Geology of the Durst Mountain-Huntsville area Morgan and Weber Counties, Utah

The Durst Mountain-Huntsville area is located about 35 miles northeast of Salt Lake City, Utah, and comprises nearly 110 square miles between Ogden and Weber Valleys. The formations exposed are the Precambrian Farmington Canyon complex; the Cambrian Tintic quartzite, Ophir shale, and Cambrian limestones and dolomites undifferentiated; Devonian Three Forks (?) formation; Mississippian Madison limestone and the Brazer formation; the Triassic Thaynes limestone; and the Tertiary Knight conglomerate, Norwood tuff, and Huntsville fanglomerate. Three episodes of faulting were noted within the area. The Durst thrust is related to mid-Laramide activity. An east-west episode of normal faulting occurred during the Miocene (?). North-south normal faulting occurred during the Pliocene and Pleistocene. The Herd Mountain erosion surface is the oldest erosion surface within the north-central Wasatch Mountains. It is dated as late Oligocene or Miocene age. A more recent erosion surface is the Weber Valley surface. The formation of this occurred in Pliocene or Pleistocene time. An arm of Lake Bonneville extended into both Ogden Valley and Weber Valley.

GEOLOGY OF THE DURST MOUNTAIN-HUNTSVIIXE AREA MORGAN AND WEBER COUNTIES, UTAH by G i l b e r t L. Coody 3 S A t h e s i s s u b m i t t e d t o t h e f a c u l t y of t he U n i v e r s i t y U t a h i n p a r t i a l f u l f i l l m e nt o f t h e r e q u i r e m e n t s f o r t h e d e g r e e of M a s t e r of S c i e n ce D e p a r t m e n t of G e o l o gy C l C ^ j University of Utah A u g u s t , 1957 ^ LIBRARY UNIVERSITY O F UTAH 37'6.2 if Z C7b 9; ~ q£ 3.? /q~7 c: bh ' / ! GEOLOGY OF THE DURST MOUNTAIN-HUNTSVILLE AREA MORGAN AND WEBER COUNTIES, UTAH by Gilbert L. Coodr A thesis submitted to the f~culty of the University of Utah in partipl fulfillment of the requirements for the degree of Master of Science Department of Geology University of Utah August, 1957 r LIBRARY UNIVERSITY OF UTAH ~,.,. T h i s T h e s i s f o r t h e M. S. d e g r ee G i l b e r t L. Coody h a s b e e n a p p r o v e d by C h a i r m a n 7 / S u p e r v i s o r y C o m m i t t ee e a d , Major D e p a r t m e nt D e a n , G r a d u a x e Sc J 8 S 0 1 2 · i \. This Thesis for the M. S. degree by Gilbert L. Coody has been approved by Dean, Gradu e Sc 01 38801.2 TABLE OF CONTENTS P a g e ABSTRACT i ACKNOWLEDGMENT . . . . . . « . . . . . . . . . ii INTRODUCTION L o c a t i o n and a c c e s s i b i l i t y , 0 1 P u r p o s e and s c o p e , , * . . . . « F i e l d work • . G e o l o g i c s e t t i n g . . . . . . . P r e v i o u s g e o l o g i c work GEOGRAPHY . . . . . . . 6 T o p o g r a p h y . . . . . . . . . 6 Land u t i l i z a t i o n and v e g e t a t i o n Rock e x p o s u r e s . . . . . . . • . STRATIGRAPHY P r e c a m b r i a n s y s t e m . 8 F a r m i n g t o n C a n y o n c o m p l e x . 8 C a m b r i a n s y s t e m 11 G e n e r a l s t a t e m e n t . 11 T i n t i c q u a r t z i t e 12 O p h i r s h a l e 14 C a m b r i a n l i m e s t o n e s and d o l o m i t e s 17 D e v o n i a n s y s t e m 20 T h r e e F o r k s ( ? ) f o r m a t i o n 20 M i s s i s s i p p i a n s y s t e m 23 M a d i s o n l i m e s t o n e . 23 B r a z e r l i m e s t o n e . . 24 P e n n s y l v a n i a n s y s t e m 26 G e n e r a l s t a t e m e n t 26 Round V a l l e y l i m e s t o n e 26 M o r g a n f o r m a t i o n . . 27 Weber q u a r t z i t e 27 T r i a s s ^ c s y s t e m . 28 T n a y n e s l i m e s t o n e . 28 T e r t i a r y s y s t e m . . 29 K n i g h t f o r m a t i o n • 29 Norwood t u f f . . . . . 30 H u n t s v i l l e f a n g l o m e r a t e . 32 Q u a t e r n a r y s y s t e m . 35 D e p o s i t s r e l a t e d t o Lake B o n n e v i l l e 35 A l l u v i a l d e p o s i t s . . . 36 \ TABLE OF CONTENTS ABSTRACT •••• ACKNOWLEDGMENT • • • • • • • e • • • • ·· .. .. .. 0. .. i 1i INTRODUCTION • • • 0 • • • 0 a 0 0 • • • • • • 0 • 0 c 1 Location and accessibility . • • . • • • • • . •. 1 Purpose and scope. .. . • • • • • • • • . 1 Field work . • . 0 • • 0 • 0 • •• •••••• 2 Geologic setting . . . . • • . . • • • 2 Previous geologic work . .• • • • • • • • .. 3 GEOGRAPHY •. • • • Ia . . Topography • • . • • • . • . . Land utilization and vegetation Rock exposures • •. ••. STRATIGRAPHY . . . . . · . . . . . • • • • • • • 0 • . . . . . . . . · . . . . . 6 6 6 7 8 Precambrian system • • • • • • • • • • • • • • •. 8 Farmington Canyon complex . . . . 8 Cambrian system • • • • • • • . • . • • . . • •• 11 General statement . • • • . . • . • • . • .. 11 Tintic quartzite • • •. .•• •.• 12 Ophir shale • . .• ..•... ... 14 Cambrian limestones and dolomites .••• 17 Devonian system • • • . . .. •..• • • 20 Three Forks (?) formation. .•••••• 20 Mississippian system • • • • • • • • • • • • • 23 Madison limestone . • . • • • • • • • . • 23 Brazer limestone . • • • • • • • • • • • 24 Pennsylvanian system . • • •• •••••• 26 General statement . . . • 0 • • ~ • • • • 26 Round Valley limestone . . • • • • • • . • . 26 Morgan formation.. .••••..•• 27 Weber quartzite. • • • • • • • • • • • • 27 Triass~system . . • • • .. •• • • • • 28 Thaynes limestone . • • . • • • . • . . . 28 Tertiary system . . • • • •• .••• • . 29 Knight formation . • • • •• •• • • 29 Norwood tuff . • • • • . . • • . • . • . 30 Huntsville fanglomerate . . • • • . • . • • • 32 Quaternary system . • • • • • . • • • • • • . 35 Deposits related to Lake Bonneville. • • •• 35 Alluvial deposits. . • . • • • . • • . . 36 Pacje. STRUCTURE 37 T h r u s t s D u r s t t h r u s t . . . o E a s t - w e s t f a u l t s . G e n e r a l s t a t e m e n t . . . . . . S p r i n g B r a n c h f a u l t . 40 B e n n e t t C r e e k f a u l t . . 41 N o r t h - s o u t h f a u l t s . 42 G e n e r a l s t a t e m e n t 42 M o r g a n f a u l t 42 F o l d s and u n c o n f o r m i t i e s . 43 P r e - K n i g h t f o l d s and u n c o n f o r m i t i e s . . . . . 43 M o r g a n V a l l e y s y n c l i n e . 44 P o s t - N o r w o o d f o l d s and u n c o n f o r m i t i e s . . . . 45 GEOMORPH0L0GY . 47 G e n e r a l s t a t e m e n t . H e r d M o u n t a i n s u r f a c e 48 Weber V a l l e y s u r f a c e B o n n e v i l l e Lake h i s t o r y 50 ECONOMIC CONSIDERATIONS 51 A r g e n t a d i s t r i c t . 52 O t h e r m i n i n g p o s s i b i l i t i e s 53 S a n d and g r a v e l 53 GEOLOGIC HISTORY 55 P r e c a m b r i a n 55 C a m b r i a n 55 O r d o v i c i a n , S i l u r i a n and D e v o n i a n 56 C a r b o n i f e r o u s 57 L a t e P e n n s y l v a n i a n t h r o u g h T r i a s s i c . 57 C r e t a c e o u s . . . . . . . . . a . . . . . . . . . . 57 T e r t i a r y . 58 P a l e o c e n e 58 E o c e n e 58 O l i g o c e n e and M i o c e n e 58 P l i o c e n e . 59 P l e i s t o c e n e and r e c e n t e v e n t s . 59 LITERATURE CITED 60 STRUCTURE .•• . . . . . . . . . . . . . . . . . . . . Thrusts . . . . .• ••. Durst thrust . • • • . . East-west faults .....•. General statement . . • . Spring Branch fault Bennett Creek fault. • • • • It • • • ooeo •• goo ~ 37 37 37 39 39 40 41 North-south faults • • • • • . . . • . • . . . 42 General statement . . . . . . • . . . . • . . 42 Morgan fault . • • . . . . . . . . • . . 42 Folds and unconformities. . . • . . . . . . . 43 Pre~Knight folds and unconformities • • . 43 Morgan Valley syncline . . . . . . . . . 44 Post-Norwood folds and unconformities. . 45 GEOMORPHOLOGY . . . . . . . • . . . . General statement . . . . . . . . • . Herd Mountain surface . . . • . . . • . • . ~ Weber Valley surface . . • • . . . . . . . Bonneville Lake history. ... ECONOMIC CONSIDERATIONS . . . . . . Argenta district . • . . . • • Other mining possibilities. Sand and gravel . • . . • • • . . . . . GEOLOGIC HISTORY • • • • • • • • • • • • • • • • 0 47 47 48 49 50 51 52 53 53 55 Precambrian • • . • • • • • • . • • • • . . . .. 55 Cambrian . . . . . . . . . . 0 • 0 • • • • • • • It 55 Ordovician, Silurian and Devonian . . . • . • 56 Carboniferous .•. .• . .. ...... 57 Late Pennsylvanian through Triassic .... . 57 Cretaceous . • . • . . . . . • . . . . 57 Tertiary . .. ...........•.. 58 Paleocene • • • • • • •. ..• • 58 Eocene. . . • . • . . . . • • . • . • . . 58 Oligocene and Miocene ....•••. 58 Pliocene . • • . • • • . • . . • • . • . 59 Pleistocene and recent events •.•• 59 LITERATURE CITED • • • • 0 • • • • Q • • • • • • • 60 \ . ABSTRACT The D u r s t M o u n t a i n - H u n t s v i l l e a r e a i s l o c a t ed a b o u t 35 m i l e s n o r t h e a s t of S a l t Lake C i t y , U t a h , and c o m p r i s e s n e a r l y 110 s q u a r e m i l e s b e t w e e n Ogden and Weber V a l l e y s . f o r m a t i o n s e x p o s e d a r e t h e P r e c a m b r i an F a r m i n g t o n C a n y o n c o m p l e x ; t h e C a m b r i a n T i n t i c q u a r t z i t e, O p h i r s h a l e , C a m b r i a n l i m e s t o n e s d o l o m i t e s un­d i f f e r e n t i a t e d ; D e v o n i a n T h r e e F o r k s ? ) f o r m a t i o n; M i s s i s s i p p i a n M a d i s o n l i m e s t o n e t h e B r a z e r f o r m a t i o n; t h e T r i a s s i c T h a y n e s l i m e s t o n e ; t h e T e r t i a r y K n i g ht c o n g l o m e r a t e , t u f f , H u n t s v i l l e f a n g l o m e r a t e. T h r e e e p i s o d e s of f a u l t i n g w e r e n o t e d w i t h in t h e a r e a . D u r s t t h r u s t i s r e l a t e d t o m i d - L a r a m i de a c t i v i t y . e a s t - w e s t e p i s o d e n o r m a l f a u l t i n g o c c u r r ed d u r i n g t h e M i o c e n e ? ) . N o r t h - s o u t h n o r m a l f a u l t i ng o c c u r r e d d u r i n g t h e P l i o c e n e P l e i s t o c e n e. M o u n t a i n e r o s i o n s u r f a c e i s t h e o l d e st e r o s i o n s u r f a c e w i t h i n t h e n o r t h - c e n t r a l W a s a t c h M o u n t a i n s. I t i s d a t e d l a t e O l i g o c e n e M i o c e n e a g e . more r e c e n t e r o s i o n s u r f a c e i s t h e V a l l e y s u r f a c e . The f o r m a t i o n t h i s o c c u r r e d i n P l i o c e n e P l e i s t o c e n e t i m e. B o n n e v i l l e e x t e n d e d i n t o b o t h V a l l ey a n d V a l l e y. r ABSTRACT The Durst Mountain~Huntsville area is located about 35 miles northeast of Salt Lake City, Utah, and comprises nearly 110 square miles between Ogden and Weber Valleys. The formations exposed are the Precambrian Farmington Canyon complex; the Cambrian Tintic quartzite, Ophir shale, and Cambrian limestones and dolomites un­differentiated; Devonian Three Forks ( 7) formation; Mississippian Madison limestone and the Brazer formation; the Triassic Thaynes limestone; and the Tertiary Knight conglomerate, Norwood tuff, and Huntsville fanglomerate. Three episodes of faulting were noted within the area. The Durst thrust is related to mid-Laramide activity. An east~west episode of normal faulting occurred during the Miocene ( 7). North~south normal faulting occurred during the Pliocene and Pleistocene. The Herd Mountain erosion surface is the oldest erosion surface within the north-central Wasatch Mountains. It is dated as late Oligocene or Miocene age. A more recent erosion surface is the Weber Valley surface. The formation of this occurred in Pliocene or Pleistocene time. An arm of Lake Bonneville extended into both Ogden Valley and Weber Valley. " i \ ' ' ACKNOWLEDGMENTS The w r i t e r w i s h e s t o e x p r e s s s i n c e re a p p r e c i a t i o n t o D r . A. J . E a r d l e y who s u g g e s t e d t he p r o b l e m , h e l p e d w i t h i t i n t h e f i e l d , g u i d e d it t o c o m p l e t i o n . a r e D r . S t o k e s and R o b e r t B r i g h t , U n i v e r s i t y U t a h , f o r t h e i d e n t i ­f i c a t i o n f o s s i l s . J , D r . F . C h r i s t i a n s en c r i t i c a l l y r e a d t h e m a n u s c r i p t. G r a t i t u d e i s e x p r e s s e d t o my w i f e f o r h er u n t i r i n g e f f o r t s i n t y p i n g t h e m a n u s c r i p t and d o i ng a m a j o r p a r t of t h e d r a f t i n g. T h a n k s a r e a l s o due t h e U n i o n P a c i f i c R a i l r o ad Company who c o n t r i b u t e d f i n a n c i a l a s s i s t a n c e t o w a r d t he c o m p l e t i o n of t h e t h e s i s p r o b l e m. i i ACKNOWLEDGMENTS The writer wishes to express sincere appreciation to Dr. A. J. Eardley who suggested the problem, helped with it in the field, and guided it to completion. Thanks are due Dr. W. L. Stokes and Robert Bright, University of Utah, for the identi­fication of fossils. Dr. J. Berg and Dr. F.Christiansen critically read the manuscript. Gratitude is expressed to my wife for her untiring efforts in typing the manuscript and doing a major part of the drafting. Thanks are also due the Union Pacific Railroad Company who contributed financial assistance toward the completion of the thesis problem. ii L o c a t i o n & a c c e s s i b i l i ty The D u r s t M o u n t a i n - H u n t s v i l l e a r e a d e s c r i b e d i n t h is r e p o r t c o v e r s a r e a a b o u t s q u a r e m i l e s i n T o w n s h i p s a n d n o r t h , R a n g e s e a s t , S a l t M e r i d i a n , Morgan a n d C o u n t i e s , U t a h , i s p a r t t h e n o r t h - c e n t r al W a s a t c h d e l i n i a t e d E a r d l e y 1 9 4 4 ) . a r e a i s m i l e s n o r t h e a s t S a l t C i t y , U t a h 2 / / m i l e s e a s t O g d e n , U t a h . V a l l e y b o u n d s t h e a r e a t h e n o r t h , Herd M o u n t a i n i s a p p r o x i m a t e l y t h r e e m i l e s w e s t t h e e a s t l i n e, D u r s t M o u n t a i n i s t h e s o u t h l i n e , t h e w e s t l i n e i s a b o ut o n e m i l e w e s t t h e r o a d b e t w e e n M o u n t a i n G r e e n H u n t s v i l l e. S e e i n d e x f i g u r e 1.) D u r s t M o u n t a i n - H u n t s v i l l e a r e a r e a c h e d from O g d e n , U t a h , v i a e i t h e r C a n y o n . d i r t r o a d in C o t t o n w o o d Canyon t r a v e r s e s t h e a r e a . To t h e s o u t h of C o t t o n ­wood C a n y o n j e e p " r o a d s p e r m i t a c c e s s t o t h e b a s e t h e moun­t a i n s ; t h e p e a k s a r e i n a c c e s s i b l e by j e e p . North of C o t t o n w o od C a n y o n r o a d s t h a t can be t r a v e l e d by p a s s e n g e r c a r s p e r m it f a i r l y good c o v e r a g e . This n o r t h e r n a r e a c a n be r e a c h e d v ia U t a h Highway 39 w e s t of H u n t s v i l l e , t h e n c e s o u t h p a s t t he " M o n a s t e r y " and e a s t a l o n g S h e e p h e r d C r e e k. P u r p o s e s c o pe D u r s t M o u n t a i n - H u n t s v i l l e a r e a by E a r d l e y 1 9 4 4 ) p a r t l a r g e r s t u d y t h e g e o l o g y t he INTRODUCTION Location & accessibility The Durst Mountain=Huntsville area described in this report covers an area of about 110 square miles in Townships 5 and 6 north~ Ranges 1, 2, and 3 east, Salt Lake Meridian, Morgan and Weber Counties, Utah. It is a part of the north-central Wasatch Range as deliniated by Eardley ( 1944). I The area is 30 miles northeast of Salt Lake City, Utah and 2P: miles east of Ogden, Utah. Ogden Valley bounds the area on the north, Herd Mountain is approximately three miles west of the east line, Durst Mountain is on the south line, and the west line is about one mile west of the road between Mountain Green and Huntsville. ( See index map, figure 1.) The Durst Mountain-Huntsville area may be reached from Ogden, Utah, via either Weber or Ogden Canyon. A dirt road in Cottonwood Canyon traverses the area. To the south of Cotton-wood Canyon " jeep" roads permit access to the base of the moun-tains; the peaks are inaccessible by jeep. North of Cottonwood Canyon roads that can be traveled by passenger cars permit fairly good coverage. This northern area can be reached via Utah Highway 39 west of Huntsville~ thence south past the "Monastery" and east along Sheepherd Creek. Purpose and scope The Durst Mountain-Huntsville area was mapped by Eardley ( 1944) as part of a larger study of the geology of the F i g . I. I n d e x m a p of t h e D u r s t M t n . - H u n t s v i l l e a r ea A C H E CITY s A L T L A K E " Fi g. t. Index map of the Du r s1 R I I \ G ,/ AN, I --~ Mtn.