Geology of the South Fork of the Ogden River area, Weber County, Utah

The South Fork of the Ogden River area is in eastern Weber County , Utah approximately two miles east of the town of Huntsville and comprises a portion of the northcentral Wasatch Mountains. The rocks exposed in the area range in age from Pre- cambrian to Quaternary. The Precambrian consists of quart- zite, quartzitic sandstone, arkosite, and phyllite (10,000-feet) ; the Cambrian rocks are meta-quartzite', limestone, dolomite and shale (3500 feet); the Ordovician is limestone5 dolomite and shale (600+feet); the Silurian rocks are largely arenaceous dolomite (243- feet); the Devonian is dolomite, arenaceous limestone and dolomite, sandstone, and shale (1144 feet); the Mississippian system is represented largely by limestone and sandstone (3300- feet); the Pennsylvanian is limestone and sandstone. The Eocene Knight (?) formation, which once covered the entire area, is a cobble and boulder conglomerate with sandstone lenses; Quaternary deposits consist of Lake Bonneville sediments and alluvium. The Upper Cambrian and base of the Ordovician are not exposed in the area. The Paleozoic strata were found to correlate with the formations of the Logan auadrangle. Detailed measured sections are included. Except for minor disconformities, sedimentation was probably continuous from Precambrian to Pennsylvanian time. No evidence for an unconformity could be found at the base of the Cambrian. The area is located very near the southern limit of Ordovician and Silurian deposition; neither system is represented in the Uinta Mountains to the south. The most important structural feature of the area is a north-trending syncline. The trace of the Willard (?) thrust is believed to be exposed in the western part of the area near Ogden Valley.

GEOLOGY OF THE SOUTH FORK OF THE OGDEN RIVER AREA, WEBER COUNTY, UTAH b y W i l l i a m L a r a w ay t h e s u b m i t t e d t o t h e f a c u l t y t he U n i v e r s i t y of U t a h i n p a r t i a l f u l f i l l m e nt t h e 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 S c i e n ce D e p a r t m e n t G e o l o g y .. U n i v e r s i t y U t ah J u n e s 1958 SOlITH R lVER AREA . COUNTY. IITAH by William H. Laraway A the;s i s submitted to the faculty of the Univ e rsity o ~ Ut ah in partial fulfillment of ~he r equirements for the degree of Master of Science Depar tment of Geology Un ~v e r si t y of Utah June. 1958 UNIVERSITY OF 1.11 li8Ri.RY T h i s T h e s i s f o r t h e M. S. d e g r ee W i l l i a m H, L a r a w ay h a s b e e n a p p r o v e d by • - / ; - : C h a i r m a n , S u p e r v i s o r y C o m m i t t ee R e a d e r , S u p e r v i s o r y C o m m i t t ee R e a d e r JySupervisory Comcd.ttee H e a d , M a j o r D e p a r t m e nt A D e a n , r a d u a K e S c h a ol 4 9 8 0 2 0 This Thesis for t he M. S. degree by Wi lliam H. Lar away has been approved by --zu-==~ ~r~<A-J .Chairman, Supervisory Committee · d . . ~----,- /~~ - Reader, Supervisory Committee Reader COITInl' ..... t tee Head, Major Department Dean, G 498020 5 /.& • ABSTRACT « • • • • • . . • « . » • . . » • • • • • • • • vi ACKNOWLEDGMENTS vi INTRODUCTION # 1 i L o c a t i o n • P u r p o s e • • • • • • • • • » • • • • • • • • • • • • F i e I d Work • • • • • • • « • • • • • • • • • • • • P r e v i o u s G e o l o g i c I n v e s t i g a t i o n s 2 GEOGRAPHY . • , 4 T o p o g r a p h y and D r a i n a g e . . . . . . . 4 C l i m a t e and V e g e t a t i o n 4 Roclc E x p o s u r e s « • • • • • • • • • • • • • • • • • -5 Si.,, LA r XGRAPHY . « « « » » . . . < « • . • • » « • • • « » « • ~j P r e c a m b r i a n S y s t e m • • . • • P r o t e r o z o i c ( ? ) Rocks C a m b r i a n S y s t e m . . . • G e n e r a l S t a t e m e n t . B r i g h a m Q u a r t z i te L a n g s t o n F o r m a t i o n U t e F o r m a t i o n • B l a c k s m i t h D o l o m i t e . . . . ..17 M i d d l e U p p e r ( ? ) C a m b r i a n U n d i f f e r e n t i a t e d . 19 O r d o v i c i a n S y s t e m • « . . * » 20 G a r d e n C i t y F o r m a t i o n ....20 F i s h - H a v e n D o l o m i t e 23 S i l u r i a n S y s t e m • . • » L a k e t o w n D o l o m i t e •••••25 D e v o n i a n S y s t e m « • 27 G e n e r a l S t a t e m e n t 27 W a t e r C a n y o n F o r m a t i o n « 28 J e f f e r s o n F o r m a t i o n 30 T h r e e F o r k s F o r m a t i o n 34 M i s s i s s i p p i a n S y s t e m 38 M a d i s o n L i m e s t o n e 38 B r a z e r F o r m a t i o n • 42 P e n n s y l v a n i a n S y s t e m • • • • • 43 G e n e r a l S t a t e m e n t • 43 V a l l e y L i m e s t o n e • • •..44 D u r s t G r o u p © • • 45 T e r t i a r y S y s t e m 46 K n i g h t ( ? ) F o r m a t i o n 46 Q u a t e r n a r y . S y s t em 47 L a k e B o n n e v i l l e D e p o s i t s <> 47 A l l u v i a l D e p o s i t s • • • * i i i 4 8 TABLE OF CONTENTS ABSTAACT • ACKNOWLEDGHENTS. INTRODUCTION • Location • o .. • o • • o • .. • .. .. .. . Purpose •• • a .. Field Work • Previous Geologic ~ • • Q o. Investigat,ions GEOGRAPHY . . . ~ . . . • Topography and Drainage • Climate and Vegetation • Rock Exposures • • STRP.T IGRAPHY • • • .. . Precambrian System • • Proterozoic (?) Rocks • • • .. " " • • • Cambrian System.. • o .. • .. .. General Statement .. Brigham Quartzite Langston Formation • " " 0 · " .. " • .. .. • • • • • • .. .. • • • • • • • • • • .. • • .. • • .. • • .. • • • • • • • • • • • • • • • • • • • " . • • • • .. .. .. · .. • • • .. " .. " • • • • • • • • ... • • e • • • • • • • • • • • • • • • • " • • • • • • Ute Formation .. Blacksmith Dolomite Middle and Upper (?) Cambrian Undifferentiated .. Ordovician System .. " Garden City Formation Fish-Haven Dolomite. " · .. • • • • · .. . · " • · ... . . . " Silurian System. .. .. • • • • • • · .. v Laketown Dolomite .. 0 • • • • o • • • o 0 0 • • • Devonian System • • • General Statem8ct. o • • • • • • Wate~ Canyon Formation Jefferson Formation. Three Forks Formation. ~ MissisSippian System •• Madison Limestone •• Brazer Formation • • • • • o Pennsylvanian System •• General Statement • 0 • Round Valley Limestone Durst Group • 0".. Tertiary System 0 • 0 o. Knight (?) Formati'on 0 .. Quaternary .System • .. • 0 Lake Bonneville Deposits Alluvial Deposits. 0 • 0 iii • • • • o o o • • o .. o • o o • o o • • • • o o o o • • o • • • • • • • • • • • • • • • • • • o • • • o • • • • • • • • • • • .. • • • • o • o • .. o • • • • • • o • • • " • • .. .. • • • • • • • • • • • • • • • • • • • • · .. • • • • • • • • • • • • • vi • viii .. • • • • • • • .. • • • 1 1 1 2 2 4 4 4 5 6 6 8 8 9 12 15 17 19 20 20 23 • 25 25 • 27 • 27 28 30 34 • 38 • 38 • 42 • 43 • 43 • 44 ; 45 • 46 • 46 • 47 • 47 • 48 STRUCTURE . . . . . . * 49 G e n e r l S t a t e m e n t . . . . . . . 49 T h r u s t s . . . . . . . . . . . . 49 W i l l a r d ( ? ) T h r u s t . 49 F o l d s . . . . . . . . . . . . . . . . 52 B e a v e r C r e e k S y n c l i n e • • 52 U n c o n f o r m i t i e s . . . . . . . . . . . . 52 GEOMORPKQLOGY . . . . . . . . . . . . . . . . . . . . . . 54 G e n e r a l S t a t e m e n t . . . . . . . . . . . 54 H e r d M o u n t a i n S u r f a c e • • • • • • • • 54 Weber V a l l e y S u r f a c e • • • • • • • • • • • 55 ECONOMIC GEOLOGY . . . . . . . . . 57 GEOLOGIC HISTORY . . . . P r e c a m b r i a n • • C a m b r i a n 53 O r d o v i c i a n S i l u r i a n ..... 59 D e v o n i a n 60 M i s s i s s i p p i a n and P e n n s y I v a n i a n 60 P e r m i a n and M e s o z o i c T e r t i a r y • 62 BIBLIOGRAPHY i v STRUCTURE . • • • • • • Gener a l Statement . • Thr usts . .. .. .. .... .. Ihllard (? ) Thrus t Folds .... .. .. • • • • • • Beaver Creek Syncline .. Unconformities .. .. .. , .. .. .. .. .... ........ .. .. .... .... .... .. • • .. .. .... .... .. • .. .. .. .. .. .. .... .... • • .. .. .. .. .. .... .. .... • .. .......... .... • .. .. .... .. • GEOI'.oRPHOWGY • .. .. .. .. .. .. .. .... .. .. .. .. .. · , . Gener al Stat ement • • Herd Mountain Surface Weber Va lley Surface .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. • • • • •• • • .. .. .. .. • ECONOMIC GEOWGY • • • .. .. .. .. .. .. .. .. .. .. • • GEOWGIC HISTORY Precambrian Cambrian .. • .. .. .. .. .. .. • • • • • • • Ordovician and Silurian Devonian • • • • • • • • • • • • • • • • Mississippian and Pennsylvanian Permian and Mesozoic.. .... .. Tertiary .. .. ...... .. .. .. • • • • • BIBLIOGRAPHY .. .. .. .. .. .. .. .. .. .. .. iv • • • • • • • · .. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • .. .. .. .. .. .. ,I 49 49 49 49 52 52 52 54 54 54 55 57 58 58 58 59 60. 60. 61 62 64 F o l l o w i n g p a g e G e o l o g i c a n d c r o s s - s e c t i o n t h e S o u t h F o r k t h e R i v er C o r r e l a t i o n l o w e r M i d d le C a m b r i a n i n N o r t h e r n U t a h . . • . C o r r e l a t i o n D e v o n i a n S y s t e m N o r t h e r n U t a h I n d e x Map G a r d e n C i t y f o r m a t i o n and F i s h Haven c o l o m i t e • • • » » • • • • • 26 W a t e r C a n y o n a n d J e f f e r s o n f o r m a t i o ns i n K i e s e l C a n y o n 26 s p e c i m e n T h r e e F o r k s f o r m a ­t i o n s h o w i n g c a s t s h a l i t e c r y s t a l s 37 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 e x p o s e d i n K i e s e l C a n y o n • • • • • • • • • • • 38 L o c a l l y c o n t o r t e d s t r a t a t he M a d i s o n l i m e s t o n e . • „ 38 C l i f f s K n i g h t ( ? ) f o r m a t i o n . • 46 V i e w e a s t w a r d i n V a l l e y s h o w i ng P r o t e r o z o i c s t r a t a and H e r d M o u n t a in s u r f a c e . . 54 L a k e B o n n e v i l l e t e r r a c e s n e a r t he " M o n a s t e r y " 54 ILLUSTRATIONS Following, Plate ,I Geologic map and cross-section of the South Fork of the Ogden River page { 1-' Area ••••• • • • • • • • • • • In pocket II III 1 2 3 4 Correlation of Lower and Middle Cambrian in Northern Utah • • Correlation of Devonian System in 'Northern Utah • • • • • • • • • • Index Map Garden City fon::ationand Fish Haven colomite • • • ,0 • Q • 0 • • • • • Water Canyon and Jefferson formations in Camp Kiesel Canyon ••• • • • Hand specimen of Three Forks forma­tion showing casts of halite crystals 5 Three Forks formation and Madison limestone exposed in Camp Kiesel 6 7 8 Canyon • • • • • • • • 0 . . .0. Locally contorted strata of the 'Madison limestone •• 0 ••• Cliffs of Knight (?) formation • • "! • View eastward in Ogden Valley showing Proterozoic strata and Herd Mountain surface • • • • • • • • • • • • • 9 Lake Bonneville terraces near the . . .0. . . . . . . 8 27 1 26 26 37 38 38 46 54 54 ABSTRACT T h e S o u t h F o r k t h e R i v e r a r e a i s i n e a s t e rn W e b e r C o u n t y , U t a h a p p r o x i m a t e l y two m i l e s e a s t of t h e town o f H u n t s v i l l e and c o m p r i s e s a p o r t i o n of t h e n o r t h c e n t r al W a s a t c h M o u n t a i n s. T h e r o c k s e x p o s e d i n t h e a r e a r a n g e i n a g e f r o m P r e - c a m b r i a n t o Q u a t e r n a r y . P r e c a m b r i a n c o n s i s t s q u a r t - z i t e , q u a r t z i t i c s a n d s t o n e , a r k o s i t e , p h y l l i t e ( 1 0 , 0 0 0- f e e t ) ; t h e C a m b r i a n r o c k s a r e m e t a - q u a r t z i t e ' , l i m e s t o n e, d o l o m i t e and s h a l e 3 5 0 0 f e e t ) ; t h e O r d o v i c i a n i s l i m e s t o n e5 d o l o m i t e and s h a l e ( 6 0 0 + f e e t ) ; t h e S i l u r i a n r o c k s a r e l a r g e ly a r e n a c e o u s d o l o m i t e 243- f e e t ) ; t h e D e v o n i a n i s d o l o m i t e, a r e n a c e o u s l i m e s t o n e d o l o m i t e , s a n d s t o n e , s h a le ( 1 1 4 4 f e e t ) ; t h e M i s s i s s i p p i a n s y s t e m i s r e p r e s e n t e d l a r g e ly b y l i m e s t o n e s a n d s t o n e (3300- f e e t ) ; t h e P e n n s y l v a n i an i s l i m e s t o n e s a n d s t o n e . E o c e n e K n i g h t ( ? ) f o r m a t i o n, w h i c h o n c e c o v e r e d t h e e n t i r e a r e a , i s a c o b b l e and b o u l d er c o n g l o m e r a t e w i t h s a n d s t o n e l e n s e s ; 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 B o n n e v i l l e s e d i m e n t s a l l u v i u m . U p p er C a m b r i a n b a s e t h e O r d o v i c i a n a r e n o t e x p o s e d i n t he a r e a . The P a l e o z o i c s t r a t a w e r e f o u n d t o c o r r e l a t e w i t h t he f o r m a t i o n s of t h e Logan a u a d r a n g l e . D e t a i l e d m e a s u r e d s e c t i o ns a r e i n c l u d e d. v i • 497690 ABSTRP.CT The South Fork of the Ogden River area is in eastern Weber County~ Utah approximately two miles east of the town of Huntsville and comprises a portion of the northcentral Wasatch Mountains. The rocks exposed in the area range in age from Pre-cambrian to Quaternary. The Precambrian consists of quart­zitc, quartzitic sandstone + t arkosite, and phyllite (10,000- feet); the Cambrian rocks are meta-quartzite, limestone, dolomite and shale ( 3500+ feet); the Ordovician is limestone, dolomite and shale (600+ feet); the Silurian rocks are largely arenaceous dolomite (243+ feet); the Devonian is dolomite, arenaceous limestone and dolomite, sandstone, and shale 1144 feet); the Mississippian system is represented largely by limestone and sandstone 3300+- feet); the Pennsylvanian is limestone and sandstone. The Eocene Knight (?) formation, which once covered the entire area~ is cobble boulder conglomerate with sandstone lenses; Quaternary deposits con-sist of Lake Bonneville sediments and alluvium. The Upper Cambrian and base of the Ordovician are not exposed in the area. Paleozoic strata were found to correlate with the formations the ouadrangle. Detailed measured sections are included. vi E x c e p t f o r m i n o r d i s c o n f o r m i t i e s 9 s e d i m e n t a t i o n p r o b a b l y c o n t i n u o u s f r om P r e c a m b r i a n t o P e n n s y I v a n i a n t i m e. e v i d e n c e f o r u n c o n f o r m i t y c o u l d b e f o u n d a t t h e b a se o f t h e C a m b r i a n . a r e a s l o c a t e d v e r y n e a r t h e s o u t h e rn l i m i t of O r d o v i c i a n and S i l u r i a n d e p o s i t i o n ; n e i t h e r s y s t em i s r e p r e s e n t e d i n t h e U i n t a M o u n t a i n s t o t h e s o u t h. T h e m o s t i m p o r t a n t s t r u c t u r a l f e a t u r e of t h e a r e a is a n o r t h - t r e n d i n g s y n c l i n e . The t r a c e of t h e W i l l a r d ( ?) t h r u s t i s b e l i e v e d t o be e x p o s e d i n t h e w e s t e r n p a r t of t h e a r e a n e a r V a l l e y. Except for minor disconformities, sedimentation was probably continuous from Precambrian to Pennsylvanian time . No evidence for an unconformity could be found at the base of the Cambrian. The area i s located very near t~southern limit of Ordovician and Silurian deposition; neither system is r epr esented in the Uinta Mountains to the south. The most i mportant structural feature of the area is a north-trending syncline . The trace of the Willard (?) thrust is believed to be exposed in the western part of the area near Ogden Va lley. ACKNOWLEDGEMENTS T h e w r i t e r i s p a r t i c u l a r l y g r a t e f u l t o D r . W i l l i am L e e S t o k e s , t h e D e p a r t m e n t G e o l o g y , U n i v e r s i ty o f U t a h , f o r h i s g u i d a n c e i n t h e p r e p a r a t i o n t h i s , r e p o r t. H i s h e l p f u l s u g g e s t i o n s b o t h i n t h e f i e l d d u r i n g t he w r i t i n g t h e m a n u s c r i p t a r e d e e p l y a p p r e c i a t e d. T h a n k s a r e e x p r e s s e d t o D r s . J . E a r d l e y and Norman W i l l i a m s f o r c r i t i c a l r e a d i n g t h e m a n u s c r i p t. T h e w r i t e r i s i n d e b t e d t o M r s . C h r i s t i n a B a lk o f t h e M e x i c o S c h o o l M i n e s f o r i d e n t i f i c a t i o n t he C a m b r i a n f a u n a . D o n a l d B l u e F r e d e r i c k E. S c h a e f f e r h e l p f u l l y a s s i s t e d i n t h e m e a s u r i n g s t r a t i - g r a p h i c s e c t i o n s. A e r i a l p h o t o g r a p h s of t h e a r e a w e r e g e n e r o u s l y p r o v i d ed b y t h e S t a n d a r d O i l Company of C a l i f o r n i a. S p e c i a l t h a n k s a r e d u e my p a r e n t s f o r e n c o u r a g e m e n t and f i n a n c i a l h e l p and t o my w i f e M a r i l y n f o r h e r c o n f i d e n c e and p a t i e n c e . v i i i ACKNOWLEDGB1ENTS The writer is particularly grateful to Dr. William Lee Stokes, Head of the Department of Geology, University of Utah, for his guidance in the preparation of this report. His helpful suggestions both in the field and during the writing of the manuscript are deeply appreciated. Thanks are expressed to Drs. Armand J. Eardley and i~orman C. Williams for critical reading of the manuscript. The writer is indebted to Mrs. Christina Lockman Balk of the New Mexico School of ·Mines for identification of the Cambrian fauna. Mr. Donald M. Blue and Mr. Frederick E. Schaeffer helpfully assisted in the measuring of strati­graphic sections. Aerial photographs of the area were generously provided by the Standard Oil Company of California. Special thanks are due my parents for encouragement and financial help and to my wife Marilyn for her confidence and patience. viii INTRODUCTION L o c a t i o n T h e S o u t h F o r k of t h e Ogden R i v e r a r e a i s i n e a s t e rn Weber C o u n t y , U t a h a p p r o x i m a t e l y two m i l e s e a s t of t h e town o f H u n t s v i l l e . It c o m p r i s e s 85 s q u a r e m i l e s i n p a r t s of T o w n s h i p s 6 a n d 7 N o r t h 9 R a n g e s 2 a n d 3 E a s t , S a l t Lake B a se " a n M e r i d i a n . a r e a i s p a r t t h e n o r t h - c e n t r a l W a s a t ch a s d e s i g n a t e d by E a r d l e y ( 1 9 4 4 ) . It i s b o u n d e d on t h e s o u th b y t h e S o u t h F o r k t h e R i v e r , t h e n o r t h T o w n s h ip l i n e N o r t h , t h e w e s t V a l l e y , t h e e a s t by d i v i d e a s L i g h t n i n g R i d g e. T h e a r e a b e r e a c h e d f r o m H u n t s v i l l e v i a U t a h Highway 3 9 , a p a v e d s e c o n d a r y r o a d w h i c h f o l l o w s t h e c o u r s e of t he S o u t h F o r k t h e R i v e r . E x c e p t i n g t h e r o u t e s of U t ah H i g h w a y a n d t h e K i e s e l C a n y o n r o a d , t h e a r e a i s a c c e s ­s i b l e o n l y j e e p " , h o r s e b a c k o r f o o t. P u r p o s e T h e c h i e f p u r p o s e s t h e i n v e s t i g a t i o n w e r e t o t he a r e a i n d e t a i l , t o m e a s u r e a n d d e s c r i b e s t r a t i g r a p h i c s e c ­t i o n t h e P a l e o z o i c f o r m a t i o n s , t o c o r r e l a t e t he e x p o s e d r o c k s w i t h t h o s e i n a d j a c e n t a r e a s. IN"'TRODUCT ION Location The South Fork of the Ogden River area is in eastern Weber County, Utah approximately t'\vO miles east of the town of Huntsville. It comprises 85 square miles in parts of TO\Vnships 6 and 7 North~ Ranges 2 and 3 East, Salt Lake Base ':;'.d Neridian. The area is part of the north-central Wasatch as designated by Eardley (1944). It is boun,d ed on the south by the South Fork of the Ogden River~ on the north by Township line 8 North, on the west by Ogden Valley, and on the east by a divide known as Lightning Ridge. The area may be reached from Huntsville via Utah Highway 39, a paved secondary road which follows the course of the South Fork of the Ogden River. Excepting the routes ofOtah Highway 39 and the Camp Kiesel Canyon road, the area is acces~ sible only by " jeep", horseback or foot. Purpose The chief purposes of the investigation were to map the area in detail, to measure and describe a stratigraphic sec= tion of the Paleozoic formations, and to correlate the exposed rocks with those in adjacent areas. I N D E X MAP S H O W I N G L O C A T I O N OF S O U T H FORK O F THE OGDEN R I V E R A R E A - F I G . I , ) \ I ." \ l \ B O X \, " ""-, \ EL D ER W E Ogd en . D , / ' ,.I[~ , ~ .. . J Logon ,~-~ . :.. • ..: Hyrum C A C B E R l , ) \ Rondolph J / I I H E i R C H ~ ... Morgon I;, '\i]---'1,L ___ I I UTA H I //r. L I ... ,/ .f-fr ===.==='"'i, ...... L_ __ _ r ",: . r-~ :;".::",,:,:>"., 5011 Loke Cily o !) 10 ~ I , ' , . I L.. __ = ____ J IND EX MAP SHOWING LOCA T i ON OF SOU TH FORK OF THE OGDEN RI VER AREA - FIG. F i e l d Work F i e l d w o r k s t a r t e d i n J u n e c o m p l e t e d in t h e a t t h a t y e a r . d o n e w i t h t h e a id o f U . S . S o i l C o n s e r v a t i o n S e r v i c e a e r i a l p h o t o g r a p h s a t a c a l e 1 : 2 0 , 0 0 0 . b a s e p r e p a r e d - f r o m t h e p h o t o ­g r a p h s by t h e s l o t t e d t e m p l a t e m e t h o d , t h e c u l t u r e , d r a i n ­a g e and g e o l o g y t r a n s f e r r e d m e a n s of a r a d i a l p l a n i m e t r ic p l o t t e r . S e c t i o n c o r n e r w e r l o c a t e d i n t h e f i e l d p o s s i b l e p l o t t e d h e b a s e m a p . s t r a t i g r a p h ic s e c t i o n s w e r e m e a s u r e d B r u n t o n - t a p e t r a v e r s e. P r e v i o u s G e o l o g i c Work The. g e o l o g y of 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 was f i r s t i n v e s t i g a t e d by w o r k e r h e e a r l y T e r r i t o r i a l s u r v e ys B r a d l e y 1 8 7 2 ) , w i t h t h e G e o l o g i c a l S u r v e y s t he T e r r i t o r i e s , made o b s e r v a t i o n s i n t h e " W h a s a t c h " M o u n t a i ns f r o m O g d e n , U t a h t o F o r t H a l , I d a h o . 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 a l s o p r e s e n t e d b r i ef d e s c r i p t i o n of t h e W a s a t c h R a n g e , G. E, G i l b e r t ( 1 8 9 0 ) , in h i s m o n o g r a p h B o n n e v i l l e , b r i e f l y d i s c u s s e d t he s e d i m e n t s s h o r e l i n e f e a t u r e s i n V a l l e y . E x t e n s i ve w o r k B o u t w e l l ( 1 9 0 7 ) i n 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 a d d e d g r e a t l y t o t h e k n o w l e d g e of t h e s t r a t i g r a p h y of t he g e n e r a l a r e a. 2 Field Work Field work was started in June of 1957 and completed in the l at e summer of that year. Mapping was done with the aid of U.S. Soil_Conservation Service aerial photogr aphs at a s cale of 1:20 ,000. A base map was prepared -from the photo­gr aphs the slotted template method, and the culture, drain­age and geology transferred by means of a radial planimetric plotter. Section corner s wer e located in the field when possible and plotted on t he base map. The stratigraphic sections were measured by Br unton-tape traverse. Previous Geologic Work The. geology of t he north-central Wasatch Mountains was first investigated worker s of t he early Territorial surveys. Bradley ( 1872), with the U. S. Geological Surveys of the Territories, observations in the Whasatch11 Mountains from Ogden, Utah to Fort Ha l l, Idaho. Hague and Emmons ( 1877) of the 40th Parallel Survey also pres ented a brief description the Wasatch Range. E. Gilbert 1890) in his monograph on Lake Bonneville, briefly discussed the "-­sediments and shoreline features in Ogden Valley. Extensive work by Boutwell (1907) in the Park City mining district added greatly to the knowledge .of the stratigraphy of the general area. B l a c k w e l d e r ( 1 9 1 0 a ) made t h e f i r s t s t u d i e s of t h e S o u th F o r k a r e a i n c o n n e c t i o n w i t h e p o r t t h e p h o s p h a t e d e p o s i ts o f n o r t h e r n U t a h . B l a c k w e l d e r ( 1 9 1 0 b ) a l s o r e p o r t e d on t he g e o l o g y i n t h e v i c i n i t y V a l l e y . 1927 M a n s f i e l d p u b l i s h e d c o m p r e h e n s i v e r e p o r t t h e g e o l o gy a n d m i n e r a l r e s o u r s e s of s o u t h e a s t e r n I d a h o w h i c h c o n t r i b u t ed g r e a t l y t o t h e k n o w l e d g e of t h a t r e g i o n. D e t a i l e d t u d i e s of t h e R a n d o l p h q u a d r a n g l e by R i c h a r d s on ( 1 9 4 1 ) and of t h e Logan u a d r a n g l e by W i l l i a m s ( 1 9 4 8 ) c o n t r i ­b u t e d t o t h e k n o w l e d g e of t h e g e o l o g y of n o r t h - e a s t e r n U t a h. S e v e r a l p a p e r s p e r t a i n i n g t o t h e s t r u c t u r e , s t r a t i g r a p h y and g e o l o g i c h i s t o r y t h e r e g i o n h a v e b e e n p u b l i s h e d E a r d l ey ( 1 9 3 0 , 1 9 4 0 , 1 9 4 4 , 1 9 5 1 ) , A l s o a n u m b e r of u n p u b l i s h ed t h e s e s 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 U n i v e r s i t y U t ah s t u d e n t s u n d e r t 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 C, W i l l i a m s. T h e s t u d y t h e S o u t h F o r k a r e a t h e n o r t h - c e n t r al W a s a t c h M o u n t a i n s was u n d e r t a k e n t h e w r i t e r i n t h e S p r i ng o f a t t h e s u g g e s t i o n W i l l i a m S t o k e s , Head o f t h e D e p a r t m e n t G e o l o g y , U n i v e r s i t y U t a h. 3 Blackwelder (1 910a) made the first studies of the So~th Fork area in connection with a r eport on the phosphate deposits of 'nor thern Utah . Blackwelder (1910b) also reported on the geology in the vicinity of Ogden and Ogden Valley . In 19,2 7 Mansfield published a comprehensive report on the geology and mineral resourses of southeastern Idaho which contributed greatly to the knowledge of t hat r egion. Detailed s t~di es of the Randolph q~ad rangle by Richar dson (1941) and of the Logan q ~adrangle by Williams (1948) contri- ,b~ted to the knowledge of the geology of north-eastern Ut ah. .." Several pape.r s pertaining to the structure, stratigraphy and geologic history of the region have been p~blished by Eardley (1930 , 1940, 1944, 1951). Also a number of ~np~blished . theses on local areas have been wri tten by University of Utah students under the Direction of Doctors A. J. Eardley and N. C. Williams. The study of the South Fork area of the north-centra l Wasatch Mountains was undertaken by the writer in the Spring of 1957 at the suggestion of Dr. William Lee Stokes, Head of the' Department of Geology, University of Utah. GEOGRAPHY T o p o g r a p h y D r a i n a ge E l e v a t i o n s i n t h e t h e s i s a r e a r a n g e f r o m 5100 f e e t in O g d e n V a l l e y , t o a p p r o x i m a t e l y f e e t H i g h w a y a t t he n o r t h e r n e d g e t h e a r e a . l a n d s u r f a c e r i s e s a b r u p t ly f r o m t h e f l o o d p l a i n t h e S o u t h F o r k t h e R i v e r to t h e e x t r e m e l y l e v e l t e r r a i n t h e H e r d M o u n t a i n s u r f a c e. T h e a r e a n o r t h t h e r i v e r i s c h a r a c t e r i z e d r o l l i n g h i l ls e x c e p t w h e r e t h e t r i b u t a r i e s h a v e c u t b e l o w t h e T e r t i a ry c o n g l o m e r a t e s t o e x p o s e t h e P a l e o z o i c r o c k s . t h e s e d e e p er c a n y o n s t h e t o p o g r a p h y i s v e r y r u g g e d. T h e a r e a i s d r a i n e d t h e S o u t h F o r k of t h e Ogden R i v er a n d i t s m a j o r t r i b u t a r i e s , M a g p i e C r e e k , C o b b l e C r e e k , B e ar W a l l o w C r e e k , B e a v e r C r e e k . S o u t h F o r k f l o w s w e s t ­w a r d t o t h e P i n e V i e w R e s e r v o i r and t h e n c e t h r o u g h Ogden C a n y o n t o t h e G r e a t S a l t L a k e. C l i m a t e V e g e t a t i on T h e c l i m a t e t h e S o u t h F o r k a r e a i s s e m i - a r i d and H u n t s v i l l e h a s a n n u a l r a i n f a l i n c h e s snow a n d c o l d make t h e a r e a i n a c c e s s a b l e f o r f i e l d w o r k f r o m l a te O c t o b e r t o e a r l y J u n e. T h e f o o t h i l l s i n t h e l o w e r e l e v a t i o n s a r e l a r g e ly c o v e r e d by s a g e b r u s h . At h i g h e r e l e v a t i o n s s c r u b oak GEOGRAPHY Topography and Drainage Elevations in the thesis area range from 5100 feet i n Ogden Valley, to appr oximately 6600 feet on Highway 39 at the northern edge of the area. The land surface rises abruptly from the flood plain of the South Fork of the Ogden River to the extremely level terrain of the Herd Mount ain surface . The area north of the river is characte rized by rolling hills, except where the tributaries have cut below the Tertiary conglomerates to expose the Paleozoic rocks~ In these deeper canyons the topography is very r.ugged . The area is drained by the South Fork of the Ogden River and its major tributaries, Magpie Creek, Cobble Creek, Bear Wallow Creek, and Be~ver Creek. The South Fork flows west­ward to the Pine Vi ew Reservoir and thence through Ogden Canyon to the Great Salt Lake . Climate and Vegetation The climate of the South Fork area is semi-arid and Huntsville has an annual ra infal l of 28 inches . Heavy snow and cold make the area inaccessable for field work from late October to early June. The foothills in the lower elevations are largely covered by sagebrush. At higher elevations s crub oak a n d m o u n t a i n m a h o g a n y a r e common. Q u a k i n g a s p e n a r e f o u nd i n t h e c a n y o n b o t t o m s , s c a t t e r e d c o n i f e r s g r o w n o r th f a c i n g s l o p e s. R o c k E x p o s u r es T h e P a l e o z o i c s t r a t a a r e b e s t e x p o s e d i n s t r i k e c a n y o ns w h e r e t h e o v e r l y i n g T e r t i a r y c o n g l o m e r a t e h a s b e e n s t r i p p ed a w a y . e x p o s u r e s a r e f o u n d i n t h e c a n y o n t h e S o u th F o r k n e a r M a g p i e C a n y o n a n d f u r t h e r e a s t i n t h e 8 8 S o u t h F o rk N a r r o w s " . m a i n t r i b u t a r i e s t o t h e S o u t h F o r k , Dry B r e a d H o l l o w a n d K i e s e l C a n y o n , a l s o a f f o r d e x p o s ­u r e s . The P r e c a m b r i a n s t r a t a a r e w e l l e x p o s e d i n a w i de b e l t f r o m t h e m o u t h t h e S o u t h F o r k t o M a g p i e C a n y o n. 5 and mountain mahogany are common . Quaking aspen ar~ found in the canyon bottoms, and scattered conifers grow on north f~cing slopes . Rock Exposures The Paleozoic strata are best exposed in strike canyons where the overlying Tertiary conglomerate has been stripped away_ Good exposures are found in the canyon of the South Fork near Magpie Canyon and further east in the USouth Fork Narrows". Two main tributaries to the South Fork, Dry Bread Hollow and Camp Kiesel Canyon, also afford good expos­ures . The Precambrian strata are well exposed in a wide belt from the mouth of the South Fork to Magpie Canyon . • • STRATIGRAPHY • • R o c k s e x p o s e d i n t h e S o u t h F o r k t h e R i v e r a r e a ' r a n g e i n a g e f r o m P r e c a m b r i a n t o Q u a t e r n a r y . P r e c a m b r i an a n d P a l e o z o i c s t r a t a c r o p o u t o n l y w h e r e m a j o r s t r e a m s h a v e c ut t h r o u g h t h e E o c e n e K n i g h t f o r m a t i o n w h i c h b l a n k e t s t h e a r e a. T h e r o c k s e x p o s e d a r e e n t i r e l y s e d i m e n t a r y ; h o w e v e r , t h e P r o - t e r o z o i c ( ? ) h a s b e e n s l i g h t l y m e t a m o r p h o s e d i s c l a s s e d as • a m e t a s e d i m e n t. T h e P r o t e r o z o i c ? ) C a m b r i a n s t r a t a c r o p o u t i n w i de n o r t h - t r e n d i n g b e l t f r om V a l l e y t o M a g p i e C r e e k . Ordo­v i c i a n S i l u r i a n r o c k s c r o p o u t i n t h e " N a r r o w s 1 1 t h e S o u th F o r k . D e v o n i a n , M i s s i s s i p p i a n , P e n n s y l v a n i a n r o c k s com­p r i s e t h e r e m a i n d e r t h e P a l e o z o i c s e c t i o n c r o p o u t : in K i e s e l C a n y o n a n d B r e a d H a l l o w . t o p s t he C a m b r i a n and P e n n s y l v a n i a n s y s t e m s a r e n o t e x p o s e d . 