i a t i o n to the f o l l o w i n g people and organizat ions f o r t h e i r ass is tance . Thanks are due to my supervisor , Dr . G. Clarke , f o r h i s guidance and encouragement; during the course of t h i s work; to H.W.C. Aamot of the U . S . Army T e r r e s t r i a l Sciences Center f o r design of the thermal probe system; to A . Stanley f o r h i s continued i n t e r e s t ; to. D. Cross ley , T . Brewer, and S. C o l l i n s f o r h e l p f u l d i s c u s s i o n s ; to B. Chandra f o r advice on thermistor c a l i b r a t i o n and f o r p r o v i d i n g a computer program f o r the c a l i b r a t i o n reduct ions ; to P. Michelow and D. Schrieber f o r t e c h n i c a l advice and const ruc t ion of-equipment; and to D. Gray f o r h i s help i n the f i e l d . S p e c i a l thanks also go to Dr .W.A. Wood, M r . R . H . Ragle, and the A r c t i c I n s t i t u t e of North America f o r valuable support; to the Chemical Engineering Department of the U n i v e r s i t y of B r i t i s h Columbia f o r use of c a l i b r a t i o n equipment; and to the U . S . Army T e r r e s t r i a l Sciences Center f o r loan of seismic equipment. T h i s project was supported by grants from the Nat ional Advisory Committee on Water Resources; from the Nat ional Research C o u n c i l , and from the U . B . C . Committee on A r c t i c and Alpine Research. This assistance i s g r a t e f u l l y acknowledged. 1 1 . INTRODUCTION I t i s the purpose of t h i s t h e s i s t o p r e s e n t t h e r e s u l t s of t h e r m a l d r i l l i n g and deep i c e - t e m p e r a t u r e measurements made d u r i n g the summer o f 1 9 6 9 on the "Fox""'' G l a c i e r , Yukon T e r r i t o r y . 1 . 1 S u r g i n g G l a c i e r s A s u r g i n g g l a c i e r as d e f i n e d by P o s t ( 1 9 6 9 ) i s one wh i c h p e r i o d i c a l l y ( 1 5 - 1 0 0 + y e a r s ) d i s c h a r g e s an i c e r e s e r v o i r by means o f a sudden, b r i e f , l a r g e - s c a l e i c e d i s p l a c e m e n t , which moves many t i m e s f a s t e r t h a n the g l a c i e r ' s n o r m a l f l o w r a t e between s u r g e s . D u r i n g i t s a c t i v e phase a s u r g i n g g l a c i e r can be r e c o g n i z e d by i n t e n s e c r e v a s s i n g , sheared m a r g i n s , and l a r g e i c e d i s p l a c e m e n t s . When i n a c t i v e i t r e t a i n s d i s t i n c t i v e s u r f a c e f e a t u r e s f r o m p a s t v a r i a t i o n s of f l o w r a t e . Through the use o f a e r i a l r e c o n n a i s s a n c e M e i e r and P o s t ( 1 9 6 9 ) and P o s t ( 1 9 6 9 ) have i d e n t i f i e d 204 s u r g i n g g l a c i e r s i n w e s t e r n N o r t h A m e r i c a . These g l a c i e r s o c c u r i n the A l a s k a n Range, t h e C h i g m i t , e a s t e r n W r a n g e l l , e a s t e r n Chugach, and S t . E l l a s M o u n t a i n s . T h i s l i m i t e d d i s t r i b u t i o n o f s u r g i n g g l a c i e r s s u g g e s t s the presence o f c e r t a i n common f e a t u r e s w h i c h i n d u c e p e r i o d i c i n s t a b i l i t i e s . I n d i c a t e d f a c t o r s a re u n u s u a l b e d r o c k 1 The g l a c i e r names "Fox", "Hyena", " J a c k a l " , and "Dingo" are u n o f f i c i a l ; h e n c e f o r t h q u o t a t i o n marks w i l l be o m i t t e d . 2 roughness o r p e r m e a b i l i t y i n c e r t a i n a r e a s , a n o m a l o u s l y h i g h ground-water t e m p e r a t u r e s , and/or abnormal g e o t h e r m a l heat f l o w . 1 . 2 Surge Mechanisms The phenomenon of g l a c i a l s u r g i n g i s not w e l l u n d e r s t o o d . I n i t i a t i o n mechanisms have been proposed and d i s c u s s e d by a number of a u t h o r s and r e v i e w e d by R o b i n ( 1 9 6 8 ) . S t r e s s i n s t a b i l i t i e s have f r e q u e n t l y been s u g g e s t e d as a mechanism f o r t r i g g e r i n g s u r g e s . Temperature i n s t a b i l i t i e s ( i n s t a b i l i t i e s w hich r e s u l t f r o m d e f o r m a t i o n of b a s a l i c e due t o an i n c r e a s e d b a s a l t e m p e r a t u r e ) were s u g g e s t e d by R o b i n ( 1 9 5 5 ) . Water f i l m i n s t a b i l i t i e s a t t h e boundary s u r f a c e have been s u g g e s t e d by Weertman ( 1 9 6 2 ) . N i e l s e n ( 1 9 6 8 ) has i n d i c a t e d t h e p r o b a b l e p r e s e n c e of m e c h a n i c a l i n s t a b i l i t i e s a s s o c i a t e d w i t h s u r g i n g t r i b u t a r y g l a c i e r s . Methods f o r r a i s i n g the b a S a l t e m p e r a t u r e commonly i n v o k e changes i n g e o t h e r m a l h e a t f l o w , s u r f a c e a c c u m u l a t i o n , and b a s a l s l i d i n g v e l o c i t y . I t i s q u i t e p o s s i b l e t h a t more t h a n one mechanism may be i n v o l v e d i n i n i t i a t i n g a g l a c i e r s u r g e . G l a c i e r f l o w v e l o c i t i e s are e x t r e m e l y s e n s i t i v e t o the i c e t e m p e r a t u r e s n e a r the c h a n n e l boundary and i n o t h e r r e g i o n s o f h i g h shear s t r e s s . T h i s i s due t o the t e m p e r a t u r e dependence of t h e f l o w law f o r i c e ( G l e n , 1 9 5 5 ) and t h e p o s s i b i l i t y o f s l i d i n g due t o r e g e l a t i o n o f i c e a t i t s p r e s s u r e m e l t i n g p o i n t (Weertman, 1 9 6 4 , 1 9 6 7 ; L l i b o u t r y , 1 9 6 8 ) . 1.3 Purpose of the Program -• • —— — 1 — ....... ...... ^ F o r a q u a n t i t a t i v e t h e o r y of surge mechanisms and g l a c i e r flow, i n f o r m a t i o n c o n c e r n i n g the channel shape and temperature regime of a s u r g i n g g l a c i e r i s e s s e n t i a l . T h i s , however, has not yet been accomplished due to the tremendous d i f f i c u l t y of o b t a i n i n g " i n s i t u " measurements d u r i n g and immediately a f t e r a surge. Under these circumstances i t i s l i k e l y t h a t measurements on a "pre-surge" g l a c i e r may p r o v i d e the most u s e f u l i n f o r -mation f o r understanding surge mechanisms. Fo r t h i s reason, a long-term program was i n i t i a t e d i n 19^7 on the Fox G l a c i e r , Yukon T e r r i t o r y . The i n t e n t i s to produce a d e t a i l e d d e s c r i p t i o n of the p h y s i c a l s t a t e of a g l a c i e r b efore a surge. I n d i v i d u a l r e s e a r c h p r o j e c t s a l r e a d y undertaken i n c l u d e mapping of the g l a c i e r s u r f a c e and i c e t h i c k n e s s ; measurement of flow r a t e s , mass balance, and shallow i c e temperatures; and s t u d i e s r e l a t i n g to hydrology, g l a c i a l geology, and geomorphology. The present i n v e s t i g a t i o n concerns deep ice-temperature measurements and surge a c t i v i t y . 1.4 Fox G l a c i e r The Fox G l a c i e r , a s m a l l v a l l e y g l a c i e r , i s l o c a t e d i n the S t e e l e Creek Drainage B a s i n on the i n t e r i o r s i d e of the I c e f i e l d Ranges. I t l i e s west of the S t e e l e G l a c i e r and n o r t h of the Hodgson G l a c i e r ( F i g u r e 1 ) . The g l a c i e r i s at an approximate a l t i t u d e of 2250 meters w i t h the accumulation Fig.' 1. Fox Glacier location map. 5 a r e a a t i t s s o u t h e r n end. The l e n g t h i s 6-7 km and i t s s u r f a c e r e l a t i v e l y s t e e p . The J a c k a l and Hyena G l a c i e r s . share a common r u n - o f f system w i t h the Fox. The s u r r o u n d i n g r e g i o n i s mountainous w i t h Mt. Wood ( 1 5 , 8 8 5 ' ) t o t h e west and Mt. S t e e l e (16,644') t o t h e s o u t h . The S t e e l e Creek B a s i n i s r e p o r t e d t o have s i x t e e n s u r g i n g g l a c i e r s . The S t e e l e and Hodgson G l a c i e r s , and c e r t a i n t r i b u t a r i e s , have surged as r e c e n t l y as 1 9 6 6 . E x a m i n a t i o n o f m o r a i n a l p a t t e r n s (Sharp, 1 9 4 3 ) s u g g e s t s a g e n e r a l advance i n the a r e a w i t h a s i m u l t a n e o u s advance of the Fox, J a c k a l , and Hyena G l a c i e r s about 1 0 0 - 2 0 0 y e a r s ago. F u r t h e r e v i d e n c e i n d i c a t e s t h a t the Fox, J a c k a l , and Hyena G l a c i e r s have surged i n d e p e n d e n t l y s i n c e t h a t t i m e . Fox G l a c i e r ' s h i s t o r y of surge a c t i v i t y and i t s d i s t i n c t i v e s u r f a c e f e a t u r e s l e d A. S. P o s t t o suggest i t s s t u d y i n a n t i c i p a t i o n of a f u t u r e s u r g e . 