-Huntsville area ",'" n o r t h - c e n t r a l W a s a t c h M o u n t a i n s . The p u r p o s e of t h e p r e s e nt s t u d y i s t o r e m a p t h e a r e a i n d e t a i l p a r t i c u l a r l y to s t u d y t h e d e t a i l s t h e T e r t i a r y h i s t o r y . S e v e r a l t h e s es h a v e b e e n c o m p l e t e d s t u d e n t s a t t h e U n i v e r s i t y d u r i n g t h e p a s t y e a r s u n d e r t h e d i r e c t i o n E a r d l e y. R o b e r t B. S c h i c k 1 9 5 5 ) g e o l o g i c a l s t u d y t h e Morgan H e n e f e r a r e a a d j a c e n t t o t h e w r i t e r * s a r e a h e s o u t h. E0 L o f g r e n i s s t u d y i n g V a l l e y t o t h e n o r t h - w e s t W i l l i a m L a r a w a y h a s u n d e r t a k e n t h e g e o l o g i c s t u d y a d j a c e n t to t h e p r e s e n t a r e a t o t h e n o r t h e a s t. F i e l d work s t u d y t h e D u r s t M o u n t a i n - H u n t s v i l l e a r e a b e g u n i n t h e e a r l y 1 9 5 6 . F i e l d c o n t i n u ed t h r o u g h t h e f a l l 1 9 5 6 , c o m p l e t e d d u r i ng t h e e a r l y 1 9 5 7 . F i e l d m a p p i n g d o n e a e r i al p h o t o g r a p h s o b t a i n e d t h e U n i t e d S t a t e s S o i l C o n s e r v a t i on S e r v i c e . g e o l o g y t r a n s f e r r e d t h e D e p t . of A g r i c u l t u r e , S o i l C o n s e r v a t i o n S e r v i c e P l a n i m e t r i c b a s e maps U t a h - 4 5 U t a h - 4 6. G e o l o g i c s e t t i ng The D u r s t M o u n t a i n - H u n t s v i l l e a r e a i s p a r t of t he M i d d l e M o u n t a i n p h y s i o g r a p h i c p r o v i n c e . s p e c i f i ­c a l l y i t i n c l u d e d i n t h e n o r t h - c e n t r a l W a s a t c h M o u n t a i ns a s d e l i n i a t e d E a r d l e y ( 1 9 4 4 ). - 2 - north- central Wasatch Mountains . The purpose of the present study is to remap the area in detail and particularly to study the details of the Tertiary history. Sever al theses have been comple ted by students at the University of Utah during the past few years under the direction of Dr. Eardley. Robert 8. Schick ( 1955) made a geological study of the Morgan­Henefer area adjacent to the writer's area on t he south. Ben E. Lofgren is studying Ogden Valley to the north-west and William Laraway has undertaken the geologic study adjacent to the present area to the northeast . · Field work The study of the Durst Mountain-Huntsville area was begun in the early summer of 1956. Field work continued through the summer and fall of 1956, and was completed during the early summer of 1957. Field mapping was done on aerial photographs obtained from the United States Soil Co nservation Service. The geology was transferred to the U. S. Dept. of Agriculture, Soil Conservation Service Planimetric bas~ maps Utah-45 and Utah-46. Geologic setting The Durst Mountain-Huntsville area is part of the Middle Rocky Mountain physiographic province. More spec ifi­cally it i s included in the north-central Wasatch Mountains as del iniated by Eardley (1944). - 3 - s t r u c t u r a l c o m p l e x i t y t h i s a r e a h a s l o ng b e e n W a s a t c h F r o n t s c o m p o s e d P r e c a m b r i an m a s s w h i c h a c t e d " n u c l e u s a r o u n d w h i c h c o m p r e s s i o n al s t r u c t u r e s i n t h e y o u n g e r o v e r l a p p i n g s t r a t i f i e d r o c k s a re s h a p e d " E a r d l e y , 1 9 4 4 p . 8 4 7 ) . T h r u s t i n g s c o n s p i c u o us a r o u n d t h e n o r h e r n n o r t h e a s t e r n p o r t i o n t h e r a n ge n e a r w h e r e a o l d i n g p r e d o m i n a t e s h e s o u t h . U i n t a u p l i f t e x t e n d s e a s t w a r d f r om t h e s o u t h e r n l i m i t L " i s f o r m e d w i t h t h e n o r t h s o u t h t r e n d i n g c r y s t a l l i n e m a s s. T e r t i a r y f o l d i n g o c c u r r e d i n t h e a n g l e t h e n e ar H e n e f e r C o a l v i l l e . t h r u s t s a t t h e n o r t h e r n e d g e t h i s P r e c a m b r i a n c r y s t a l l i n e c o m p l e x a r e a t r i g h t a n g l es a p p r o x i m a t e l y ) t h e f o l d s t h e I d a h o - W y o m i n g a r e a. E x c e l l e n t e x p o s u r e s t h e t h r u s t s t h e c r y s t a l ­l i n e c o m p l e x c a n s e e n i n t h e c a n y o n s c u t by t h e w e s t w a rd f l o w i n g R i v e r s w h i c h a r e e s p e c t i v e l y n o r th a n d s o u t h t h e D u r s t M o u n t a i n - H u n t s v i l l e a r e a . B e c a u s e of t h e s e r i v e s t h e a r e a w e l l d r a i n e d . i f i t w e r e n ot f o r t h e r i v e r , h i g h p l a t e a u w o u l d p r o b a b l y p r e s e n t e a st o f t h e W a s a t c h F r o n t . However, i s l a n d s P a l e o z o i c Meso z o i c r o c k s w h i c h a r e s u r r o u n d e d by b l a n k e t T e r t i a r y s e di m e n t s a r e i n e x i s t e n c e. > P r e v i o u s g e o l o g i c work • S t a n s b u r y 1 8 5 2 ) v i s i t e d t h e n o r t h - c e n t r a l W a s a t ch M o u n t a i n s when, i n s e a r c h o u t h r o u g h t h e Rocky M o u n t a i n s p a s s e d t h r o u g h O g d e n * s H o l e V a l l e y ) and - The stru ctur al complexity of thi s area has long been known. The Wasatch Front i s composed of a Precambrian mass which acted as a IInucleus around which compressional structures in the younger overlapping str atif ied rocks are shaped . " ( Eardley, 1944 , p. 847) . Thrusting i s conspicuous around the nor t hern and northeastern portion of the range near Ogden wherea s f olding pr edominates on t he south . The Uinta uplift extends eastward from the southern limit and an " L" is formed with the north - south trending crystalline mass . Tertiary folding occurred in the angle of the "L" near Henefer and Coalville . The thrusts at the northern edge of thi s Precambrian crystalline complex are at right angles ( approximately) t o the folds of the Idaho-Wyomi ng area, Excelle nt exposures of the thru sts and the crystal­line complex can be seen in the canyons cut the wes tward flowi ng Ogden and Weber Rivers wh ich are r espec tively north and south of the Durst Moun t ain- Huntsville area. Because of these rive r s the area i s well drained. And if it were not for the river s , a high pla teau would probably be present east of the Wasatch Front. However , islands of Paleozoic and Mes o­zoic rocks which are surrounded a blanket of Tertiary sedi­me nts are now in existence . Previous geo logic work Stansbury ( 1852 ) visited the north-central Wasatch Mountains whe n, in search of a new r ou t e through the Rocky Mou ntains , he passed through Ogden's Hole (Ogden Valley) and 4 - O g d e n C a n y o n , Engelmann ( 1 8 7 6 ) was p r o b a b l y t h e f i r s t q u a l i ­f i e d g e o l o g i s t t o v i s i t t h e a r e a . A l t h o u g h he s t u d i e d t he g e o l o g y of t h e E a s t C a n y o n a r e a i n 1858 and 1 8 5 9 , h i s d i s ­c o v e r i e s w e r e w i t h h e l d from p u b l i c a t i o n u n t i l 1 8 7 6 , F o l l o w ­i n g E n g e l m a n n w e r e t h e e a r l y T e r r i t o r i a l s u r v e y s of t h e Rocky M o u n t a i n R e g i o n . B r a d l e y ( 1 8 7 2 ) , who was w i t h t h e U. S. G e o l o g i c a l S u r v e y of t h e T e r r i t o r i e s , made o b s e r v a t i o n s of t h e " W a h s a t c h " M o u n t a i n s f r om Ogden t o F o r t H a l l , I d a h o. G i l b e r t ( 1 8 7 5 ) v i s i t e d t h e " W a h s a t c h " Range as p a r t of h is c o n t r i b u t i o n t o t h e S u r v e y t h e H u n d r e d t h M e r i d i a n. H a g u e 1 8 7 7 ) t h e 4 0 t h P a r a l l e l S u r v e y p r e s e n t ed g e n e r a l d i s c u s s i o n t h e W a s a t c h R a n g e . t r a ­v e r s e f r om H u n t s v i l l e t o M o u n t a i n G r e e n a l s o r e c o g n i z ed t h e P a l e o z o i c r o c k s i n t h e v i c i n i t y D u r s t M o u n t a i n. G i l b e r t 1 8 9 0 ) i n h i s c l a s s i c M o n o g r a p h B o n n e v i l le n o t e d t h e p r e s e n c e l a k e s e d m e n t s i n Weber V a l l e y s a l s o d e s c r i b e d o l d f a u l t s c a r p n e a r t h e town o f M o r g a n. D u r i n g t h e e a r l y 1 9 0 0 ? c o a l o i l s t u d i e s by V e a t c h ( 1 9 0 6 , 1907) p r o v i d e d a b e t t e r u n d e r s t a n d i n g f o r t he C r e t a c e o u s and T e r t i a r y s y s t e m s of t h e r e g i o n , B o u t w e ll ( 1 9 0 7 ) c o n t r i b u t e d f u n d a m e n t a l l y t o t h e s t r a t i g r a p h y i n h is s t u d y t h e P a r k C i t y m i n i n g d i s t r i c t . s t u d y p h o s ­p h a t e d e p o s i t s F e r r i e r 1 9 0 7 ) , B l a c k w e l d er 1 9 1 0 a , 1 9 1 0 b ) , G a l e R i c h a r d s 1 9 1 0 ) f u r t h e r e d t he g e o l o g i c k n o w l e d g e t h e r e g i o n . B u t l e r 1 9 2 0 ) b r i e f ly d e s c r i b e d t h e o r e d e p o s i t s w i t h i n t h e a r e a. - 4 - Ogden Canyon. Engelmann (1876) was probably the first quali­fied geologist to visit the area. Although he studied the geology of the East Canyon area in 1858 and 1859, his dis­coveries were withheld from publication until 1876. Follow­ing Engelmann were the ear ly Territorial surveys of the Rocky Mountain Region. Bradley (1872), who was with the U. S. Geological Survey of the Territories, made observations of the "Wahsatch" Mountains from Ogden to Fort Hall, Idaho. Gilbert (1875) visited the "Wahs atch" Range as part of his contribution to the Survey West of the One Hundredth Meridian. Hague and Emmons ( 1877) of the 40th Parallel Survey presented a general discussion of the Was'atch Range. They made a t ra­verse from Huntsville to Mountain Green and also recognized the Paleozoi~ rocks in the vicinity of Durst Mountain. Gilbert ( 1890) in his classic Monograph on Lake Bonneville noted the presence of lake sed i ment s in Ogden and Weber Valleys . He also described an old fault scarp near the town of Morgan. During the early 1900's coal and oil studies by Veatch (1906, 1907) provided a better understanding for the Cretaceous and Tertiary systems of the region. Boutwel l (1907) contributed fundamentally to the stratigraphy in his study of the Park City mining district. The study of phos­phate deposits by Weeks and Ferrier ( 1907), Blackwelder ( 1910a, 1910b), and Gale and Richards ( 1910) furthered the geologic knowledge of the region. B. S. Butler ( 1920) briefly described the ore deposits within the area. - H i n t z e ( 1 9 1 3 ) , E a r d l e y ( 1 9 3 3 , 1 9 3 4 , 1 9 4 4 ), J . S t e w a r t W i l l i a m s 1 9 4 3 , 1 9 4 5 , 1 9 4 8 ) , 1 9 3 1 ), a n d 1 9 5 3 ) h a v e c o n t r i b u t e d c o n s i d e r a b l e d e t a i l to t h e s t r a t i g r a p h y , s t r u c t u r e p h y s i o g r a p h y t h e n o r t h - c e n t r a l W a s a t c h M o u n t a i n s . A l s o , e x c e l l e nt t h e s e s d e s c r i b i n g l o c a l a r e a s h a v e b e e n w r i t t e n Univer-*- s i t y U t a h s t u d e n t s u n d e r h e d i r e c t i o n D o c t o r s J. E a r d l e y and Norman C, W i l l i a m s. - 5 - Hintze (1913), Eardley (1933, 1934, 1944), J. Stewart Williams ( 1943, 1945, 1948), Mathews ( 1931), and Kummel ( 1953) have contributed considerable detail to the stra tigraphy, structure and physiography of the north­ce ntral Wasatch Mountains. Also, a number of excellent theses describing local areas have been written by Univer­sity of Utah stude nts under t he direction of Doctors A. J. Eardley and Norman C. Willi ams . - GEOGRAPHY T o p o g r a p h y F o r t h e m o s t p a r t t h e D u r s t M o u n t a i n - H u n t s v i l l e a r ea i s c o m p o s e d r o l l i n g h i l l s f l a t u p l a n d s , b u t a l o n g t he s t r i k e of t h e P a l e o z o i c f o r m a t i o n s i n t h e v i c i n i t y of D u r st M o u n t a i n and E l k M o u n t a i n t h e t e r r a i n i s v e r y r u g g e d . There i s a b o u t a 4 , 0 0 0 f o o t c h a n g e i n e l e v a t i o n from C o t t o n w o o d C r e ek t o D u r s t M o u n t a i n i n l e s s t h a n two m i l e s h o r i z o n t a l d i s t a n c e. h i g h e s t p e a k i n t h e a r e a i s D u r s t M o u n t a i n w h i c h a t t a i n s a l t i t u d e 9 , 2 6 5 f e e t . l o w e s t a r e a i s t h e R i v er a n d t h e a l t i t u d e a t t h i s p o i n t i s 4 , 8 8 0 f e e t . w e s t e r n p o r ­t i o n i s r e l a t i v e l y f o r m s d i v i d e b e t w e e n V a l l e y. Land u t i l i z a t i o n and v e g e t a t i on t h e l a n d t h e D u r s t M o u n t a i n - H u n t s v i l le a r e a i s i n c l u d e d i n t h e C a c h e N a t i o n a F o r e s t , b u t s m a ll p o r t i o n s a r e p r i v a t e l y l a n d i s p r i m a r i l y u s e d as t h e r a n g e f o r s h e e p . S e v e r a l h e r d s a b o u t 1 , 0 0 0 s h e ep p e r h e r d a r e g r a z e d i n t h e a r e a e v e r y summer. T u r k e y s a re r a i s e d i n t h e l o w e r p a r t s C o t t o n w o o d C a n y o n . C a t t l e g r a z i ng a c c o u n t s f o r m i n o r p a r t t h e l a n d u t i l i z e d . o n l y l a nd u n d e r c u l t i v a t i o n i s i n t h e w e s t e r n p a r t h e a r e a . G r a in a n d a l f a l f a a r e g r o w n . f a r m s a r e a l l t h e t u f f; r i c h s o i l i s f o r m e d f r om t h e t u f f w h e r e v e r t h e l a n d is l e v e l e n o u g h i t i s c u l t i v a t e d . o n l y y e a r - r o u n d " i n h a b i t a n ts - 6 - GEOGRAPHY Topography For the most part the Durst Mountain-Huntsville area is composed of rolling hills and flat uplands, but along the strike of the Paleozoic formations in the vicinity of Durst Mountain and Elk Mountain the terrain is very rugged . There is about a 4,000 foot change in elevation from Cottonwood Creek to Durst Mountain in less than two miles horizontal dista nce. The highest peak in the area is Durst Mountain which attains an altitude of 9,265 feet. The lowest area is on the Weber River and the altitude at this point is 4,880 feet. The western por­ti on is relatively low and forms a divide between Morgan and Ogden Valley. Land utilization and vegetati on Most of the land of the Durst Mountain-Huntsville area is included in the Cache Nationa l Forest, but some small portions are privately owned. The land is primarily used as the summer range for sheep. Several herds of about 1,000 sheep per herd a~e grazed in the area every summer . raised in the lower parts of Cottonwood Canyon. accounts for a minor part of the land utilized. Turkeys are Cattle grazing The only land under culti vation is in the western part of t he area. Grain and alfalfa are grown. The farms are all on the Norwood tuff; a rich soil is formed from the tuff and wherever the land is level enough it is cultivated. The only " year- round" inhabitants l i v e on t h e s e f a r m s. f o o t h i l l s t h e s o u t h w e s t s l o p e s t he a r e a a r e g e n e r a l y c o v e r e d l a r g e s a g e - b r u s h . t he f o o t h i l l s s c r u b m o u n t a i n a r e d e n s e h i k i n g i n s u c h a r e a s d i f f i c u l t . a s p e n a r e f o u n d in t h e c a n y o n s , a t h i