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 s s e d i m e n t s d e p o s i t e d i n L a k e B o n n e ­v i l l e , a l l u v i u m . i g n e o u s r o c k s a r e e x p o s e d i n t h e a r e a. P r e c a m b r i a n S y s t em P r o t e r o z o i c ? ) Rocks T h e o l d e s t r o c k e x p o s e d i n t h e a r e a i s t h i c k s e q u e n c e of P r o t e r o z o i c ( ? ) q u a r t z i t e p h y l l i t e . T h e s e s t r a t a f o r m t he n o r t h t r e n d i n g m o u n t a i n m a s s f r o m t h e m o u t h the* S o u t h F o rk t o M a g p i e C a n y o n. Rocks exposed in the South Fork of the Ogden River area range in age from Precambria.o to Quaternary. The Precambrian and Paleozoic strata crop out only where major s treamS have cut through the Eocene Knight formation which blankets the area. The r ocks exposed are entirely sedimentary ; however, the Pro­terozoic (?) has been slightly metamorphosed and is classed as -a metasediment. The Proterozoic ( 1) and Cambrian strata, crop out in a wide north-trending belt from Ogden Valley to Magpie Creek. Ordo­vician and Silurian rocks crop out in the IINarrows" of the South Fork. Devonian, Mississippian, and Pennsylvanian rocks com­prise the remainder of the Paleozoic section and crop out I in Camp Kiesel Canyon and Dry Bread Hallow. The tops of t he Cambrian Pennsylvanian systems are not exposed. Qua~~r ­nary deposits consists of sedimentOs depOSited in Lake Bonne­vllle, and alluvium. No igneous rocks "are exposed in the area. Precambrian System Proterozoic ( 1) Rocks Th~ oldest rock exposed in the area is a thick sequence of Proterozoic 1) quartzite and phy llite. These strata form the north trending mountain mass from the mouth of the' South Fork to Magpie Canyon. E a r d l e y 1 9 4 4 ) r e c o g n i z e s d i v i s i o n s w i t h i n t h e P r o t e r ­o z o i c ( ? ) s e q u e n c e : l o w e r f o o t u n i t i n t e r b e d d e d q u a r t - z i t e , a r k o s i t e p h y l l i t e u p p e r f o o t u n i t r u s t w e a t h e r i n g q u a r t z i t i c s a n d s o n e . q u a r t z i t e s q u a r t z i t ic s a n d s t o n e s a r e b u f f , p i n k , p u r p l e a n d m a r o o n . p a r t i c l es r a n g e f r o m m e d i u m t o c o a r s e g r a i n e d p e b b l e s t o i n c h e s in d i a m e t e r a r e o c c a s i o n a l l y f o u n d . p h y l l i t e s c o n s t i t u t e m i n o r t h e s e c t i o n a r e d a r k g r a y a n d g r e e n. No e v i d e n c e of an u n c o n f o r m i t y was d e t e c t e d b e t w e e n t he P r o t e r o z o i c ( ? ) s t r a t a and t h e o v e r l y i n g B r i g h a m q u a r t z i t e. T h e u p p e r P r e c a m b r i a n q u a r t z i t e s and l o w e r B r i g h a m a r e r e m a r k ­a b l y h o m o g e n e o u s , and a l t h o u g h s m a l l l e n s e s of c o n g l o m e r a t e w e re f o u n d , w i d e s p r e a d b a s a l c o n g l o m e r a t e n o t e d. E a r d l e y ( 1 9 4 4 ) i n d i s c u s s i n g t h e P r o t e r o z o i c ( ? ) r o c ks o f t h e n o r t h - c e n t r a l W a s a t c h s t a t e s : " T h e s e d i m e n t s w e r e p r o b a b l y d e p o s i t ed i n d e e p t r o u g h in. l a t e P r o t e r o z o ic a n d e a r l y C a m b r i a n t i m e s a n d o v e r l ap t h e A r c h e o z o i c r o c k s t h e n o r t h e rn U t a h h i g h l a n d . a r e p r o b a b l y s e p a ­r a t e d f r o m t h e o v e r l y i n g C a m b r i a n s t r a ta b y an u n c o n f o r m i t y , b u t i n t h e t r o u gh a r e a t h e u n c o n f o r m i t y n o t f o u nd e x c e p t i n t h e C o t t o n w o o d u p l i f t of t he c e n t r a l W a s a t c h ". T h e t h i c k n e s s of t h e P r o t e r o z o i c S e c t i o n i s e s t i m a t e d t o be 1 0 , 0 0 0 f e e t . The b a s e of t h e S e c t i o n i s n o t e x p o s e d i n t he S o u t h F o r k a r e a , and t h e u n d e r l y i n g A r c h e o z o i c F a r m i n g t on 7 Eardley ( 1944) recognizes two divisions within the Proter-azoic (?) sequence: a lower 3000 foot unit of interbedded quart-zite, arkosite and phyllite and an upper 7000 foot unit of rust - weathering quartzitic sands t one. The quartzites and quartzitic sandstones are buff, pink, purple and maroon. Sand particles range from medium to coarse grained and pebbles to 2 inches in diameter are occas ionally found. The phyllites constitute a minor amount of the section and are dark gray and green . No evidence of an unconformity was .detected between the • Proterozoic (1) strata and the overlying Brigham quartzite. The upper Precambrian quart zites and lower Brigham are remark-ably homogeneous, and although small l enses of cong lomerate were found, no widespread basal conglomerate was noted. Eardley (1944) in discussing t he Proterozoic (1) rocks of the north-central Wasatch s tates: liThe sediments were probab.ly deposited in a deep trough in late Proterozoic and early 'Cambrian times and overlap the Archeozoic rocks of the northern Utah highland. They are probably sepa ­rated from the overlying Cambrian strata by ~n unconformity, but in the trough area the unconformity was not found except in the Cottonwood uplift of the central Wasatchll. The thickness of the Proterozoic Section is estimated to be 10,000 feet. The base of the section is not exposed in the South Fork area, and the underlying Archeozoic Farmi~gton C a n y o n C o m p l e x d o e s n o t c r o p o u t. 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 nt T h e C a m b r i a n r o c k s t h e S o u t h F o r k a r e a o u t c r o p on b o t h s i d e s t h e S o u t h F o r k R i v e r f r o m M a g p i e C a n y o n to C o b b l e C r e e k . A p p r o x i m a t e l y f e e t s t r a t a a r e e x p o s e d. T h e g e o g r a p h i c s t r a t i g r a p h i c r e l a t i o n s t h e Cam­b r i a n r o c k s of t h e a r e a p o s e a p r o b l e m i n C a m b r i a n nomen­c l a t u r e , i . e . , s h o u l d t h e f o r m a t i o n t h e q u a d ­r a n g l e t o t h e n o r t h , o r t h o s e t h e G r e a t B a s i n t o t h e s o u th a n d w e s t , u s e d ? Most w o r k e r s i n t h e W a s a t c h M o u n t a i ns s o u t h t h e t h e s i s a r e a h a v e u s e d G r e a t B a s i n f o r m a t i o n al n a m e s E a r d l e y , 1 9 4 4 , G i l l u l y , 1 9 3 2 ) . c a r e f u l e x a m i n a t i on o f t h e u n i t s i n t h e a r e a t h e p r e s e n t s t u d y c o n v i n c e d t he w r i t e r t h a t t h e y a r e e a s i l y c o r r e l a t e d w i t h t h o s e t he L o g a n q u a d r a n g l e. d i f f e r e n t b u t g r a d a t i o n a l C a m b r i a n s e q u e n c e s a r e pre^ s e n t i n t h e W a s a t c h M o u n t a i n s . S o u t h t h e S o u t h F o r k a r e a, r e l a t i v e l y t h i n s h e l f d e p o s i t s a r e p r e s e n t w h e r e a s t o t he n o r t h t h e t h i c k e r m i o g e o s y n c l i n a l s e d i m e n t s a r e p r e s e n t. T h e t h e s i s a r e a e v i d e n t l y i n t h e t r a n s i t i o n z o n e b e t w e en t h e s e a r e a s d e p o s i t i o n . S h e l f s e d i m e n t s a r e p r e s e nt i n t h e D u r s t M o u n t a i n a r e a m i l e s t o t h e s o u t h in 8 Canyon Complex does not crop out. Cambrian System General Statement The Cambrian rocks of the South Fork area outcrop on both sides of the South Fork River from Magpie Canyon to Cobble Creek. Approximately 3000 feet of strata are exposed. The geographic and stratigraphic relations of the Cam-brian rocks of the area pose a problem in Cambrian nomen-clature, i.e., should the forrr~tion names of the Logan quad- • rangle to the north, or those of the Great Basin to the south and west, be used? Host workers in the Wasatch Mountains' south of the thesis area have used Great Basin formational names ( Eardley, 1944, Gilluly, 1932). A careful examination of the units in the area of the present study convinced the writer that they are easily correlated with those of the Logan quadrangle. Two different but gradational Cambrian sequences are pre-sent in the Wasatch Mountains. South of the South Fork area, relatively thin shelf deposits are present whereas to the north the much thicker miogeosynclinal sediments are present. The thesis area was evidently in the transition zone b?tween these two areas of deposition. Shelf sediments are present in the Durst Mountain area 10 miles to the south and in Promont o r y Ra. (Olson, 1957) 2 3 Logon Quod. Randolph Quad. (Williams, J.S., ',943/ (After Ricnardson, 1941) \ Marjum fm. Wheeler fm, Swcsey Is. Condor fm. -' Dome Is. - Burnt Can. fm. Burrows f m. Millard fm. -\Busby fm./- Pioche sh. Tintic qtzt. , \ \ \ \ \ \ \ Bloomington fm. Blacksmith dol. Ute fm. Spence sh. Longs ton fm. Brigham qtzt. 31oomington fm. Blacksmith dol. Ute fm >pence sn. Langston fm. Brigham qtzt 4 South Fork A r (This paper) (Covered Bloomington fm. Blacksmith dol. Ute fm. Lcngston fm, -/Sponce sh\-j Brigham qtzt. ^ W A A / W V I A A | C O R R E L A T I O N OF L O W E R AND M I D D L E C . .- I Promonto y Ro. (OJ so n, 1957l ~ 2 3 Logan Ouod. Randolph Quod. . (W illiams , J.S; . 19 48) (After Richardson, 19 41) ~O",h F;' k A, (Th IS paper) \ - - \ I Mur julTl \ I I I \ Bloomingt on I' 3 loo lTl lr,glon fm. \ - \ (Covell'c ) \ • \ Bloominl;110n f1"l. W!'leeler 1m. SWCl'oev I •. I B!acksmlTh doL. Blac ksmiTh Bl ocksmlln (loL \ ,• COl\dor 1m. \ , I Dome 1$, '--- \ I I Slant Can. 1m. \ I I \ 1m. - . U" qurrow$ 1m. \ Uto 1m. U" 1m. \ I \ '-----~. I ,"hUard 1m. --..c pence sy I h9usb~ fm ,r- f--- - -- I f-Sp-en-ce- '"-. Lonljiiton ffl:. Long fo lon fm . .,. . LOfl gSlon 1m. S:>onc eo ~ h\ .-- I Tint;c (PH . . Brigh am <;111. Brigham qll T. I3riQ hO'll (ll z T. I 'vvv' . I 'VA 'AV .', A,~ \fW'/'vV' ", vVvt lAMA'V , AM VV' , . CORRELAT ION OF LOWER AND MIDDLE C 941) South Fork .Area (This paper) Covered Bloomington fm. dol. Ute fm. Langston fm. /Soonce sh: Brigham qtzt. 5 Durst ML (Ecrdley, 1344) L. 8t M. Camorion Undif f. Ophir sh. fintic qtzt. INDEX MAP Western Uinta Mfs. (Williams, N. C , 1953) Op n i r sh. Tin tic qtzt. VwViA/yyvv^ 200 - o-' A N D M I D D L E C A M B R I A N • IN N O R T H E R N UTAH -----------+-------------------------------~---. uod. n, 1941) 41 , S:uth For k Ar,e o "" (Th IS p o pe:) I., , I I ~ I. (Covefee l • Bloominqton fll'l. I , , , Blacksmith <101. U t e 1m. l ! Lcogslon fm . 5;lClrH;.~ ~ h. 1 I l3riQhom ql ll. ~ 5 Ec rdley , 1. Mt, 1944) Opn ir $ 11. TUHic qlll. I u T A I I ,L -- INDEX MAP , 6 We sl e r n Uinta MI S. (Williams , N.C., 19 5 3 ) a nif sll. Tin tic qllt. v 'V" AND MIDDLE CAMBRIAN , IN NORTHERN UTAH H O g d e n C a n y o n t o t h e w e s t ; t w e n t y m i l e s n o r t h i n t h e q u a d r a n g l e , t h e much h i c k e r 6 , 0 0 0 t o 1 0 , 0 0 0 f e e t ) m i o g e o - s y n c l i n a l s e q u e n c e i s e x p o s e d. T h e C a m b r i a n s t r a t a h e W e s t e r n n t e r i o r a r e g e n e r a l ly d i v i s i b l e i n t o t h r e e u n i t s : a t h i c k b a s a l q u a r t z i t e , a m i d d le s h a u n i t , u p p e r c a b o n a t e u n i t . t h e S o u t h F o rk a r e a t h i s s e q u e n c e i s e p r e s e n t e d by t h e B r i g h a m q u a r t z i t e , t h e s h a l e s t h e L a n g s t o n U t f o r m a t i o n s , t h e c a r b o n at r o c k s t h e B l a c k s m i t h B l o o m i n g t o n f o r m a t i o n s . p r e - s e n c e u p p e r C a m b r i a n r o c k s i n t h e a r e a i s q u e s t i o n a b l e. B r i g h a m Q u a r t z i te T h e B r i g h a m q u a r t z i t e , o l d e s t C a m b r i a n f o r m a t i o n i n t he S o u t h F o r k a r e a by W a l c o t t 1 9 0 8 ) f r o m e x p o s u r es n e a r B r i g h a m C i t y , U t a h a p p r o x i m a t e l y m i l e s n o r t h t he t h e s i s a r e a . T h i s m a s s i v e l y b e d d e d f o r m a t i o n f o r m s r u g g ed c l i f f s a l o n g b o t h d e s S o u t h F o r k C a n y o n w e s t f r o m M a g p ie C r e e k . B r i g h a m c o n s i s t b e d s b u f f , y e l l o w , p i nk a n d m a r o o n q u a r t z i t e . s a n d p a r t i c l e s a r e w e l l r o u n d e d, r a n g e f r o m m e d i u m t o c o a r s e g r a i n e d , and h a v e a v i t r e o us l u s t e r . L o c a l l y , c o n g l o m e r a t e " p o d s " a r e p r e s e n t w h i ch c o n t a i n p e b b l e s a s a s i n c h i n d i a m e t e r . t h i c k ­n e s s t h e B r i g h a m q u a r t z i t e i s e s t i m a t e d t o b e 1 , 5 0 0 f e e t. No f o s s i l s w e r e f o u n d. 9 Ogden Canyon to the west; twenty miles north in the Logan quadrangle, the rnoch t hicker ( 6,000 to 10,000 feet) miogeo-synclinal sequence is exposed. The Cambrian strata of t he t.J'estem I nterior are generally divisi ble into three units: a thick basal quartzite, a middle sha l e unit, and an upper ca r bonate unit . In the South Fork ar ea this sequence is r epresented the Bri gham quartzite, " the shales of the Langs ton and Ut e formations, and the c arbonate . rocks of the Blacksmith and Bl oomington formations. The pre-sence of upper Cambrian rocks in the area is ques tionable. Brigham Ouartzite The "Brigham quartzite, oldest Cambri an formation in the South Fork area , was named Walcott ( 1908) from exposures near Brigham City, Utah approximately 20 miles north of the thesis ea. This massively bedded ormation forms rugged cliffs .along both s i des of South Fork Canyon west from Magpie Creek. The Brigham cons ist s of beds of buff, yellow, pink and maroon quartzite. The sand particles are well rounded , range from medium to coarse grained, have vitreous luster. locally, conglomerate IIpods ll are present which contain pebbles as much as 1 inch in diameter. The thiek-ness of the Brigham quartzite is estimated to be 1,500 feet . No fossils were found. 