6 2. INSTRUMENTATION 2.1 Thermal Probe The placement of t e m p e r a t u r e s e n s i n g d e v i c e s i n the Fox G l a c i e r r e q u i r e d a s m a l l p r a c t i c a l d r i l l c a p a b l e of p r o d u c i n g plumb h o l e s t o depths of 100 meters or more i n s u b - p o l a r i c e . The development of an e l e c t r i c a l l y - p o w e r e d , c a b l e - s u s p e n d e d d r i l l t o p e n e t r a t e mountain g l a c i e r s i s r e p o r t e d by L a C h a p e l l e (1963). P h i l b e r t h (1966) and Aamot (1967) d i s c u s s means of a t t i t u d e s t a b i l i z a t i o n . Aamot (1968) d e s c r i b e s a buoyancy-s t a b i l i z e d hot p o i n t d r i l l f o r use on temperate g l a c i e r s and s u g g e s t s a d a p t a t i o n s f o r d r i l l i n g i n s u b - p o l a r i c e . D r i l l i n g i n c o l d i c e p r e s e n t s a s p e c i a l p r o b l e m s i n c e the h o l e i s l i k e l y t o r e f r e e z e , a n c h o r i n g the power c a b l e i n the i c e , b e f o r e any g r e a t d e p t h can be r e a c h e d . Hole c l o s u r e must be p r e v e n t e d or reduced t o a r a t e c o m p a t i b l e w i t h d r i l l i n g speed and e s t i m a t e d i c e t h i c k n e s s . H.W.C. Aamot ( p e r s o n a l communication, 1969) d e s i g n e d a t h e r m a l probe s u i t a b l e f o r use on t h e Fox G l a c i e r . The d e s i g n was based on an e a r l i e r model (Aamot, 1968) w i t h an added p r o v i s i o n f o r l i n e h e a t i n g t o reduce t h e h o l e c l o s u r e r a t e . 2.2 D e s i g n D e s c r i p t i o n The h o t p o i n t suggested f o r use on t h e Fox G l a c i e r p r o j e c t i s shown i n F i g u r e 2. The s o l i d c opper p o i n t i s l o n g t o a c h i e v e a l a r g e c o n t a c t p r e s s u r e w i t h the i c e . The e l e c t r i c h e a t i n g element c o n t a i n e d i n t h e l o w e r t w o - t h i r d s SOLDER: T IN-LEAD ALLOY ADHESIVE: EPOXY RESIN 350 °F STABILITY SPIRAL V-GROOVE .010" DEEP 12 TURNS/INCH TEFLON SEAL BUOYANCY CHAMBER .10 =3 =3 FIREROD HEATING CARTRIDGE 120 V 20.8 A LAMINATED PLASTIC GRADE G- l l .062 WALL FUSITE FEED-THROUGH TERMINALS HIGH CONDUCTIVITY COPPER LAMINATED PLASTIC OR ALUMINUM Pig. 2. Thermal probe design. 8 o f t h e c a r t r i d g e i s s o l d e r e d i n t o the c o p p e r . The buoyancy s e c t i o n c o n s i s t s of a tube of l a m i n a t e d p l a s t i c and i s bonded t o the hot p o i n t and cap w i t h an epoxy r e s i n a d h e s i v e . F u s i t e f e e d - t h r o u g h t e r m i n a l s i n the cap c o n n e c t t o the power c a b l e . The probe d i m e n s i o n s and power s p e c i f i c a t i o n s were s e l e c t e d .to p e r m i t c o m p l e t i o n of 1 6 0 meter h o l e s i n -6.0°C i c e (Aamot, 1 9 6 7 ) . A probe d i a m e t e r of 3.0 i n . (3.8 cm) w i t h 2 5 0 0 w a t t s d i s s i p a t e d i n the t i p and 4.8 w a t t s / f t ( 1 5 . 7 5 watts/m) a l o n g the 1 6 0 meter power c a b l e was chosen. T h i s arrangement p r o v i d e d a d r i l l i n g speed of 4 . 0 m/hr and 4 0 h o u r s of d r i l l i n g time b e f o r e the h o l e c l o s e d t o 2 . 2 cm, a d i a m e t e r s l i g h t l y l a r g e r t h a n the c a b l e package. S e v e r a l m o d i f i c a t i o n s of Aamot 1s d e s i g n were i n t r o d u c e d . The o r i g i n a l system, w h i c h c a l l e d f o r h i g h v o l t a g e and low c u r r e n t ( 1 1 5 0 v, 4.3 amp), was r e p l a c e d w i t h a h i g h - c u r r e n t , l o w - v o l t a g e arrangement ( 2 4 0 v, 2 0 . 6 amp). T h i s e l i m i n a t e d t h e need of an i s o l a t i o n t r a n s f o r m e r , a h i g h - v o l t a g e a u t o - t r a n s f o r m e r , and e x p e n s i v e h i g h - r e s i s t a n c e nichrome w i r e . T e s t s p r i o r t o f i e l d use i n d i c a t e d t h a t the w a l l t h i c k n e s s o f the buoyancy chamber was n o t s u f f i c i e n t t o w i t h s t a n d the a n t i c i p a t e d p r e s s u r e s . I n s u f f i c i e n t time p r e v e n t e d r e p l a c e m e n t o f t h i s s e c t i o n . To c o r r e c t t h i s f a u l t s i x p r obes were c o m p l e t e l y f i l l e d w i t h an epoxy r e s i n . I n two o t h e r s t h e buoyancy chamber was p e r f o r a t e d and a l l o w e d t o f i l l w i t h water which e q u a l i z e d the p r e s s u r e . The end cap 9 was r e d e s i g n e d t o p e r m i t attachment o f a seven f o o t s t e e r i n g r o d . T h i s f e a t u r e , which r e p l a c e d the buoyancy guidance mechanism prove d u n n e c e s s a r y s i n c e the de p t h s a c t u a l l y e n c o u n t e r e d were v e r y s h a l l o w ( 5 0 - 8 0 meters) and c a v i t i e s i n t he i c e were not e v i d e n t . 2.3 F i e l d O p e r a t i o n s A 5 kva K o h l e r g e n e r a t o r (Model 5RMS65) s u p p l i e d e l e c t r i c a l power t o the hot p o i n t . The g e n e r a t o r , r a t e d a t 120/240 v o l t s , 20.8 amps, was equi p p e d w i t h a v o l t a g e r e g u l a t o r , a f u e l pump and l i n e , and a c o n t r o l p a n e l w i t h v o l t m e t e r and ammeter. The v o l t a g e r e g u l a t o r a l l o w e d a c o n t i n u o u s c u r r e n t t o be drawn. V o l t a g e was v a r i e d by a d j u s t i n g the engine speed, e l i m i n a t i n g the n e c e s s i t y of a v a r i a b l e • t r a n s f o r m e r . F u e l was t a k e n f r o m a f i f t y - g a l l o n drum so t h a t no d r i l l i n g time was l o s t f i l l i n g a s m a l l mounted t a n k . The power s u p p l y c a b l e , B e l d e n 84-71, was s e l e c t e d t o d i s s i p a t e a p p r o x i m a t e l y 1 5 - 7 5 watts/m. A l6-gauge w i r e was used, 17-gauge b e i n g u n a v a i l a b l e . T h i s gave a r e s i s t a n c e o f 5 ohms per thousand f e e t a t 82°C w i t h 14.10 watts/m power d i s s i p a t i o n i n the l i n e . P r o v i s i o n s were made f o r t o t a l as w e l l as p a r t i a l l i n e h e a t i n g w i t h the a d d i t i o n o f a 22-gauge, B e l d e n 8 7 4 0 , copper c a b l e . By c o n n e c t i n g t h i s c a b l e i n s e r i e s w i t h one o f t h e c o n d u c t o r s , the t o t a l 5 kva power c o u l d be d i s s i p a t e d i n t h e 10 l i n e d o u b l i n g the heat d e l i v e r e d t o the m e l t w a t e r . I f the h o l e c l o s u r e proved t o be l e s s t h a n e s t i m a t e d , the l i n e h e a t i n g c o u l d be reduced t o one h a l f by p a r a l l e l c o n n e c t i o n o f the c a b l e s . F i g u r e 3 shows l i n e h e a t i n g arrangements and power d i s s i p a t i o n v a l u e s . The power c a b l e package was l a i d out on the i c e t o p r e v e n t o v e r h e a t i n g and r e s u l t i n g i n s u l a t i o n d e t e r i o r a t i o n w h i c h c o u l d o c c u r w i t h the c a b l e on a s p o o l . The t h e r m i s t o r c a b l e was a t t a c h e d t o the package a t 5-meter i n t e r v a l s as the probe descended. The Appendix c o n t a i n s a complete l i s t of components and s u p p l i e r s . 2.4 S t a c e y - t y p e P r o b e s An a d d i t i o n a l e i g h t hot p o i n t probes were p u r c h a s e d f r o m J . C. Savage of the U n i v e r s i t y of T o r o n t o . These were d e s i g n e d f o r d r i l l i n g i n temperate g l a c i e r s and the g e n e r a l c o n s t r u c t i o n was based on the p r o t o t y p e model d e v e l o p e d by S t a c e y (i960). The main d i f f e r e n c e s were the shape i n which t h e C a l r o d h e a t e r s were wound, the t e r m i n a t i o n of the h e a t e r (no l o n g e r a copper b l o c k ) , and the t h r e a d e d s e a l w i t h a n n e a l e d copper g a s k e t which r e p l a c e d the Kovar s e a l . The p r o b e s , h e a t e d by C a l r o d e l e m e n t s w i t h n o m i n a l r e s i s t a n c e s o f 17 ohms, drew a p p r o x i m a t e l y 10 amps. As a r e s u l t o n l y one q u a r t e r o f the power was d i s s i p a t e d i n the l i n e and the probes had a 35 meter d e p t h l i m i t i n the -6.0°C i c e . 11 NORMAL OPERATION TOTAL LINE HEATING REDUCED LINE HEATING ( 50 % ) # 2 2 AWG 8 n 3300 W #16 AWG-2.5 n 1100 W 160 m CABLE LENGTH # 16 AWG 2.5 SI 1100 W 5.9 11 120 V 20.6 A| 2500 W Pig. 3. Line heating - 240 vo l t operation. 12 2.5 T h e r m i s t o r s P o r the e n g l a c l a l t e m p e r a t u r e measurements Fenwal GB31P2 t h e r m i s t o r s were s e l e c t e d . These g l a s s bead t h e r m i s t o r s were probe mounted f o r ease of h a n d l i n g , the probe b e i n g 1/2 i n . l o n g w i t h 2 i n . l e a d s . The u n i t s had a n o m i n a l r e s i s t a n c e o f 1000 ohms a t 25°C, p o f 3500, and a d i s s i p a t i o n c o n s t a n t of 1 milliwatt/°C. • P i n a l r e s u l t s a c c u r a t e t o 0.10°C over t h e range -10.00°C t o 0.00°C were sought. T h i s u n i t w i t h t h e a p p r o p r i a t e b r i d g e would a l l o w an a c c u r a c y o f io.03°C f o r t h e f i e l d measurements. 