g h e r e l e v a t i o n s s t a n d s t h e a s p e n a re i n t e r m i x e d w i t h D o u g l a s f i r , W h i t e f i r , A l p i n e f i r. Rock e x p o s u r es R o c k e x p o s u r e s , g e n e r a l l y , a r e s c a r c e . The t r a n s ­v e r s e c a n y o n of C o t t o n w o o d C r e e k g i v e s a f a i r l y good c r o s s - s e c t i o n a l v i e w of t h e a r e a . E l s e w h e r e t h e p r o l i f i c g r o w t h of s c r u b m o u n t a i n t h e t h i c k s o i l m a n t l e p re v e n t s t h e d i r e c t t r a c i n g b e d s o v e r l o n g d i s t a n c e s . It was n e c e s s a r y t o r e m o v e t h e m a n t l e i n p l a c e s t o d e t e r m i n e t he l i t h o l o g i e s u n d e r f o o t s u b s e q u e n t l y t o t h e b a s is o f s o i l t y p e s . o n l y d i d t h e v e g e t a t i o n o b s c u r t h e e x ­p o s u r e s b u t i t a l s o p r e v e n t e d t h e a c c u r a t e l o c a t i o n g r o u n d p o i n t t h e a e r i a l p h o t o g r a p h s , f o r t h e s c r u b b r u sh was w e l l o v e r t h e w r i t e r 1 s h e a d w h i c h p r e v e n t e d t h e s i g h t i ng o f l a n d m a r k s. - 7 - live on these farms. The foothills and the south and west slopes of the area are genera l ly covered by large sage-brush. Above the foothill s scrub oak and mountain mahogany are dense and make hiking in such areas difficult. Quaking aspen are found in the canyons, and at higher elevations stands of the aspen are intermixed with Douglas fir, White fir, and Alpi ne fir. Rock exposures Rock exposures, generally, are scarce . The trans­verse canyon of Cottonwood Creek gives a fairly go od cross­sectional view of the area . Elsewhere the prolific growth of scrub oak and mountain mahogany and the thick soil mantle pre ­vents the direct tracing of beds over long dista nces. I t was necessary to remove the mantle in places to determine the lithologies under foot and subsequently to map on the basis of soil types. Not only did the vegetation obscur e the ex­posures but it also pr event ed the accurate location of a ground pOint on the aerial photographs , for the scrub brush well over the writer ' s head which prevented the sighting of landmarks. - 8 - STRATIGRAPHY The r o c k s p r e s e n t i n t h e D u r s t M o u n t a i n - H u n t s ­v i l l e a r e a r a n g e f r om P r e c a m b r i a n t o Q u a t e r n a r y . A c o r e of P r e c a m b r i a n P a l e o z o i c r o c k c r o p s o u t i n t h e c e n t r a l p a rt o f t h e a r e a . s t r a t a a r e e n t i r e l y s e d i m e n t a r y e x c e p t f or t h e P r e c a m b r i a n s e q u e n c e w h i c h i s w h o l l y m e t a m o r p h i c . C a m b r i a n s e d i m e n t s a r e v e r t i c a l d i p s l i g h t l y t o t h e e a st e x c e p t w h e r e i n f l u e n c e d f a u l t i n g . C a m b r i a n s e q u e n ce i s p a r t l y r e p e a t e d f a u l t i n g . D e v o n i a n , M i s s i s s i p p i an a n d P e n n s y l v a n i a n s t r a t a c r o p o u t e a s t t h e C a m b r i a n b ut t h e d i p t h e s e f o r m a t i o n s i s n o t s t e e p . s m a l l a r ea u n d e r l a i n T r i a s s i c r o c k s f o u n d n o r t h B e n n e tt C r e e k . e a s t e r n p a r t t h e a r e a i s b l a n k e t e d E o c e ne c o n g l o m e r a t e s w h i c h r e s t u n c o n f o r m a b l y o l d e r r o c k s . w e s t e r n p o r t i o n c o v e r e d O l i g o c e n e t u f f a c e o u s s e d i m e n ts w h i c h a r e i n t u r n c a p p e d l o c a l l y f l a t - l y i n g P l i o c e ne f a n g l o m e r a t e . Q u a t e r n a r y d e p o s i t s c o n s i s t of a l l u v i u m and l a k e s e d i m e n t s d e v e l o p e d a l o n g t h e s h o r e l i n e of Lake B o n n e v i l le P r e c a m b r i a n s y s t em F a r m i n g t o n C a n y o n c o m p l e x . o l d e s t r o c k s e x ­p o s e d i n t h e a r e a a r e m e t a m o r p h i c c r y s t a l l i n e c o m p l e x. T h e s e r o c k s w e r e d e s i g n a t e d E a r d l e y H a t c h 1 9 4 0 a ) t h e F a r m i n g t o n C a n y o n c o m p l e x f o r t h e e x p o s u r e s i n F a r m i n g - t o n C a n y o n and a t B o u n t i f u l Peak e a s t of t h e town of B o u n t i ­f u l . They a s s i g n e d a m i d d l e ( ? ) P r e c a m b r i a n age t o t h is s e q u e n c e . - STRATIGRAPHY The rocks pre sent i n t he Dur st Mountai n-Hunts-ville area ra nge " from Precambrian to Quaternary. A core of Precambrian and Paleozoic rock crops out in the central part of the area. The strata are entirely sedimentary except for the Precambrian sequence which is wholly metamorphic. The Cambrian sediments are vertical or dip slightly to the east except where influenced by faulting. The Cambrian sequence is partly repeated by faulting . The Devonian, Mississippian and Pennsylvani an strata crop out east of the Cambrian but the dip of these formations is not so steep. A small area underlain by Triassic rocks was found north of Bennett Creek. The eastern part of the area is blanketed by Eocene conglomerates which rest unconformably on older rocks. The western portion i s covered by Oligocene tuffaceous sed iments which are in turn capped locally by a flat-lying Pliocene fanglomerate. Qua ternary deposits consist alluvi um lake sediments developed along the shor eline BonneviUe. Precambrian system Farmington Canyon complex. The oldest rocks ex­posed in the area are a metamorphic crystalline complex. These rocks were designated by Eardley and Hatch ( 1940a) as the Farmington Canyon complex for the exposures in Farming­ton Canyon at Bountiful east the Bounti ­ful. ass igned mi ddle 7) Precambrian to this sequence. The P r e c a m b r i a n i s g e n e r a l l y e r o d e d t o a r o l l i ng t o p o g r a p h y b u t w h e r e i t i s i n c o n t a c t w i t h t h e o v e r l y i ng T i n t i c q u a r t z i t e v e r y s t e e p s l o p e s a r e f o r m e d . s o il m a n t l e c o v e r i n g t h e c o m p l e x i s u s u a l l y v e r y d e e p , g e n e r a l ly r e d d i s h - b r o w n , c o n t a i n s a b u n d a n c e m i c a f l a k e s. h e a v i l y c o v e r e d s l o p e s w h e r e o u t c r o p s w e r e s c a r c e, t h e f l o a t a i d e d i n d e t e r m i n i n g t h e l i t h o l o g y u n d e r f o o t. o u c r o p s t h e g n e i s s e s s c h i s t s w e r e u s u a l l y e x ­t r e m e l y w e a t h e e d f r e s h s u r f a c e s w e r e d i f f i c u l t to o b t a i n . The P r e c a m b r i a n i s c o m p o s e d of g n e i s s e s and s c h i s ts t h a t a r e i n t r u d e d p e g m a t i t e d i k e s . o c k s a r e f o l i a t ed a n d g e n e r a l l y t h e b a n d i n g i s p a r a l l e l t o t h e b e d d i n g p l a n es w h i c h a r e v e r t i c a l . p e g m a t i t e s i n C o t t o n w o o d C a n y o n a re b e i n g p r o s p e c t e d f o r r a d i o a c t i v e r a r e e a r t h m i n e r a l s. T h o r i u m Y t t r i u m a r e r e p o r t e d t h e p r o s p e c t o r s t o be p r e s e n t i n t h e p e g m a t i t e s b u t t h i s n o t v e r i f i e d . Mica i s a b u n d a n t i n t h e p e g m a t i t e s t h e c o m b i n a t i o n r a d i o -* a c t i v e m a t e r i a l w i t h t h e m i c a i s t h e i n c e n t i v e f o r t h e c o n ­t i n u e d p r o s p e c t i n g . t h e g r a d e t h e and u r a n i u m t h e t o u g h n e s s t h e h o s t o c k l e a d s t h e w r i t er t o c o n c l u d e t h a t t h e m i n i n g t h e s e c o m m o d i t i e s w o u l d be u n e c o n o m i c a l . w r i t e r , w h i l e d o i n g r e c o n n a i s s a n c e work i n t h e P r e c a m b r i a n e x p o s u r e s as mapped by S c h i c k ( 1 9 5 5 ) in t h e v i c i n i t y S p r i n g H o l l o w , f o u n d m i c a b o o k s r a n g i n g in s i z e up t o one i n c h a c r o s s. p e t r o l o g i c a l h a s b e e n d o n e t he - 9 - The Precambrian is generally eroded to a rolling topography but where it is in contact with the overlying Tintic quartzite very steep slopes are formed. The soil mantle covering the complex is usually very deep, generally reddish- brown, and contain s an abundance of mica flakes. On heavily covered slopes and where outcrops were scarce, the mica float aided in determining the lithology underfoot . The ou t crops of the gneisses and schists were usually ex­tremely wea the r ed and fresh surfaces were difficult t o obtain. The Precambrian is composed of gneisses and schists that are intruded by pegmatite dikes. The r ocks are foliated and generally the banding is parallel to the bedding planes which are vertical. The pegmatites in Cottonwood Canyon are being prospected for radioactive and rare earth minerals. Thorium and Yttrium are reported by the prospectors to be present in the pegmatites but this was not verified. Mica is abundant in the pegmatites and the combination of radio­active material with the mica is the incentive for the con­tinued prospecting. However, the low grade of the mica and uranium and the toughness of the host r ock leads the writer to conclude that the mining of these commodities would be uneconomical. The writer , while doing reconnaissance work in the Precambrian expos~ res Schick 1955) in the vicinity of Spring Hollow, found mica books ranging in size to inch across. Much petrological work has been done on the F a r m i n g t o n Canyon c o m p l e x . E a r d l e y and H a t c h ( 1 9 4 0 a ) were t h e f i r s t t o i n t e n s i v e t u d y t h i s f o r m a t i o n. T h e y a l s o c o r r e l a t e d E a r d l e y H a t c h , t h e m e t a ­m o r p h i c c r y s t a l l i n e c o m p l e x t h e W a s a t c h M o u n t a i n s w i th t h a t A n t e l o p e s l a n d . D e t a i l ^ s t u d i e s w e r e B e ll 1 9 5 1 ) i n t h e F a r m i n g t o n M o u n t a i n s L a r s e n 1 9 5 7 ) A n t e l o p e I s l a n d . E a r d l e y 1 9 4 4 ) d e s i g n a t e d h e P r e c a m b r i an o f t h e C o t t o n w o o d C a n y o n * a r e a a l s o t h e F a r m i n g t o n Canyon c o m p l e x . m e t a m o r p h i c c o m p l e x c o n s i s t s s t r a t i f i c r y s t a l l i n e s e r i e s m e t a s e d i m e n t s , m e t a m o r p h i c s i l i ic i g n e o u s r o c k s , i n j e c t i o n g n e i s s e s , m e t a m o r p h i c m a f ic r o c k s E a r d l e y H a t c h , 1 9 4 0 a ) . t e n t a t i v e l y p l a ce t h i s c o m p l e x i n t h e m i d d l e ( ? ) P r e c a m b r i a n and p o s t u l a te t h e d e p o s i t i o n of o v e r 1 0 , 0 0 0 f e e t of s e d i m e n t s f o l l o w e d by t h e i n j e c t i o n of s i l l s and d i k e s d u r i n g a p e r i o d of o r o g e ny t h a t was more i n t e n s e t h a n any s u b s e q u e n t d e f o r m a t i o n. T h i m e t a m o r p h i c c o m p l e x i s n o r m a l l y o v e r l a i n by s e q u e n c e P r o t e r o z o i c (?) s t r a t a c o m p o s e d i n t e r b e d d ed q u a r t z i t e , p h y l l i t e , s h a l e , a r k o s i t e s , t i l l i t e , l i m e s t o n es w h c h i s h a n 1 2 , 0 0 0 f e e t t h i c k E a r d l e y and H a t c h, 1 9 4 0 b ) . P r o t e r o z o c s e q u e n c e i s p r e s e n t m i l e s to t h e n o r t h i n t h e C a n y o n t h e S o u t h F o r k t h e R i v er * C o t t o n w o o d C a n y o n u n l e s s s t a t e d , r e f e r s t o t h e e a s t - w e s t c a n y o n C o t t o n w o o d C r e e k , i n t h e s o u t h e r n p a r t t he a r e a . s h o u l d n o t c o n f u s e d w i t h t h e C o t t o n w o o d C r e e ks e a s t S a l t C i t y t h o s e a d j a c e n t t o t h e e a s t e rn b o r d e r t h e a r e a. - 10 - Farmington Canyon complex . Eardley and Hatch (1940a) were the first to make an intensive s tudy of thi s formation. They also correlated ( Eardley and Hatch, 1940b) the meta - morphic crystalline complex of the ~ Wa satc h Mountains with that of Antelope I sland. Detai1J studi es were made by Sell ( 1951) in the Farmington Mountains and Larsen ( 1957) on Antelope Island, Eardley ( 1944 ) des ignated t he Precambrian of the Cot tonwood Ca nyon* area also as the Farmington Canyon complex. The metamorphic complex consists of a stratifi ed crystalline series of metasediments, metamorphic sili c i c igneous rocks, injection gneisses, and metamorphic mafic rocks ( Eard ley and Hatch, 1940a). They tentatively place this complex in the middle 7) Precambrian postulate the deposition over 10,000 feet sediments followed the injection sills dikes during period orogeny that intense than subsequent deformation . Thi s metamorphic complex is normally overlain by a sequence of Proterozoic (7) strata composed of interbedded quartzite, phyllite , shale, arkosites , tillite, and l imestones wh i ch is more t han 12 ,000 feet thick ( Eardley a nd Hatch , 1940b). This Proterozo i c sequence is present a few miles to the north in the Ca nyon of the South Fork of the Ogden River * Cottonwood Canyon , unless so stated , refers to the east­west canyon of Cottonwood Creek, in the southern part of the area. It should not be confused with the Cottonwood Creeks east of Salt Lake City and those adjacent to the eastern bord er of the area . • ( W i l l i a m L a r a w a y , p e r s o n a l c o m m u n i c a t i o n ) , t o t h e e a s t i n t he U i n t a M o u n t a i n s ( W i l l i a m s , N. C . , 1 9 5 3 ) , and t o t h e w e s t and s o u t h E a r d l e y H a t c h , 1 9 4 0 b ) . t h e s e l e s s m e t a ­m o r p h o s e d s e d i m e n t s a r e a b s e n t i n t h i s l o c a l a r e a . e x p l a n a t i o n f o r t h e a b s e n c e t h e P r o t e r o z o i c s t r a t a i s p o s t u l a t e e a s t w a r d e x t e n d i n g t h e U t a h H i g h l a nd d e s c r i b e d E a r d l e y , 1 9 3 9 ) . M a p p i n g E a r d l e y 1 9 4 4 ) t h e W a s a t c h M o u n t a i n s w e s t t h e a r e a u n d e r c o n s i d e r a t i on d o e s n o t r e v e a l t h e p r e s e n c e P r o t e r o z o i c s t r a t a. T h e r e f o r e , i t c o u l d a s s u m e d t h a t t h e P r o t e r o z o i c s t r a ta w e r e n e v e r d e p o s i t e d i n t h e D u r s t M o u n t a i n - H u n t s v i l l e a r e a. C a m b r i a n s y s t em G e n e r a l s t a t e m e n t . o l d e s t s e d i m e n t a r y r o c ks r e c o g n i z e d w i t h i n t h e a r e a a r e C a m b r i a n a g e . Sedimen­t a t i o n b e g a n w i t h t h e d e p o s i t i o n c o a r s e e l a s t i c s w h i ch g r a d e d i n t o f i n e r s e d i m e n t s f o l l o w e d d e p o s i t i on o f c h e m i c a l s e d i m e n t s . Tne t o t a l t h i c k n e s s i s a b o u t 2 , 6 00 f e e t . C a m b r i a n s y s t e m c r o p s o u t i n n o r t h - s o u t h p a s s i n g t h r o u g h D u r s t i n t h e s o u t h - c e n t r a l p o r t i o n of t h e a r e a. T h r o u g h o u t t h e w e s t e r n i n t e r i o r t h e U n i t e d S t a t es t h e C a m b r i a n s y s t e m c a n d i v i d e d i n t o t h r e e p a r t s . l) b a s a l q u a r t z i t e u n i t , r e l a t i v e l y t h i n m i d d l e s h a l e u n i t, a n d 3 ) u p p e r c a r b o n a t e u n i t p r e d o m i n a t e l y l i m e s t o n e. T h i s r e p r e s e n t s t r a n s g r e s s i v e p h a s e t h e s e a t h a t s t a r t ed i n l o w e r m o s t C a m b r i a n o r v e r y l a t e P r e c a m b r i a n ) C a l i f o r n ia - 11 - (William Laraway. personal communication), to the east in the Uinta Mountains (Williams, N. C., 1953), and to the west and south ( Eardley and Hatch, 1940b). However, these less meta-morphosed sediments are absent in this local area. One explanation for the abse nce of the Proterozoic strata is to