1 0 I n t h e D u r s t M o u n t a i n a r e a a f e w m i l e s s o u t h of t he t h e s i s a r e a t h e B r i g h a m ( T i n t i c ) q u a r t z i t e r e s t s on t h e o l d er P r e c a m b r i a n F a r m i n g t o n C o m p l e x w i t h a c o a r s e c o n g l o m e r a t e at t h e b a s e . No P r o t e r o z o i c s t r a t a a r e p r e s e n t . In t h e S o u th F o r k a r e a t h e B r i g h a m q u a r t z i t e r e s t s w i t h a p p a r e n t c o n f o r m i ty o n t h e P r e c a m b r i a n P r o t e r o z o i c ( ? ) s t r a t a , and no b a s a l c o n ­g l o m e r a t e was f o u n d . Most w r i t e r s ( E a r d l e y and H a t c h , 1 9 4 0, W h e e l e r , 1 9 4 3 , W i l l i a m s , 1948) b e l i e v e t h a t s e d i m e n t a t i o n ;' was c o n t i n u o u s f r o m l a t e P r e c a m b r i a n i n t o e a r l y C a m b r i a n t i m e. T h e u p p e r 200 f e e t of t h e B r i g h a m q u a r t z i t e a r e i n t e r - i b e a d e d w i t h t h i n ( s e v e r a l i n c h e s t o 1 f o o t ) o l i v e g r e e n, m i c a e o u s s h a l e b e d s . Such i n t e r b e d d i n g i s a l s o s e e n i n t he D u r s t M o u n t a i n a r e a t o t h e s o u t h and t h e Logan q u a d r a n g le t o t h e n o r t h . In t h e D u r s t M o u n t a i n a r e a t h e s h a l e s g r a de - i n t o t h e o v e r l y i n g O p h i r s h a l e . However, i n t h e S o u t h F o rk a n d Logan a r e a s , t h e B r i g h a m i s o v e r l a i n , w i t h a p p a r e n t c o n ­f o r m i t y , by a p p r o x i m a t e l y SO f e e t of d o l o m i t e f o l l o w e d by t h e S p e n c e s h a l e member of t h e L a n g s t o n f o r m a t i o n. S e v e r a l w r i t e r s ( W i l l i a m s , 1 9 4 8 , W h e e l e r , 1 9 4 3 ) h a ve s u g g e s t e d a c o r r e l a t i o n b e t w e e n t h e S p e n c e a n d O p h i r s h a l e s. The w r i t e r f e e l s s u c h i s n o t t h e c a s e . The p r e s e n c e of d o l o m i t e i m m e d i a t e l y a b o v e t h e B r i g h a m q u a r t z i t e , and t he s o m e w h a t d i f f e r e n t l i t h o l o g i e s of t h e O p h i r a n d S p e n ce s h a l e s s e e m t o i n d i c a t e t h e y a r e two d i s t i n c t u n i t s . In 10 In the Durst Mountain ar ea a few miles south of the thesis area the Brigham (Tintic) quartzite rests on the older Precambrian Farmington Comp l ex with a coarse congl omer ate at the ' base . No Proterozoic str ata are present . In the South Fork area the Brigham quartzite rests with apparent conformity on the Precambrian Proterozoic (?) strata, and no basal con-glomerate was found. Most writers (Eardley and Hatch, 1940, Wheeler, 1 94~~ Williams, 1948) believe that sedimentation 1 was continuous from late Precambrian into early Cambrian t~2 . The upper 200 feet of the Brigham quartzite are inte~~ _ beaded with thin (several inches to 1 foot) olive green, micaeous shale beds . Such interbedding' is also seen in the Durst Mountain area to the south and the Logan quadrangle tOo the north. In the Durst Mountain ar ea the shales gr ade "#"into the ove17lying Ophir shal e. However, in the South Fork and Logan areas , the Brigham is overlai n, with apparent con-tormity, by approximatelY So f eet of dolomite fOllowed by the Spence shale member of the Langston formation. Several writers (Williams, 1948, Wheel er, 1943) have suggested a correlation between the Spence and Ophir shales. The writer fe els such is not the case. The presence of . dolomite i mmedi ately above the Brigham quartzite, and the somewhat different lithologies of the Ophir and Spence sha les seem to indic ~te they are t wo distinct units. In 11 r e g a r d t o t h i s p r o b l e m , W h e e l e r 1 9 4 3 ) s t a t e s: I f t h e S p e n c e P i o c h e O p h i r ] s h a l es 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 he l a t t e r i n n o r t h - c e n t r a l U t a h i s some­w h e r e b e t w e e n B l a c k s m i t h F o r k ". T h e w r i t e r a g r e e s w i t h h i s i n t e r p r e t a t i o n . l o w e r and m i d d l e C a m b r i a n c o r r e l a t i o n c h a r t , P l a t e I I) T h e u p p e r m o s t p o r t i o n t h e B r i g h a m q u a r t z i t e was m e a s u r e d t h e e a s t s i d e M a g p i e C a n y o n w h e r e t h e s h a le u n i t s a r e w e l l e x p o s e d. T h i c k n e s s in L a n g s t o n f o r m a t i o n feet D o l o m i t e : m e d i u m r y s t a l l i n e ^ medium g r a y w e a t h e r d a r k g r a y , medium b e d d e d , s l o p e f o r m e r . . . . . 69 C o n t a c t c o n f o r m a b le B r i g h a m q u a r t z i te 1 1 Q u a r t z i t e : b u f f t o l i g h t r e d , medium t o c o a r s e , w e l l - r o u n d e d s a n d g r a i n s, o c c a s i o n a l g r a i n s t o V ' , medium b e d d e d t o m a s s i v e . . . . . . . . . . 15 1 0 . S h a l : l i v e - d r a b t o d i r t y " y e l l o w, m i c a c e o u s b e d d i n g p l a n e s , f r i a b l e, s l i g h t l y a r e n a c e o u s . . . % Q u a r t z i t e , i n No. a b o v e . . . . 131 I n t e r b e d d e d q u a r t z i t e anu s h a l e: s h a l e a s i n No. a b o v e , b e ds a v e r a g e 1 - 2 " i n t h i c k n e s s . 7 . Q u a r t z i t e : i n a b o v e . . . . 31 regard to this problem, Wheeler ( 1943) states: " If the Spence and Pi oche [ Ophir] sha les are distinct the northern limit of the latter in north-central Utah is some­where between Ogden and Blacksmith Forkll • The writer agrees wi th t his interpretati on. (See lower and middle Cambrian correlation chart, Plate II) The uppermost port ion of the Brigham quartzite was measured on the east side of Magpie Canyon , where the shale units are well exposed. Langston formation Thickness in feet Dolomite: medium c rystalline, medium gray , weather s dark gray, medium bedded , s lope former .. .. . .. .. .. .. .. .. .. . . 69 Contact conformable Brigham quartzite 11 . Quartzite : buff to light red, medium to coar se , well-rounded sand grains , occasional gr ains to ~", roedi .urn bedded to massive .... . . ............ .. 10. Shal e : o live- drab to " dirty" yellow, micaceous on bedding planes, friable, slightly arenaceous • • • • .• • •• 9 . Quartzite, as in No . 11 above •••• 8 . Interbedded quartzite and shale : shale as in No . 10 above, beds average 1_21t in thickness • • • • • • 7. Quartzite : as in No. 11 above • • • • 15 131 5 31 T h i c k n e s s in B r i g h a m q u a r t z i t e c o n t i n u e d ) feet S h a l e : a s i n 1 0 , b u t more f i s s i l e , l e s s m i c a c e o u s . . . . . . . 1 5 . Q u a r t z i t e : as i n No. 11 a b o v e • * • «, 40 4 . S h a l e : a s i n No. 10 a b o v e . . . . . . 1 3 . Q u a r t z i t e : as i n No. 11 a b o ve b u t m o r e r e d . . . . . . . . . . . . 64 2 . S h a l e : a s i n No. 10 a b o v e . . . . . . 2 1 . Q u a r t z i t e : as i n N o . 11 a b o v e . . . . 100 L a n g s t o n F o r m a t i on T h e L a n g s t o n f o r m a t i o n i s w e l l e x p o s e d on t h e c l i f fs o v e r l o o k i n g t h e S o u t h F o r k of t h e Ogden R i v e r , j u s t e a s t of M a g p i e C a n y o n . It c o n s i s t s of a b a s a l , b l a c k a r e n a c e o us d o l o m i t e , f o l l o w e d s u c c e s s i v e l y by a b u f f w e a t h e r i n g , l i g ht g r a y l i m e s t o n e b e d , two g r e e n s h a l e u n i t s s e p a r a t e d by a g r ay l i m e s t o n e , and an o v e r l y i n g s e q u e n c e of g r a y l i m e s t o n e s. T h e L a n g s t o n f o r m a t i o n r e s t s c o n f o r m a b l y on t h e B r i g h am q u a r t z i t e and t h e b a s e of t h e f i r s t d o l o m i t e u n i t o v e r l y i ng t h e q u a r t z i t e was c h o s e n as t h e l o w e r c o n t a c t . The u p p er c o n t a c t was p l a c e d a t t h e t o p of t h e t h i c k b e d d e d l i m e s t o n es u n d e r t h e U t e s h a l e . The L a n g s t o n f o r m a t i o n i s 398 f e et t h i c k i n t h e S o u t h F o r k a r e a. T h e d a r k g r e e n , v e r y f o s s i l i f e r o u s S p e n c e s h a l e member o f t h e L a n g s t o n i s b e s t e x p o s e d on t h e c r e s t of t h e r i d ge 12 Thickness in Brigham auartzite ( continued) feet 6 . Shale: as in No. 10, but mote fissil e ; l ess micaceous • • • • • • • 1 '5. Quartzite: as in No . 11 above • • • • 40 4 . Shale : as in No. 10 above • • • • • • 1 ::> 3. Quartzite : as in No . 11 above but mor e red • • • • • • • • • • • • 64 2. Shale : as i n No. 10 above • • • • • • 2 l. Quartzite : as in No. 11 above • • • • 100 Langston Formation The Langston fo rmation i s well exposed on the cliffs overlooking "the South Fork of the Ogden River, just east of Magpie Canyon . It consis t s of a basal, black arenaceous dolomite, followed successively by a buff weathering, light gray limestone ped, t wo green shal e unit s separated by a gr ay limestone, and an overlying sequence of gray limestones . The Langston formation r es t s conformably on the Brigham quartzite an~ the base of the fir st do lomit e unit overlying the quartzite was chosen as t he lower contact. The upper contact was placed at the top of the thick bedded limestones under the Ute shale . The Langston formation is 398 feet thick in the South Fork a r ea . The dark green, very fossiliferous Spence shale member of the Langston is best exposed on the crest of the ridge a b o v e t h e S o u t h F o r k w h e r e i t f o r m s p r o m i n e n t s a d d l e . s a d d l e i s m a r k e d a l a c k of v e g e t a t i o n , and c h a r a c t e r ­i s t i c g r e e n S p e n c e s h a l e d e b r i s on t h e s u r f a c e . A l t h o u gh t h e s h a l e d o e s n o t c r o p o u t , s h a l l o w e x c a v a t i n g e x p o s ed r o c k s i n p l a c e. M r s C h r i s t i n a L o c k m a n B a l k , e x a m i n e d t h e f a u na c o l l e c t e d f r o m t h e S p e n c e s h a l e , b e l i e v e s i t t o r e p r e s e n t t he G l o s s o p l e u r a z o n e M i d d l e C a m b r i a n a g e S p e c i f i c forms a r e l i s t e d i n t h e f o l l o w i n g d e t a i l e d s e c t i o n ,. I n t h e Logan q u a d r a n g l e , t o t h e n o r t h of t h e t h e s is a r e a , e x t r e m e l y f o s s i l i f e r o u s a c k l i m e s t o n e t he b a s e t h e L a n g s t o n f o r m a t i o n h a s b e e n d e s i g n a t e d t h e P t a m i - g a n i a t h e L a n g s t o n R e s s e r , 1 9 3 9 ) 9 b l a c k d o l o ­m i t e u n i t a t t h e b a s e t h e f o r m a t i o n t h e S o u t h F o r k a r ea c o r r e l a t w i t h t h i s a l t h o u g h c o n f i r m i n g f o s s i ls w e r e f o u n d. T h e f o l l o w i n g s e c t i o n was m e a s u r e d on t h e s o u t h s i d e of t h e S o u t h F o r k , i m m e d i a t e l y e a s t of M a g p i e C a n y o n: T h i c k n e s s in U t e F o r m a t i o n feet S h a l e : l i g h t o l i v e g r e e n , a r e n a c e o u s, c a l c a r e o u s , t h i n b e d d e d t o f i s s i l e . I n t e r b e d d e d l i m e s t o n e b e c o m e s p r o m i n e nt t o w a r d t o p u n i t . 137 13 above the South Fork where it forms a prominent saddle . The saddle is mar ked by a lack of veget ation, and by character-ist, i c green Spence shale debris on the surface . Although the shale does not crop out, shallow excavating exposed 0. rocks in place. Mrs . Christina Lockman - Balk , who examined the fauna collected from the Spence shale, believes it to represent the Glossopleura zone of Mi ddle Cambrian age . Specific forms are listed in the followi ng detailed se ction~ In the Logan quadrangle , to the north of the thesis area, an extremely fossiliferous b l ack limestone a t the base of ~he Langston formation has been deSignated the Ptami-gania member of the Langs ton ( Resser, 1939). The black dolo-mite unit at the base of the -formation i n the South Fork area may correlat e with this member although no confirming fossils were found . The following section was measured on the south side of the South Fork, immediately east of Magpie Canyon: Ute Formation Shale: light olive green, arenaceous , calcareous, thin bedded to fissile. Interbedded limes tone becomes prominent Thickness in­feet toward top of unit • • •• ' . '. • • • • • • 137 L a n g s t o n f o r m a t i on 6 . 5 . 4 . 3 , 2 . 1 . L i m e s t o n e : t h i n b e d d e d , f i n e ly c r y s a l l i n e ^ v e r y d a r k g r a y, w e a t h e r s m e d i um g r a y , t a n s h a le p a r t i n g s . . . . . . < , . . . . , S h a l e : m e d i u m t o d a r k o l i v e g r e e n, v e r y f i s s i l e t o t h i n b e d d e d , forms d e p r e s s i o n s . G l o s s o p l e u r a b i on W a l c o t t , W e s t o n i a l l a W h i t e ," A l o k i s t o c a r e i d a h o e n s e R e s s e r , A# c f , l e R e s s e r . # . # . . . • L i m e s t o n e : d a r k g r a y t o b l a c k, c o a r s e l y c r y s t a l l i n e , w e a t h e rs m e d i um g r a y , o c c a s i o n a l b e d s of l i m e s t o n e c o n g l o m e r a t e , forms a g g e d c l i f f s . . . . . . . . S h a l e : a s i n No. 5 a b o v e. A l o k i s t o c a r e i d a h o e n s e R e s s e r, E h m a n i e l l a s p . . . . . . . . « T h i c k n e s s f e e t 6 9 D o l o m i t e : l i g h t g r a y t o t a n , medium t o c o a r s e l y c r y s t a l l i n e , w e a t h e rs l i g h t b u f f , r e n a c e o u s , c l i f f f o r m e r . D o l o m i t e : ' m e d i u m g r a y w e a t h e rs d a r k g r a y c r y s t a l l i n e , m e d i u m b e d d e d , f o r m s s l o p e s . . . . . . T o t a l L a n g s t on C o n t a c t c o n f o r m a b le 4 4 6 9 3 98 B r i g h a m Q u a r t z i te Q u a r t z i t e : b u f f t o l i g h t e d , medium t o c o a r s e w e l l - r o u n d e d s a n d g r a i n s, o c c a s i o n a l g r a i n s t o V% m e d i um b e d d ed t o m a s s i v e I n t e r b e d d e d o l i v e d r a b s h a l es 14 Langston fo rmation 6 . 5. Limestone: t hin bedded , finely crys t alline, very dark gr ay, weathers medium gr ay , tan shale partings • • • • • • • • • • • • • Shale: medium to dark olive green, very fi ssile t o thin bedded , f orms depr essions. Glossopleura bion Walcott, Westonia e lla White , ' Alokistocar e idahoen se Resser, A. cf . n a t a le Resser ••••• ••• 4. Limestone: dark gray "to black, coar sely crystalline , weather s medium gr ay, occasional beds of limestone congl omerat e, forms • • • • Thickness in feet 69 19 r agged cliffs • •••••• ••••• 46 3. Shale : as in No . 5 above . Alokistocar e idahoense Resser, Ehmaniella sp. • • • • • • • • • • • 2. Dolomite: l i ght gr ay to ' t an, medium to coar sely crystalli ne, weathers 44 light ' buff, a renaceous , cliff former • 51 Dolornite: "medium gr ay , weathers dark gray , medium crystalline, medi um bedded, fo~ slopes . • • Total Langston Contact conformable Br igham Quartzite • • • Quartzite : buff to light r ed, medium to coar se , well- rounded sand grains , occasional grains to t l1 , medium bedded to massive . Interbedded olive drab shal es . 