2.6 C a l i b r a t i o n C a l i b r a t i o n of 5 6 t h e r m i s t o r s was performed u s i n g the f o l l o w i n g equipment: Haake TP-41 c o n s t a n t t e m p e r a t u r e b a t h w i t h a P o l y S c i e n c e C o r p o r a t i o n model KR-30, q u a r t e r - h o r s e compressor c o o l i n g u n i t ; a Dymec model 2801-A d i g i t a l r e a d o u t q u a r t z thermometer as s t a n d a r d ; a G e n e r a l R a d i o Company 1432M decade r e s i s t o r w i t h a Leeds and N o r t h u r p (L+N) 2437 n u l l d e t e c t o r i n a b r i d g e c i r c u i t w i t h 25,000 ohm l e g s ; and a v o l t a g e d i v i d e r m o n i t o r e d by a KEW66 m u l t i m e t e r . A s e l e c t o r s w i t c h a l l o w e d b a t c h c a l i b r a t i o n o f 23 t h e r m i s t o r s . The t h e r m i s t o r s were p r e p a r e d by c o n n e c t i n g one l e a d o f each t o a c o n d u c t o r o f a 24-co n d u c t o r c a b l e and the o t h e r l e a d t o a common c o n d u c t o r . The l e a d s were c o v e r e d w i t h p l a s t i c t u b i n g and t h e j o i n t s i n s u l a t e d t o p r e v e n t c u r r e n t l e a k a g e and s h o r t i n g . The t h e r m i s t o r s were coded 13 a c c o r d i n g t o c a l i b r a t i o n b a t c h (A,B,C) and p o s i t i o n number (1-23). The c o n s t a n t t e m p e r a t u r e b a t h f l u i d was a m i x t u r e of 80$ water and 20$ m e t h y l a l c o h o l w h i c h a l l o w e d t e m p e r a t u r e s below 0.00°C. The t h e r m i s t o r s were c a l i b r a t e d i n 3.00-0.01°C i n t e r v a l s over the range -12.00°C t o 0.00°C, the a n t i c i p a t e d range of g l a c i e r t e m p e r a t u r e s . F i g u r e 4 shows the t h e r m i s t o r c a l i b r a t i o n c i r c u i t . The c a l i b r a t i o n d a t a are c o n t a i n e d i n T a b l e 1 of the appe n d i x . 2.7 R e d u c t i o n of C a l i b r a t i o n Data The c a l i b r a t i o n d a t a were reduced t o t a b l e s of tem p e r a t u r e v e r s u s r e s i s t a n c e . V a l u e s of r e s i s t a n c e were g i v e n f o r each i n d i v i d u a l t h e r m i s t o r over t h e range of c a l i b r a t i o n t e m p e r a t u r e s i n i n c r e m e n t s of 0.01°C. The d i f f e r e n c e between c a l i b r a t e d r e s i s t a n c e and computed r e s i s t a n c e a t the c a l i b r a t i o n p o i n t s was a l s o i n d i c a t e d p r o v i d i n g an e s t i m a t e o f the f i t a c c u r a c y . The r e d u c t i o n was based on a method d e v e l o p e d f o r l e a s t - s q u a r e s c u r v e - f i t t i n g of n o n - e q u i d i s t a n t d a t a i n terms of o r t h o g o n a l p o l y n o m i a l s and power moments (Quest, 1950). The t e c h n i q u e was a p p l i e d t o the t h e r m i s t o r c a l i b r a t i o n d a t a f o r the f u n c t i o n R=EXP(A+B/T+C/T ) u s i n g a computer program w r i t t e n by B. Chandra of the Department of G e o p h y s i c s , U n i v e r s i t y of B r i t i s h C o l u m b i a . 23-POSITION SELECTOR SWITCH DECADE BOX WHEATSTONE BRIDGE "5 VOLTAGE DIVIDER NULL MONITOR INDICATOR 24-CONDUCTOR CABLE QUARTZ THERMOMETER STANDARD DIGITAL READOUT CONSTANT TEMPERATURE BATH P i g . 4. .Thermistor c a l i b r a t i o n c i r c u i t . 1 5 2.8 P r e p a r a t i o n of T h e r m i s t o r C a b l e s The i n s t a l l a t i o n of t h e r m i s t o r s i n a m u l t i c o n d u c t o r c a b l e r e q u i r e d c a r e f u l a t t e n t i o n s i n c e each t h e r m i s t o r had t o be c u s h i o n e d , w a t e r p r o o f e d , and p r o p e r l y i d e n t i f i e d . The c o n s t r u c t i o n o f the t h e r m i s t o r c a b l e s was based on p r o c e d u r e s d e v e l o p e d by the U.S. G e o l o g i c a l S u r v e y (Raspet, e t a l . , 1 9 6 6 ) . B e l d e n 8488, e i g h t c o n d u c t o r , 22-gauge, antenna r o t o r c a b l e was s e l e c t e d f o r use as the t h e r m i s t o r c a b l e . Each c o n d u c t o r was v i n y l i n s u l a t e d and the e n t i r e package encased i n a chrome v i n y l j a c k e t . The c a b l e was c u t t o the p r o p e r l e n g t h as d e t e r m i n e d from g r a v i t y d e p t h s ( C r o s s l e y , M.Sc. T h e s i s , 1 9 6 9 ) and t h e r m i s t o r p o s i t i o n s i n d i c a t e d . M a r k e r s were a l s o p l a c e d a t 1 0 - m e t e r i n t e r v a l s f o r d e t e r m i n g h o l e d e p t h . A p p r o x i m a t e l y 1 0 cm o f the o u t e r j a c k e t was c u t away a t the p r o p e r p o s i t i o n t o a c c e p t the t h e r m i s t o r . The c o n d u c t o r , l o c a t e d by c o l o r code, was c u t , s t r i p p e d , and c o v e r e d w i t h i n s u l a t i n g t u b i n g . The t h e r m i s t o r l e a d s were s o l d e r e d t o the c o n d u c t o r w i t h a low-powered i r o n and the t u b i n g p l a c e d o v e r t h e j o i n t s t o p r e v e n t s h o r t i n g . The t h e r m i s t o r was t h e n p l a c e d a g a i n s t the c a b l e , cemented w i t h Ambroid, and s e a l e d w i t h A l p h a F I T - 3 0 0 h e a t - s h r i n k t u b i n g . A f i n a l w r a p p i n g w i t h s e l f - v u l c a n i z i n g tape c o m p l e t e d the pod. Only s i x t h e r m i s t o r s were i n s t a l l e d on a c a b l e , t h e 16 r e m a i n i n g two c o n d u c t o r s used t o measure t h e l e a d r e s i s t a n c e . The l e a d r e s i s t a n c e i s s u b t r a c t e d f rom t h e t o t a l c i r c u i t r e s i s t a n c e t o g i v e the t h e r m i s t o r r e s i s t a n c e . S i n c e the c a b l e s were t o be used o n l y once, no s p e c i a l c o n n e c t o r s were i n s t a l l e d on the upper end. The l e a d s were s i m p l y taped i n t o a p l a s t i c bag u n t i l i t was time t o t a k e t h e measurements. 2.9 F i e l d Measurements F i e l d measurements were made w i t h a Leeds and N o r t h r u p 4760 D-C Wheatstone B r i d g e and a 2340-C p o i n t e r t y p e g a l v a n o m e t e r . Power was s u p p l i e d by a 1-1/2 v o l t d r y - c e l l b a t t e r y . A v o l t a g e d i v i d e r m o n i t o r e d by a KEW66 m u l t i m e t e r p e r m i t t e d the use o f low v o l t a g e s (0.2 v o l t s ) t h u s e l i m i n a t i n g e r r o r s due t o s e l f - h e a t i n g of t h e t h e r m i s t o r . F i g u r e 5 shows the f i e l d measurement c i r c u i t . T h i s arrangement a l l o w e d r e s i s t a n c e measurements o f moderate p r e c i s i o n . The l i m i t of e r r o r was -0.15% of the d i a l r e a d i n g o r ^0.02 t o io .03°C over the range of r e s i s t a n c e s e n c o u n t e r e d . 2.10 S e l f - h e a t i n g C o n s i d e r a t i o n s The Fenwal GB31P2 t h e r m i s t o r has a d i s s i p a t i o n c o n s t a n t (D.C.) of 1 milliwatt/°C. T h i s means t h a t a power o f 1 m i l l i w a t t b e i n g d i s s i p a t e d i n the t h e r m i s t o r w i l l change i t s body t e m p e r a t u r e by 1°C due t o s e l f - h e a t i n g . T h i s i n t u r n 17 1 A © \ li W H E A T S T O N E * BR IDGE L8t N 4 7 6 0 9 5 0 0 K y" 1.5V N U L L D E T E C T . L 8 N 2 3 4 0 - C V O L T A G E DIVIDER 8 - C 0 N D U C T 0 R C A B L E O " T H E R M I S T O R J F i g . '5. F i e l d measurement c i r c u i t . 18 changes the r e s i s t a n c e by 5$. To reduce the s e l f - h e a t i n g and the r e s u l t i n g e r r o r s i n measurement, i t i s n e c e s s a r y t o l i m i t the c u r r e n t t h r o u g h the t h e r m i s t o r t o a l e v e l c o m p a t i b l e w i t h t h e d e s i r e d a c c u r a c y . T h i s i s a c c o m p l i s h e d by p l a c i n g a v o l t a g e d i v i d e r a c r o s s the b r i d g e power s u p p l y so t h a t the v o l t a g e may be reduced t o the r e q u i r e d l e v e l . T h e , b r i d g e i n p u t v o l t a g e , E i n , i s d e t e r m i n e d f r o m the r e l a t i o n s h i p E i n 2E , where E = ( P R ) 1 / / 2 . R i s the r e s i s t a n c e of the t h e r m i s t o r a t m i d p o i n t of the t e m p e r a t u r e range and P i s the d i s s i p a t i o n c o n s t a n t of the t h e r m i s t o r w h i c h w i l l g i v e the d e s i r e d a c c u r a c y . F o r 0.01°C a l l o w a b l e o f f s e t , P = 0.01 m i l l i w a t t s . I n t h i s case R i s 4000 ohms which g i v e s an E of 0.2 v o l t s . The maximum i n p u t v o l t a g e i s t h u s 0.4 v o l t s . A b r i d g e v o l t a g e o f E ^ n = 0 . 2 v o l t s was used f o r the f i e l d measurements w h i c h reduced t h e e r r o r , due t o s e l f -h e a t i n g f a r below t h e e r r o r i n v o l v e d i n the measurement a p p a r a t u s i t s e l f . 