postulate an eastward extending arm of the Utah Highland ( described by Eardley, 1939). Mapping by Eardley ( 1944) in the Wasatch Mountains west of the area under consideration does not reveal the presence of any Proterozoic strata. Therefore, it could be assumed that the Proterozoic strata were never deposited in the Durst Mountain-Huntsville area. Cambrian system Ge neral statement. The oldest sedimentary rocks recognized within the area are of Cambrian age. Sedimen­tation began with the deposition of coarse clastics which graded into finer sediments and was followed by deposition of chemical sediments. The total thickness is about 2,600 feet. The Cambrian system crops out in a north-south band passing through Durst Peak in the south-central portion of the area. Throughout the western interior of the United States the Cambrian system can be divided into three parts: (1) a basal quartzite unit, (2) a relatively thin middle shale unit, and ( 3) an upper carbonate unit predominately of limestone. This represents a transgressive phase of the sea that started in lowermost Cambrian ( or very late Precambri an) in California - a n d s o u t h e r n Nevada and e n c r o a c h e d upon t h e l a n d from s o u t h ­w e s t t o n o r t h e a s t . The C a m b r i a n r e s t s u n c o n f o r m a b l y on t he P r e c a m b r i a n m e t a m o r p h i c c o m p l e x. T i n t i c q u a r t z i t e . T i n t i q u a r t z i t e b y G. 0 . S m i t h ( 1 9 0 0 ) f o r e x p o s u r e s i n t h e T i n t i c M o u n t a i n s. f o r m a t i o n c r o p s o u t n t h e s o u t h - c e n t r a l p o r t i o n t he a r e a s t r i k e s g e n e r a l l y n o r t h . N e a r l y e v e r y w h e r e t he a t t i t u d e h e T i n t i c i s w i t h i n f ew d e g r e e s t h e v e r t i c a l. Good e x p o s u r e s may be o b s e r v e d w e s t of D u r s t Peak and n o r th of C o t t o n w o o d C r e e k. The T i n t i c q u a r t z i t e i s a c l i f f f o r m i n g h a r d and d e n s e q u a r t z i t e and q u a r t z i t i c s a n d s t o n e t h a t p r e d o m i n e n t ly p i n k and b u f f , b u w i t h s h a d e s g r a y , e d , p u r p l e g r e e n. q u a r t z g r a i n s , w h i c h a r c e m e n t e d s i l i c a , a r e medium-s i z e d o c o a r s e , w e l l - r o u n d e d h a v e g l a s s y a p p e a r a n c e. F r e q u e n t l y t h e o c k w i l l f r a c t u r e t h r o u g h t h e g r a i n s w e ll a s a r o u n d t h e m E a r d l e y 1 9 4 4 ) s t a t e s , s e c o n d a r s i l i ca i n o p t i c a l c o n t i n u i t y w i t h t h e q u a r t z g r a i n s , b u t i n t he p i n k r e d q u a r t z i t e s t h i n o n o x i d e b o d e r s u r r o u n ds m o s t t h e g r a i n s n a b l e s t h e o b s e r v e r t o d i s t i n g u i t h e o r i g i n a l g r a i n s t h e a d d e d m a t e r i a l . " b e d s have v i t r e o u s a p p e a r a n c e b u t a r s u g a r y. T h i n b e d s i n t r a f o r m a t i o n a l c o n g l o m e r a t e s a re common n u m e r o u s b e d s g r i t , t o s e v e a l i n c h es t h i c k , were o b s e r v e d C r o s s - b e d d i n g n o t e d t h r o u g h o ut t h e f o r m a t i o n b u t d e t e r m i n a t i o n p r e v a i l i n g d i r e c t i on - 12 - and sou th ern Nevada and encroached upon the land f r om south­west t o northe ast. The Cambrian rests unco nfo rmably on the Precambrian metamorphic complex. Tintic quartzite. The Tint!c quartzite was named by G. O. Smith (1900) for exposur es in the Tintic Mountains . The fo rmat i on cr ops out i n the south- central portion of the area and strikes gener ally north. Nearly ever ywhere the attitude of t he Tintic is within a few degr ees of the vertical. Good exposures may be observed west of Dur st Peak and north of Cottonwood Cr eek. The Tintic quartzite i s a cliff forming hard and dense qua rtzite a nd quartzitic sandstone that i s predominentiy pink a nd buff, bu t with shades of gray, r ed , purple and green . The quartz grains, which ar e cemented by silica , are mediuffi­s ized t o coarse , well-rounded and have a glassy appea r ance. Frequently the r ock will fracture through the gra ins as well as around them . Eardley ( 1944) states , "The secondar y silica i s in optical continui ty with the quartz grains , but in the pink and red quartzites a thin i r on ox ide bo r der surrounds most of the gr ains and e nables the observer to distingui sh the original grains from the added materi a!. " Most beds have a vitr eous appearance but some ar e sugary. Thin beds of intraformational conglomerates are Common and numerous beds of grit, up to seve r al inches thick, wer e obser ved . Cross-bedding was noted t hroughout the formation but no determination of prevailing direction » 13 - c o u l d made, c o a s e b a s a l c o n g l o m e r a t e , n o e d by E a r d l e y 1 9 4 4 ) i s w e l l e x p o s e d t h e v e r t i c a l o u t c r op n o r t h C o t t o n w o o d C r e e k , p e b b l e s a r e m o s t l y w e l l - r o u n d e d a n g e t o i n c h e s i n s i z e . c o n ­g l o m e r a t e v a r i e d c o l o r e d l a m i n a t ed q u a r t z i t e s w h i c h a p p e a r t o s i m i l a r t o t h e v a r i e t i e s of n e a r - b y P r o t e r o z o i c ? ) q u a r t z i t e . E a r d l e y 1 9 4 4 ) r e p o r ts h a t h e b a s a l c o n g l o m e r a t e i s h i n n e r i n H a r d s c r a b b le C a n y o n t o t h e s o u t h a b s e n t i n C a n y o n , C, W i l l i a m s 1 9 5 3 ) f i n d s b a s a l c o n g l o m e r a t e f e e t t h i ck a t v a r i o u s l o c a t i o n s a l o n g t h e b a s e t h e T i n t i c q u a r t ­z i t e i n t h e U i n t a M o u n t a i n s , h a s c o m p a e d t h i s w i th t h e c o n g l o m e r a t e a t C o t t o n w o o d C r e e k and h a s f o u n d t h em to b e " e s s e n t i a l l y i d e n t i c a l ". T h i n b e d s b r o w n i s h - b u f f , m i c a c e o u s s h a l e b e ­come i n c r e a s i n g l y a s t h e o p t h e f o r m a t i o n is a p p r o a c h e d . h e t o p , t h e s h a l e t a i n s g r e e n i sh c a s w i t h i n c r e a s e m i c a a p p e a s t o a l m o st s c h i s t o s e . This s h a l e g r a d e s i n t o t h e o v e r l y i n g O p h ir s h a l e . b o r i n g s ( ? ) p r o b a b l y f o r m e d S c o l i t h u s ) are w i t h i n f e e t t h e t o p t h e T i n t i c . t r a i l s ( ? ) a i n d r o p i m p r i n t s a r e t h e b e d d i ng p l a n e s t h e s h a l e. t h i c k n e s s t h e T i n t i c q u a r t z i t e i n t he D u r s t M o u n t a i n - H u n t s v i l l e a r e a i s a b o u t 1 , 0 0 0 f e e t . It - 13 - could be made. A coa r se basal conglomerate, as no t ed by Ea r dley ( 1944) , is well exposed i n the vertical outcrop north of Cottonwood Creek. The pebbles are mostly well­rounded and r ange from 1 to 4 inches in size. The con­glomerate i s made up of varied color ed and laminated qua rtzites whi ch appear to be simi lar to the varieties of near-by Proterozoic ( 7 ) quartz ite. Ear dley ( 1944) reports t ha t the basal conglomer ate is t hinner in Hardscr abble Canyon to the south and absent in Ogden Canyon. Norman C. Wi lliams ( 1953) fi nds a basal conglomerate 1-3 feet th ick at various locations alo ng the base of the Tintic quart­zite in the Uinta Mounta ins. He has compa r ed this with he conglomerate at Cottonwood Creek ha fou nd hem to be ne ssentially identical'l. Thin beds of browni sh-buff, micaceous shale be­. come increasingly common as the t op of the formation is approached. Near t he top, the shale a t ta ins a greenish cas t with an increase of mica and appea r s to be almost schistose . Thi s shale gr ades into the overlyi ng Ophir sha le. Worm borings(7) ( pr obably formed by Scolithus) ar e common within 100 feet of the top of the Tintic. Worm trails (?) and r ain dr op imprints are common on the bedding planes of the shale. The thickness of the Tintic quartzite in the Durst Mou ntain ~ H u nt sv il le area is about 1, 000 feet. It r e s t s w i t h a n g u l a r d i s c o r d a n c e on t h e P r e c a m b r i a n F a r m i n g - t o n C a n y o n c o m p l e x s c o n f o r m a b l y o v e r l a i n h e O p h ir s h a l e 0 a d j a c e n t a r e a s w h e r e P r o t o z o i c (?) q u a r t z i t es a r e p r e s e n t , i t i s d i f f i c u l t o p l a c e t h e c o n t a c t b e t w e en t h e w o . From o b s e r v a t i o n s i n t h e s e a r e a s , E a r d l e y and H a c h 1 9 4 0 b ) s u g g e s t t h a t t h e c o n t a c t s b o t h c o n ­f o r m i t y d i s c o n f o r m i t y. common u s a g e t h e b a s a l C a m b r i a n q u a r t z i t es n o r t h of t h e Ogden R i v e r a r e r e f e r r e d t o as t h e B r i g h am q u a r t z i t e , and T i n t i c q u a r t z i t e i s t h e t e r m i n o l o g y a p p l i ed h o s e o c c u r r e n c e s t o t h e s o u t h . w r i t e r s h a v e d e s ­c r i b e d t h e b a s a l q u a r t z i t e s c o n c l u d e d h a t t h e q u a r t ­z t e s a r a l p a r t t h i c k b l a n k e t h a t was d e p o s i t e d as t h e s e a a n s g r e s s e d from w e e a s d u r i n g h e f i r st P a l e o z o i c i n v a s o n t h e w e e r n n t e r i o r . f o r m a t i on c r o s s e d i m e b o u n d a r i e s d e p o s o n e x t e n d e d e a s t w a r d. l a c k f o s s l s p r e v e n t s a c c u r a t e d a i n g t h is f o r m a t i o n . S t e w a r t W i l l i a m s 1 9 4 8 ) a s s g n s t h e B r i g h am q u a r t z i t e of Logan Q u a d r a n g l e t o t h e W a u c o b i a n. O p h i r s h a l e O p h i r s h a l e by F, L o u g h l 1 9 1 9 ) o r e x p o s u r e s n e a r t h e town O p h ir i n h e O q u i r r h M o u n t a i n s h e D u r s t M o u n t a i n - H u n t s v i l le a r e a i t c r o p s o u t a s h e T i n t i c q u a r t z t e p o o r ly e x p o s e d D e p r e s s o n s a r e f o r m e d a l o n g t h e t r i k e t he o r m a t i o n n o t c h p r e s e n t w h e r e v e r h e s h a l e i n t e r ­s e c t s r i d g e b e s t x p o s u r e s a r e a l o n g h e h i g h r i d ge - 14 - re sts wi th angular discorda nce on t he Pr ecambrian Fa rmi ng ­t on Canyon complex and i s conformably over lain by t he Ophir shale . In adjac ent areas where Prot e r ozoi c ( ?) qua r tzites ar e pr esent , it is di ff i cult t o place the contact between the t wo. Fr om obser va ti ons in these areas. Eardley and Ha t ch ( 1940b ) suggest that the contact i s one of both co n­f ormity and di s conform i t y . By c ommon us age the basal Cambrian quartz i tes north of t he Ogden Ri ver ar e r e f erred to as th e Br igham qua r t zite, and Tintic quartz i t e i s the te rminology appli ed t o t hose oc curre nces to the south. Many wri ter s have des­cribed the basal qua r tzites and conclud ed t hat the quar t ­z i tes ar e al l part of a thi ck bl anket t hat wa s deposi ted as the sea t r ansgressed f r om we s t t o eas t during t he firs t Pa le ozoic invas i on of the we s t ern i nteri or . The formation cr ossed t i me boundaries as depos i t i on extended e astward . The lack of fo ss i ls prevents an accurate da t ing of thi s for mati on. J. St ewart Williams ( 1948 ) ass i gns the Brigham quartz e Quadrang e the Waucobi an. Ophir shale . The Ophir shale was named by G. F. Loughl i n ( 1919 ) f or exposur es near the t own of Ophir in t he Oquirrh Mountains . In t he Dur st Mountain-Huntsv i lle area it cr ops out e as t of t he Tintic quartz i te and i s poorly exposed . Depress i ons are formed along the s trike of the f ormati on and a notch i s present whe r ever t he shale inter­sects a ridge . The best e xposures are along t he high ridge - • • e x t e n d i n g w e s t w a r d f r om D u r s t P e a k , i n t h e mouth of D u r st C a n y o n , and on t h e s t e e p s l o p e n o r t h of C o t t o n w o o d C r e e k. The O p h i r s h a l e r e p r e s e n t s a t r a n s i t i o n from c l a s t i c t o c a r b o n a t e d e p o s i t i o n d u r i n g t h e M i d d l e C a m b r i a n. S h a l e i s h e d o m i n a t e l i t h o l o g y b u t q u a r t z i t i c , s a n d y, a r k o s i c l i m y b e d s a r e p r e s e n t . c l a s t i c l a y e r s a re m o r e t o w a r d t h e b a s e t h e a r k o s i c l a y e r s a re p r e s e n t t h r o u g h o u t t h e f o r m a t i o n . m i c a c e o u s a p p e a r a n c e t h e s h a l e s d i s t i n c t i v e t h a t l i h o l o g ic c o r r e l a t i o n s w i t h i n t h e D u r s t M o u n t a i n - H u n t s v i l l e a r e a a re r e l i a b l e . O p h i r s h a l e s o g r e e n i s h - g r a y w i th a p a r t i c u l a r l y w e l l - d e v e l o p e d m i c a c e o u s s h e e n on t h e p a r t ­i n g s u r f a c e s . Most of t h e l a y e r s a r e f i s s i l e b u t some a re h e a v y - b e d d e d . East of D u r s t M o u n t a i n t h e O p h i r s h a l e is a b o u t f e e t t h i c k. O p h i r s h a l e c o n f o r m a b l e w i t h e u n i ts a b o v e b e l o w i t . s h a l y b e d a t t h e t o p h e T i n ­t i c q u a r t z i t e g r a d e i n t o t h e O p h i r , t h e i m e s t o n e s at t h e t o p t h e O p h i r g r a d e n t o t h e o v e r l y i n g u n d i f f e r e n t i ­a t e d l i m e s t o n e. Few f o s s i l s w e r e f o u n d i n t h e O p h i r s h a l e . A n n e l id ( ? ) r a i l s and f u c o i d s ( ? ) a r t h e b e d d i n g s u r ­f a c e s . e x c e l e n t t r i l o b i t e s p e c i m e n f o u n d n e a r t he b a s e t h e O p h i r i n t h e NW^, NE^j, s e c 3 4 , 3E. I n a r t i c u l a t e b r a c h i p o d s w e r e t h e o n l y o t h e r f o s s i l s f o u n d, R o b e r t B r i g h t , g r a d u a t e s t u d e n t a t t h e U n i v e r s i t y U t a h, - 15 - extendi ng westward f rom Dur st Peak, in the mouth of Durst Canyon, and on the steep slope nor t h of Cottonwood Creek . The Ophi r shale r epr esents a tra nsition from clastic to car bonate deposition during t he Middle Cambria n. Shale is t he dominate lithology but quartziti c, sandy, arkosic and limy beds are present. The clasti c layer s are more common toward the base and the arko sic layers ar e present throughout the formation . The micaceous and wormy appearance of the shale i s so di stinc tive that l i t hologic correlations within the Dur st Mountai n-Huntsville ar ea are reliable . The Ophir shale i s brown t o greeni sh-gray with particularly well- developed micaceous sheen the part­ing surfaces . the layers ar ss le but are heavy- bedded . Dur st Mountain the Ophir shale i s about 200 feet thi ck . The Ophir shale i s conformable wi t h the units above and below it. The shaly bed s at the top of t he Tin­tic quartzite grade into the Ophir, and the l imestones at the top of the Ophir grade i nto the over lyi ng undi ff erenti­ated l imestone . Few fos s ils were f ound in t he Ophir sha l e . Annelid (?) t rail s a nd fucoids ( ? ) ar e common on the bedding sur­faces. One excel l ent trilobite specimen was found near the base of the Ophir in the NW~ , NE~, sec . 34, T. 5N, R. 3E . Inarti culate br ac hipods were the only ot her fossils fo und . Robert Bright, gr aduate student at the Uni ver sity of Utah , i d e n t i f i e d t h e f o l l o w i n g g e n e r a: G l o s s o p l e u r a L i n q u l e l l a O b o l u s D i c e l l o m i s B r i g h t s t a t e s t h a t t h e l i t h o l o g y and t h e p r e s e n c e of G l o s s o p l e u r a s u g g e s t M i d d l e C a m b r i a n S p e n c e s h a l e or O p h ir s h a l e e q u i v a l e n t s. W h e e l e r ( 1 9 4 3 , p . 