69 398 U t e F o r m a t i on T h e s e q u e n c e of s o f t s h a l e s and t h i n b e d d e d l i m e s t o ne l y i n g b e t w e e n t h e m a s s i v e l i m e s t o n e s of t h e L a n g s t o n and B l a c k s m i t h f o r m a t i o n s i s c o r r e l a t e d w i t h t h e U t e f o r m a t i o n . The U t e i s s l o p e f o r m e r t h r o u g h o u t , i s v e r y p o o r l y e x p o s ed i n t h e S o u t h F o r k a r e a e x c e p t ' o n t h e h i g h r i d g e e a s t M a g p i e C a n y o n S J j c _ h u n d r e d f i f t y n i n e f e e t t h e U t e f o r m - . a t i o n w e r e m e a s u r e d a l o n g t h i s r i d g e. T h e s h a l e s of t h e U t e f o r m a t i o n a r e d a r k g r e e n , g r a y, a n d b r o w n . S c r a p s f l o a t u s u a l l y i n d i c a t e t h e i r p r e s e n ce i n s o i l a r e a s . The l i m e s t o n e s a r e p r e d o m i n a t e l y g r a y , t h in b e d d e d , f i n e l y c r y s t a l l i n e , and a r g i l l a c e o u s . C a l c i te t r i n g e r s a r e i n c e r t a i n b e d s , L i m e s t o n e b r e c c i as a r e t o w a r d t h e t o p t h e u n i t. I n t h e S o u t h F o r k a r e a , f o s s i l s w e r f o u n d i n t he U t e f o r m a t i o n . W i l l i a m s 1 9 4 1 ) e p o r t a M i d d l e C a m b r i a n f a u n a f r o m h e U t e i n t h e q u a d r a n g l e. B o t h t h e u p p e r l o w e r c o n t a c t s t h e U t e f o r m a t i on a p p e a r t o b e c o n f o r m a b l e . l o w e r c o n t a c t p l a c e d at t h e b a s e h e f i r s t g r e e n s h a l e a b o v e t h e L a n g s t o n l i m e ­s t o n e s h e u p p e r c o n t a c t p l a c e d t h e t o p t he l a s g r e e n s h a l e. T h e f o l l o w i n g s e c t i o n m e a s u r e d t h e r i d g e e a st 15 Ute Formation The sequence of soft shales and thin bedded limestone l ying between the massive limestones of the Langston and Blacksmith formations is correlat ed with the Ute formation. The Ute is a slope former throughout, and is very poorly exposed in the South Fork area except'on the high ridge east of Magpie Canyon . ~iK hundred fifty nine feet of the Ute form­ation were measured along this ridge . The shales of the Ute formation are dark green, gray, and brown. Scr aps of float usually indicate their presence in soil areas . The limzstones are predominately gray , thin bedded, finely crystalline, and argillaceous. Calcite s tringer s are common in certain beds. Limestone breccias are common toward the top of the' unit . In the South Fork area, no fossils wer e found in t he Ute formation. However Williams and Maxey ( 1941) r eport a Middle Cambrian fauna from t he Ute .in the Logan quadrangle. Both the upper and lower contacts of the Ute fo~tion appear to be cqnformable. The lower contact was placed at the base of t he first green shale above the Langston lime­stones and t he upper contact was placed a t the top of the las t green shale . The following section was measured on the ridge east o f M a g p i e C a n y o n: T h i c k n e s s in B l a c k s m i t h f o r m a t i o n feet L i m e s t o n e d a r g r a y , n e l y c r y s t a l ­l i n e , w e a t h e r s d a r k g r a y , t h i n to m a s s i v e l y b e d d e d . • « » • • • • » . • • « 27 C o n t a c t c o n f o r m a b le U t e f o r m a t i on 5 . L i m e s t o n e i m e s t o n e b r e c c i a s, o c c a s i o n a l i n t e r b e d d e d s h a l e: l i m e s t o n e m e d i u m t o c o a r s e ly c r y s t a l l i n e , m e d i u m g r a y , medium b e d d e d . " S h a l d a r k g r e e n , v e ry f i s s i l e , l o p e f o r m e r . « 182 4 . C o v e r e d : f l o a t i n d i c a t e s i n t e r ­b e d d e d l i m e s o n e s h a l e. L i m e s t o n e h i n b e d d e d , b l a c k, v e r y a r g i l l a c i o u s * S h a l e b r o w n, v e r y c a l c a r e o u s , s l o p e f o r m e r . . . . 94 3 . L i m e s t o n e : d a r k g r a y , w e a t h e rs d a r k g r a y , n e l y c r y s t a l l i n e, l c i t e t r i n g e r s v e r y p r o m i ­n e n t . f e e t u n i t i s c o n s p i c u o u s l e d g e i m e s t o n e . . . . 132 2 . L i m e s t o n e : d a r k g r a y b l a c k, b a n d e d , w e a t h e r s m e d i u m g r a y, a r g i l l a c e o u s p a r t i n g s , f i n e ly c r y s t a l l i n e t o s u b - l i t h o g r a p h i c, t h i n b e d d e d . n o d u l a r t o ­w a r d t o p u n i t . P r o b a b l y t h i n s h a l e b e d s - • 114 1 . S h a l e : l i g h t o l i v e g r e e n , a r e n a ­c e o u s l c a r e o u s , h i n b e d d e d to f i s s i l e . I n t e r b e d d e d l i m e s t o ne b e c o m e s p r e d o m i n a t e t o w a r d t op o f u n i t • j: 37 T o t a l U t e f o r m a t i on 6 5 8 16 of Magpie Canyon: Blacksmith formation , Limes t one : dar k gr ay, f i nely crystal­line, weathers dark gray, thin to massively bedded .. . ............. . Contact conformab l e Ute format ion 5. • • L i~~s tone and l imestone breccias, occasional interbedded shale : limestone medium to coarsely crystalline, medium gray, 'medium bedded. · Shal e dark gr een, very fissile, s lope fo~er ..... .... • • • 4. Covered: float indicates inter ­bedded limes t one and sha l e . Limestone t hin bedded, black, very argillacious. Shale brown, very calcareous, slope fo~er .. .... 3. 2. Limestone : dark gray , weathers dark gr ay , f i nely cryst alline , c a lcite s tringers very promi­nent. Top 7 feet of unit is a co nsp ic~ous ledge of l imestone • • • • • Limestone : dark gray t o black , banded, weather s medi um gray, a ~g ill a ceous partings, finely crystalline to sub- l ithographic, thin bedded . Becomes nodular to­ward top of unit. Probably some thin shale beds' •••• ••• • • • • 1. Shale: light olive green, ar ena­c eous , c a lcareous, t hin bedded to fi ssile. Interbedded limestone becomes predominate towar d top Thickness in feet 27 182 94 132 ll4 of unit •• • • • • • • • • • • • • • 137 Total Ute formation 658 17 C o n t a c t c o n f o r m a b le T h i c k n e s s in L a n g s t o n f o r m a t i o n feet L i m e s t o n e : t h i n b e d d e d , f i n e ly c r y s t a l l i n e , v e r y d a r k g r a y, w e a t h e r s m e d i u m g r a y , t s h a l e p a r t i n g s . . . . . . O « . o « > . . * 69 B l a c k s m i t h F o r m a t i on O v e r l y i n g t h e s o f t , e a s i l y e r o d e d U t e f o r m a t i o n i s t he m a s s i v e , c l i f f f o r m i n g B l a c k s m i t h f o r m a t i o n . i s v e ry w e l l e x p o s e d i n t h e h i g h c l i f f w h i c h f o r m s t h e e a s t b a n k of C o b b l e C r e e k a n d a l s o a l o n g t h e s o u t h s i d e t h e S o u t h F o rk R i v e r . l i m e s t o n e s d o l c m i t i c l i m e s t o n e s w h i c h c o m p o se t h e B l a c k s m i t h f o r m a t i o n a r e m e d i um t o d a r k g r a y , r a n g e f r om m e d i u m t o f i n e l y c r y s t a l l i n e , a r e o o l i t i c . When v i e w e d f r o m a d i s t a n c e t h e B l a c k s m i t h a p p e a r s b a n d e d i n s e v ­e r a l s h a d e s of g r a y. T h e l o w e r c o n t a c t t h e B l a c k s m i t h f o r m a t i o n p l a c ed a t t h e t o p t h e u p p e r m o s t s h a l e u n i t t h e U t e f o r m a t i o n. T h e u p p e r c o n t a c t d r a w n a t t h e b a s e t h i c k , v e ry f i s s i l e , g r e e n s h a l e u n i t w h i c h i s p r e s u m a b l y t h e Hodge s h a le member of t h e B l o o m i n g t o n f o r m a t i o n . Both c o n t a c t s a p p e ar c o n f o r m a b l e . T h B l a c k s m i t h f o r m a t i o n m u s t b e M i d d l e C a m b r i an a g e a s i t l i e s b e t w e e n b e d s c o n t a i n i n g M i d d l e C a m b r i an f o s s i l s . r e g a r d t o t h e f o s s i l s f o u n d i n t h e B l a c k s m i th 17 Contact conformable Thickness in Langston formation feet Ltmestone: thin bedded, finely crystalline, very dark gray, weathers medium gray, t an shale partings • • • • • • • • • • • • • • 69 Blacksmith Formation Overlying the soft, easily eroded Ute formation is the massive, cliff forming Blacksmith formation. It is very well exposed in the high cliff which forms the east bank of Cobble Creek and also along the south side of the South Fork River. The l~estones and dolomitic limestones which compose the Blacksmith formation are ~~ium to dark gray, range from medium to finely crystalline, and are commonly oolitic. ~en viewed from distance the Blacksmith ~ppears banded in sev-eral shades gray . The lower contact of the Blacksmith formation was placed at the top of the ,upper most shale unit of the Ute formation. The upper ,contact was drawn at the base of a thick, very fissile, green shale unit which is presumably the Hodge shale member of the Bloomington formation. Both contac~appear confonnab le. Th.e Blacksmith forma~ion must be of Middle Cambrian age as it lies between beds containing Middle Cambrian fossils. In regard to the fossils found in the Blacksmith f o r m a t i o n t h e a u t h o r , C h r i s t i n a L o c k m a n - B a l k s t a t e s : . B a t h y u r i s c u s - S l r a t h i n a z o n e . . T h e B l a c k s m i t h i i t h i c u n i t s e e m s to c o v e r t h e - t i m e h e B a t h y u r i s c u s - E l r a t h i n a z o n e a l t h o u g h t h e t o p t he z o n e r e a c h i n t o t h e H o d g e s s h a l e - h a v e n e v e r h a d f o s s i l s f r o m t h is u n i t r e p o r t e d b e f o r e . . ; f a u n as o f h i s z o n e a r e s e v e r a l , o w e r , m i d d le a n d u p p e r a t l e a s t , t o d a t e h a ve n o t b e e n a b l e t o p l a c e t h e d i v i s i o n v e ry a c c u r a t e l y . s p e c i e s A s a n h i s c us i n t h i s m a t e r i a t o b e n e w , b u t is m o s t s i m i l a r t o w h e e l e r i t h e t y pe w h i c h a c c o r d i n g t o P a l m e r i s t o b e p l a c ed s o m e w h e r e i n h e m i d d l e p a r t t h e z o n e. T h e f o l l o w i n g s e c t i o n m e a s u r e d t h e s o u t h s i de o f t h e S o u t h F o r k R i v e r e a s t of M a g p i e C a n y o n: T h i c k n e s s in B l o o m i n g t o n f o r m a t i o n feet S h a l e : d a r k g r e e n , v e r y f i s s i l e, w e a t h e r s d a r k ' g r e e n , s l o p e f o r m e r . . . . . 120 C o n t a c t c o n f o r m a b le B l a c k s m i t h f o r m a t i on 6 . C o v e r e d : p r o b a b l y m e d i u m g r l i m e s t o n e . . . . . . . . . . . . . . . . 83 5 . L i m e s t o n e , d o l o m i t i c : medium g r a y , f i n e l y c r y s t a l l i n e , n o d u l a r, t h i n b e d d e d , h a c k l y s u r f a c e ,, o o l i t i c i n p a r t , w e a t h e r s m o t t l ed b l a c k a n d b r o w n . K o o t e n i a sp . . . . . 4 . C o v e r e d : p r o b a b l y l i m e s t o n e as i n No. b e l o w 174 18 formation by the author, Christina Lockman-Balk states: • • • Bathyuriscus-Elrathina zone • • • The Bl acksmith lithic unit seems to cover the time of t he Bathyuriscus­Elr athina zone although the top of the zone may reach into the Hodges shale - we have never had fossils from this unit reported befor e. • ~ The f aunas of t his zone are several, l ower, middle and upper at least, and to date we have not been able to place the division very accurately. The species of Asaphiscus in this materia l seems to be new, but is most similar to "A. ~mee l eri the type which according to Palmer is to be placed somewhere in t he. middle part of the zone • • The following section was measured on the south side of the South Fork River east o~ Magpie Canyon: Bloomington formation Shale : dark green , very fissile, weathers dark "green, slope former. Conta9t conformable Blacksmith formation 6. • • • • Covered: probably medium gr ay limestone ••••• •••••• • • • • • 5. L~es tone, dolomitic: medium gray , finely crystalline, nodular, thin bedded, hackly surface, oolitic in part, weathers mottled Thickness in feet lW 83 black and brown. Kootenia 22 • • • • • 146 4. Covered: probably limes tone as in No . 3 below • • • • • • • • • • • • • 174 19 T h i c k n e s s in B l a c k s m i t h f o r m a t i o n c o n t i n u e d ) , feet 3 . L i m e s t o n e : b a n d e d b l a c k and medium g r a y , f i n e l y r y s t a l l i n e , a r g i l ­l a c e o u s , v e r y f o s s i l i f e r o u s. A s a p h i s c u s n . s p . , A s a p h i s c u s s p ., W e s t o n i a e l l a . ( W h i t e ) , E h m a n i e l la c f . W a p t a e n s i s R a s e t t i , B o l a s p i d e l l a ' s p . , B a t h y u r i s c u s s p , , L i n g u l e l l a s p ,, M i c r o m i t r a s p . , A c r o t h e l e s p . , s p o n ge 2 . L i m e s t o n e , d o l o m i t i c :" d a r k g r a y ' to , b l a c k , f i n e l y c r y s t a l l i n e , t h in b e d d e d t o m a s s i v e , w e a t h e r s d a r k ' g r a y , K o o t e n i a p e c t e n o i d e s R e s s e r, M e x i c e l l a s t a t o r W a l c o t t ) . . . . . . 213 . L i m e s t o n e : d a r k g r a y , f i n e ly c r y s t a l l i n e , t h i n t o m a s s i ve b e d d i n g , w e a t h e r s d a r k g r a y . . . . . . 27 T o t a l B l a c k s m i t h f o r m a t i o n 730 C o n t a c t c o n f o r m a b le U t e F o r m a t i on ' L i m e s t o n e and l i m e s t o n e b r e c c i a s, i n t e r b e d d e d s h a l e s : L i m e s t o ne m e d i um t o c o a r s e l y c r y s t a l l i n e, m e d i um g r a y b e d d e d . S h a l es d a r k g r e e n , v e r y f i s s i l e , s l o pe x o r m e r . . . . . . . . . . . . . . . . . . 182 M i d d l e U p p e r (_?) C a m b r i a n U n d i f f e r e n t i a t ed O v e r l y i n g t h e m a s s i v e B l a c k s m i t h f o r m a t i o n u n i t of d a r k g r e e f i s s i l e s h a l e u n i t f o r m s t h e d i p s l o p e e a st o f C o b b l e C r e e k and p r o b a b l y r e p r e s e n t s t h e Hodge s h a l e member o f t h e B l o o m i n g t o n f o r m a t i o n . e x p o s u r e s e a s t of t h i s a r e a s t r a t i g r a p h i c a l l y h i g h e r t h a n h e s h a l e u n i t ) a re 19 Blacksmith formation ( continued) Thickness in feet 3. Limestone : banded black and medium gray, finely c rystalline, argil­l a c eous, very foss iliferous . . Asaphiscus :9.. ~., Asaphiscus .2.,2.., Westonia ella. (White) , Ehmaniella ct . Waptaensis Raset ti , Bolaspidella ' sp., Bathyuriscus .2.2.