19 3. EXPERIMENTAL RESULTS 3 . 1 D r i l l i n g R e s u l t s Thermal d r i l l i n g r e s u l t e d i n a t o t a l of seven i n s t r u m e n t e d h o l e s a t s i x l o c a t i o n s on the g l a c i e r ; t h r e e h o l e s a p p a r e n t l y reached b e d r o c k . F i g u r e 6 i n d i c a t e s the p o s i t i o n of t h e s e s i t e s i n r e l a t i o n t o the network o f s u r v e y markers on the g l a c i e r . F i v e of the l o c a t i o n s are a l o n g the l o n g i t u d i n a l a x i s of the g l a c i e r , the s i x t h n e a r a head w a l l a t the s o u t h e r n end of the a c c u m u l a t i o n r e g i o n . The h o l e s are numbered 1 t h r o u g h 6 i n the o r d e r of t h e i r c o m p l e t i o n , two h o l e s b e i n g d r i l l e d at S i t e 2. Survey marker r e f e r e n c e numbers are a l s o i n c l u d e d i n the diagram. F i g u r e 7 i s a g r a v i t y d epth map of the Fox G l a c i e r a f t e r D. C r o s s l e y (M.Sc. T h e s i s , 1 9 6 9 ) showing the d r i l l i n g l o c a t i o n s . The f o l l o w i n g t a b l e g i v e s a condensed summary o f the d r i l l i n g r e s u l t s and compares d r i l l e d d e p t h s w i t h g r a v i t y d e p t h s . The h o l e s c ompleted t o bedr o c k are i n d i c a t e d . Hole Stake Depth(m) G r a v i t y ( m ) Bottom 1 20 48.8 5 0 . 6 X 2 3 2 2 0 . 4 8 7 . 6 2-B 3 2 3 0 . 5 8 7 . 6 3 3 6 E 6 3 0 . 2 64.6 4 2 6 1 4 . 6 5 7 . 7 -5 1 6 2 7 . 7 3 0 . 6 X 6 1 2 3 2 . 0 2 9 . 0 X i 20 F i g . 6. Location map of Fox Glacier thermal d r i l l i n g s i t e s . 21 Fig. 7. Contour map of calculated gravity depths f o r Fox Glacie r . 22 The d e c i s i o n t h a t c e r t a i n p robes bottomed was based on the r a p i d r e d u c t i o n o r c e s s a t i o n of the d r i l l i n g r a t e w i t h o u t e v i d e n c e of probe burn-out o r h o l e c l o s u r e and the c o m p a t a b i l i t y w i t h g r a v i t y d e p t h s . F o r t h e s e h o l e s t h e g r a v i t y d e p t h s are w i t h i n 5$-10$ of the d r i l l e d d e p t h s , i n d i c a t i n g a v e r y a c c e p t a b l e g r a v i t y d e p t h a c c u r a c y . I n c o m p l e t e h o l e s are a c c o u n t e d f o r by probe and g e n e r a t o r f a i l u r e s . 3.2 Probe A n a l y s i s P erformance o f t h e U.B.C. c o n s t r u c t e d probes was below e x p e c t a t i o n s . I n o n l y one i n s t a n c e d i d t h e a c t u a l d r i l l i n g r a t e match t h e a n t i c i p a t e d r a t e of 4.0 m/hr. I n t h e r e m a i n i n g c a s e s , the r a t e s ranged f r o m 1.0-1.5 m/hr w i t h s u b s t a n t i a l s i d e w a l l m e l t i n g . There were a number o f f a c t o r s w h i c h a p p a r e n t l y e x p l a i n t h i s p e r f o r m a n c e . D i s s e c t i o n of a f a u l t y probe r e v e a l e d t h a t the S i l a s t i c - l 4 0 s e a l i n the moat around the upper s e c t i o n o f t h e element had f a i l e d . S i n c e the element had no t been s o l d e r e d i n t o the copper t i p (a t h e r m a l compound was u s e d ) , water seeped i n t o t h e s m a l l c a v i t y a t the base o f t h e h e a t i n g element. T h i s reduced c o n d u c t i o n t o the t i p o f the probe c a u s i n g g r e a t e r s i d e w a l l h e a t i n g and a s l o w e r d r i l l i n g r a t e . I n a d d i t i o n i t was l a t e r n o t e d t h a t t h e h e a t i n g element r e s i s t a n c e s were as much as 1 ohm l e s s t h a n s p e c i f i e d due 23 t o m a n u f a c t u r i n g i n t o l e r a n c e s . T h i s r e s u l t e d i n a 17$ power l o s s a t the p o i n t . I t i s a l s o f e a s i b l e t h a t t h e elements were n o t i n s e r t e d f a r enough i n t o the copper t i p . A l l o f t h e s e f a c t o r s presumably c o n t r i b u t e d t o the o v e r a l l probe performance. Only one element burn-out was e x p e r i e n c e d d u r i n g d r i l l i n g and t h i s was due t o a c c i d e n t a l o v e r l o a d i n g . P e r s i s t a n t g e n e r a t o r d i f f i c u l t i e s , however, p r e v e n t e d c o m p l e t i o n of t h r e e h o l e s . The S t a c e y - t y p e probes performed w e l l but due t o t h e i r l o w e r power and s m a l l e r d i a m e t e r were l i m i t e d t o s h a l l o w h o l e s . Only 10 amps were drawn by t h e s e p r o b e s which reduced the l i n e h e a t i n g t o 25$ o f the d e s i r e d v a l u e . The r e s u l t i n g 35-meter d e p t h l i m i t r e s t r i c t e d t h e i r use t o the t h i n n e r s e c t i o n s o f the g l a c i e r . 3.3 T h e r m i s t o r D i s t r i b u t i o n T h i r t y s i x t h e r m i s t o r s were p l a c e d -in t h e Fox G l a c i e r d u r i n g the c o u r s e o f the p r o j e c t . Of t h e s e , s i x were p l a c e d w i t h a s m a l l g l y c o l - c i r c u l a t i n g hand d r i l l f o r a t e m p e r a t u r e c o m p a r i s o n e x p e r i m e n t w h i c h w i l l be d e s c r i b e d l a t e r . The remainder of the t h e r m i s t o r s were s e t w i t h t h e t h e r m a l d r i l l i n g a p p a r a t u s . One a d d i t i o n a l t h e r m i s t o r was p l a c e d i n the tongue of the Hyena g l a c i e r t o d e t e r m i n e i t s t e m p e r a t u r e c l a s s i f i c a t i o n . T a b l e 2 of the appendix l i s t s t h e t h e r m i s t o r d i s t r i b u t i o n 24 a c c o r d i n g t o h o l e number, de p t h , and t h e r m i s t o r number. A l s o g i v e n i s the p a r t i c u l a r c o l o r code wh i c h e n a b l e s p r o p e r i d e n t i f i c a t i o n o f the d e v i c e s d u r i n g measurement. A c c e s s t o the t h e r m i s t o r c a b l e s was m a i n t a i n e d by a t t a c h i n g the c a b l e end t o a l o n g p o l e anchored i n the i c e . F i g u r e 8 i s a c r o s s s e c t i o n of the g l a c i e r showing the t h e r m i s t o r d i s t r i b u t i o n a l o n g the l o n g i t u d i n a l a x i s . (The v e r t i c a l e x a g g e r a t i o n i s f o u r . ) H o l e s 1 and 5 g i v e the most complete t e m p e r a t u r e c o v e r a g e . 3.4 C o o l i n g Curve The use o f h o t p o i n t d r i l l i n g p r o c e d u r e s r e s u l t s i n a l a r g e t h e r m a l c o n t a m i n a t i o n o f the s u r r o u n d i n g i c e . C o o l i n g c u r v e s were e s t a b l i s h e d i n o r d e r t o d e t e r m i n e the time r e q u i r e d f o r t h e d i s t u r b e d i c e t o r e a c h an e q u i l i b r i u m t e m p e r a t u r e . T h e r m i s t o r measurements were made a t Hole 4 o v e r s h o r t time i n t e r v a l s a f t e r power t o t h e probe was s h u t o f f . Data were o b t a i n e d f o r depths of 5-5 meters and 14.6 m e t e r s . T a b l e 3 g i v e s the t i m e , r e s i s t a n c e , and t e m p e r a t u r e l i s t i n g s . F i g u r e 9 shows t h e s e d a t a as te m p e r a t u r e v e r s u s e l a s p e d time f o r the p e r i o d o f measurement. The te m p e r a t u r e d r i f t i n b o t h c a s e s i s a p p r o x i m a t e l y 0.20°C between the f o u r t h and e i g h t h day and 0.10°C between the e i g h t h and t w e l f t h day. There i s no i n d i c a t i o n t h a t e q u i l i b r i u m has been r e a c h e d . Weather c o n d i t i o n s w h i c h f o r c e d an e v a c u a t i o n of T 2 0 500 1000 1500 2000 HORIZONTAL DISTANCE , m Pig. o. Thermistor d i s t r i b u t i o n along the longitudinal axis of the g l a c i e r . V e r t i c a l exaggeration 4x. ' • 4 6 8 10 ELAPSED TIME AFTER POWER CUTOFF , days F i g . 9. Cooling curve taken at Hole 4, ro 27 t h e f i e l d camp p r e v e n t e d f u r t h e r e x t e n s i o n of the measurements. An a d d i t i o n a l c o o l i n g c u r v e was c o n s t r u c t e d f o r a f i f t y - d a y p e r i o d f r o m the p r i m a r y f i e l d d a t a . The t h e r m i s t o r s a t each d r i l l e d l o c a t i o n were measured t h r e e t i m e s o v e r t h e c o u r s e o f t h e f i e l d season and the d a t e s n o t e d . T h i s i n f o r m a t i o n was s u f f i c i e n t t o e s t a b l i s h t h e c u r v e i n F i g u r e 10. I n t h i s f i g u r e , t e m p e r a t u r e o f f s e t i s p l o t t e d a g a i n s t e l a p s e d time and i n d i c a t i o n s are t h a t e q u i l i b r i u m i s d e f i n i t e l y r e ached a f t e r t h i r t y s i x days. Temperatures measured at the t w e n t y - f i f t h day are a t e q u i l i b r i u m w i t h i n t h e a c c u r a c y o f measurement and r e d u c t i o n . Measurements p r i o r t o the t w e n t y - f i f t h day can be a d j u s t e d t o e q u i l i b r i u m v a l u e s by u s i n g the c u r v e . The p o s s i b i l i t y of a d d i t i o n a l d r i f t o v e r a l o n g e r p e r i o d o f t i m e , such as 0.10°C o v e r f i f t y more days, Cannot be e x c l u d e d . I t I s f e l t , however, t h a t a l l f i n a l t e m p e r a t u r e s are w e l l w i t h i n io.10°C'-;-of e q u i l i b r i u m v a l u e s , 3.5 Temperature R e s u l t s R e s i s t a n c e measurements were made on each t h e r m i s t o r t h r e e t i m e s o ver t h e two-month f i e l d s e ason. A s t a n d a r d Wheatstone b r i d g e arrangement (L+N 4760) was employed and e r r o r s due t o s e l f - h e a t i n g were a v o i d e d by m a i n t a i n i n g the i n p u t v o l t a g e a t 0.2 v o l t s . Lead r e s i s t a n c e was E L A P S E D T I M E A F T E R P O W E R C U T O F F , d a y s Fig. 10. Fifty-day cooling curve. 