1813) s t a t e s t h a t t h e P i o c he s h a l e and t h e O p h i r s h a l e a r e f o r m a t i o n a l l y t h e same, b ut t h a t t h e s h a l e s a r e p r o g r e s s i v e l y y o u n g e r t o w a r d t h e e a s t. I t h a s b e e n t h o u g h t t h a t t h e O p h i r s h a l e a l s o c o r r e l a t es w i t h t h e S p e n c e s h a l e of t h e Logan Q u a d r a n g l e . The w r i t er h e s i t a t e s t o make t h i s c o r r e l a t i o n . P r e l i m i n a r y work by W i l l i a m L a r a w a y ( p e r s o n a l c o m m u n i c a t i o n ) , w o r k i n g a d j a c e nt t o t h e a r e a of t h i s r e p o r t on t h e n o r t h , r e v e a l s a s h a le u n i t w h i c h b e i e v e s t o t h e O p h i r s h a l e o v e r l a i n by a b o u t 50 f e e t of d o l o m i t e ; t h e d o l o m i t e i n t u r n i s o v e r l a in b y a n o t h e r s h a l e u n i t w h i c h i s p o s s i b l y t h e S p e n c e s h a l e. He f e e l s c o n f i d e n t t h a t b o t h t h e O p h i r and t h e S p e n c e a re much t h i n n e r t h a n t h e i r c o r r e l a t i v e s e i t h e r t o t h e n o r t h or t h e s o u t h . W h e e l e r 1 9 4 3 , p . s t a t e s: " I f t h e S p e n c e P i o c h e s h a l e s a r e d i s ­t i n c t t h e n o r t h e r n l i m i t t h e l a t t e r in n o r t h - c e n t r a l U t a h i s s o m e w h e r e b e t w e en B l a c k s m i t h F o r k , somewhere s o u t h P r o m o n t o r y P o i n t ." - 16 - identified the following genera: Glossopleura Lingu lel l a Obo lus Dicellomi s Bright s t ate s that the lithology and the pre sence of Glossopleura suggest Middle Cambrian Spence shale or Ophir shale equiva lents. Wheeler (1943, p. 1813) states that the Pioche shale and the Ophir s hale are f ormational ly the same, but that the shales are pr ogressively younger t oward the east. It has been thought that the Ophir shale also correlates with the Spe nce shale of the Logan Quadrangle. The writer he sitates to make this correlation . Preliminary work by William Laraway (per sona l communication) , working a9jacent to the area of this report on the north, revea ls a shale unit which he be l ieves to be the Ophir shale overlain by about 50 feet of dolomitej the do lomi te in turn i s overlain by another shale unit which is possibly the Spence shale. He feels confident that both the Ophir and the Spence are mu ch thinner than their correlatives either to the north or the south. Wheeler ( 1943, p. 1815) states : ( I'lf the Spence and Pioche shales are dis ­tinct the northern limit of the latter in north-central Utah is somewhere between Ogden and Blac ksmith Fork, and somewhere south of Promontory Point. II - 17 - I t i s p o s s i b l e t h a t t h e S p e n c e s h a l e was d e p o s i t e d d u r i ng a t e m p o r a r y r e g r e s s i o n of t h e s e a w h i c h e x t e n d e d s o u t h ­w a r d f r om t h e a r e a , t o t h e R i v e r . r e ­g r e s s i o n a f t e r t h e w e s t t o e a s t t r a n s g r e s s i o n d u r i ng w h i c h t h e O p h i r was d e p o s i t e d. C a m b r i a n l i m e s t o n e s and d o l o m i t e s . Above t he O p h i r s h a l e i s a s e q u e n c e of l i m e s t o n e s , d o l o m i t e s , and s h a l e s t h a t h a v e b e e n mapped as one u n i t . These r o c ks o u t c r o p f r om t h e s o u t h e r n l i m i t t h e a r e a t o w i t h i n f ew m i l e s t h e n o r t h e r n l i m i t . a r e b e s t e x p o s e d in t h e v i c i n i t y D u r s t M o u n t a i n , r e s i s t a n t c a r ­b o n a t e members w h i c h a r e s e p a r a t e d by t h i n b e d s of s h a le a r e e r o d e d i n t o s u c c e s s i o n r i d g e s d e p r e s s i o n s. F o r t h e m o s t p a r t t h e u n i t s a r e c o v e r e d by p r o l i f ic g r o w t h v e g e t a t i o n. b a s a l i s d a r k , a l m o s t b l a c k l i m e ­s t o n e t h a t i s m o s t l y o o l i t i c p i s o l i t i c ; w e a t h e r e d s u r ­f a c e s a r e d a r k g r a y - b l u e . m u d s t o n e m a t e r i al i s d i s t r i b u t e d a l o n g t h e b e d d i n g s u r f a c e s a t c l o s e ly s p a c e d i n t e r v a l s t h e s e a r e c o n n e c t e d s t r e a k s n o r m a l to t h e b e d d i n g . b l o t c h y , m o t t l e d , b a n d e d m u d s t o ne o c c u r s i n v a r i e t y p a t t e r n s a t o t h e r h o r i z o n s i n t he l i m e s t o n e . Small c o n c r e t i o n s of p y r i t e f r om o n e - e i g h t to o n e - q u a r t e r i n c h i n d i a m e t e r a r e common, A v e i n of i r on o x i d e c a n be t r a c e d a l o n g t h e s t r i k e of t h i s u n i t f r om t he b a s e t h e s t e e p s l o p e n o r t h C o t t o n w o o d C r e e k t o h a l f w ay - It is possible that the Spence shale was deposited during a temporary regression of the sea which extended south­ward from the Logan area, to the Ogden River. This re­gression was after the west to east transgression during which the Ophir was deposited. Cambrian limestones and dolomites. Above the Ophir shale is a sequence of limestones, dolomites. and shales that have been mapped as one unit . These rocks outcrop from the southern limit of the area to within a few miles of the northern limit. They are best exposed in the vicinity of Durst Mountain. The more resistant car­bonate members which are separated by thin beds of shale are eroded into a succession of low ridges and depressions. For the most part the units are covered a prolific growth of vegetation. The basal member is a dark, almost black lime­stone that is mostly oolitic and pisolitic; weathered sur­faces are dark gray-blue. Buff and brown mudstone material is distributed along the bedding surfaces and at closely spaced intervals these are connected by streaks normal to the bedding. The blotchy, mottled, and banded mUdstone OCcurs in a variety of patterns at other horizons in the limestone. concretions pyrite from one-eight to one quarter inch in diameter are common. vein iron oxide can traced along the strike this unit from the base of the steep slope north of Cottonwood Creek to halfway - up t h e s l o p e . J u s t n o r t h of D u r s t P e a k a n o t h e r o c c u r r e n ce o f i r o n o x i d e was n o t e d . Both of t h e s e l o c a t i o n s a re d o t t e d w i t h o l d p r o s p e c t h o l e s. The p e r s i s t e n c e of t h e n e x t y o u n g e r u n i t s c o u ld n o t be d e t e r m i n e d f o r e x p o s u r e s w e r e p o o r . Except f o r t he o u t c r o p s w e s t of D u r s t P e a k , w h e r e E a r d l e y ( 1 9 4 4 ) m e a s u r ed t h i s s e c t i o n , t h e s e q u e n c e l i t h o l o g y c o u l d n o t d e t e r ­m i n e d . However, d i s t i n c t d o l o m i e u n i t s w e r e o b s e r v ed b u t t h e r e l a t i o n s h i p b e t w e e n t h e two n o t d i s c e r n a b l e. f i r s t d a r k g r a y , b l a c k w e a t h e r i n g d o l o m i t e t h at c o n t a i n e d i g h t c o l o r e d o d s v e r m i c u l a r u b e l i k e mark­i n g s w h i c h a r q u a r t e r o h a l f i n c h n l e n g t h a b o ut o n e x t e e n t h n c h i n d i a m e t e r . s e c o n d l i g h t s - g r a y , f i n e l y l a m i n a t e d d o l o m i t e t h a w e a t h e r e d t o d u l l , c h a l k y w h i t e. h a e s t h a t a r e i n t e r b e d d e d w i t h t h e c a r b o n a te u n i t s a r e m o s t l y t h i n - b e d d e d r a n g e f r om t a n t o o l i v e - d r a b. a u t h o r f o u n d d e n t i f i e d L i n q u l e l a from t a n s h a le b e d n e a r t h e t o p t h e o r m a t o n . o n l y o t h e r f o s s i ls l o c a t e d i n t h e s e q u e n c e m e o n e s d o l o m i t e s w e re f o u n d i n t h e o a d c u t b e t w e e n t h e D u r s C a n y o n M i l l e r ' s G u l c h . f o l l o w i n g g e n e r a w e r i d e n t i f i e d t he w r i t e r i O b o l u s A c r o t h y r a L i n q u l e l l a - 18 - up the s lope. Jus t north of Durst Peak another occurrence of iron oxide was noted. Both of the se locations are dotted with old prospect holes. The persi stence of the next younger units could not be determined f or expo sures were poor. Except for the outcrops west of Durst Pea k , where Eard ley (1944) measured this section , the sequence of lithology could not be dete r~ mined. However , two di stinct dolomi t e units wer e observed but the relationshi p between the t wo was not· discernable. The first was a dar k gray, black wea thering dolomite that cont ained l ight colored r ods and ver micular t ube - like mark­ings which ar e a quarter t o half an inch i n length and about one s i xteenth of an i nch in diame ter . The second was a light­gray , finely laminated dolomite tha t weathered to a dull, cha lky white. The s ha l es that are interbedded with the carbonate units are mostly thin-bedded and range from tan to oli ve-drab. The author fou nd and i dentified Lingule l la f rom a tan shale bed near the top of the f ormat i on. The only other fos sils located in the sequence of l i me s t one s and dolomi tes were found in the r oad cut between the mouth of Durs t Canyon and Miller's Gulch. The following genera wer e identified by the writer: Obolus Acrothyra Lingulella - E a r d l e y ( 1 9 4 4 , p . 829) m e a s u r e d 1 , 3 7 5 + f e e t of C a m b r i a n r o c k a b o v e t h e O p h i r s h a l e w e s t of D u r s t P e a k, T h e s e r o c k s a r e c o n f o r m a b l e w i t h t h e O p h i r s h a l e , and a l so a p p e a r t o c o n f o r m a b l e w i t h t h e o v e r l y i n g D e v o n i a n r o c ks a l t h o u g h c o n s i d e r a b l e h i a t u s e x i s t s b e t w e e n t h e s y s t e m s . The p a u c i t y of f o s s i l s p r e v e n t e d t h e w r i t e r from s u b d i v i d i n g t h e C a m b r i a n l i m e s t o n e s and d o l o m i t e s as was h i s o r i g i n a i n t e n t i o n . E i t h e r s y s t e m s nomen­c l a t u r e c o u l d b r o u g h t i n t o -the a r e a m a p p e d , i . e . , the L o g a n Q u a d r a n g l e t h e S t o c k t o n F a i r f i e l d Q u a d r a n g l e s. W i t h c u r s o r y u d y t h e n o m e n c l a t u r e w o u l d t he m o s t s u i t a b l e f o r b o t h a r e a s a r e s i t u a t e d w i t h i n t h e M i d d le R o c k y M o u n t a i n P r o v i n c e t h e s t r i k e t h e C a m b r i a n r o c ks i s g e n e r a l l y n o r t h t o w a r d t h e Q u a d r a n g l e . However, t h e a u t h o r c o n c u r s w i t h E a r d l e y 1 9 4 4 ) i n f a v o r i n g t h e Great B a s i n t e r m i n o l o g y . G i l l u l y 1 9 3 2 ) i n h i s s t u d y t he S t o c k t o n F a i r f i e l d Q u a d r a n g l e s p r e s e n t e d v e r y e x c e l l e nt l i t h o l o g i c d e s c r i p t i o n s of t h e C a m b r i a n f o r m a t i o n s . The a u t h o r h a s c o m p a r e d t h e s e w i t h t h e d e s c r i p t i o n s g i v e n by J . S t e w a r t W i l l i a m s ( 1 9 4 8 ) and o t h e r s t u d e n t s of t h e Logan a r e a . D e s c r i p t i o n s of t h e p e c u l i a r t y p e s of l i t h o l o g y , such a s t h e b l o t c h y and m o t t l e d l i m e s t o n e s t h a t o c c u r w i t h i n t he D u r s t M o u n t a i n - H u n t s v i l l e a r e a c o u l d n o t be f o u n d i n l i t e r a ­t u r e c o n c e r n i n g t h e Logan a r e a . However, G i l l u l y ( 1 9 3 2 ) des c r i b e s C a m b r i a n r o c k s t h a t a r e v e r y s i m i l a r t o t h o s e found w i t h i n t h e mapped a r e a . The b l o t c h y and m o t t l e d l i m e s t o n es - 19 - Eardley (1944, p. 829) measured 1,375 ~ feet of Cambrian rock above the Ophir shale west of Durst Peak. These rocks are co nformable with the Ophir shale, and also appear to be conformable with the overlyi ng Devonian rocks although a considerable hiatus exists between the two systems. The paucity of fossils prevented the writer from subdividing the Cambrian limestone s and dolomites as was his origina l intention. Either of two systems of nomen­clatur e could be brought into ~he ar ea mapped, i.e., the Logan Quadrangle or the Stockton and Fairfield Quadrangles . With cursory s t udy the Logan nomenclature would seem the most suitable for both areas are situated within the Middle Rocky Mountain Province and the strike of the Cambrian roc~ is generally north toward the Logan Quadrangle. However, the author concurs with Eardley ( 1944) in favoring the Great Basin terminology. Gilluly ( 1932) in his study of the Stockton and Fairfield Quadr angles presented very excellent lithologic descriptions the Cambri an formations. The author has ~ompared these with the descriptions given by J. Stewart Williams 1948) other students the Logan area. Descriptions the peculiar types lithology, such as the blotchy mottled limestones that occur within the Durst Mountain-Huntsville area could not found in litera ­tUre concerning the area. Gilluly 1932) des­cribes Cambrian rocks that ar ver similar to those found within the ar ea. blotchy mottled limestones a n d d o l o m i t e s a r e v e r y s i m i l a r t o t h e H a r t m a n n and Bowman f o r m a t i o n s . The d a r k d o l o m i t e c o n t a i n i n g t h e v e r m i c u l ar t u b e - l i k e m a r k i n g s v e r y m i l a r t o t h e B l u e b i r d t y p e" a s i s t h e f i n e l y l a m i n a t e d d o l o m i t e t o t h e " L y n c h t y p e ". w r i t e r r e a l i z e s h a t d e f i n i t e c o r r e l a t i o n s c a n n o t u n t i l p a l e o n t o l o g i c a 1 e v i d e n c e s f o u n d . w r i t er i s t h e o p i n i o n t h a t t h e i m i l a r i t y t h e s e u n u s u al s e d i m e n t a r y o c k s s s t r o n g e v i d e n c e f o r t h e c o r r e l a t i on b e t w e e n h e D u r s t M o u n t a i n - H u n t s v i l l e a r e a t h e G r e at B a s i n . G i l l u l y h a s a s s i g n e d t h e H a t m a n n f o r m a t i o n s t o h e M i d d l e C a m b r i a n t h e d o l o m i te t o t h e M i d d l e C a m b r i a n. D e v o n i a n s y s t em T h r e e F o r k s ? ) f o r m a t i o n . T h r e e F o r k s (?) f o r m a t i o n c a n t r a c e d n o r t h w a d t h e s o u t h e r n l i m it o f t h e a r e a o n g t h e e a s l o p e D u r M o u n t a in t o w i t h i n t h r e e m i l e s t h e n o r t h e r n b o u n d a r y . s o ft D e v o n i a n f o r m a t i o n w e a t h e r t o t o p o g r a p h i c b e t w e en t h e e s i s t a n t C a m b r i a n M i s s i s s p p i a n l i m e s t o n e s. N o r t h C o t t o n w o o d C r e e k t h e f o r m a t i o n t r a c e d m a i n ly o n o p o g r a p h i c e v i d e n c e b e s t e x p o s u r e s s e e n on t h e r i d g e s l e a d i n g D u r s t M o u n t a i , p a t i c u l a r l y t h e h i gh r i d g e t h e h e a d M i l l e r G u l c h n o w h e r e was c o m p l e t e x p o s u r e t h e f o r m a t i o n f o u n d ; c o n s e q u e n t l y, t h e l i t h o l o g y i s n o t c o m p l e t e l y known. The T h r e e F o r ks , - 20 - and dolomites are ver y simi lar to t he Hartmann and Bowman formations. The dark dolomite conta ining the vermicular tube-like mar king i s very s i milar to the " Bluebir d type " as is the finely laminated dol omite to the IILynch type". The writer realizes t hat definite correlations cannot be made until paleo ntological evidence i s fou nd. The writer is of the opinion that the s imi larity of these unusual sedimentary r ocks i s strong evidence for the corre lation between t he Durst Mou nt ain-Huntsvi lle are a and the Gr eat Basin . Gilluly has assig ned the Ha r tma nn and Bowmann formations to t he Mi ddle Cambrian and the Lynch dolomite to the Middle and Upper Cambrian. Devonian system Three Forks ( 7) formation. The Three Forks (7 ) formati on can be traced northwa r d from the southern