-, Lingule lla fR., Micromitra sp., Acrothele sp., sp'onge ' spicule. • • • • • • • . • • • • • • • 87 2. Limestone, dolomitic :" dark" gray' to black, finely crysta lline, thin bedded to massive, weathers dark gray, Kootenia pecterioides Resser, Mexicella stator ( Wa lcott) • . • • • 213 1 • Limestone: dark gray , finely crystalline, thin to massive bedding, weathers dark gray • • Total Blacksmith formation Contact conformable Ute Formation "Limestone and " limestone brecci9s, interbedded shales: Limestone medium to coarsely crystalline, medium gray , medium bedded. Shales dark green, very fis sile, slope • • • • 27 730 fonner • • • • • • • • • • • • • • • • •• 182 Middle and Upper (?) Cambrian Undifferentiated , Overlying the massive Blacksmith formation i s a unit of dark gree.n fissile shale . This unit forms the dip slope east . of Cobble Creek probably represents the shale member of the Bloomington formation. · However, exposures east of th~area ( stratigraphically higher than t he shale unit) are 20 o b s c u r e d v e g e t a t i o n d e b r i s f r o m t h e K n i g h t f o r m a t i o n. o u t c r o p m e d i um t o m a s s i v e l y b e d d e d , d a r k g r a y , b r e c c i a t ed l i m e s t o n e i s e x p o s e d a l o n g h i g h w a y e a s t C o b b l e C r e e k . f o s s i l s c o u l d b e f o u n d i n t h e u n i t h o w e v e r , and i t s a g e is u n k n o w n . The w r i t e r b e l i e v e s t h a t t h i s a r e a i s p r o b a b l y u n d e r ­l a i n , a t l e a s t i n p a r t , t h e t h i c k 1 2 0 0 1 i n q u a d r a n g l e) B l o o m i n g t o n f o r m a t i o n . p r e s e n c e u p p e C a m b r i a n r o c ks ( N o u n a n S t . C h a r l e s f o r m a t i o n s ) i s c o n j e c t u r a l. O r d o v i c i a n S y s t em G a r d e n C i t y F o r m a t i on T h e u p p e r p o r t i o n t h e G a r d e n C i t y f o r m a t i o n c r o p s o ut i n t h e N a r r o w s t h e S o u t h Fork' t h e R i v e r w h e re i t i s e x p o s e d i n t h e c o r e of a s m a l l a n t i c l i n a l f o l d . The f o r m a t i o n i s s l o p e f o r m e r a p p e a r a s v e r y d i s t i n ct b u f f w e a t h e r i n g u n i t b e l o w t h e m a s s i v e g r a y c l i f f s t he o v e r l y i n g F i s h d o l o m i t e. T h a t p a r t t h e G a r d e n C i t y f o r m a t i o n e x p o s e d i s com­p o s e d t h i n t o m e d i um b e d d e d l i m e s t o n e i n t r a f o r m a t i o n al c o n g l o m e r a t e s w i t h o c c a s i o n a l t h i n b e d s b u f f t o y e l l ow c a l c a r e o u s s h a l e c o a r s e l y c r y s t a l l i n e l i m e s t o n e is c h a r a c t e r i z e d r e d d i s h t i n g e f r e s h l y b r o k e n . s u r f a c e s. W e l l - r o u n d e d d i s k s h a p e d p e b b l e s a r e p r e s e n t i n t h e c o n g l o m - l e r a t e s . u n i t v e r y f o s s i l i f e r o u s , a l t h o u g h w e ll 20 obscured by vegetation and debris from the Knight formation. An outcrop of medium to massively bedded, dark gray, brecciated limestone is exposed along high.yay 39 east of Cobble Creek . No fossils could be found in the unit however, and its age is unknown. The writer believes that this area is probably under­lain, at least in part, by the thick ( 1200' in Logan quadrangle) Bloomington formation. The presence of uppe r Cambrian rocks .(Nounan and St . Charles formations) is conj ectural. Ordovician System Garden City Formation The upper portion of the ·Garden City formation crops out in the " Narrows " of the South Fork of the Ogden River where it is exposed in the core of a small anticlinal fold. The formation is a slope former and appear s as a very dis t inct buff weathering unit below the massive gray cliffs of t he overlying Fish Haven dolomite. That part of the Garden City formation exposed is com­posed of thin to medium bedded limestone and intraformational conglomerates with occas ional thin beds of buff ~o yellow .~~ calcareous shale . The coarsely crystalline limestone is characterized by a reddish tinge on freshly broken .sur(aces. Well-rounded disk shaped pebbles are present in the conglom­erates. The unit i s very fossiliferous, although well p r e s e r v e d s p e c i m e n s a r e s c a r c e. U n f o r t u n a t e l y o n l y t h e o p e e t t h e G a r d e n C i ty f o r m a t i o n i s e x p o s e i n t h e S o u t h F o r k a r e a . The t r i l o b i te e f f e r s o n i a p e l t a b e l l a , c o l l e c t e d n e a r h e t o p t h e u n it p l a c e s t h e s t r a t a , a t l e a s t i n p a r t , i n z o n e G ( 2 ) e of R o s s ( 1 9 5 1) I n t h e Logan q u a d r a n g l e t h i s z o n e l i e s 522 f e e t b e l o w t h e t op o f t h e G a r d e n C i t y f o r m a t i o n . T h e r e f o r e i t a p p e a r s t h a t t he e q u i v a l e n t s of a t l e a s t 300 f e e t of G a r d e n C i t y s t r a t a a re a b s e n t i n t h e S o u t h F o r k a r e a . Owing t o t h e a p p a r e n t l y c o n f o r m ­a b l e n a t u r e of t h e c o n t a c t w i t h t h e o v e r l y i n g F i s h Haven d o l o ­m i t e i t i s b e l i e v e d t h e a b s e n c e of p a r t of t h e G a r d e n C i t y is d u e t o n o n - d e p o s i t i o n r a t h e t h a n e r o s i o n . 1 9 5 1 ) h as d e s c r i b e d e x t e n s i v e c h e r t b e d s i n t h e u p p e r o n e - t h i r d of t he G a r d e n C i t y f o r m a t i o n w h i c h a r e n o t f o u n d i n t h e S o u t h F o rk a r e a . a b s e n c e t h e c h e r t a l s o s u g g e s t s t h a t t h e u p p er p a r t t h e f o r m a t i o n i s u n r e p r e s e n t e d. T h e e n v i r o n m e n t d e p o s i t i o n t h e ' G a d e n C i t y f o r m a ­t i o n was p r o b a b l y o n e of v e r y s h a l l o w s e a s w i t h a l t e r n a t i ng p e r i o d s of s u b m e r g e n c e and e m e r g e n c e ( R o s s , 1 9 5 1 ) . The S o u th F o r k a r e a may b e v e r y n e a r t o t h e s o u t h e r n l i m i t of O r d o v i c i an d e p o s i t i o n . o r d o v i c i a n i s e p o r t e d a e w m i l e s s o u t h w a rd i n t h e D u r s t M o u n t a i n a r e a ( C o o d y , 1957) o r w e s t w a r d i n t he Ogden C a n y o n a r e a ( E a r d l e y , 1 9 4 4 ). , - - 21 preserved specimens a r e s carc e . Unfortunately only the t op 296 f eet: of the Garden City formation i s expos~d in the South Fork a r ea. The trilobite J effersonia peltabella, collected near t :he top of the unit p laces the s tra t a, at least in part, in zone G(2)e of Ross (1951) . In the Logan quadr angle this zone lies 522 f eet be low t he t op of the Garden City . fo nnation . ThereforE! it appears that the equivalents of at least 300 feet of Garden City s trata are absent in the South Fork area. Owing t o the ,a pparently conform-able nature of t he contact with t he overlying Fish Haven dolo-mite it is believed the absence of part of t he Ga r den City is due to non-deposition rathe r than erosiclo. Ross ( 1951) has described extensive chert beds in the upper one-third of the Garden City formation which are not found in the South Fork area . The absence of the chert also suggests that the upper part of the formation is unrepresented. The environment of deposition of the· Ga r den City fonna - tion was probably one of very shallow se:as with alternating periods of submergence and emer gence. (Rolss , 1951). The South Fork area may be very near to t he southe:rn limit of Ordovician , deposition . No ordovician is r eport ed a. f ew miles southward -e-in the Durst Mountain area (Coody, 1957) or westward in t he Ogden Canyon area (Eardley, 1944). 22 R o s s ( 1 9 5 1 ) b e l i e v e s t h e d i v i s i o n b e t w e e n l o w e r ( C a n a d i a n) a n d u p p e r O r d o v i c i a n ( C h a z y a n ) l i e s . w i t h i n 30 t o 40 f e e t of t he t o p t h e G a r d e n C i t y f o r m a t i o n i n t h e q u a d r a n g l e S i n ce t h i s i n t e r v a l i s m i s s i n g i n t h e S o u t h F o r k a r e a , t h e f o r m a t i on h e r e m u s e n t i r e l y e a r l y O r d o v i c i a n i n a g e. T h e a b s e n c e of t h e u p p e r p o r t i o n of t h e G a r d e n C i t y and t h e e n t i r e P e a k f o r m a t i o n i n d i c a t e s t h a t c o n s i d e r a b le h i a t u s m u s t e x i s t a t t h e G a r d e n C i t y F i s h c o n t a c t. N e v e r t h e l e s s , no p h y s i c a l e v i d e n c e f o r an u n c o n f o r m i t y c o u ld b e d e t e c t e d , and t h e c o n t a c t a p p e a r s e n t i r e l y c o n f o r m a b l e. T h e f o l l o w i n g s e c t i o n was m e a s u r e d i n t h e " N a r r o w s " of t h e S o u t h F o r k of t h e Ogden R i v e r . I t s h o u l d be n o t e d t h at t h e b o t t o m of . t h e m e a s u r e d s e c t i o n r e p r e s e n t s t h e l o w e st s t r a t i g r a p h i c l e v e l l o c a l l e x p o s e d , n o t t h e s t r a t i g r a p h ic b a s e t h e f o r m a t i o n: T h i c k n e s s in F i s h Haven d o l o m i t e feet D o l o m i t e : m e d i u m g r a y t o l i g h t t a n, f i n e l y c r y s t a l l i n e , w e a t h e r s d a r k to l i g h t g r a y , p r o m i n e n t c l i f f f o r m e r . . . G a r d e n C i t y f o r m a t i on 3 . L i m e s t o n e , b e c o m i n g d o l o m i t ic t o w a r d s t o p u n i t : g r ay w i t h r e d d i s h t i n g e f r e s h ly b r o k e n s u r f a c e s , w e a t h e r s medium t o l i g h t g r a y g m e d i u m t o c o a r s e ly c r y s t a l l i n e , s l o p e f o r m e r . . . . . . . 37 22 Ross (1951) believes the division between lower (Canadian) and upper Ordovician (Chazyan) lies. within 30 to 40 feet of the top of the Garden City formation in the Logan quadrangle . Since this interval is missing in the South Fork area, the formation here mus t be entirely early Ordovician in age. The absence of the upper portion of the Garden City and the entire Swan Peak formation indicates that a considerable • hiatus must exist at the Garden City - Fish Haven contact. Nevert heless, no physical evi dence for an unconformity could , be detected, and the contact appears entirely conformable. The following section was measured in the ItNarrows" of the South Fork of the Ogden River . It should be noted that the bottom of ,the measured s ection represents the lowest stratigraphic level local+y exposed, and not the stratigraphic base of the formation: Fish Haven dolomite Dolomite : medium gray to light tan, finely crystalline, weathers dark to light gray, prominent cliff former •• Garden City formation 3. Limes tone, becoming dolomitic towards top of unit : medium gray with reddish tinge on freshly broken surfaces, weathers medium to light gray, medium to coarsely · crystalline, slope former •• • • • . • • • Thickness in feet 40 37 2 3 T h i c k n e s s in G a r d e n C i t y f o r m a t i o n ( c o n t i n u e d ) feet 2 . L i m e s t o n e , d a r k t o m e d i u m g r a y 3 r e d d i s h t i n g e on f r e s h s u r f a c e s, i n t e r 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 r e n a c e o u s l e n s , m e d i u m t o t h in b e d d i n g . J e f f e r s o o i a p e l t a b e l l a, c f . L i n g u l e o i s s Or t h i s S_P. , T e n t a c u l i t e s ? ) s p . , c y s t o i d p l a t e . . 228 I . L i m e s o n e , t o d a r k g r a y , f i ne m e d i u m c r y s a l l i n e , w e a t h e r s l i g ht g r a y t o b u f f , v e r y i n l y b e d d e d, 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 , Dark g r a y s h a 2 ' t h i c k b o t t o m u n i t, C l o n o g r a p t u s ? ) s p , , P i e t y o n e m a s p , # , T o t a l G a r d e n C i t y f o r m a t i o n v 296 B a s e n o t e x p o s ed F i s h Haven D o l o m i te T h e F i s h Haven d o l o m i t e was named f o r e x p o s u r e s i n F i sh H a v e n C a n y o n w e s t of B e a r L a k e i n s o u t h w e s t e r n I d a h o . In t h e t h e s i s a r e a t h e f o r m a t i o n o u t c r o p s i n t h e " N a r r o w s " of t h e S o u t h F o r k of t h e Ogden R i v e r and f o r m s a l t e r n a t i n g m a s s i ve c l i f f s s m o o t h s l o p e s a b o v e h e s l o p e - f o r m i n g G a r d e n C i ty f o r m a t i o n . It c o n s i s t s of m e d i u m t o d a r k g r a y , f i n e l y c r y ­s t a l l i n e t o s u b l i t h o g r a p h i c , a r e n a c e o u s d o l o m i t e . Gray b a n d ­i n g c a n b e d i s t i n g u i s h e d when v i e w e d f r o m a d i s t a n c e , b u t is n o t d i s c e r n a b l e on t h e o u t c r o p. A l t h o u g h o c c a s i o n a l f o s s i l " s h a d o w s " a r e s e e n i n t he F i s h H a v e n i d e n t i f i a b l e r e m a i n s a r e v e r y a r c e s i n g le c o r a l c o l l e c t e d by t h e a u t h o r was t e n t a t i v e l y i d e n t i f i ed 23 Garden City format ion (continued) 2 . Limes t one, dark t o medium gr ay, r eddi sh t inge on fresh surfaces , inte r format iona l cong l omerates , ar enac eous l ens , medium to thin bedding . J eff er soni a pelt abel l a , cf . Lingulepis , Ort his ~., Thickness in feet Te ntaculit es ( ? ) ~. , cys t oid plate.. 228 1. Limes t one , medium to dark gray, fine t o medi um crys t alli ne, weathers light gray to buff, very t h inly bedded, intraformationa l conglomer ates. Dark gray sha l e 2' thick a t bottom of unit. Clonogr aptus ( 1) ~. , Di ctvonema §R. •• 31 Total Garden Ci ty formation 296 Base not exposed Fish Haven Dolomit e The Fish Haven dolomi t e was named for exposures in F~sh Haven Canyon west of Bear Lake in southwestern Idaho. In the thesis area the formation outcrops in the "Narrows" of the South Fork of the Ogden River and forms alt ernating massive cliffs and smooth ~lo pe above t he slo?e- forming Garden City formation . It cons ists of medium to dark gray, finely c ry-s t a lline to s ublithographic, arenaceous dolomite . Gray band-ing can be distinguished when v iewed from a distanee, but is not discernable on the outcrop . Alt;.hough occas i onal fOSSil "shadows" are s een in the Fish Haven , identifiable remains are very s c arce . A single coral coll ected by the author was ten t atively identified a s S t r e p t e l a s m a ? ) s p. T h e F i s h Haven d o l o m i t e i s 500 f e e t t h i c k a t t h e t y pe s e c t i o n i n t h e R a n d o l p h q u a d r a n g l e , ( R i c h a r d s o n , 1941) and 1 4 0 f e e t i n t h e Logan Q u a d r a n g l e ( W i l l i a m s , 1 9 4 8 ) . The f o r ma t i o n i s a p p r o x i m a t e l y 381 f e e t t h i c k i n t h e S o u t h F o r k a r e a, a l t h o u g h t h i s f i g u r e may b e i n e r r o r as t h e c o n t a c t w i t h t he o v e r l y i n g L a k e t o w n d o l o m i t e v e r y i n d o u b t . F i sh H a v e n and L a k e t o w n d o l o m i t e s a r e shown a s o n e u n i t on t he g e o l o g i c map of t h e a r e a , P l a t e I. T h e a g e of t h e F i s h Haven d o l o m i t e h a s b e e n c o n s i d e r ed t o b e L a t e O r d o v i c i a n R i c h m o n d ) s i n c e i t s o r i g i n a l d e s c r i p ­t i o n . R e c e n t e v i d e n c e h o w e v e r , s u m m a r i z e d by R o s s ( 1 9 5 3) i n d i c a t e s i t may b e M i d d l e O r d o v i c i a n ( T r e n t o n ) o r p e r h a p s, a s R o s s s u g g e s t s , i t s p a n s t h e M i d d l e - L a t e O r d o v i c i an b o u n d a r y c o n c l u d e s , p r e s e n t c a u t i o n i s c o u n s e l ed i n r e g a r d t o t h e d a t i n g of t h e F i s h H a v e n d o l o m i t e and i ts e q u i v a l e n t s i n t h e C o r d i l l e r a n r e g i o n ". T h e f o l l o w i n g s e c t i o n was m e a s u r e d on t h e n o r t h s i de o f t h e " N a r r o w s " of t h e S o u t h F o r k R i v e r: T h i c k n e s s in L a k e t o w n d o l o m i t e feet M o s t l y c o v e r e d , p r o b a b l y l i g h t g r ay d o l o m i t e b e c o m i n g v e r y a r e n a c e o u s at t o p u n i t . S l o p e f o r m e r . . . . . . . 