29 d e t e r m i n e d by me a s u r i n g the r e s i s t a n c e of the two common c o n d u c t o r s c o n n e c t e d i n s e r i e s . T a b l e 4 c o n t a i n s the r e s i s t a n c e d a t a and e l a p s e d time between placement and measurement d a t e s . A l s o i n c l u d e d are t e m p e r a t u r e s c o n v e r t e d from the measured r e s i s t a n c e s c o r r e c t e d f o r l e a d r e s i s t a n c e u s i n g t h e c a l i b r a t i o n t a b l e s mentioned i n S e c t i o n 2.7. Measurement e r r o r s are i n d i c a t e d . T a b l e 5 g i v e s a l i s t i n g of f i n a l t e m p e r a t u r e s and de p t h s f o r each h o l e . The f i n a l t e m p e r a t u r e was i n most c a s e s t h e l a s t measured t e m p e r a t u r e f o r a p a r t i c u l a r t h e r m i s t o r . I n e v e r y case e x c e p t Hole 4, t h e f i n a l t e m p e r a t u r e was t a k e n twenty f i v e o r more days a f t e r placement and can be c o n s i d e r e d a t e q u i l i b r i u m w i t h i n t h e a c c u r a c y o f measurement, -0.05°C, and d e f i n i t e l y w i t h i n • a io.lO°C a c c u r a c y . The e r r o r i n v o l v e d i n c a l i b r a t i o n and r e d u c t i o n of c a l i b r a t i o n d a t a was n e v e r g r e a t e r t h a n io .01°C and i s i n c l u d e d i n the measurement a c c u r a c y v a l u e . Temperature v a l u e s were averaged f o r t h e r m i s t o r s w h i c h were a t e q u i l i b r i u m f o r two o r t h r e e o f t h e measurements. T h e r m i s t o r s above the 10-meter l e v e l showed, w i t h o u t e x c e p t i o n , an i n c r e a s e i n t e m p e r a t u r e w i t h t i m e a t a r a t e w h i c h d e c r e a s e d w i t h d e p t h . T h i s e f f e c t i s a t t r i b u t e d t o the p e n e t r a t i o n of the warming segment o f the a n n u a l t e m p e r a t u r e wave and does n ot i n f l u e n c e the deep i c e p r o f i l e s . i • • • 30 Temperatures f o r Hole 4 were c o r r e c t e d t o e q u i l i b r i u m . v a l u e s by a d d i n g -0.20°C, the f a c t o r o b t a i n e d from F i g u r e 10. F i n a l t e m p e r a t u r e s were p l o t t e d i n the f o r m of t e m p e r a t u r e p r o f i l e s ( t e m p e r a t u r e v e r s u s depth) w i t h g r a v i t y b e d r o c k d e p t h s i n d i c a t e d on the p r o f i l e s . F i g u r e s 11 t h r o u g h 16 show t h e s e p r o f i l e s . The t e m p e r a t u r e d a t a f o r Hole 3 must be d i s c o u n t e d i n an a n a l y s i s o f the g l a c i e r ' s t h e r m a l regime. The m e l t water d r a i n e d f r o m t h e h o l e due t o a s u b s u r f a c e c r a c k and p r e v e n t e d the t h e r m i s t o r s f rom b e i n g f r o z e n i n t o the s u r r o u n d i n g i c e . As a r e s u l t a i r o r snow t e m p e r a t u r e s were p r o b a b l y measured. 31 O 0 8 10 20 3 0 UJ 4 0 5 0 6 0 - 6 1 - 2 ~~r HOLE I 77777777 GRAVITY BOTTOM 0 Pig. 11. Temperature p r o f i l e , Hole 1. 32 F i g . 12. Temperature p r o f i l e , Hole 2. 33 0 - 8 - 6 10 20 h- 3 0 4 0 50 6 0 9 -2 — i — i — r HOLE 3 rrnrrm GRAVITY BOTTOM 1 1 T I • I , I • I F i g . 13. Temperature p r o f i l e , Hole 3. 34 0 TE - 8 - 6 - 2 0 10 20 f - 3 0 4 0 50 6 0 i — | — i — | — i — j — r 1 • • I HOLE 4 GRAVITY TT/rrrry BOTTOM i P i g . 14. Temperature p r o f i l e , Hole 4. 3 5 0 8 - 6 - 4 10 20 30 Q 4 0 5 0 6 0 - 2 0 1 ' 1 1 1 1 1 ' 1 © \ \ \ HOLE 5 _ — © V \ ft — TTTTuTiT GRAVITY -— BOTTOM 1 . 1 1 1 , 1 , 1 F i g . 1 5 . Temperature p r o f i l e , Hole 5 » 36 0 - 8 - 6 10 20 h- 3 0 4 0 5 0 6 0 1 - 2 0 HOLE 6 GRAVITY BOTTOM i Pig. 16. Temperature p r o f i l e , Hole 6.' 37 3.6 A d d i t i o n a l R e s u l t s A 6.4-meter h o l e was d r i l l e d i n t h e tongue r e g i o n of the Hyena G l a c i e r w i t h a s m a l l c i r c u l a t i n g hand d r i l l ' d e s i g n e d by S. C o l l i n s of t h e American G e o g r a p h i c a l S o c i e t y . A s a l t s o l u t i o n was used f o r the d r i l l i n g o p e r a t i o n and f l u s h e d out of t h e h o l e w i t h f r e s h water b e f o r e t h e t h e r m i s t o r was p l a c e d . A measurement t a k e n a f t e r n i n e days and c o r r e c t e d t o an e q u i l i b r i u m v a l u e i n d i c a t e d t h a t t h e Hyena t e m p e r a t u r e was -6.75°C. The same d r i l l was used f o r a h o l e a t S i t e 4 and an e t h y l g l y c o l s o l u t i o n c i r c u l a t e d t h r o u g h the h o l e . T h i s s o l u t i o n was l e f t i n t h e h o l e and t h e r m i s t o r s were p l a c e d a t d e p t h s e q u a l t o t h o s e p l a c e d by t h e r m a l d r i l l i n g and w i t h i n 10-meters o f t h a t l o c a t i o n . The t a b l e below compares the e q u i l i b r i u m t e m p e r a t u r e s f o r the two methods. Depth, m Thermal H o l e , °C G l y c o l H o l e , °C 3.1 -5.12 - 4.68 5.5 -6.55 - 6 . 6 2 8.5 -6.74 - 6 . 6 8 14.6 -6.12 - 5.82 E x c e p t f o r the 5.5-meter d e p t h , the g l y c o l t e m p e r a t u r e s are s l i g h t l y warmer. The d i f f e r e n c e s , however, are n o t s y s t e m a t i c w h i c h may i n d i c a t e the i n f l u e n c e o f l o c a l f e a t u r e s . S i n c e t h e s e r e s u l t s are n o t c o n c l u s i v e and t h e e f f e c t of g l y c o l on i c e - t e m p e r a t u r e measurements i s a m a t t e r o f c o n t r o -v e r s y , a r i g i d l y c o n t r o l l e d e x p e r i m e n t would be v a l u a b l e . 38 4 . DISCUSSION 4 . 1 Geothermal Heat F l o w E s t i m a t e s of g e o t h e r m a l heat f l o w were d e t e r m i n e d f o r the t h r e e d r i l l i n g l o c a t i o n s a t which g l a c i e r b e d r o c k was r e a c h e d . These v a l u e s , c o r r e c t e d f o r the e f f e c t s of t o p o -g r a p h i c d i s t o r t i o n , i n d i c a t e an anomalous heat f l o w . The heat f l u x Q was c a l c u l a t e d u s i n g the r e l a t i o n s h i p f o r u n i f o r m heat f l o w t h r o u g h a s l a b , Q = ( k / d ) ( t ^ - t ^ ) where k =' the t h e r m a l c o n d u c t i v i t y ; d = d i s t a n c e between' the bottom two t h e r m i s t o r s ; t ^ = bottom t e m p e r a t u r e ; X, = t e m p e r a t u r e a d i s t a n c e d f r o m the bottom. The t h e r m a l c o n d u c t i v i t y of i c e v a r i e s w i t h t e m p e r a t u r e and d e n s i t y . F o r the g e o t h e r m a l e s t i m a t e s based on the Fox G l a c i e r d a t a , v a l u e s o f k were d e t e r m i n e d f r o m the f o r m u l a k = 5 . 3 5 x l O ~ 3 ( l - 4 . 8 x l O * " ^ 0 ) where 9 i s the i c e t e m p e r a t u r e i n °C between t ^ and ( P o u n d e r ) . I t was n o t n e c e s s a r y t o a d j u s t the c o n d u c t i v i t y . f o r d e n s i t y v a r i a t i o n s s i n c e such v a r i a t i o n s were s l i g h t . An e x a m i n a t i o n of the g r a d i e n t s o f F i g u r e s 1 1 , 1 5 , and 1 6 i n d i c a t e a n o n - l i n e a r i t y of the p r o f i l e s w i t h t h e g r a d i e n t v a l u e s d e c r e a s i n g w i t h d e p t h . An i n c r e a s e i n d e n s i t y w i t h d e p t h i s not s u f f i c i e n t t o t o t a l l y e x p l a i n t h i s c u r v a t u r e . I t i s p o s s i b l e t h a t t h i s r e f l e c t s the e f f e c t s o f a p r e v i o u s surge and t h i n n i n g of the g l a c i e r o r a g e n e r a l c l i m a t i c change. I n o r d e r t o o b t a i n heat f l o w e s t i m a t e s i t was assumed t h a t the bottom g r a d i e n t s were n e a r e q u i l i b r i u m . 3 9 The p a t t e r n of heat f l o w f r o m the e a r t h ' s i n t e r i o r i s d i s t o r t e d n e a r the s u r f a c e by t o p o g r a p h i c r e l i e f . 