limit of the area mapped a l ong the ea s t slope of Dur s t Mountain to within three miles of the northern bou ndary. This soft Devonian formation weather s to a topographic low between the more r esistant Cambri an and Mississ i ppian limestones . North of Cottonwood Cr eek the formation was traced mainly on t opogra phic evidence . The best exposures can be seen on the ridges leading t o Durst Mountai n , pa r ticularly the high ridge a t the head of Miller ' s Gulch . However, nowhere was a complet e exposure of the formation found ; consequent ly , the 11 tho logy not completely Three Forks - 21 - f o r m a t i o n was named by A. C0 P e a l e ( 1 8 9 3 ) f o r t h e o c c u r ­r e n c e s i n t h e v i c i n i t y of T h r e e F o r k s , M o n t a n a. The T h r e e F o r k s ( ? ) f o r m a t i o n i s an e a r t h y , r ed t o t a n , s a n d s t o n e and s h a l e u n i t . In p l a c e s t h i n b e d s of l i m e s t o n e or d o l o m i t e c a n be f o u n d , e s p e c i a l l y n e a r t he b o t t o m of t h e s e c t i o n . The b a s a l l i m e s t o n e s a r e c o n ­s i d e r a b l y more a r e n a c e o u s t h a n t h e u n d e r l y i n g C a m b r i an l i m e s t o n e s ; t h e y a r e b l o t c h y and somewhat m o t t l e d . Sand­s t o n e s h a l e a r e i n t e r b e d d e d w i t h t h e l i m e s t o n e s t h e f o r m a t i o n g r a d e s i n t o e n t i r e l y c l a s t i c s e d i m e n t s. t h e h e a d M i l l e r ' s G u l c h t h e s a n d s t o n e s h a l e is b r i c k - r e d ; t h e s e c l a s t i c u n i t s a r e i n t e r b e d d e d w i t h t h in l a y e r s w h i t i s h w e a t h e r i n g l i m e s t o n e . C o n g l o m e r a t ic b e d s c o m p o s e d s m a l l r e d p i e c e s c r u m p l e d s h a l e , em­b e d d e d i n c a l c a r e o u s m a t r i x , a r e t h e u p p er p o r t i o n t h e f o r m a t i o n E a r d l e y , 1 9 4 4 ) „ p a r t i c u l ar t y p e c o n g l o m e r a t e i s b e l i e v e d t o d i a g n o s t i c t he T h r e e F o r k s. t h e h e a d M i l l e r ' s G u l c h t h e s e c t i o n was a, e s t i m a t e d t o be 750 f e e t t h i c k . The u p p e r and l o w e r c o n ­t a c t s w e r e n o t o b s e r v e d i n t h e f i e l d b u t t h e s i m i l a r i t y of a t t i t u d e s of t h e u n d e r l y i n g C a m b r i a n l i m e s t o n e s and t he o v e r l y i n g M a d i s o n l i m e s t o n e , i n d i c a t e s t h a t t h e D e v o n i an i s c o n f o r m a b l e w i t h t h e s e f o r m a t i o n s a l t h o u g h a c o n s i d e r a b le h i a t u s i s r e p r e s e n t e d by t h e l o w e r c o n t a c t . E d v a l s o n (1947, p . 43) s t a t e s t h a t no m a r k e d a n g u l a r u n c o n f o r m i t y i s p r e s e nt b e t w e e n t h e D e v o n i a n and t h e M a d i s o n l i m e s t o n e i n t he - formation was named by A. C. Peale (1893) for the occur-rences in the vicinity of Three Forks, Montana. The Three Forks (7) for mation is an earthy, red to tan, sandstone and shale unit. In places thin beds of limestone or dolomite can be found, especially ne ar the bottom of the section. The basal l ime stone s are con-siderably more arenaceous than the underlying Cambri an limestonesj they are blotchy and somewhat mottled. Sand­stone and shale are interbedded with the limestones and the formation grades upward into entirely clastic sediments. At the head of Miller's Gulch the sandstone and shale is brick-red; these clastic units are interbedded with thin layers of whitish weathering limestone. Co nglomeratic beds composed of small red pieces of crumpled shale, em-bedded in a calcareous matrix, are common i n the upper portion of the formation ( Eardley, 1944). This particular type of co nglomerate is believed to be diagnostic of the Three Forks. At the head of Miller's Gulch the sec ti on was ~ . estimated to be 750 feet thick. The upper and lower con-tacts were not observed in the field but the similarity of attitudes of the underlying Cambrian limestones and the overlying Madison limestone, indi cates that the Devonian is conformable with these formations although a considerable hiatus is repre sented by the lower contact. Edvalson (l94~ p. 43) states that no marked angular unconformity is present between the Devonian and the Madison limestone i n the - 22 - c e n t r a l W a s a t c h M o u n t a i n s. No f o s s i l s w e r e f o u n d i n t h e T h r e e F o r k s (?) f o r m a t i o n ; t h e r e f o r e , t h i s f o r m a t i o n can o n l y be t e n t a t i v e ­l y a s s i g n e d t o t h e D e v o n i a n s y s t e m . A c c o r d i n g t o E a r d l ey ( 1 9 4 4 ) t h e c h i e f r e a s o n f o r a s s i g n i n g t h i s g r o u p of b e d s to t h e D e v o n i a n s t e m s f r om t h e work of R i c h a r d s o n ( 1 9 1 3 ) i n the R a n d o l p h Q u a d r a n g l e . On t h e b a s i s of p a l e o n t o l o g i c a l e v i ­d e n c e , R i c h a r d s o n was a b l e t o c o r r e l a t e t h e T h r e e F o r k s of t h e R a n d o l p h Q u a d r a n g l e w i t h t h a t of t h e t y p e s e c t i o n . The l i t h o l o g i c s i m i l a r i t y b e t w e e n t h e T h r e e F o r k s t h e a r e a t h e R a n d o l p h Q u a d r a n g l e , p l u s t h e f a c t t h a t b o th a r e c o n f o r m a b l y b e o w t h e M a d i s o n l i m e s t o n e a r e t h e c r i t e r - i o r w h i c h t h e c o r r e l a t i o n i s made. E d v a l s o n ( 1 9 4 7 ) p o s t u l a t e s t h a t a c h a n n e l e x i s t ed i n D e v o n i a n t i m e w h i c h c o n n e c t e d t h e c e n t r a l W a s a t ch a r e a w i t h t h e R a n d o l p h a r e a . s t a t e s a l s o t h a t p o s i t i ve a r e a r e l i e f p r e s e n t b e t w e e n S a l t C i t y and O g d e n d u r i n g t h e M i d d l e D e v o n i a n , t h a t t h is a r e a a c t e d s o u r c e f o r t h e c l a s t i c s e d i m e n t i n t h is a r e a . t h i s c o r r e c t , t h e n t h e T h r e e F o r k s t h e a r e a c e r t a i n l y c o r r e l a t e w i t h t h e o c c u r r e n c e s t o t he n o r t h . J . S t e w a r t W i l l i a m s 1 9 4 8 ) d e s c r i b e s t h e J e f f e r s on f o r m a t i o n i n t h e a r e a c o n t a i n i n g m e m b e r s , t he u p p e r w h i c h i s t h e B e i r d n e a u s a n d s t o n e . l i t h o l o g i es o f t h e B e i r d n e a u t h e T h r e e F o r k s f o r m a t i o n t he - central Wasatch Mountains . No fossils were found in the Three Forks (7) formation; therefore, this formation can only be tentative­ly assigned to the Devonian system. According t o Eardley (1944) the chief rea son for assigning this group of beds to the Devonian stems from the work of Richa r dson (1913) in the Randolph Quadrangle. On the basis of paleontological ev i ­dence, Richardson was able to correlate the Three Forks of the Randolph Quadrangle with that of the type section. The litholog i c similarity between the Three Forks of the mapped area and the Randolph Quadrangle,plus the fact that both are conformably be l ow the Madison limestone are the criter­ior by which the correlation is made. Edvalson (1947) postulates that a channel existed in Upper Devonian time which connected the central Wasatch area with the Randolph area . He states also that a posi tive area of low relief was present between Salt Lake Ci ty and Ogden during the Lower and Middle Devonian, and that this area acted as a source for the clasti c sediment s in this area. If this i s correct, then the Three Forks of the mapped area must certainly correlate with the occurrences to the north. J. Stewart Williams ( 1948) describes the Jefferson formation in the Logan area as containing two members, the upper of which is the Beirdneau sand stone. The lithologies of the Beirdneau member and the Three Forks formation of the D u r s t M o u n t a i n a r e a a r e s i m i l a r and B r o o k s and A n d r i c h u k (1953) c o r r e l a t e t h e . t w o . They a l s o s t a t e : "The B e i r d n e a u member of t h e J e f f e r s o n f o r m a t i o n may be c h r o n o l o g i c a l l y a c l o s e c o r r e l a ­t i v e of t h e T h r e e F o r k s f o r m a t i o n ". M i s s i s s i p p i a n s y s t em M a d i s o n l i m e s t o n e . M a d i s o n l i m e s t o n e c r o p s out a t t h e s o u t h e r n l i m i t of t h e a r e a and s t r i k e s n o r t h w a r d to S h e e p H e r d C r e e k . C l i f f s M a d s o n l i m e s t o n e t h a t a r e t y p i ­c a l t h i s f o r m a t i o n e l s e w h e r e a r e o n l y l o c a l l y p r e s e n t w i t h in t h e a r e a . t h e M a d i s o n s t a n d s o u t f a i r l y s t e e p, r o u n d e d s l o p e a b o v e t h e T h r e e F o r k s f o r m a t i o n . M a d i s on l i m e s t o n e was P e a l e 1 8 9 3 ) f o r t h e M a d i s o n R i v e r in t h e T h r e e F o r k s , M o n t a n a a r e a , b u t a i l e d d e s i g n a t e t y p e a r e a. The M a d i s o n l i m e s t o n e i s t h i n - t o - m e d i u m b e d d e d, m e d i um t o d a r k g r a y , and t h e t e x t u r e i s c o m p a c t t o g r a n u l a r. t h i n b e d s f o o t ) a r e c o m p o s e d a l m o s t e n t i r e l y of f o s s i l f r a g m e n t s . l i t h o l o g y t h e M a d i s o n i n t h i s a r e a is v e r y s i m i l a r t o t h e s e c t i o n i n t h e Q u a d r a n g l e ( J . S t e w a rt W i l l i a m s , 1 9 4 3 ) ; h o w e v e r t h e l o w e r b l a c k s h a l e i s m i s s ­i n g i n t h e D u r s t M o u n t a i n - H u n t s v i l l e a r e a. E a r d l e y 1 9 4 4 ) m e a s u r e d 650 f e e t M a d i s o n l i m e s t o ne a t t h e h e a d M i l l e r ' s G u l c h , e a s D u r s t P e a k . l o w er 2 0 0 f e e t i s d a r k g r a y , d o l ' o m i t i c l i m e s t o n e w h i c h c o n t a i n s 2 - f o o t v e i n i r o n o x i d b a r i t e F l o a t i r o n o x i d e and - 23 - Durst Mountain area are similar and Brooks and Andrichuk ( 1953) correlate the. two. They also state: "The Beirdneau member of the Jefferson formation may be chronologically a close correla­tive of the Three Forks formation". Mississippian system Madison limestone. The Madison limestone crops out at the southern limit of the area and strikes nor thward to Sheep Herd Creek. Cliffs of Mad i son lime stone that are typ i ­cal of this formation elsewhere are only locally present within the area . However, the Madison stands out as a fairly s t eep, rounded 5~ope above the Three Forks formation . The Madison limestone ~as named by Peale ( 1893 ) for the Madi son River in the Three Forks , Montana area, but he f ailed t o designate a type area. The Madison l imestone i s thin- to - med i um bedded , medium to dark gray, and the texture i s compact to granular . Some thin beds (up t o 1 foot ) are composed almost entirely of foss il fragments. The lithology of the Madison in this area i s very similar to the section in the Logan Quadrangle (J . Stewart Williams, 1943); however , the lower black shale member is miss­ing in the Durst Mountain-Huntsville area. Eardley ( 1944) measured 600 feet of Madison limes t one at the head of Miller's Gulch, eas t of Durst Peak. The lower 200 feet is dark gray, dolomitic limestone which contains a 2- foot vein of iron ox id e and bari te . Float of iron oxide and b a r i t e c a n f o u n d t h e i d g e e a s t M i l l e r ' s G u l c h and n o r t h C o t t o n w o o d C r e e k a l o n g t h e s t r i k e C a m b r i a n l i m e - s t o n e d o l o m i t e s T h e r e f o r e , v e i n p r o b a b l y e x i s t s a l o ng t h e S p r i n g B r a n c h f a u l t s l a t e r t h a n t h e f a u l t , a l t h o u gh t h e r e l a t i o n s h i p s a r e o b s c u r e . f o o t m i d d l e u n i t p i nk a r g i l l a c e o u s l i m e s t o n e o v e r l a i n 4 0 0 f e e t d a r k g r a y, c h e r t y , f o s s i l i f e r o u s l i m e s t o n e c o m p l e t e h e s e c t i o n. J . S t e w a r t W i l l i a m s 1 9 4 3 ) m e a s u r e d f e e t M a d s o n l i m e ­s t o n e a t t h e s o u t h e r n b a s e D u r s t M o u n t a i n. The M a d i s o n l i m e s t o n e i s c o n f o r m a b l e w i t h t h e T h r ee F o r k s f o r m a i o n t h e B r a z e r f o r m a t i o n. f a u n a t h e M a d i s o n l i m e s t o n e h a s e s t a b l i s h ed a n e a r l y M i s s i s s i p p i a n . S t e w a r t W i l l i a m s , 1 9 4 3 ; H o l l a n d, 1 9 5 2 ) . f o l l o w i n g s p e c i m e n s w e r d e n t i f i e d D r W i l l i am S t o k e s: S t o k e s t h a t t h i s a s s e m b l e d g e i s p r o b a b l y M a d i s o n or D e s e r e t e q u i v a l e n t s . t h e f a u n a c o l l e c t e d i n t he v i c i n i t y S h e e p H e r d C r e e k s n o t d i a g n o s t i c t h e M a d i s o n, a n d S t o k e s o r a l c o m m u n i c a t i o n ) h i n k s i t m i g h b e t t e r c a l l t h e l i m e s t o n e i n h i s a r e a u n d i f f e r e n t i a t e d M i s s i s s i p p i an l i m e s t o n e . B r a z e r f o r m a t i o n . B r a z e r f o r m a t i o n i s e x p o s ed f r om t h e S p r i n g B r a n c h f a u l t o t h e s o u t h e r n l i m i t t h e a r e a. S t r a p a t o l l u s s p. S c h u c h e r t e l l a s p. T r i p l o p h y l l u m s p. M e e k o s p i r a s p. M i c h e l i n a s p. F e n e s t e l l i d b r y o z o an P r o d u c t i d b r a c h i o p o ds C r i n o i d f r a g m e n ts C o m p o s i t a s p. c o r a ls - 24 - barite can be fo und on the r idge east of Miller' s Gulch and north of Cott onwood Creek along the strike of Cambrian lime ­stone and dolomi tes . Therefore, a vein probably exists along the Spring Branch fault and i s later than the fault, although the relationships are obscure. A 50 foot middle unit of pink argillaceous limestone over lain by 400 feet of dark gray, cherty, fossiliferous limestone complete s t he section. J. Stewart Williams ( 1943) measured 755 feet of Mad i son lime-stone at the southern base of Durst Mountain. The Mad i son l i mestone i s conformable with the Three Forks forma t ion and the Brazer formation. The fauna of the Madi son limestone has es tablished an early Mississippian age ( J . Stewart Williams, 1943; Holland , 1952). The following specimens wer e i de ntified by Dr . William Lee Stokes : Strapatollus sp. Schucherte lla sp. Triplophyllum sp . Meekospira sp. Composita sp . , Mi chelina sp. Fene stellid bryozoan Productid bra chi opods Crinoid f ragments Cup corals Stokes comments that this assembledge is probably Madison or Deseret equivalents . However, the fauna collected in the vi cinity of Sheep Herd Creek i s not di agnostic of the Mad ison, and Stokes ( oral communication) t hinks it migh t be better to call the limestone in t hi s area undifferentiated Mississippian limestone. Brazer formation. The Brazer formation is exposed fr om the Spring Branch fault t o the southern limit of the are~ N o r t h of t h e f a u l t t h e B r a z e r i s m o s t l y c o v e r e d by t h e Knight c o n g l o m e r a t e . The B r a z e r f o r m a t i o n was named by R i c h a r d s on ( 1 9 1 3 ) f o r e x p o s u r e s i n B r a z e r C a n y o n , C r a w f o r d M o u n t a i n s, U t a h . The B r a z e r f o r m a t i o n i s c o m p o s e d of 600 f e e t of s a n d s t o n e , t a n t o r e d , w i t h some c a l c a r e o u s l a y e r s above w h i c h a r e a b o u t 100 f e e t medium g r a y f i n e l y c r y s t a l l i ne l i m e s t o n e s . The B r a z e r f o r m a t i o n l i e s c o n f o r m a b l e on t he M a d i s o n l i m e s t o n e . The b a s e of t h e B r a z e r was mapped at t h e f i r s t s a n d s t o n e on t o p of t h e M a d i s o n l i m e s t o n e . B e c a u se t h e p o o r e x p o s u r e s , f i e l d i d e n t i f i c a t i o n t h e B r a z er g e n e r a l l y b a s e d t h e p r e s e n c e s a n d y u n i t b e t w e en t h e u n d e r l y i n g M a d i s o n t h e o v e r l y i n g V a l l e y l i m e ­s t o n e p a l e o n t o l o g y. E a r d l e y 1 9 4 4 ) c o r r e l a t e d t h e B r a z e r f o r m a t i o n t h e D u r s t M o u n t a i n - H u n t s v i l l e w i t h t h a t t h e Quad­r a n g l e . t h e C a n y o n a r e a J . S t e w a r t W i l l i a m s (1943) a s s i g n e d f r om M e r a m e c i a n t h r o u g h l a t e C h e s t e r a n t i m e. P a l e o n t o l o g i c a l S a d l i c k 1 9 5 5 ) l e d h im t o r e - e v a l u ­a t i o n t h e B r a z e r f o r m a t i o n n o r t h e a s t M o r g a n . S a d l i ck f o u n d P e n n s y l v a n i a n f o s s i l s i n t h e u p p e r t h r e e p a r t of t h e f o u r t h u n i t s m e a s u r e d E a r d l e y 1 9 4 4 , p . 