24 as Streotelasma ( 1) 2Q. The Fish Haven dolomite is 500 feet thick at the type section in the Randolph quadrangle, (Richardson, 1941) and 140 f eet in the Logan Quadrangle (Williams , 1948). The forma - tien is approximately 381 feet thick in the South Fork area, a lthough .this figure may be i n error as the contact with the overlying Laketown dolomite i s very much in doubt. The Fish Haven and Laketown dolomites are shown as one unit on the geologic map of the area, Plate I. The age of the Fish Haven dolomite has been considered to be Late Ordovician ( Richmond) since its original descrip-tion. Recent evidence however, summarized by Ross (1953) indicates it may be Mi ddle Ordovician (Trenton) or perhaps , ~s Ross suggests, it spans the Middle-Late Ordovician boundary . He concludes, "At present caution is counseled in regard to the dating of th~ Fish Haven dolomite and its equivalents in the Cordilleran r egion". The following section was measured on the north side of the "Narrows II of the South Fork River: Thickness in Laketown dolomite feet Mostly cover,ed, probably a light gray dolomite becoming very arenaceous at top of unit. Slope former • • • • • • • 145 25 T h i c k n e s s in f e e t L a k e t o w n d o l o m i t e ( c o n t i n u e d) D i s c o n f o r m i t y ( ?) F i s h Haven d o l o m i te 3 . D o l o m i t e m e d i u m g r a y t o l i g h t t a n, v e r y f i n e l y c r y s t a l l i n e t o s u b - l i t h o ­g r a p h i c , m a s s i v e , w e a t h e r s m e d i u m - d a r k g r a y t o l i g h t g r a y . B a n d i ng o f l i g h t d a r k g r a y c a n b e s e en f r o m d i s t a n c e b u t c a n n o t be d i s c e r n e d o u t c r o p , l i f f f o r m e r . . . 117 2 . D o l o m i t e : a s i n No.' a b o v e , b ut s l i g h t l y a r e n a c e o u s a n d s l o pe 1 . D o l o m i t e i n Kb. a b o v e, f o r m s v e r y i m p o s i n g c l i f f s . . . . . . 135 T o t a l F i s h Haven f o r m a t i o n 381 D i s c o n f o r m i t y G a r d e n C i t y f o r m a t i on L i m e s t o n e b e c o m i n g d o l o m i t i c t o w a r d t o p u n i t : m e d i u m g r a y w i t h r e d ­d i s h t i n g e f r e s h l y b r o k e n s u r f a c e s, w e a t h e r s m e d i u m t o l i g h t g r a y , medium t o c o a r s e l y c r y s t a l l i n e , s l o p e f o r m e r . . . S i l u r i a n S y s t em L a k e t o w n D o l o m i te T h e S i l u r i a n s y s t e m i n t h e n o r t h e r n W a s a t c h M o u n t a i ns i s r e p r e s e n t e d by a s i n g l e f o r m a t i o n , t h e L a k e t o w n d o l o ­m i t e . In t h e S o u t h F o r k a r e a t h e l i g h t g r a y , a r e n a c e o us L a k e t o w n o v e r l i e s t h e m a s s i v e , d a r k e r F i s h Haven d o l o m i te a n d u n d e r l i e s t h e w h i t e w e a t h e r i n g W a t e r C a n y o n f o r m a t i o n. 25 Laketown dolomite (continued) Disconforrnity (?) Fish Haven dolomite 3. Dolomite : medium gray to light tan, very finely crys talline to sub-litho­graphic, massive, weat hers medium-dark gray to light gray Banding of light and dark gray can be seen from a distance , but cannot be discerned on outcrop, c liff former .... 2. Dolomite: as in No .. slightly .arenaceous 3 above, but and a slope former • • .. .. .. .. .. .. .. .. .. .. .. • • • Dolomite : forms very as in No . 3 above, i mposing c l iffs .... .. .. .. .. Total Fish Haven f orw~tion Disconformity Garden Cit y formation Limestone becoming dolomitic tmV'ard . top of unit: medium gray with red­dish tinge on freshly broken surfaces , weathers medium to light gray, medium to coarsely crystalline, slope former .. Silurian System Lake t own Dolomite • • Thickness in feet , 117 129 135 381 37 The Silurian system in the northern Wasatch Mountains is repres ented by a single fo rmation , the Laketown dolo-mite. In the South Fork ar ea t he light gray , arenaceous Laketown overlies the massive, darker Fish Haven dolomite and underlies the white weathering Water Canyon formation. 26 As p r e v i o u s l y n o t e d t h e p o o r e x p o s u r e s and u n c e r t a i n c o n t a ct n e c e s s i t a t e d m a p p i n g t h e F i s h a n d L a k e t o w n s i n g le u n i t G e o l o g i c P l a t e I ) . T h e L a k e t o w n d o l o m i t e t h i n s r a p i d l y f r o m 1500 f e e t in t h e Logan q u a d r a n g l e t o t h e n o r t h ( W i l l i a m s , 1948) t o 243 f e e t i n t h e t h e s i s a r e a . The a b s e n c e of S i l u r i a n s t r a t a in t h e D u r s t M o u n t a i n r e g i o n t o t h e s o u t h ( G o o d y , 1 9 5 7 ) i n d i c a t es t h a t t h e S o u t h F o r k a r e a l i e v e r y c l o s e t o t h e s o u t h e rn m a r g i n S i l u r i a n d e p o s i t i o n . A l t h o u g h o c c a s i o n a l o u t l i n es o f f o s s i l s w e r e o b s e r v e d i n t h e L a k e t o w n of ' t h e S o u t h F o rk a r e a , no i d e n t i f i a b l e r e m a i n s c o u l d b e f o u n d . However f a u n a l c o l l e c t i o n s f r o m t h e f o r m a t i o n i n o t h e r a r e a s i n d i c a te m i d d l e S i l u r i a n a g e S t o k e s , 1 9 5 3 ). T h e a b s e n c e l o w e r a n d u p p e r S i l u r i a n r o c k s i n d i c a t es t h a t a c o n s i d e r a b l e h i a t u s m u s t e x i s t a t b o t h c o n t a c t s of t he m i d d l e S i l u r i a n L a k e t o w n d o l o m i t e . The n a t u r e of t h e c o n t a c ts h o w e v e r , i s l a r g e l y o b s c u r e d v e g e t a t i o n s o i l . As n o t e d i n t h e d i s c u s s i o n of t h e F i s h Haven d o l o m i t e, t h e c o n t a c t s c h o s e n i n t h e m e a s u r e d s e c t i o n s b e i n e r r o r, a n d p e r h a p s t h e L a k e t o w n i s t h i c k e r t h a n i n d i c a t e d. T h e f o l l o w i n g s e c t i o n m e a s u r e d i n t h e N a r r o w s M t he S o u t h F o r k R i v e r: 26 As previously noted t he poor exposures and uncertain contact necessitated mapping the Fish Haven and Laketown as a single unit ( Geologic map, Plate I). The Laketown dolomite t hins r apidly from 1500 feet in the Logan quadrangle to the north (Williams, 1948) to 243 feet in the thesis area. The absence of Silurian strata in the Durst Mountain r egion to the south (Coody, 1957) indicates that the South Fork area may lie very close to the southern margin of Silurian deposition. Although occasional outlines of fossils were observed in the Laketown of 'the South Fork area, no identifiable remains could be found . However faunal collections from the formation in other areas indicate a middle Silurian age ( Stokes, 1953) . The absence of lower and upper Silurian rocks indicates that a considerable hiatus must exis t at both contacts of the middle Silurian Laketown dolomite. The nature of the contacts ~owever, is largely obscured by vegeta~ion and soil. As noted in the discussion of the Fish Haven dolomite~ the contacts chosen in the measured sections may be in error, and perhaps the Laketown is somewhat thicker than indicated. The fol~o~ing section was measured in the " Narrows II of the South Fork River: F i g * 2 C l i f f s of F i sh H a v e n d o l o m i t e e x - . p o s e d i n t h e " N a r r o w s 85 o f t h e S o u t h F o rk R i v e r * S l o p e f o r m i ng G a r d e n C i t y f o r m a t i on a t l o w e r r i g h t* i g * a t m o u th o f K i e s e l Canyon s h o w i n g - W a t e r Canyon a n d J e f f e r s o n fms4> \ - r . • h. ,.' '. , .".. '" Fig. 3 View at mouth of Camp Kiesel Canyon showing-water Canyon and Jefferson fms. , ,, J • I . "•• <" Fig. 2 Cliffs of Fish Haven do lond te ex­. posed in the "Narrows l1 of the South Fork River. Slope formi.ng Garden City forma tion at lower r ight • • • , /. , . .-.; ~ ~ .. ...... _.... 27 T h i c k n e s s W a t e r C a n y o n f o r m a t i o n 'feet D o l o m i t e , l i g h t g r a y o w h i t e, c o a r s e l y c r y s t a l l i n e , o o l i t i c, w e a t h e r s n e a r l y w h i t e , s l o pe f o r m e ®«^«.» • L a k e t o w n d o l o m i te 2 . D o l o m i t e : l i g h t g r a y , m e d i u m to c o a r s e l y c r y s t a l l i n e , f o s s il " s h a d o w s " , c l i f f - f o r m e r 1 . C o v e r e d : p r o b a b l y a l i g h t g r ay d o l o m i t e b e c o m i n g v e r y a r e n a ­c e o u s a t t o p of u n i t , s l o pe f o r m e r . . « c « « « c » * < ? * * * « ^ ^ 5 V T o t a l L a k e t o w n d o l o m i t e f o r m a t i o n 243 D i s c o n f o r m i t y F i s h Haven d o l o m i te D o l o m i t e : m e d i u m g r a y t o l i g h t t a n, v e r y f i n e l y c r y s t a l l i n e , m a s s i v e, w e a t h e r s m e d i u m - d a r k g r a y , b a n d e d . . . . 117 D e v o n i a n S y s t em G e n e r a l S t a t e m e nt T h e D e v o n i a n S y s t e m i n t h e a r e a u n d e r s t u d y i s c o m p o s ed o f e e t m a r i n e d o o m i t e i m e s t o n e a n d s h a l e . T h r ee d i s t i n c t l i t h o l o g i c u n i t s a r e e c o g n i z e d : l o w e r d o l o m i te u n i t i n t e r b e d d e d w i t h t h i n s h a l e b e d s ; a m i d d l e s e q u e n c e of b l a c k , a r e n a c e o u s d o l o m i t e , l i m e s t o n e a n d l i m e s t o n e b r e c c i a, a n d an u p p e r u n i t of v a r i e g a t e d r e d , b r o w n a n d g r e e n s h a l e. T h e s e u n i t s h a v e b e e n c o r r e a t e d w i t h h e W a t e r C a n y o n, 27 Water Canvon formation Dolomite : ligh t gray ' t o whit.e, . coar sely crystal l i ne, oolitic, weat hers nearly whit e, s lope , fenne r . • • • • • • • • • • • • Laketmvn dolomite • • • • • 2. Dolomit e : light gray, medium to coar sely crystalline, fossi l Thickness in 'feet 54 II shadows n , cliff - fanner • • • • • • • 98 1. Covered: probabl y a l ight gr ay dolomite becoming v ery a r ena­c eous at top of unit , ~lo fanner • • • • • • • • • • • • • • • 145 Tota l Laketown dolomit e formation 243 Disconformity Fish Haven dolomite Dol omite: medi um gr ay to light tan, v ery finely crys talline, massive, weathers medium- dar k gray , banded Devonian System Gen er a l Sta t ement • • • • 117 The Devonian Sys t em in t he ar ea under study is composed of 1144 f eet of marine do l omi te , l imestone and shale. Three distinct lithologic units a~r ec ognized : a lower dolomite unit interbedded with thin shale beds ; a middle sequence of black , a r enaceous dolomite, limestone and limestone brecCia, and an upper unit of variegat ed r ed, brown and green sha le. These units have been corre l at ed with t he Water Canyon, 9 3 4 Lakeside Mts ( You n q, 19 5 3) Promontory Ra. (Olson , 1956 ). Randolph Quad. . R i c h a r d s o n , 19 41 L o g r n Quad. Williams. 19 4 8) L i :L I / J ; r h 1 / i i .1 I /•/• / / / J r i C O R R E L A T I O N OF D E V O N I A N SY M t 5. Young , 1953) I ~l 0r p:::."-- 1 ~--A o~ o . ~ 2 3 4 Proman t ar y Ro. R cndolpt, Qu od. 0 q ("" n Qu ac . (Olson , 1956 l. .R: cho r d son , -o ~ 0 1 ~ Ih-'---,-"-1 : ~,-"c-7-'-1 ~ V'-r-.L-J CORRELA TION OF 1941 ' (Will iam", 19 4 a 1 DEVON I AN Sy E V O N I A N S Y S T E M IN N O R T H E R N UTAH ~ uod , ,9 41 c -•o o o ~ 4 Loge n (Will i o",.; . DE VO NIAN 5 Qu cc. 5",. For k Ar ea 19 .. 8) Th:s P {;~ Cr} SYSTEM IN 6 7 Dur _ t ". W e~ t er l'l Uin ta ,C,,\';dv, J ~5 7 1 (Vlilliofr::. , N.': I I I 1---l--l~4~J~ __ NOR THERN I I I UTA H I I I L --- I NDE X M ~P UTAH Mt !>. 1',)~31 I I. I , I I I 28 J e f f e r s o n and T h r e e F o r k s f o r m a t i o n s r e s p e c t i v e l y. T h i s s t r a t i g r a p h i c s e q u e n c e r e p r e s e n t s . t h e m o s t c o m p l e te D e v o n i a n s e c t i o n 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 ; t he T h r e e F o r k s f o r m a t i o n i s n o t p r e s e n t i n t h e Logan q u a d r a n g le t o t h e n o r t h t h e W a t e r C a n y o n i s a b s e n t s o u t h w a r d i n t he M o r g a n - K e n e f e r a r e a . T h e e n t i r e D e v o n i a n s e c t i o n was m e a s u r e d i n Camp K i e s el C a n y o n , T, 7 N # , R. 3 E. W a t e r Canyon F o r m a t i on T h e l o w e r D e v o n i a n W a t e r C a n y o n f o r m a t i o n c r o p s o u t at t h e m o u t h of Camp K i e s e l C a n y o n w h e r e 121 f e e t of s t r a ta w e r e m e a s u r e d . The u n i t c o n s i s t s of i n t e r b e d d e d l i g h t g r ay d o l o m i t e s and g r a y t o b l a c k , t h i n b e d d e d s h a l e s . The W a t er C a n y o n w e a t h e r s l i g h t b u f f t o n e a r l y w h i t e a n d i s e a s i l y d i s t i n ­g u i s h e d f r o m t h e g r a y L a k e t o w n d o l o m i t e b e l o w t h e m a s s i v e, n e a r l y b l a c k J e f f e r s o n f o r m a t i o n a b o v e. T h e f o s s i l r e m a i n s f o u n d i n t h e W a t e r C a n y o n f o r m a t i on c o n s i s t of a s i n g l e f i s h p l a t e and u n i d e n t i f i a b l e p l a nt r e m a i n s . However, t h i s m e a g e r c o l l e c t i o n p l u s t h e s t r a t i ­g r a p h i c p o s i t i o n d i s t i n c t i v e l i t h o l o g y t h e u n i t l e a ve l i t t l e d o u b t t h a t t h e f o r m a t i o n i s t h e c o r r e l a t i v e t he t y p e W a t e r C a n y o n t o t h e n o r t h. A l t h o u g h W i l l i a m s 1 9 4 8 ) n o t e d m a r k e d d i s c o n f o r m i ty 28 Jefferson and Three Forks formations respectively. This stratigraphic sequence represents the most complete Devonian section in the north-central \.]asatch Mountains ; the Three Forks formation is noc pr e s ent in the Logan quadrangle to the north and the Water Canyon is absent southward in the Horgan-Henefer area. The entire Devonian section was measured in Camp Kiesel Canyon, T. 7N., R. 3 E. Water Canyon Formation The lower Devoniap Water Canyon formation crops Qut a~ the mouth of Camp Kiesel Canyon where 121 feet of strata were measured . The unit consists of interbedded light gray dolomites and gray to black, thin bedded shales . The Water Canyon weathers light buff to nearly whi te and is easily distin­guished from the gray Laketown dolomite below and the massive, nearly black Jefferson formation above . The fossil remains found in the Watl~ Canyon formation consist of ~ single fish plate and unidentifiable plant remains.. However, this meager collection plus the strati­graphic position and distinctive lithology of the unit leave little doubt that the formation is the correlative of th~ type Water Canyon to the north .. Although Williams ( 1948) noted a marked disconformity 29 a t t h e o p t h e W a t e r C a n y o n , h e c o n t a c t a p p e a r e d e v e r y ­w h e r e c o n f o r m a b l e w h e r e i t e x p o s e d i n t h e t h e s i s a r e a. T h e f o l l o w i n g s e c t i o n m e a s u r e d a t t h e m o u t h K i e s e l C a n y o n: T h i c k n e s s in J e f f e r s o n f o r m a t i o n feet D o l o m i t e : m e d i u m g r a y , medium c r y s t a l l i n e 5 s l i g h t l y a r e n a c e o u s, b e d d i n g m e d i u m t o m a s s i v e , w e a t h e rs d a r k g r a y t o b l a c k < » e < a * * 0 « e « . . C o n t a c t c o n f o r m a b l e ( ?) W a t e r C a n v o n f o r m a t i on D o l o m i t e : g r a y , f i n e t o medium c r y s t a l l i n e , medium b e d d e d , w e a t h e rs l i g h t b u f f t o n e a r l y ' w h i t e . F i sh p l a t e f o u n d n e a r t o p of u n i t . . . . 28 7 . C o v e r e d p r o b a b l y b l a c k s h a l e as i n u n i t No. 5 . . . . . . . . . . . 18 S h a l e d a r k g r a y t o b l a c k , f i s s i l e, c o n t a i n s p o o r l y p r e s e r v e d p l a n t e m a i n s 4 5 . S h a l e : b l a c k , d o l o m i t i c , medium b e d d e d , w i t h p l a n t r e m a i n s 5 4 . S h a l e : m e d i u m t o d a r k g r a y , f i s s i l e 1 3 . D o l o m i t e : as i n u n i t No. 1 10 2 . I n t e r b e d d e d s h a l e d o l o m i t e : t h in b e d d e d 1 " ) , s h a l e l i g h t o l i v e g r a y, f i s s i l e , d o l o m i t e l i g h t g r a y . . . . D o l o m i t e : l i g h t g r a y t o w h i t e , ' c o a r s e ly c r y s t a l l i n e , o o l i t i c w e a t h e r s n e a r ly w h i t e , s l o p e f o r m e r . . . . . . . . 