'The f l u x i s i n t e n s i f i e d by v a l l e y s and a t t e n u a t e d by r i d g e s . To o b t a i n r e g i o n a l l y s i g n i f i c a n t h e a t f l o w v a l u e s i n a r e a s o f appre-c i a b l e r e l i e f , t h e s e e f f e c t s must be c o r r e c t e d . A r a p i d e s t i m a t i o n method (Lachenbruch, 1 9 6 8 ) based on s u p e r f i c i a l g r a d i e n t measurements a t a h o r i z o n t a l s u r f a c e between two p l a n e s l o p e s was a p p l i e d t o the p r e v i o u s l y d e t e r m i n e d v a l u e s . P l a n e v a l l e y models were c o n s t r u c t e d u s i n g t o p o g r a p h i c p r o f i l e s , the a n o m a l i e s c a l c u l a t e d , and the c o r r e c t i o n s a p p l i e d . The r e s u l t s are g i v e n below. Hole C a l c u l a t e d Q C o r r e c t e d Q x c a l / c m ^ s e c /tcal/cm^sec 1 5 . 4 5 4 . 3 6 5 7 . 5 9 5 . 6 2 6 5 . 3 9 4 . 2 1 A method f o r c a l c u l a t i n g c l i m a t i c c o r r e c t i o n s t o heat f l o w measurements was p r e s e n t e d by C r a i n ( 1 9 6 9 ) . I t was shown t h a t the s m a l l d e t a i l s o f the c l i m a t i c v a r i a t i o n s have l i t t l e u l t i m a t e e f f e c t on the heat f l o w c o r r e c t i o n . The c r i t i c a l f a c t o r s are t h e t r a n s i t i o n t i m e s between g l a c i a l and i n t e r g l a c i a l p e r i o d s and the d i f f e r e n c e i n mean a n n u a l t e m p e r a t u r e between t h e s e p e r i o d s . The most r e c e n t d e g l a c i a t i o n a l o n e a c c o u n t s f o r ^0% o f the c o r r e c t i o n . 40 C a l c u l a t i o n s based on the near s u r f a c e a p p r o x i m a t i o n f o r d e p t h s l e s s t h a n 150 meters g i v e c o r r e c t i o n s of +0.52 /<,cal/cm sec f o r the most' r e c e n t d e g l a c i a t i o n (10 ,000 y e a r s 2 ago) and - 0 .21 ^ p a l / c m sec f o r the p r e v i o u s g l a c i a t i o n (60,000 y e a r s ago) assuming a te m p e r a t u r e i n c r e m e n t of 10.0°C. The t o t a l c o r r e c t i o n i s + 0 . 3 2 ^ c a l / c m se c . T h i s i n d i c a t e s t h a t the a p p a r e n t l y h i g h heat f l o w i s n o t due t o an u n c o r r e c t e d P l e i s t o c e n e e f f e c t . The averaged c o r r e c t e d Q, i s 4 .73 ^ c a l / c m s e c . R e asonable changes i n the v a r i o u s p a r a m e t e r s would n ot s i g n i f i c a n t l y change the heat f l o w e s t i m a t e s . S i n c e the commonly c i t e d w o r l d average heat f l o w i s 1.20 ^ c a l / c m sec, i t i s e v i d e n t ; t h a t t h e v a l u e o b t a i n e d f r o m the Fox G l a c i e r d a t a i s anomalous. Heat f l o w v a l u e s i n the range 3 - 00 - 4 . 00 ^ c a l / c m sec and h i g h e r are n o t uncommon (Lee and Uyeda, 1 9 6 5 ) . These o c c u r m a i n l y near the c r e s t s of o c e a n i c r i d g e s , g e o t h e r m a l a r e a s , and C e n o z o i c v o l c a n i c a r e a s . The l a t t e r are o f t e n a s s o c i a t e d w i t h some o f the h i g h e s t heat f l o w v a l u e s r e c o r d e d . G e o l o g i c a l i n v e s t i g a t i o n s by R. P. Sharp (1943) i n t h e S t e e l e Creek v i c i n i t y i n d i c a t e t h a t the I c e f i e l d Ranges i s an a r e a of C e n o z o i c v o l c a n i c a c t i v i t y . Thus the h i g h e s t i m a t e s of heat f l o w appear r e a s o n a b l e . These v a l u e s s u p p o r t P o s t ' s (1969) s u g g e s t i o n t h a t a c o n t r i b u t i n g f a c t o r t o the e x t e n s i v e r e g i o n a l o c c u r r e n c e o f s u r g i n g g l a c i e r s i n the S t . E l i a s M o u n t a i n s and e s p e c i a l l y the I c e f i e l d Ranges i s a broad r e g i o n of anomalous heat f l o w . 41 4 . 2 Lapse Rate I n the t r o p o s p h e r e , mean a i r t e m p e r a t u r e d e c r e a s e s w i t h a l t i t u d e . I n the d r y snow and upper p e r c o l a t i o n f a c i e s of g l a c i e r s and i c e s h e e t s , the snow t e m p e r a t u r e measured a t 10-meter d e p t h g i v e s a r e l i a b l e e s t i m a t e of the mean a n n u a l a i r t e m p e r a t u r e a t the s u r f a c e (Benson, 1 9 6 2 ) . I t i s p o s s i b l e , t h e n , t o de t e r m i n e a t m o s p h e r i c l a p s e r a t e s f r o m 1 0 - m e t e r t e m p e r a t u r e and e l e v a t i o n d a t a . A l a p s e r a t e was c a l c u l a t e d u s i n g 1 0 - m e t e r t e m p e r a t u r e s and 1 9 6 9 s u r f a c e e l e v a t i o n s . The d a t a , shown below, were p l o t t e d and a l e a s t - s q u a r e s f i t t o the p o i n t s d e t e r m i n e d , t h e s l o p e b e i n g the l a p s e r a t e . E l e v a t i o n , m 1 0 - m e t e r Temperature, °C Hole 2 1 8 2 -4.8 6 2242 -5.7 5 2 2 9 1 - 6 . 2 1 2 3 7 8 -6.4 4 2459 - 8 . 1 2 The r e s u l t i n g g r a d i e n t of - 1 0 . 6 °C/km i s shown i n F i g u r e 1 7 . T h i s i s compared w i t h the v a l u e - 1 6 . 0 °C/km fo u n d i n the S t . E l i a s by Grew and M e l l o r ( 1 9 6 6 ) and -14.0 °C/km f o r the same l a t i t u d e ( 6 l ° N ) i n G r e e n l a n d d e t e r m i n e d by Mock and Weeks ( 1 9 6 5 ) . As a m a t t e r o f i n t e r e s t t he d r y a d i a b a t i c l a p s e r a t e , -10.0°C/km, and th e U.S. S t a n d a r d Rate, - 6 . 5 °C/km, are p l o t t e d w i t h the Fox G l a c i e r g r a d i e n t i n F i g u r e 1 8 . ' 42 0 - 4 o 0 ** UJ - 8 01 ZD • < Q: LU Q_ -12 LU h--16 -20 ST. ELIAS MTS. GREENLAND 61 °N 1 2000 1 3000 E L E V A T I O N , m P i g . 17. V a r i a t i o n of te m p e r a t u r e w i t h s u r f a c e e l e v a t i o n , 43 I I I 2100 2200 2300 2400 2500 E L E V A T I O N , m P i g . 1 8 . Pox G l a c i e r , d r y a d i a b a t i c , and U.S. S t a n d a r d l a p s e r a t e s . 4 4 Mock and Weeks ( 1 9 6 5 ) found that gradients f o r northern Greenland were close to the dry adiabatic lapse rate and surmised that adiabat ic warming of katabatic winds was the c o n t r o l l i n g mechanism. In south Greenland gradients were markedly greater than those i n the n o r t h . T h i s i s thought to i n d i c a t e the downward t r a n s f e r of la tent heat i n the snow due to p e r c o l a t i n g melt water. Since the Fox G l a c i e r i s a small , n o r t h - f a c i n g v a l l e y g l a c i e r surrounded by a complex topographic system, katabatic winds are not l i k e l y to be the primary c o n t r o l l i n g f a c t o r i n determining the lapse rate as might be expected f o r an ice cap. Since p e r c o l a t i n g melt water increases the lapse rate value determined from snow temperatures, i t i s i n t e r e s t i n g to note the e f f e c t of e l i m i n a t i n g such data. If the data from Hole Z, the only • l o c a t i o n inf luenced by t h i s f a c t o r , are discarded from the Fox lapse rate c a l c u l a t i o n , a value of -8.0°C/km i s obtained. This value i s remarkably s i m i l a r to summer environmental lapse rates determined by Marcus ( 1 9 6 5 ) f o r the Kluane area using radiosonde data from a Whitehorse s t a t i o n . His values range from -6.5 ° C / k m to -8.4°C/km f o r the c o n t i n e n t a l s lope . This suggests that the l o c a l c l imatology i s the most d i r e c t l y c o n t r o l l i n g f a c t o r present . •4.3 Bottom Temperature Models Hypothet ica l g l a c i e r bottom temperature models were developed based on lapse rate , ice thickness , and e n g l a c i a l 4 5 t e m p e r a t u r e g r a d i e n t s . U s i n g the p r e v i o u s l y d e t e r m i n e d l a p s e r a t e of -10.6°C/i f o r the Fox G l a c i e r , 1 0 - m e t e r t e m p e r a t u r e s were c a l c u l a t e d f o r each s u r v e y s t a k e p o s i t i o n . Each t e m p e r a t u r e was t h e n e x t r a p o l a t e d , based on I c e d e p t h and a s e l e c t e d t e m p e r a t u r e g r a d i e n t , t o o b t a i n a b a s a l v a l u e . Two bottom t e m p e r a t u r e maps were c r e a t e d . F o r the f i r s t , Model A, a s i n g l e r e a s o n a b l e t e m p e r a t u r e g r a d i e n t was s e l e c t e d as r e p r e s e n t i n g the e n t i r e g l a c i e r and a p p l i e d t o d e t e r m i n e the b a s a l t e m p e r a t u r e s . The g r a d i e n t , 0.11°C/r was o b t a i n e d from Hole. 1 and i s a l i n e a r f i t t o the d a t a . A v a r i a b l e g r a d i e n t was used f o r Model B. Each d r i l l i n g s i was g i v e n a g r a d i e n t v a l u e , shown below, d e r i v e d f r o m t h e t e m p e r a t u r e p r o f i l e f o r t h a t l o c a t i o n . T h i s v a l u e was a p p l i e d t o the n e i g h b o r i n g p o i n t s so t h a t the g l a c i e r was d i v i d e d i n t o f i v e r e g i o n s c h a r a c t e r i z e d by t h e s e g r a d i e n t s . The f i n a l models are shown i n F i g u r e s 1 9 and 2 0 w i t h the bottom t e m p e r a t u r e s c o n t o u r e d . Stake G r a d i e n t , °C/m 1 2 0 . 