8 3 2 ). S a d l i c k f o r m a t i o n , t h e V a l l e y l i m e s t o n e, f o r t h e s e u p p e r u n i t s and l i m i t e d t h e B r a z e r t o 700 f e e t of s a n d s t o n e and l i m e s t o n e i n s t e a d of t h e o r i g i n a l 1 , 1 0 0 f e et a s m e a s u r e d by E a r d l e y . S a d l i c k s t a t e s t h a t t h e Round V a l l ey - 25 - North of the fault the Brazer is mos tly covered by the Knight conglomerate. The Brazer formation was named by Richardson (1913) for exposure s in Br azer Canyon, Crawford Mountains, Utah. The Brazer formation is composed of 600 feet of sandstone, tan to red, with some calcareous layers above which are about 100 fe~ medium gray finely crystalline limes tones. The Brazer formation lies conformable on the Madison limestone . The base of the Brazer was mapped at the first sandstone on top of the Madison limestone. Because of the poor exposures, field identification of the Brazer was generally based on the presence of a sandy unit between the underlying Madi son and the overlying Round Valley lime­stone and on paleontology. Eardley ( 1944) correlated the Brazer formation of the Durst Mountain-Huntsville with that of the Logan Quad­rangle. In the Weber Ca nyon area J . Stewart Williams (1943) assigned an age from Meramecian through late Chesteran time. Paleontological work by Sad lick ( 1955) led him to a re-evalu­ation of the Brazer formation northeast of Morgan. Sad lick found Pennsylvanian fossils in the upper three and part of the fourth units as measured by Eardley ( 1944, p. 832) . Sadlick named a new formation, the Round Valley lime s tone , for these upper units limited the Brazer to feet of sandstone limestone instead the original 1,100 feet as measured Eardley. Sad ck states that the Valley i s c o n f o r m a b l y o v e r t h e B r a z e r f o r m a t i o n, P e n n s y l v a n i a n s y s t em G e n e r a l s t a t e m e n t . The P e n n s y l v a n i a n r o c k s w i t h ­i n t h e a r e a a r e e x p o s e d s o u t h t h e S p r i n g B r a n c h f a u l t, e x c e p t f o r s m a l l o u t c r o p q u a r t z i t e ? ) s o u t h B e n n e t t C r e e k , P e n n s y l v a n i a n r o c k s s t r i k e n o r t h ; t he K n i g h t c o n g l o m e r a t e c o v e r s t h e s e r o c k s t o t h e n o r t h. The h e a v y c o v e r of m a n t l e and v e g e t a t i o n p r e v e n ­t e d t h e a u t h o r f r om a c c u r a t e l y m a p p i n g t h e P e n n s y l v a n i an f o r m a t i o n s . i s any one t h e P e n n s y l v a n i a n f o r m a ­t i o n s c o m p l e t e l y e x p o s e d a n d , t h e r e f o r e , l i t h o l o g i c d e s ­c r i p t i o n s v e r y g e n e r a l . S c h i c k ( 1 9 5 5) t o t h e s o u t h h a s a i d e d t h e w r i t e r c o n s i d e r a b l y i n p l a c i ng t h e c o n t a c t s . w r i t e r f o u n d t h e c o n t a c t s by S c h i c k t r a c e d t h em n o r t h w a r d. V a l l e y l i m e s t o n e . W a l t e r S a d l i c k ( 1 9 5 5) d e t a i l e d s t u d y t h e M i s s i s s i p p i a n « P e n n s y l v a n i an b o u n d a r y i n n o r t h - e a s t e r n U t a h r e s u l t h i s i n ­v e s t i g a t i o n named t h e Round V a l l e y l i m e s t o n e f o r m a t i o n. V a l l e y l i m e s t o n e i s l i g h t - g r a y , c h e r ty a n d d o l o m i t i c l i m e s t o n e . d o e s r e s i s t e r o s i o n p o o r l y and g e n e r a l l y f o r m s r o u n d e d h i l l s . S a d l i c k r e p o r t s t h a t t he V a l l e y l i m e s t o n e t h i n s f r o m f e e t i n V a l l e y, n o r t h e a s t M o r g a n , t o a b o u t f e e t i n B r e a d H o l l o w, n o r t h e a s t H u n t s v i l l e . f a u n a t h e V a l l ey - 26 - is conformably over the Brazer formation. Pennsylvanian system General statement . The Pennsylvanian rocks with­in the area are exposed south of the Spring Branch fault , except for a small outcrop of Weber quartzite ( 7) south of Bennett Creek . The Pennsylvanian rocks strike northj the Knight conglomerate covers these rocks to the north. The heavy cover of mantle and vegetation preven­ted the author from accurately mapping the Pennsylvanian formations. Nowhere is anyone of the Pennsylvanian forma ­tions completely exposed and, therefore, lithologic des~ criptions must be very general . The work of Schick (1955) to the south has aided the writer considerably in placing the contacts. The writer found the contacts as mapped Schick and traced them northward. Round Valley limestone. Walter Sadlick (1955) made a detailed study of the Mississippian-Pennsylvanian boundary i~ north-eastern Utah and as a re sult of his in­vestigation named the Round Valley lime stone formation. The Round Valley limestone is a light- gray, cherty, and dolomitic limestone. It does resist erosion poorly and generally forms rounded hills. Sadlick reports that the Round Valley limestone thins from 395 feet in Round Valley, northeast of Morgan, to about 150 feet in Dry Bread Hollow, northeast of Huntsville. The fauna of the Round Valley 27 - l i m e s t o n e a s s u r e s a l o w e r P e n n s y l v a n i a n age f o r t h e l i m e - s t o n e . l i m e s t o n e i n t e r f i n g e r s w i t h s a n d s t o n e s a t b o th t h e u p p e r and l o w e r c o n t a c t s. M o r g a n f o r m a t i o n . The Morgan f o r m a t i o n c r o p s out e a s t of t h e Round V a l l e y l i m e s t o n e and i s p o o r l y e x p o s e d. B l a c k w e l d e r ( 1 9 1 0 b ) p u b l i s h e d t h e name Morgan t h a t was g i v en b y B, Weeks f o r t h e r e d - b e d s b e l o w t h e Weber q u a r t z i t e in C a n y o n. The M o r g a n f o r m a t i o n i s an e a r t h y s a n d s t o n e t h a t is w h i t e t o p i n k on a f r e s h s u r f a c e , b u t w e a t h e r s r e d . Thin b e d s of s h a l e and l i m e s t o n e a r e p r e s e n t i n t h e u p p e r p o r t i on o f t h e f o r m a t i o n . G e n e r a l l y t h e f o r m a t i o n i s more t h i n ly b e d d e d i n t h e l o w e r p o r t i o n s t h a n t h e u p p e r p o r t i o n s . The M o r g a n f o r m a t i o n i s c o n f o r m a b l e w i t h b o t h t h e o v e r l y i n g and u n d e r l y i n g f o r m a t i o n s. L a r a w a y ( p e r s o n a l c o m m u n i c a t i o n ) s t a t e s t h a t t he M o r g a n i s p r o b a b l y a b s e n t t o t h e n o r t h . E a r d l e y ( 1 9 4 4 ) s t a t es t h a t t h e M o r g a n f o r m a t i o n i s a b o u t 1 , 0 0 0 f e e t t h i c k a t Round V a l l e y . J. S t e w a r t W i l l i a m s ( 1 9 4 3 ) a s s i g n s an e a r l y P e n n s y l ­v a n i a n age t o t h e M o r g a n f o r m a t i o n i n Round V a l l e y. Weber q u a r t z i t e . A s m a l l a r e a a l o n g t h e s o u t h e rn l i m i t t h e a r e a e a s t t h e K n i g h t c o n g l o m e r a t e is u n d e r l a i n t h e q u a r t z i t e . s m a l l e x p o s u r e q u a r t z i t e ( ? ) i s p r e s e n t i n r o a d c u t s o u t h B e n n e t t C r e e k. q u a r t z i t e was 1 8 7 6 ) f o r e x p o s u r e s in C a n y o n. - - limestone assures a lower Pennsylvanian age for the lime ­stone. The limestone interfingers with sandstones at both the upper and lower conta c t s . Morgan formati on. The Morgan formation crop s out east of the Round Valley limestone an'd i s poorly exposed . Blackwelder (1910b) published the name Morgan that was given by F. B. Weeks for the red~beds below the Weber quartzite in Weber Canyon. The Morgan formation is an earthy sandstone that is white to pink on a fresh surface, but weathers red. Thin beds of shale and limestone are present in the upper portion of the formation. Generally the formation is more thinly bedded in the lower portions than the upper portions. The Morgan formation is conformable with both the overlying and underlying formations. Laraway (pers onal communication) states that the Morgan is probably absent to the north. Eardley (1944) states that the Morgan formation is about 1,000 feet thick at Round Valley. J. Stewart Wi lliams (1943) assigns an early Pennsyl­vanian age to the Morgan formation in Round Valley. Weber quartzite. A small area along the southern limit of the area and east of the Knight conglomerate is underlain by the Weber quartzite. A small exposure of Weber quartzite (?) is present in a road cut south of Bennett Creek. The Weber quartzite wa s named by King ( 1876) for expos ure s in Weber Canyon. - The Weber q u a r t z i t e i s a m i s n o m e r f o r t h is f o r m a t i o n as i t i s m a i n l y c o m p o s e d of s a n d s t o n e w i t h some q u a r t z i t e b e d s . a m o u n t l i m e s t o n e d o l o m i t es a r e p r e s e n t e s p e c i a l l y n e a r t h e b o t t o m . s a n d s t o n es a r e f i n e t o medium g r a i n e d , t h i c k - b e d d e d t o m a s s i v e , and s o m e t i m e s c r o s s ^ - b e d d e d. S o u t h of B e n n e t t C r e e k a b a d l y b r o k e n and b r e c c i a t e d zone of f i n e - g r a i n e d , w h i t e , c a l c a r e o u s s a n d ­s t o n e and b r e c c i a t e d l i m e s t o n e i s e x p o s e d f o r a b o u t 50 y a r d s , i n r o a d c u t . E a r d l e y e x a m i n e d t h i s o u t c r op w i t h t h e w r i t e r b o t h c o n c l u d e t h a t t h i s i s p r o b a b ly q u a r t z i t e t h e b a s i s l i t h o l o g y . o u t c r op i s e x p o s e d a l o n g t h e s t r i k e t h e B e n n e t t C r e e k f a u l t. J . S t e w a r t W i l l i a m s ( 1 9 4 3 ) a s s i g n s a Lower P e n n s y l v a n i a n t h e q u a r t z i t e . K n i g h t c o n ­g l o m e r a t e o v e r l i e s t h e q u a r t z i t e w i t h a n g u l a r d i s - c o r d a n c e , b u t t h e u n d e r l y i n g f o r m a t i o n g r a d e s i n to t h e W e b e r . q u a r t z i t e i s 3 , 0 0 0 f e e t i n Weber C a n y o n E a r d l e y , 1 9 4 4 ), T r i a s s i c s y s t em T h a y n e s f o r m a t i o n . T h a y n e f o r m a t i o n c r o ps o u t t h e s o u t h s i d e h i l l , n o r t h B e n n e t t C r e ek T h i s s m a l l , i s o l a t e d e x p o s u r e i s p a r t i a l l y c o v e r e d by d e b r is o f K n i g h t b o u l d e r s . t h e b a s e t h e h i l l s m a l l r o ad c u t e x p o s e s s h a l e u n i t ; a b o v e t h i s o n l y few s e p a r a te - 28 - The Weber quartzite is a misnomer for this formation as it is mainly composed of sandstone with some quartzi te beds. Minor amount.s of limestone and dolomites are present especially near the bottom. The sandstones are fine to medium grained, thick-bedded to ma ss ive, and sometimes cross-bedded . South of Bennett Creek a badly broken and brecciated zone of fine-grained, white, calcareous sand ­stone and brecciated limes t one is exposed for about 50 yards, in a road cut. Dr. Eardley examined this outcrop with the writer and both conclude that this is probably Weber quartzite on the basis of lithology. This outcrop is exposed along the strike of the Bennett Creek fault. J. Stewart Wi lliams (1943) assigns a Lower Pennsylvanian age t o the Weber quartzite . The Knight con­glomerate overlies the Weber quartzite with angular dis­cordance, but the underlying Morgan formation grades info the Weber. The Weber quartzite is 3,000 feet in Weber Canyon ( Eardley, 1944). Trias sic sys tem Th~ynes formation. The Thayne s formation crops out on the south side of a low hill, north of Bennett Creek. This small, isolated exposure is partially covered by debris of Knight boulders. Near the base of the hill a small r oad cut exposes a shale unit ; above this only a f ew separate - b e d s of l i m e s t o n e , p e r h a p s e a c h a f o o t t h i c k , can be o b ­s e r v e d . The T h a y n e s f o r m a t i o n was named by B o u t w e l l ( 1 9 0 7) f r om t h e P a r k C i t y m i n i n g d i s t r i c t U t a h, A c a l c a r e o u s , t a n , and e a r t h y s h a l e u n i t makes up t h e l o w e r t h i r d of t h e h i l l . R i p p l e m a r k s and r a i n - d r op i m p r i n t s a r e f o s s i l s w e r e f o u n d w i t h i n t h e s h a l e. t h e s h a l e t h e l i m e s t o n e c r o p s o u t w h i c h h a s y i e l d ed f o s s i l s . b e d s c a n n o t t r a c e d a l o n g t h e s t r i ke a n d d i l i g e n t s e a r c h m u s t i n o r d e r t o l o c a t e t h e m. l i m e s t o n e s a r e t a n t o g r a y ; t h e t a n u n i t s a r e e a r t h y. D r . S t o k e s , e x a m i n e d t h e f o s s il c o l l e c t i o n s s t a t e d : f a u n a w e l l t h e l i t h o l o g y t h e s p e c i m e n s t h a t t h i s c o l l e c t i o n i s f r om t h e l o w er p a r t t h e T h a y n e s f o r m a t i o n , T r i a s s i c " . i d e n t i ­f i e d t h e f o l l o w i n g g e n e r a: O p h i c e r a s s p (?) M e e k o c e r a s s p (?) t h i c k n e s s t h i s o u t c r o p e s t i m a t e d t o be 2 0 0 f e e t ; h o w e v e r , n e i t h e r c o n t a c t i s e x p o s e d. T e r t i a r y s y s t em K n i g h t f o r m a t i o n . K n i g h t f o r m a t i o n named f o r e x p o s u r e s c o n g l o m e r a t e s a n d s t o n e n e a r K n i g ht S t a t i o n , c o n g l o m e r a t e c a l l e d W a s a t c h H a y d e n 1 8 6 9 ) , b u t V e a t c h 1 9 0 7 ) d e s i g n a t e d t h i s c o n g l o m e r a te a s t h e K n i g h t f o r m a t i o n t h e W a s a t c h g r o u p . K n i g ht - 29 - beds of limestone, perhaps each a foot thick, can be ob ­served. The Thaynes formation was named by Boutwell (1907) from the Park City mining district of Utah. A calcareous, tan, and earthy shale unit makes up the lower third of the hill. Ripple marks and rain-drop imprints are common. No fossils were found within the shale. Above the shale the limestone crops out which has yielded some fossils. The beds cannot be traced along the strike and a diligent search must be made in order to locate them. The limestones are tan to gray; the tan units are earthy. Dr. Wm. Lee Stokes, who examined the fossil collections stated: "The fauna as well as the lithology of the specimens show that this collection is from the lower part of the Thaynes formation, Lower Triassic lt • He identi ~ fied the following genera: Ophiceras sp . (7) Meekoceras sp . (7) The thicknes s of this outcrop was estimated to be 200 feet; however, neither contact is exposed. Tertiary ~ystem Knight formation . The Knight formation was named for exposures of conglomerate and sandstone near Knight Station, Wyoming. The conglomerate was called Wasatch by Hayden ( 1869), but Veatch ( 1907) designated this conglomerate as the Knight formation of the Wasatch group. The Knight f o r m a t i o n b l a n k e t s o l d e