1 4 1 6 0 . 1 6 20 0 . 1 1 2 6 0 . 1 0 3 2 0 . 0 8 46 Pig. 1 9 . ' Pox Glacier bottom temperature map, Model A. 47 Pig. 20. 'Pox Glacier bottom temperature map, Model B. 48 B o t h models i n d i c a t e the pr e s e n c e of a "hot s p o t " , an a r e a i n w h i c h the p r e d i c t e d b a s a l t e m p e r a t u r e i s a t the p r e s s u r e m e l t i n g p o i n t . I n Model A the h o t spot i s l o c a t e d i n the a c c u m u l a t i o n r e g i o n n e a r Stake 32. S i n c e the g r a v i t y i n t e r p r e t a t i o n was based on an i n f i n i t e s l a b model, depths are l i k e l y t o be u n d e r e s t i m a t e d . I t i s t h e r e f o r e p o s s i b l e t h a t the a c t u a l d e p t h s i n the upper r e g i o n s of the g l a c i e r are g r e a t e r , i n wh i c h case the h o t spot a r e a would be more e x t e n s i v e t h a n i n d i c a t e d . R e s u l t s of the 1969 s u r v e y (S. C o l l i n s , p e r s o n a l communication) r e v e a l t h i s t o be the a r e a of maximum g l a c i e r movement. T h i s f l o w r a t e maximum may, however, be a conse-quence o f the i c e t h i c k n e s s r a t h e r t h a n an i n d i c a t i o n of m e l t i n g a t the bed. Model B shows no b a s a l m e l t i n g zone i n the upper r e g i o n s o f t h e g l a c i e r . However, the g r a d i e n t i n f o r m a t i o n f o r t h i s a r e a i s not c o n c l u s i v e s i n c e the o n l y a v a i l a b l e d a t a were f r o m h o l e s v e r y s h a l l o w r e l a t i v e t o the g l a c i e r d e p t h a t t h a t l o c a t i o n . S i n c e s l i g h t changes i n the g r a d i e n t v a l u e cause r e a s o n a b l y l a r g e v a r i a t i o n s i n b a s a l t e m p e r a t u r e a t t h e s e d e p t h s , the p o s s i b i l i t y of b a s a l h o t s p o t s cannot be d i s r e g a r d e d f o r t h i s model. The. hot spot which i s i n d i c a t e d i n Model B i s o f doubt-f u l e x i s t e n c e . I t i s t h o u g h t t h a t the e f f e c t o f the i c e f a l l has n o t been c o m p l e t e l y e l i m i n a t e d f r o m t h e g r a v i t y d e p t h c a l c u l a t i o n s so t h a t a s p u r i o u s l y l a r g e i c e t h i c k n e s s r e s u l t s . 49 S i n c e the i c e i s assumed t o warm w i t h d e p t h , t h i s would account f o r the apparent hot s p o t . 4.4 C o n c l u s i o n Thermal d r i l l i n g on the Fox G l a c i e r , Yukon, r e s u l t e d i n t h r e e h o l e s t o be d r o c k . Temperature measurements i n d i c a t e d t h a t the g l a c i e r was below the p r e s s u r e - m e l t i n g p o i n t t h r o u g h o u t . Temperature p r o f i l e s s u g g e sted a memory of the d i s t u r b e d t h e r m a l regime due t o a p r e v i o u s s u r g e . E s t i m a t e s of g e o t h e r m a l heat f l o w were d e t e r m i n e d and c o r r e c t e d f o r the e f f e c t s of t o p o g r a p h i c d i s t o r t i o n . These v a l u e s i n d i c a t e a he a t f l o w w h i c h i s anomalous but not u n r e a s o n a b l e f o r the a r e a . Lapse r a t e s d e t e r m i n e d from 10-meter i c e t e m p e r a t u r e s and e l e v a t i o n d a t a g i v e v a l u e s i n agreement w i t h o t h e r l a p s e r a t e i n f o r m a t i o n f o r the a r e a . G l a c i e r bottom t e m p e r a t u r e models were d e v e l o p e d and b o t h i n d i c a t e the p o s s i b i l i t y of a r e a s i n which the b a s a l • te m p e r a t u r e i s a t the p r e s s u r e m e l t i n g p o i n t . Model A i n p a r t i c u l a r s u g g e s t s a hot spot i n the a c c u m u l a t i o n r e g i o n . 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Philberth, K., Remarque sur une sonde thermique pour mesurer l a temperature des couches de glace, Compt. Rend., 255, 3022-3024, 1962b. Philberth, K., Uber zwei elektro-schmelzsonden mit v e r t i k a l -s t a b i l i s i e r u n g , Polarforschung, 34, 278-280, 1964. Philberth, K., Eine schmelzssonde zur messung des temperature p r o f i l s in eiskalotten, Umschau in wissenschaft und technik, 66, 360, 1966a. Philberth, K., Sur l a s t a b i l i s a t i o n de l a course d'une sonde thermique, Compt. Rend., 262, 456-459, 1966b. Post,A. S., D i s t r i b u t i o n of surging g l a c i e r s in western North America, J. G l a c i o l . , 8, 229-240, 1969. Pounder, E. R., Physics of i c e , Pergamon Press, Toronto, 1965. Taspet, R., J . H. Swartz, H. E. L i l l a r d , and E. C. Robertson, Preparation of thermistor cables used i n geothermal investigations, U. S. Geol. Surv. B u l l . , 1203-C, C l - C l l , 1966. 55 Robertson, E.C., R. Raspet, J . H. Swartz, and M. E. L i l l a r d , Properties of thermistors used in geothermal i n v e s t i -gations, U. S. Geol. Surv. B u l l . , 1203-B, B1-B34, 1966. Robin, G. de Q. , I n i t i a t i o n of g l a c i e r surges, Can. J . Earth S c i . , 6 , 919-928 , 1969. Robin, G. de Q., Ice movement and temperature d i s t r i b u t i o n i n g l a c i e r s and ice sheets, J . G l a c i o l . , 2, 523, 1955. Sharp, R., Geology of the Wolf Creek area, St. E l i a s Range, Yukon T e r r i t o r y , Canada, B u l l . Geol. Soc. Am., 54, 625-649, 1943. Shreve, R. L., Theory of performance of isothermal s o l i d -nose hotpoints boring in temperate i c e , J. G l a c i o l . , 4, 151-160, 1962. Stacey, J . S., A prototype hotpoint for thermal boring on the Athabaska Gla c i e r , J. G l a c i o l . , 3, 783-686, 1960. Tien, C., Preliminary c a l c u l a t i o n of the energy requirement for placing an instrument package under i c e , CRREL Research Report 146, 1965. Weertman, J . , Theory of g l a c i e r s l i d i n g , J. G l a c i o l . , 5, 287-303, 1964. Weertman, J . , S l i d i n g of non-temperate g l a c i e r s , J . Geophys. Res., 72, 521-523, 1967. 5 6 APPENDIX T A B L E S OP R E S U L T S 57 LIST OF COMPONENTS Ge n e r a t o r : K o h l e r Model 5RMS65, 5kva c o n t i n u o u s , 120/240 v o l t s , 20.8 amps, 3600 rpm, w i t h f u e l pump and v o l t a g e r e g u l a t o r . Power C a b l e : B e l d e n 8471, #16 AWG, 600 v o l t , 2 - conductor, v i n y l i n s u l a t e d copper w i t h chrome v i n y l j a c k e t , 4.1 ohms/1000' a t 20°C, 5 ohms/1000' a t 82°C. H e a t i n g C a b l e : B e l d e n 8740, #22 AWG, 200 v o l t , 1 - c onductor, v i n y l i n s u l a t e d copper, 16 ohms/1000' a t 20°C. H e a t i n g Element: F i r e r o d , 2500 w a t t s , 120 v o l t s , 20.6 amps, 3/4" O.D., 6" l e n g t h , 4" h e a t e d l e n g t h ( f r o m t i p ) , t e f l o n s e a l e d w i t h 10" l e a d s . Watlow M a n u f a c t u r i n g Company, S t . L o u i s , M i s s o u r i . Copper: T e l l u r i u m , s u l f u r , o r any o t h e r h i g h c o n d u c t i v i t y c o p p e r . F e e d - t h r u T e r m i n a l s : F u s i t e t y p e 1/8(27)NPT-FP„ P l a s t i c Tube: L a m i n a t e d p l a s t i c grade G - l l o r s i m i l a r . T h e r m i s t o r C a b l e : B e l d e n 8488, #22 AWG, 8-conductor u n s h i e l d e d r o t o r c a b l e , c o l o r coded, v i n y l i n s u l a t e d copper, c a b l e d , chrome v i n y l j a c k e t , 0.205" O.D. T h e r m i s t o r : Fenwal GB31P2, g l a s s bead, probe mounted, 1000^20$ ohms at 25°C. 58 TABLE 1 CALIBRATION DATA T h e r m i s t o r Number C a l i b r a t i o n • P o i n t R e s i s t a n c e , ohms 0.00°C -3 .oo°c -6.00°C -9 .oo°c -12.00°C A - l 3231 3694 4241 4833 5633 A-2 3173 3639 • 4183 4320 5567 A-3 2939 3420 3928 4525 5226 A-4 2671 3051 3501 4025 4648 A-5 2906 3327 3321- 4397 5033 A-6 2879 3295 3734 4352 5025 A-7 3013 3446 3956 4554 5261 A -3 2772 3172 3640 4190 4833 A-9 2725 3115 3572 4106 4739 A-10 2793 3199 3674 4229 4334 A-11 2932 3354 3353 4444 5132 A-12 3132 3530 4105 4719 5446 B - l 2419 2781 3203 3701 4235 B-2 2755 3156 3614 4184 4336 B-3 3006 3441 3947 4557 5252 B-4 2607 2991 3442 3962 4557 B-5 2306 3229 3713 4295 4974 B-6 3027 3475 3984 4605 5334 B-7 2590 2969 3416 3922 4536 • B-3" 2381 3239 3776 4353 5022 B-9 2708 3122 3595 4152 B-10 3117 3580 4049 4733 B - l l 3246 3717 426l 4896 B-12 2760 3179 3642 4206 B-13 3173 3638 4163 4787 B-15 2920 3346 3347 4434 B-16 2782 3195 3657 4223 B-17 2689 3038 3556 4103 B-18 2452 2 3 l 4 3233 3731 B-19 2383 2741 3157 3637 5 9 TABLE 1 ( c o n t i n u e d ) T h e r m i s t o r C a l i b r a t i o n P o i n t R e s i s t a n c e , ohms  Number 0.00°C -3.00°C -6.00°C -9.00°C - 1 0 . 0 0 ° C B - 2 0 2 5 2 4 2 8 9 5 3 3 4 4 3 8 6 7 B - 2 1 2 7 6 6 3 1 7 0 3 6 5 2 4204 B - 2 2 3 1 0 5 3 5 5 6 4 0 8 2 4 7 0 9 B - 2 3 3 0 6 8 3 5 0 9 4 0 2 6 4 6 1 6 C - l 2 6 0 2 2 9 7 5 3 4 1 6 4 0 9 6 C-2 2 5 6 5 2 9 6 4 3 3 8 4 4 0 1 7 C-3 2 7 3 5 3 1 2 4 3 5 8 2 4 3 1 3 c-4 2 7 0 6 3 1 2 0 3 5 8 3 4 3 2 6 c-5 2 6 4 5 3 0 3 9 3 4 7 4 4 1 4 4 c-6 2 6 4 2 3 0 2 9 3 4 7 8 4 1 8 6 C-7 2 7 7 7 3 1 3 4 3 6 5 5 4 4 1 0 C-8 2 6 6 4 3 0 6 5 3 5 1 5 4 2 2 2 c-9 2 6 7 8 3 0 8 6 3 5 5 2 4 2 7 0 C - 1 0 2 6 6 5 3 0 7 5 3 5 6 1 4 2 4 8 C - l l 2 7 3 3 3 1 4 1 3 6 0 2 4 3 5 4 C - 1 2 2 5 4 8 2 9 2 3 3 3 5 4 4 0 6 1 c - 1 3 2 5 9 9 2 9 9 1 3 4 4 7 4 l 4 l C - 1 5 2 7 7 0 3 1 9 3 3 6 6 4 4 3 9 2 C - l 6 2 7 8 4 3201 3 6 7 5 4 4 3 3 C - 1 7 2 7 2 2 3 1 1 4 3 5 7 8 4 3 1 7 c - 1 8 2 7 2 1 3 1 1 5 3 5 9 2 4322 c - 1 9 2 6 9 7 3 0 9 5 3 5 5 6 4 2 8 3 C - 2 0 2 5 4 8 2 8 7 4 3 3 7 0 3 9 7 1 C - 2 1 2 6 5 7 3 0 4 7 3 4 9 2 4205 C - 2 2 2 7 9 5 3 1 9 3 3 6 6 9 4420 C - 2 3 2 7 1 4 3 1 1 4 3 5 7 3 4 3 0 8 6 0 TABLE 2 THERMISTOR DISTRIBUTION  T h e r m i s t o r T h e r m i s t o r Hole Depth,m Number C o l o r Hole Depth,m Number C o l o r 1 3 . 1 A-4 B l u e 5 5 . 8 C-23 B l a c k 1 7 . 4 A-3 Green 1 1 . 9 B - l Brown 32.6 A-2 Y e l l o w 1 8 . 0 B-2 B l u e 48.0 A - l Orange 2 1 . 0 B-3 Green 24.1 B-4 Y e l l o w 2 0 . 6 A-9 Green 2 7 . 1 B-5 Orange 1 1 . 3 A-8 Y e l l o w 2 0 . 4 A-7 Orange 6 2 2 . 3 c-19 B l u e 2 6 . 8 C-20 Green : - B 9 . 1 A-6 B l a c k 2 9 . 9 C-21 Y e l l o w 1 6 . 8 B - 1 9 B l u e 3 1 . 4 - C-22 Orange 24.4 B - 2 0 Green 3 0 . 5 B - 1 7 Y e l l o w 4-EG 3 . 1 c-9 Brown 5 . 5 C-10 B l a c k 3 7.3 B - 2 2 Y e l l o w 8 . 5 C-11 B l u e 1 4 . 9 A - 1 1 Brown 1 1 . 6 C-12 Green 2 2 . 6 B - 2 3 Green 1 4 . 6 c - 1 3 Y e l l o w 3 0 . 2 A-10 B l u e 14.6 c-15 Orange 4 3 . 1 B - 1 1 Brown Hyena 6.4 C-8 B l u e 5 . 5 B - 1 2 B l u e 8 . 5 B - 1 3 Green 11.6 B - 1 5 Y e l l o w 1 4 . 6 B - 1 6 Orange 61 TABLE 3 COOLING CURVE DATA T h e r m i s t o r B-12 T h e r m i s t o r B - l 6 Depth = 5 .3 m Depth = 14.6 m Time C o r r e c t e d R e s i s t a n c e ohms Temperature °C Time C o r r e c t e d R e s i s t a n c e ohms Temperature °C 0:00 Power o f f 0:00 Power o f f 6: 20 2780^5 - 0 . 1 4 - 0 . 0 5 6:00 2800±5 - 0 . 1 3 - 0 . 0 5 6:50 2765 - 0 . 0 3 6:30 2810 - 0 . 2 1 8:10 2770 - 0 . 0 6 8: 20 2815 - 0 . 2 5 9:50 2775 - 0 . 1 0 9:40 2830 - 0 . 3 7 10:40 2775 - 0 . 1 0 10:40 2837 -0.42 12:30 2775 - 0 . 1 0 12:30 2850 - 0 . 5 2 13:40 2775 - 0 . 1 0 13:40 2860 - 0 . 6 0 14: 40 2775 - 0 . 1 0 14: 40 2865 -0.64 15:35 2775 -0.10 15:40 2875 - 0 . 7 2 22: 30 2780 -0.14 22:30 2955 - 1 . 3 3 1:10:40 2843 - 0 . 6 3 1:10:40 3325 - 3 . 9 1 - 0 . 0 2 1:13:50 2870 -0.84 1:13:50 3375 - 4 . 2 3 1:16:40 2903 - 1 . 0 8 1:16:40 3410 -4.46 1:19:45 2955 - 1 . 4 7 1:19:45 3440 - 4 . 6 5 2:10:20 3450 -4.80±0.02 2:10:20 3520 -5 .14 2:12:45 3478 - 4 . 9 8 2:12:50 3533 - 5 . 2 2 2:14:10 3485 -5o02 2:14:10 3535 - 5 . 2 3 2:16:10 3510 -5 .17 2:16:10 3545 - 5 . 3 0 2:18:55 3525 - 5 . 2 6 2:18:55 3553 - 5 . 3 4 2: 22:00 3545 • - 5 . 3 8 2: 22:05 3563 - 5 . 4 0 3:11:00 3595 - 5 . 6 8 3:10:55 3585 - 5 . 5 4 3:16:25 3605 - 5 . 7 4 3:16:30 3585 - 5 . 5 4 3:21:40 3620 - 5 . 8 3 3:21:35 3595 - 5 . 6 0 5:15:40 3665 - 6 . 0 9 5:15:40 3615 - 5 . 7 2 6:11:50 3685 - 6 . 2 1 6:11:55 3620 -5 .75 •6:19:40 3685 - 6 . 2 1 6:19:40 3620 ' -5.75. 7:16:40 3690 -6.24 7:16:40 3630 - 5 . 8 0 8:14:40 3690 - 6 . 2 4 8 :14:40 3630 - 5 . 8 0 _9:13:55 3705 - 6 . 3 3 . . . .9:13:55 3635 ;.... - 5 . 8 3 9:13:55 3705 - 6 . 3 3 ' 9:13:55 3635 - 5 . 8 3 12:15:40 3710 - 6 . 3 5 12:15:40 3650 - 5 . 9 2 62 TABLE 4 RESISTANCE AND TEMPERATURE DATA Hole (Date) Ther-m i s t o r R l R 2 R 3 T l T 2 T 3 (30)1 (42) 1 A-4 3155-4 3080*5 3075-5 -3.96* .04 -3.16* .05 -3.12*.05 (6/22) A-3 3785 3795 3795 -5.17* .02 -5.23* .02 -5.23*.02 A-2 3690 3695 3700 -3.26 -3.30 -3.32 A - l 3502*2 3500 3505 -1.77- .01 -1.76 -1.79 c 6 6 6 (25) (37) (41) 2 A-9 2795*3 2345*5 2335-5 -0.55* .03 -0.95* .05 -0../r*.05 (6/27) A-3 3975-5 3995-5 3995-5 -7.37* .02 -7.98* .02 -7.98*.02 A -7 4072-4 4090 4095 -6.61 -6 . 70 -6.73 c 3 3 3 (14) (26) (30) 2-B A-6 4l20±5 4l50±5 4l45±5 -7.so* .02 -7.96* .02 -7.94*.02 (7/8 ) B-19 3275 3300 3300 -6.76 -6.92 -6.92 B-20 3445 3460 3460 -6.60 -6.70 -6.70 B-17 3550 3585 3585 -5.94 -6.14 -6.14 c 5 5 5 (22) (34) (38) 3 B-22 3397-3 3335-5 3375-5 -1.96* .02 -1 .83* .02 -1.82*.02 (6/30) A - l l 2950*5 2975 2995 •-0.10* .05 -0.29* .05 -0.44*.05 B-23 3035 3095 3100 -0.03 -0.16 -0.19 A-10 2955 2960 2965 -1.21 -1.24 - 1 . 28 c 6 6 6 Days l a p s e d between placement d a t e and d a t e o f measurement. 63 TABLE 4 ( c o n t i n u e d ) Hole Ther-(Date) m i s t o r FL R„ R- T-, T„ T {6\ (9) (13) 4 3-11 4015-5 4030*5 4062*2 -4.67* .02 -4.30* .02 -4.92* .02 (7/28) 3-12 3670 3695 3714 -6.09 -6 . 2 4 -6.35 B-13 4215 4 2 4 0 4276 -6. 22 -6.35 -6.54 B-15 I n f i n i t e B-16 3620 3635 3655 -5.72 -5 . 3 0 -5.92 c 5 5 5 (12) (24) (30) 5 C - 2 3 3665*4 3630*5 36l4±2 -6.52* . 0 2 -6.30* .02 -6.22* . 0 2 (7/10) 3-1 3070 3090 3100 -5.08+ . 0 4 -5.20* .05 -5.28-3-2 3255 3235 3 2 9 4 -3.67* . 0 4 -3.86* .02 -3.93 B-3 3415 3490 3503 -2.80* . 0 2 -3 . 2 3 -3.36 B-4 2 9 5 0 2930 2 9 3 4 - 2.66* . 0 4 -2 . 3 6 * .05 -2.90 B-5 2 9 4 0 3145 3153 -0.97 -2 . 4 2 -2 . 4 8 c 4 5 4 (7) (19) (25) 6 C-19 3030*5 3095*5 3095*2 -2.86* .05 -2.93* .05 -2.97* .02 (7A5) C-20 2850 2870 2870 -2 . 5 4 -2.69 -2.69* .05 C-21 2860 2885 2390 -1.59* .03 -1.79" -1.82* .03 C-22 2830 3010 3014 -0. 26 -I.65 -I.67 c 4 3 4 (9) Hyena c-8 3597*3 -6 . 48+ .05 64 TABLE 5 PINAL POX GLACIER TEMPERATURES L o c a t i o n Depth,m Temperature L o c a t i o n Depth,m Temperature °C Hole 1 Stake 2 0 3 . 1 17 . 4 3 2 . 6 48.0 0 . 6 1 1 . 3 20 . 4 9 . 1 16 . 8 24.4 3 0 . 5 Hole 3 7 . 3 Stake 3 2 E 6 1 4 . 9 2 2 . 6 3 0 . 2 Hole 2 Stake 3 2 Hole 2-B Stake 3 2 - 3 . 1 2 - 5 . 2 3 - 3 . 3 2 - 1 . 7 7 - O.87 - 7 . 9 8 - 6 . 7 3 • 7 . 9 4 - 6 . 9 2 - 6 . 7 0 - 6 . 1 4 - I.82 - 0 . 4 4 - 0 . 1 9 - 1 . 2 8 Hole 5 Stake 1 6 Hole 6 Stake 1 2 Hole 4-EG Stake 26 5.8 11.9 1 8 . 0 21.0 24.1 2 7 . 1 22.3 2 6 . 8 2 9 . 9 31.4 3.1 5.5 0855 11.6 14.6 14.6 - 6 . 2 2 - 5 . 2 8 • 3 . 9 3 - 3 . 3 6 • 2 . 9 0 •2.48 - 2 . 9 7 -2.46 - I.82 - 1 . 6 7 -4.68 - 6 . 6 2 • 6 . 6 8 - 6 . 2 6 -5.84 - 5 . 8 1 Hole 4 Stake 2 6 3.1 5 . 5 8 . 5 11.6 14.6 - 5 . 1 2 • 6 . 5 5 • 6 . 7 4 • 6 . 1 2 Hyena Tongue • 6 . 4 - 6 . 7 5 6 5 TABLE 6 BOTTOM TEMPERATURE DATA  1 0 - m e t e r Bottom Temperature,°C Stake E l e v a t i o n Temp.,°C Depth,m Model A Model. B 2 2 0 2 9 m - 3 . 3 1 4 . 1 - 2 . 8 - 2 . 7 3 2 0 6 0 - 3 . 6 2 0 . 8 - 2 . 4 - 2 . 1 4 2 0 8 2 - 3 . 8 1 2 . 1 - 3 . 6 - 3 . 5 5 2 1 0 2 - 4 . 0 1 1 . 3 - 3 . 9 - 3 . 8 6 2 1 1 7 - 4 . 2 5 . 5 - 4 . 1 - 4 . 0 7 2130 - 4 . 3 1 1 . 3 - 4 . 2 - 4 . 1 8 2 1 3 8 - 4 . 4 1 7 . 3 - 3 . 6 - 3 . 4 1 0 2 1 5 3 - 4 . 6 1 1 . 2 - 4 . 5 - 4 . 4 1 2 E 1 2 1 8 0 - 4 . 9 1 4 . 2 - 4 . 4 - 4 . 3 1 2 2 1 8 3 - 4 . 9 2 9 . 0 - 2 . 8 - 2 . 3 12W1 2 1 8 5 - 4 . 9 3 4 . 5 - 2 . 1 - 1 . 4 12W2 2 1 9 2 - 5 . 0 2 4 . 7 - 3 . 3 - 2 . 9 14 2 2 1 9 - 5 . 3 41.1 - 1 . 8 - 0 . 8 1 6 E 2 2244 - 5 . 5 1 6 . 7 - 4 . 7 - 4 . 4 1 6 E 1 2246 - 5 . 6 2 8 . 6 - 3 . 5 - 2 . 6 1 6 2 2 4 6 - 5 . 6 30.6 - 3 . 3 - 2 . 3 i6wi 2 2 5 1 - 5 . 6 48.0 - 0 . 2 + 0 . 0 1 6 W 2 2 2 6 5 . - 5 . 8 5 5 . 3 - 0 . 7 + 0 . 0 1 8 2 2 6 8 - 5 . 8 4 4 . 2 - 1 . 9 - 0 . 4 20E3 2 3 0 9 - 6 . 2 1 6 . 0 - 5 . 5 - 5 . 5 20E2 2 3 0 3 - 6 . 2 3 3 . 4 - 3 . 6 - 3 . 6 20E1 2 2 9 8 - 6 . 1 4 2 . 7 - 2 . 4 - 2 . 4 2 0 2 2 9 3 - 6 . 1 50.6 - 1 . 5 - 1 . 5 20W1 2 2 8 7 - 6 . 0 5 1 . 0 - 1 . 4 - 1 . 4 20W2 2 2 8 6 - 6 . 0 4 3 . 5 - 2 . 2 - 2 . 2 2 2 2317 - 6 . 3 3 5 . 9 - 3 . 4 - 3 . 4 2 4 E 6 2 4 1 8 - 7 . 4 3 3 . 0 - 4 . 8 - 5 . 0 2 4 E 4 2 3 8 9 - 7 . 1 3 5 . 3 - 4 . 2 - 4 . 5 24E2 2 3 7 1 - 6 . 9 5 3 . 8 - 2 . 0 - 2 . 4 24 2348 - 6 . 6 5 5 . 9 - 1 . 4 - 1 . 9 24W2 2348 - 6 . 6 6 2 . 2 - 0 . 7 - 1 . 3 24w4 2 3 8 6 - 7 . 0 2 8 . 0 - 5 . 0 - 5 . 2 66 TABLE 6 ( c o n t i n u e d ) 10-meter Bottom Temperature,°C Stake E l e v a t i o n Temp.,°C Depth,m Model A Model B 26 2 3 8 0 -7.0 57.7 -1.6 -2.1 28E10 2491 -8 . 2 36.5 -5.2 -6.4 28E8 2469 -7.9 49 .0 -3.5 -4.9 28E6 2439 -7.6 47.6 -3.4 -4.7 28E4 2424 -7.4 64.4 -1.3 -3.2 28E2 2420 -7.4 73.2 -0.3 -2.5 28 2420 -7.4 6 8 . 9 -0.7 -2.8 28W2 2417 -7.4 59.7 -1.8 -3.5 3 0 2449 -8.8 7 8 . 6 -1.0 -3.4 32E12 2552 -8.8 24.0 -7.2 -7.7 32E10 2547 -8.8 69.4 -2.1 -4.2 32E8 2525 -8.5 61 . 9 -2.6 -4.5 32E6 2494 -8 . 2 49 .0 -3.8 -5.2 32E4 2487 -8.1 8 2 . 1 +0.0 -2.5 32E2 2470 -7.9 86.4 +0.0 -2.7 32 2460 -7.8 8 7 . 6 +0.0 -1.7 32V/ 2 2465 -7.9 7 6 . 8 -0.4 -2.7 32V/4 2485 -8.1 50 . 4 -3.5 -4.9 34E12 2565 - 8 . 9 36 . 9 -5.9 -6.8 34E10 2565 - 8 . 9 6 7 . 7 -2.4 _4.4 34E8 2559 - 8 . 9 76 . 5 -1.4 -3.7 34 2472 -8.0 7 8 . 8 -0.2 -2.6 36E6 2551 -8.8 64.6 -2.6 -4.5 36E4 2521 -8.5 52.8 -3.7 -5.2 36E2 2500 -8 . 2 52.6 -3.4 -4.9 36 2484 -8.1 59.5 -2.5 -4.2 36W2 2509 -8.4 68.6 -1.8 -3.8 

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