r s t r a t a i n t h e e a s t e r n n o r t h ­e a s t e r n p o r t i o n s t h e a r e a . o l d e r o s i o n s u r f a c e is f o r m e d t o p t h e K n i g h t t h i s f e a t u r e i s d i s c u s s ed u n d e r G e o m o r p h o l o g y . g e n t l y s l o p i n g r i d g e s s l o pe f r om t h i s h i g h f l a t s u r f a c e. The K n i g h t f o r m a t i o n i s a c o n g l o m e r a t e composed o f h e t r o g e n o u s a s s o r t m e n t p h e n o c l a s t s t h a t r a n g e in s i z e f r om p e b b l e s t o b o u l d e r s a s e i g h t f e e t i n d i a ­m e t e r . m o s t d i s t i n g u i s h i n g f e a t u r e t h i s f o r m a t i on i s t h e b r i c k - r e d s a n d y s h a l y m a t r i x . b o u l d e r y s u r ­f a c e , w h i c h r e s e m b l e s t h e H u n t s v i l l e f a n g l o m e r a t e , i s e v e r y ­w h e r e p r e s e n t t h e p h e n o c l a s t s a r e e a s i l y e r o d e d from t h e m a t r i x . b o u l d e r s a r e m a i n l y q u a r t z i t e s w h i c h h a v e b e e n d e r i v e d e i t h e r t h e P r o t e r o z o i c T i n t ic q u a r t z i t e s . a r e P a l e o z o i c l i m e s t o n e s s a n d ­s t o n e s . G n e i s s e s and s c h i s t s of t h e F a r m i n g t o n C a n y o n com­p l e x a r e r a r e l y f o u n d . t h e s o u t h s i d e C o t t o n w o od C r e e k t h e c o n g l o m e r a t e e r o d e s i n t o p i n n a c l e s. F o s s i l s h a v e n o t b e e n f o u n d i n t h e K n i g h t f o r m a ­t i o n i n t h e D u r s t M o u n t a i n - H u n t s v i l l e a r e a . H o w e v e r , E a r d l ey 1 9 4 4 ) t e n t a t i v e l y c o r r e l a t e s t h e K n i g h t t h i s a r e a w i th t h a t G a z i n 1 9 5 2 ) c o n c l u d e s t h a t t h e K n i g ht f o r m a t i o n i n s W a s a t c h i a n E a r l y E o c e n e ). t u f f . t u f f E a r d l e y 1 9 4 4 ) f o r t h e e x p o s u r e s a t t h e m o u t h C a n y o n i n V a l l e y . t u f f c o v e r s t h e w e s t e r n t h i rd ~ 30 - formation blankets older strata in the eastern and north­eastern portions of the area. An old erosion surface is formed on top of the Knight and this feature is di scussed under Geomorphology. Long, gently sloping ridges slope away from this high flat surface. The Knight formation is a conglomerate composed of a hetrogenous assortment of phenoclasts that range in size from pebbles to boulders as much as eight feet in dia­meter. The most distinguishing feature of thi s formation is the brick-red sandy and shaly matrix. A bouldery sur­face, which resembles the Huntsville fanglomerate, is every­where present as the phenoclasts are easily eroded away from the matrix. The boulders are mainly quartzites which may have been derived from either the Proterozoic or Tintic quartzites. Less common are Paleozoic limestones and sa nd­stones. Gneisses schists the Farmington Canyon com­plex are rarely found. Along the southside of Cottonwood Creek the conglomerate erodes into pinnacles. Fossils have not been found in the Knight forma ­tion in the Durst Mountain-Huntsville area. However , Eardley ( 1944) tentatively correlates the Knight of this area with that of Wyoming. Gazin ( 1952) concludes that the Knight formation in Wyoming i s Wasatchian ( Early Eocene). Norwood tuff. The Norwood tuff was named by Eardley ( 1944) for the exposures at the mouth of Norwood Canyon in Morgan Valley. The tuff covers the western third - 31 - o f t h e a r e a f o r m s d i v i d e b e t w e e n Ogden V a l l e y M o r g a n V a l l e y . f o r m a t i o n e r o d e s t o s m a l l, r o u n d e d , l i g h t ^ g r a y h i l l s . S l u m p i n g s m a l l l a n d s l i d es a r e t h e s e a r e p r o b a b l y a s s o c i a t e d w i t h t h e s a t u r a ­t i o n t h e f o r m a t i o n . c h a r a c t e r i s t i c t o p o g r a p h y and t h e l i g h t « * g r a y h i l l s l o p e s a r e u s e f u l f e a t u r e s o r t he i d e n t i f i c a t i o n t h e t u f f a e r i a l p h o t o g r a p h s i n t he f i e l d . The Norwood t u f f i s a w e l l s t r a t i f i e d , f a i r ly w e l l i n d u r a t e d f o r m a t i o n c l a s t i c p y r o - c l a s t i c m a t e r i a l m a r l y b e d s . l a y e r s t u f f, s a n d s t o n e , s h a l e a r e w h i t e , t a n , g r e e n , p i n k . u p p e r b e d s a r e f r i a b l e w h e r e a s t h e l o w e r b e d s u s u a y h a ve c o n c o i d a l f r a c t u r e . c o a r s e r s e d i m e n t s a r e m a s s i v e. l a y e r s t u f f a r e u n i f o r m i n t h i c k n e s s w i d e s p r e ad b u t p o o r e x p o s u r e s l o n g d i s t a n c e t r a c i n g d i f f i c u l t. E a r d l e y 1 9 4 4 ) n o t e d c o m p a c t , g r e e n i s h t u f f t h a t f o r m s l e d g e o v e r t h e low d i v i d e f r om Ogden V a l l e y t o M o r g a n V a l l e y. T h i s p a r t i c u l a r u n i t was shown t o be a v e r y f r e s h r h y o d a c i te t u f f w h i c h p r o b a b l y r e p r e s e n t s a v o l c a n i c d u s t f a l l i n a t e m p o r a r y l a k e s e v e r a l m i l e s a c r o s s . On t o p of t h i s t u f f a c r o s s - b e d d e d , medium g r a i n e d s a n d s t o n e was o b s e r v e d. B e c a u s e t h e p o o r o u t c r o p s t h e a b s e n c e t h e b a s a l c o n t a c t , t h e t h i c k n e s s t h e f o r m a t i o n c o u l d n ot b e e s t i m a t e d . S c h i c k 1 9 5 5 ) c a l c u l a t e d t h i c k n e s s o v er 4 , 7 5 0 f e e t . t u f f d e p o s i t e d u r f a c e - of the area mapped and forms a low divide between Ogden Valley and Morgan Valley a This formation erodes to sma ll , rounded, light-gray hills. Slumping and small l ands l i des are common; these are probably associated with the s at ura­tion of the formation. The characteristic topography and the light-gray hill slopes are useful features f or the identification of thE! tuff on aerial photographs or in the field. The Norwood tuff is a well stratified, fairly well indurated formation composed of clastic and pyr o­clastic material and some marly beds. The layers of t uff, sandstone, and shale are white , tan, green, and pink. The upper beds are friab l e whereas the lower bed s usua l l y have a concoidal fracture . The coarser sediments are ma ss i ve. The layers of tuff are uniform in thickness and wide spread but poor exposures make long distance tracing difficult. Eardley ( 1944) noted a compact, greenish tuff that forms a ledge over the di vide from Valley to Morg an Valley. This particular unit to very fre sh rhyodacite tuff which probably represents volcanic du fall in temporary lake several miles across . top thi s uff cross-bedded, grained sandstone observed . Because of the poor outcrops and the absence of the basal contact, the thickness of the formati on could not be estimated . Schick ( 1955) calculated a thicknes s of over "4,750 feet. The "Norwood tuff was deposited on a s urface of \ - g r e a t r e l i e f . S t r e a m s c a r r y i n g v o l c a n i c d e b r i s f r om t he s o u t h and e a s t d e p o s i t e d t h e i r l o a d i n l a k e s or on f l o od p l a i n s t h a t w e r e t h e n i n e x i s t e n c e. V e r t e b r a t e r e m a i n s d i s c o v e r e d by E a r d l e y ( 1 9 4 4) e s t a b l i s h e d a Lower O l i g o c e n e age f o r t h e Norwood t u f f. A l t h o u g h t h e t u f f c a n n o t be t r a c e d t o t h e P a r k C i t y v o l ­c a n i c f i e l d , t h e e r o s i o n a l r e m n a n t s b e t w e e n t h e t h e s i m i l a r i t i e s i t h o l o g y i n d i c a t e p o s s i b l e c o r r e l a ­t i o n . H u n t s v l l e f a n q l o m e r a t e . H u n t s v i l l e f a n - g l o m e r a t e f i r s t d e s c r i b e d L o f g r e n i n t he v i c i n i t y H u n t s v i l l e , U t a h . d i d n o t t h e f o r m a ­t i o n , b u t o r a l l y r e f e r r e d t o t h e H u n t s v i l l e , w h i c h i t g e n e r a l l y known. f o r m a t i o n forms b o u l d e r y s u r f a c e o v e r l a r g e p a r t t h e a r e a s t u d i ed a n d t h e c a p r o c k t h e h i l l s e s p e c i a l l y i n t he w e s t e r n p a r t . P l a c i n g t h e c o n t a c t t h e H u n t s v i l l e t h e u n d e r l y i n g t u f f d i f f i c u l t b e c a u s e i t h as b e e n w a s h e d f r om c a p p i n g d e p o s i t s t o f o rm f l o a t p e b b l e s c o b b l e s t h e Norwood s u r f a c e . S a m p l i n g d i g g i n g t h e u s e a e r i a l p h o t o g r a p h s a i d e d t h e a u t h or i n p l a c i n g t h e c o n t a c t . C r i t e r i a f o r d i s t i n g u i s h i n g t he t u f f p h o t o g r a p h s w e r e t h e c h a r a c t e r i s t i c s l u m p ­i n g t h e s m a l l r o u n d e d h i l l s , t h e g h t c o l o r . H u n t s v i l l e f a n g l o m e r a t e was a l s o d i f f i c u l t t o d i s t i n g u i sh f r om t h e s u r f a c e of e r o d e d K n i g h t c o n g l o m e r a t e . The , , _ J - 32 - great relief. Str eams carrying volcanic debris from the south and east deposited thei~ load in lakes or on flood plains that were then in ex istence . Vertebrate r emains di scovered by Eardley (1944) established a Lower Oligocene age for the Norwood tuff. Although the tuff ca nn ot be traced to the Park City vol­canic field, the erosional remnants be~twee n the two and the similarities of l ithology indicate a possible correla­tion. Huntsv i lle fanglomerate. The Huntsville fan­glomerate was first described by Ben E. Lofgren in the vicinity of Huntsville, Utah. He did not name the forma ­tion, but ora lly referred to i t as the Huntsville, a name by which it i s now gener all y known . This formation forms a bouldery surface over a large part of the area studied and i s the cap rock of many of the hills especi ally in the western part. Placing the contact of the Huntsville and the underlying Norwood tuff was diffic:ult because it has been washed down from capping depos its to form a float of pebbles and cobbles on the Nor wood ·surface. Sampling by digging and the use of aerial photographs aided the author in placing the conta ct . Criteria for di stinguishing the Norwood tuff on photographs were the characteristic slump ~ ing , the small rounded hills, and the l i ght color. The Huntsville fanglomerate also difHcult distinguish from the surface eroded Knight conglomerate. - H u n t s v i l l e - K n i g h t c o n t a c t was a r b i t r a r i l y p l a c e d a t B e n n e tt C r e e k . b o u l d e r y s u r f a c e t y p i c a l t h e f a n g l o m e r a te s e e m e d t o c o n t i n u o u s a c r o s s t h i s a r e a . K n i g h t o u t ­c r o p s i n C o t t o n w o o d C r e e k t h e S o u t h t h e R i v e r , a t t h e e d g e t h e H e r d M o u n t a i n s u r f a c e , i n d i c a te t h a t K n i g h t c o n g l o m e r a t e c a p s t h e n o r t h e a s t e r n a r e a . H u n t s v i l l e f a n g l o m e r a t e i s c o v e r e d w i t h s a g e b r u s h g r a s s e s w i t h v e r y t r e e s s h r u b s s i z e e x c e p t t h e a r e a b e t w e e n C o t t o n w o o d C r e e k D u r s t M o u n t a i n . b o u l d e r y s u r f a c e t o w h i c h t h e f a n g l o m e r a t e w e a t h e r s i s p o or f o r f a r m i n g r o a d s b u t t h e v e g e t a t i o n i t s u p p o r t s is s u f f i c i e n t f o r t h e g r a z i n g s h e e p c a t t l e . o u t c r o ps w h e r e t h e a l t i t u d e c o u l d a s c e r t a i n e d w e r e o b s e r v e d; a p p r o x i m a t e s t r i k e s d i p s w e r e e s t i m a t e d a e r i al p h o t o g r a p h s . H u n t s v i l l e f a n g l o m e r a t e i s m a i n l y s l o pe f o r m e r . i n s e v e r a l p l a c e s i t f o r m s r i d g e s t h a t a re t h e r e s u l t of e r o s i o n. The f a n g l o m e r a t e i s c o m p o s e d u n c o n s o l i d a t e d, r o u n d e d t o s u b - r o u n d e d p e b b l e s , c o b b l e s b o u l d e r s t h a t a re u n s o r t e d . m a t r i x i s b r o w n i s h - r e d s i l t s a n d The p h e n o c l a s t s a r e m a i n l y c o m p o s e d C a m b r i a n ? ) q u a r t z i t e s, P a l e o z o i c l i m e s t o n e s , t h e P r e c a m b r i a n F a r m i n g t o n g n e i s s es a n d s c h i s t s . G e n e r a l l y , t h e q u a r t z i t e s p r e d o m i n a t e , b ut l o c a l l y t h e o t h e r o c k t y p e s h e c h i e f c o n ­s t i t u e n t t h e f a n g l o m e r a t e . b e d d i n g i s o b s c u r e. t h i c k n e s s t h e H u n t s v i l l e f a n g l o m e r a t e could - 33 - Huntsville-Knight contact was arbitrarily placed at Bennett Creek. The bouldery surface typical of the fanglomerate seemed to be continuous across this area. But Knight ou t ~ crops in Cottonwood Creek and the South Fork of the Ogden River, at the edge of the Herd Mountain surface, indicate that Knight conglomerate caps the northeastern area. The Huntsville fanglomerate is covered with sage brush and grasses with very few trees or shrubs of any size except in the area between Cottonwood Creek and Durst Mountain. The bouldery surface to which the fanglomerate weathers is poor for farming and roads but the vegetation it supports is sufficient for the grazing of sheep and cattle . No outcrops 7 where the altitude could be ascertained were observedj approximate strikes and dips were estimated from aerial photographs. The Huntsville fanglomerate is mainly a slope former . However, in several places it forms ridge s that are the result erosion . T1'1e fanglomerate is composed of unconsolidated, rounded to sub-rounded pebbles, cobbles and boulders that are unsorted. The matrix is a brownish-red silt and sand . The ph enoclasts are mainly composed of Cambrian ( 7) quartzi tes, Paleozoic limestones, and the Precambrian Farmington gneisses and schists. Generally, the quartzites predominate, but locally one of the other r ock types may be t he chief con­stituent of the fanglomerate. The bedding is obscure. The thickness of the Huntsville fanglomerate could n o t be a c c u r a t e l y d e t e r m i n e d b e c a u s e n e i t h e r t h e u p p e r n or l o w e r c o n t a c t s w e r e d i s c e r n a b l e . t h e a u t h o r e s t i m a t e t h i c k n e s s s e v e r a l h u n d r e d f e e t t he e v i d e n c e t h e t h i c k n e s s t h e r e m n a n t s t h e d i s s e c t ed f a n g l o m e r a t e . L o f g r e n 1 9 5 5 ) p o s t u l a t e s t h a t t h e i n i t i a l t h i c k n e s s i n e x c e s s f e e t i n t h e a r e a s u r r o u n d i ng H u n t s v i l l e . S c h i c k 1 9 5 5 ) t h i c k n e s s 4 0 0 + f e et i m m e d i a t e l y s o u t h t h e a r e a s t u d i e d E g b e r t ( 1 9 5 4) s t a t e s t h a t t h e f a n g l o m e r a t e i s p r o b a b l y l e s s t h a n f e et i n t h e E a s t C a n y o n a r e a. The f a n g l o m e r a t e was m o s t l i k e l y d e r i v e d from t he K n i g h t c o n g l o m e r a t e . E a r d l e y ( 1 9 5 5 ) s t a t e s , " t h e n o r m al f a u l t i n g t h a t c a u s e d t h e d e p o s i t i o n t h e l a t e P l i o c e ne f a n g l o m e r a t e t e r m i n a t e d , r e g i m e n p e d i m e n t e r o s i on s e t i n t h e p i e d m o n t a r e a s w h i c h i n g o o d p a r t w e r e t h e a l lu v i a l f a n s " . d o w n - f a u l t e d b l o c k s w e r e t h e s i t e s s e d i ­m e n t a t i o n t h e u p l i f t e d a r e a s u p p l i e d h e s e d i m e n t s. l o w e r c o n t a c t n o t o b s e r v e d i n t h e f i e ld b u t t h e a u t h o r b e l i e v e s t h a t t h e H u n t s v i l l e f a n g l o m e r a t e un-c o n f o r m a b l y o v e r l i e s t h e t u f f . p r i n c i p a e v i ­d