54 T o t a l W a t e r C a n y o n F o r m a t i o n 121 29 at the t op of the Water Canyon, t he contact appear ed every-where conformable where it was exposed in the thesis area . The following section was measured at the mouth of Camp Kiesel Ca nyon: Jeffer son formation Dolomite: medium gray, mea~um crys t alline, sli ghtly a renaceous, bedding medium to massive, weathers dark gray to black • (> ••••••• Contact conformable (?) Water Canvon formation • • 8 . Dolomite: medium gray, fine to medium crystalline, medium bedded, weathers light b~ff to nearly ~mite. Fish Thickness in feet 10 plate found near top of unit • • • • 28 7. Covered : probably black shale as in unit ·•• •• •• ••• • • 6 . Shale : dark gray to black , fissile, 18 contains poorly preserved plant r emains 4 5. Shale : black, dolomitic, medium bedded, with plant remains •• • • • 5 4. Shale: medium to dark gray, fis sile 1 3. Dolomite: as in uni t No. 1. • • • • 10 2. Interbedded "shale and dolomite: thin bedded ( l n), shale light olive gray, fissile, dolomite light gray • • • • 1 1 . Dolomite: light gray· to white, "coarsely crystalline, oolitic , weathers nearly white, slope former • • • • • • • • 54 Total Water Canyon Formation 121 30 T h i c k n e s s W a t e r C a n y o n f o r m a t i o n ( c o n t i n u e d ) feet C o n t a c t c o n f o r m a b le L a k e t o w n d o l o m i te D o l o m i t e : l i g h t g r a y , m e d i u m to c o a r s e l y c r y s t a l l i n e , c l i f f f o r m e r . . . 98 J e f f e r s o n F o r m a t i on O v e r l y i n g t h e n e a r l y w h i t e w e a t h e r i n g W a t e r Canyon f o r m a t i o n i s t h i c k s e q u e n c e d a r k g r a y t o b l a c k , d a rk w e a t h e r i n g d o l o m i t e s l i m e s t o n e s . t h e q u a d r a n g le n o r t h h e t h e s i s a r e a , W i l l i a m s 1 9 4 8 ) h a s a s s i g n e d t h is u n i t t o t h e J e f f e r s o n f o r m a t i o n. I n t h e S o u t h F o r k a r e a h e J e f f e r s o n w e l l e x p o s e d t h e w e s t s i d e K i e s e C a n y o n w h e r e i t o u t c r o p s in m a s s i v e , d a r k g r a y c l i f f s . l i m e s t o n e s d o l o m i t e s a re m e d i u m t o f i n e l y c r y s t a l l i n e and b e c o m e i n c r e a s i n g l y a r e n a ­c e o u s t o w a r d t h e t o p of t h e f o r m a t i o n . L i m e s t o n e b r e c c i as a n d g r a y s h a l e s a r e a l s o f o u n d i n t h e u n i t. T h e c o n e a c t h e J e f f e r s o n f o r m a t i o n w i t h t h e u n d e r ­l y i n g W a t e r C a n y o n f o r m a t i o n was p l a c e d a t t h e b o t t o m of t he f i r s t d a r k g r a y d o l o m i t e b e d . The u p p e r c o n t a c t was p l a c ed a t t h e b a s e of t h e f i r s t r e d s h a l e of t h e o v e r l y i n g T h r ee F o r k s f o r m a t i o n . J e f f e r s o n f o r m a t i o n i s f e e t t h i ck i n t h e S o u t h F o r k a r e a ; f o s s i l s w e r e f o u n d. 30 Water Canyon formation (continued) Contact conformab l e Laketown dolomite , Dolomite: light gray~ medium to coarsely crystalline, cliff former Jefferson Formation • • • Thickness in feet 98 Overl ying ~he nearly white weathering Water Canyon formation is a thick sequence of dark gray to black, ' dark weathering dolomites and li~~ stones . In the Logan quadrangle north of t he thesis area, il lia~ ( 1948) has assigned this unit to the Jefferson format i on. '. In the South Fork area t he Jefferson i s well exposed on the west side of Camp Kiese l Canyon 't~here it outcrops in massive, dark gray cliffs. The limestones and dolomites are medium to finely crystalline and become increasingly arena-ceous toward the top of the f ormation . L~estone breccias and gray shal es are also found in the unit. The contact of t he Jefferson formation with the under-lying Water Canyon formation was placed at the bottom of the first dark gray dolomite bed . The upper contact was placed a t the base of the first red shale of the overlying Three Forks formation. The Jefferson formation is 435 feet thick in the South Fork area; no fossils were found. 31 W i l l i a m s ( 1 9 4 8 ) h a s named two m e m b e r s w i t h i n t h e J e f f e r s on f o r m a t i o n of t h e Logan q u a d r a n g l e . The l o w e r member (Kyrum d o l o m i t e ) i s p r e d o m i n a t e l y d a r k g r a y d o l o m i t e s a n d l i m e s t o n e s. T h e , u p p e r B e i r d n e a u a n d s t o n e ) e n t i r e l y b u ff w e a t h e r i n g s a n d s t o n e . In r e g a r d t o t h e B e i r d n e a u s a n d s t o ne m e m b e r , W i l l i a m s s t a t e s: " T h e B e i r d n e a u s a n d s t o n e member may be t h e t a x o n o m i c e q u i v a l e n t of t h e T h r ee F o r k s s h a l e s and l i m e s t o n e s , b u t t he p o s s i b i l i t y of f i n d i n g f o s s i l s i n t h e se u p p e r b e d s i n t h e Logan q u a d r a n g l e is r e m o t e . . # i t seems u n d e s i r a b l e d i v i d e t h e D e v o n i a n r o c k s t h e r e g i on i n t o two f o r m a t i o n s , and i n t r o d u c e a n ew f o r m a t i o n n a m e , p a r t i c u l a r l y s i n ce t h e y a r e i e r g r a d i n g l i t h o l o g i c u n i t ." A l s o i n r e g a r d t o t h i s n o m e n c l a t u r e p r o b l e m , B r o o k s A n d r i c h uk 1 9 5 3 ) s t a t e s: " T h e 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 b e c h r o n o i o g i c a 1 l y c l o se c o r r e l a t i v e t h e T h r e e F o r k s , r e c o g ­n i z e d e l s e w h e r e i n t h e r e g i o n . However t h e i t h o l o g i e s a r e s i m i l a r o n l y i n h a t • b o t h r e p r e s e n t c h a n g e i n l a t e D e v o n i an t i m e f r o m p u r e l y c a r b o n a t e d e p o s i t i o n to t h a t m o r e c l a s t i c . " T h e s t r a t i g r a p h i c s e q u e n c e of t h e S o u t h F o r k a r e a s e e m s to s u p p o r t t h i s s u g g e s t i o n . t h i c k n e s s 4 3 5 f e e t ) t he J e f f e r s o n i n t h e a r e a i s s u b s t a n t i a l l y l e s s t h a n t h e com­b i n e d t h i c k n e s s 2 1 2 0 f e e t ) t h e a n d B e i r d n e a u m e m b e r s W i l l i a m s , 1 9 4 8 ) i t s h o u l d n o t e d t h at 31 Williams (1948) has named two members within the Jefferson formation of the Logan quadrangl e . The lower member (Hyrum dolomi.te) is predomina1:ely dark gray dolomites ~nd limestones. The . upper member ( Beirdneau s andstone) i s entirely a buff weathering sandstone. In r egard to the Beirdneau sandstone member, \.J'illifu-ns states: liThe Beirdneau sandstone member may be the taxonomic: equi valent of ' t he Three Forks shales and limes t ones, but the possibility of finding fossils in these upper beds in the Logan quadr angl e is remote • •• it seems undesirable to divide- the DE?;vonian rocks of the r~gi into two fonnations, and introduce a new formation name, particul arly since they are an :i.n t ergr ading lit hologic unit." Also in regard to this nomenclature probl em, Brooks and Andrichuk ( 1953) states : liThe Beirdneall member of the J efferson formation may be chronologically a close correlative of the Three Forks, recog­nized e lsewhere in t he r egion. However the l ithologies are similar only in t hat both represent a change in late Devonian time from purely car bonate depos ition to that of a more clas tic. 1I The stratigraphic sequ~:mce of th~ South Fork area seems to support this suggestioi,. The thickness ( 435 feet) of the Jefferson in the area is substantially less than the com-bined thickness ( 2120 feet) of the Hyrum and Beirdneau . members ( Williams, 1948) . However it should be noted that 32 i n t h e q u a d r a n g l e t h e J e f f e r s o n f o r m a t i o n s a b s e nt i n s e v e r a l l o c a l i t i e s and t h e M a d i s o n l i m e s t o n e of M i s s i s - s i p p i a n a g e r e s t s S i l u r i a n o c k s . T h i s p r o n o u n c e d u n c o n ­f o r m i t y r e p r e s e n t e r o s i o n o r n o n - d e p o s i t i o n d u r i n g T h r ee F o r k s t i m e. T h e f o l l o w i n g s e c t i o n m e a s u r e d t h e w e s t s i d e of K i e s e C a n y o n: T h r e e F o r k s f o r m a t i on w T h i c k n e s s in f e e t S h a l e a n d i n t e r b e d d e d s a n d s t o n e: s h a l e r e d , f i s s i l e , c a l c a r e o u s, s a n d s t o n e b u f f , medium t o c o a r se grc*2.n . . . . . . . . . . 3 . « « • • • • J e f f e r s o n f o r m a t i on 2 0 . L i m e s t o n e b r e c c i a : m e d i u m to c o a r s e l y c r y s a l l i n e , l i g h t g r a y, w e a t h e r s d a r k g r a y , a r e n a c e o u s, m e d i u m b e d d e d t o m a s s i v e , forms p r o m i n e n t c l i f f b e l o w T h r e e F o r ks f o r m a t x o n . . $ . ® . . « © © . « • 1 9 . C o v e r e d : p r o b a b l y i n t e r b e d d e d . s a n d ­s t o n e a n d s h a l e , f o r m s s l o p e . . . . 1 8 . L i m e s t o n e : m e d i um g r a y , f i n e ly c r y s t a l l i n e , t h i n b e d d e d , a b u n d a nt a l c i t e s t r i n g e r s . . . o 0 •• 9 « # w 1 7 . L i m e s t o n e l i m e s t o n e b r e c c i a: m e d i u m g r a y , w e a t h e r s d a r k g r a y, m e d i u m c r y s t a l l i n e , v e r y a r e n a c e o us 1 6 . C o v e r e d: « 0 9 « • 1 5 . L i m e s t o n e l i m e s t o n e b r e c c i a : as i n No. a b o v e • . . . . . 31 32 in the Logan quadrangle the Jefferson formation i s absent in several localities and the Madison limestone of Missis - sippian age rests on Siluria n r oc ks . This pronounced uncon-formity may represent erosion or non-deposition during Three Forks time . The following section was measured on the west side of Camp Kiese,l Canyon: Three Forks formation Shale and interbedded sandstone : shale red , fisSile, calcareous, sandstone buff, medium to coarse grain • . . .. . . . .. . .. . .. .. . . .. . . Jefferson formation , 20. Limestone breccia: medium to coarsely crys t alline, light gray, weathers dark gray, arenace ous, medi~ bedded to massive, ' fo~ prominent cliff belm:' Three Forks Thickness in feet 11 formation • • • • • • • • • • • • • .. 19. Covered: probably interbedded sand-stone and shale, forms slope • ••• 29 18. Limestone: medium crystalline, thin c alcite stringers gray, finely bedded, abundant •••••••• ••• 17. Limestone and limes tone breccia : medium gray, weathers dark gray, medium crys alline, ve.ry alie~a,? e<?u~ 16. Cover ed : • • • • • • • • • • • • • 15. Limestone and limestone in No . 20 above •• •• breccia: as . . . .. . . 16 29 18 8 T h i c k n e s s J e f f e r s o n f o r m a t i o n ( c o n t i n u e d ) feet 1 4 . C o v e r e d : p r o b a b l y a r e n a c e o u s d o l o m i t e 52 1 3 . D o l o m i t e : m e d i um g r a y , v e r y f i n e ly c r y s t a l l i n e , m a s s i v e * , . . . . . . . 22 1 2 . C o v e r e d : p r o b a b l y a d a r k g r a y s h a l e . 18 1 1 . D o l o m i t e : , d a r k g r a y , f i n e ly c r y s t a l l i n e , s l i g h t l y a r e n a c e o u s, s l i g h t l y c a l c a r e o u s , m e d i u m b e d d e d v . 25 1 0 . S a n d s t o n e : v e r y l i g h t b u f f , f i ne g r a i n , w e l l - r o u n d e d , n o n - c a l c a r e o u s, c r o s s b e d d e d . . . . . . . . . . . . . 2 9 . D o l o m i t e : g r a y , m e d i u m c r y s t a l l i n e , . a r e n a c e o u s , m e d i um b e d d e d t o m a s s i v e 31 8 . D o l o m i t e : d a r k g r a y t o b l a c k , f i ne t o m e d i u m c r y s t a l l i n e , w e a t h e r s d a rk g r a y , s l i g h t l y a r e n a c e o u s , m e d i um b e d d e d t o m a s s i v e 7 , D o l o m i t e : a s i n No. 1 6 , b u t t h in b e d d e d ( 2 " - 4 » ) . . . Q . . , . . . . 21 6 . D o l o m i t e : a s i n No. 16 a b o v e . . . . . 24 5 . C o v e r e d : p r o b a b l y a r e n a c e o u s s h a le b u f f . . . . . . . . . . . . . . . . . 27 4 . L i m e s t o n e a n d s h a l e b r e c c i a : medium g r a y and b u f f , l i m e s t o n e f i n e ly c r y s t a l l i n e t o s u b l i t h o g r a p h i c, b e d d i n g i n d i s t i n c t t o v e r y t h i n . . . 6 3 . D o l o m i t e : l i g h t g r a y t o w h i t e , v e ry a r e n a c e o u s , f i n e l y c r y s t a l l i n e, w e a t h e r s t o g r a y , s a n d y s u r f a c e, m e d i u m b e d d e d , c l i f f f o r m e r . . . . . 20 2 . D o l o m i t e : m e d i um g r a y , w e a t h e rs g r a y t o b u f f , t h i n t o m e d i um b e d d e d , t h in b e d s f i n e l a m i n a t i o n s 33 Jefferson formation (continued) 14. Covered: probably arenaceous dolomite 13. Do lomite : medium gray, very finely c"rystalline , massive .• . . . ~ . . . 12. Cover ed : probably a dark gray shale • 11. Dolomite :. dark gray, finely c rys t alline , slight ly arenaceous, s lightly calcareous, medium bedded • • 10. Sandstone: very light buff, fine grain, well- rounded, non-calcareous, Thickness in feet 52 22 18 25 crossbedded •••••••• • " • • • 2 9 . Dolomite : gray, medium crystalline, . arenaceous, medium bedded to massive 31 8. Dolomite : dark gray t o black, fine to medium crystalline, weathers dark gray , slightly arenac eous, medium bedded to massive . ... ..... .. 24 7. Dolomite: as in No. 16, but thin bedded '(211 _4") • • • • • • • • .. . • • 21 6. 5. Dolomite: as in No . 16 above • .. . . . Covered : bllff • • p.r o.b c.:'- b..l y .. ar.e n.. a.ce o.u s.. s.h a.. le.. .. . 4. Limestone and shale breccia: medium gray and buff, limestone fine ly crystalline to sublithographic, 24 27 bedding indistinct to very thin .... 6 3. Dolomite: light gray to t.Jhite, very arenaceous, fine ly crystalline, weather s t o gray, sandy s urface, medium bedded, cliff former .. ~ • ... 20 2. Dolomite: medium gr ay , weathers gray to buff, thin to medium bedded, thin beds show fine laminations • • ~ .. ... 22 J e f f e r s o n f o r m a t i o n ( c o n t i n u e d) T h i c k n e s s in f e e t 1 . D o l o m i t e : g r a y , w e a t h e r s d a rk g r a y t o b l a c k , m e d i u m c r y s t a l l i n e . T o t a l J e f f e r s o n f o r m a t i on 4 3 5 C o n t a c t c o n f o r m a b le W a t e r C a n y o n f o r m a t i on D o l o m i t e : m e d i u m g r a y , f i n e ' t o m e d i um c r y s t a l l i n e , w e a t h e r s w h i t e , b e d d e d T h r e e F o r k s F o r m a t i on T h e 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 i s w e l l e x p o s e d on t h e w e s t s i d e o f Camp K i e s e l Canyon w h e r e i t f o r m s a d i s t i n c t s l o p e b e l o w h e v e r y m p o s i n g c l i f f s M a d i s o n l i m e s t o n e. o f t h e u n i t ; t h e s h a l e s a r e r e d , g r e e n and c h o c o l a t e b r o w n. Two t h i n c o n g l o m e r a t i c b e d s c o m p o s e d of r e d s h a l e f r a g m e n t s. i n t e r b 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 c o n s p i c u o u s . C a s ts o f h a l i t e c r y s a l s a l s o i n h e l o w e r u n i t . The u p p e r p o r t i o n t h e f o r m a t i o n , g e n e r l l y p o o r l y e x p o s e d , is p r e d o m i n a t e l y i n t e r b e d d e d e d d i s h s a n d s t o n e g r a y, c a l c a r e o u s s h a l e. T h e l o w e r c o n t a c t t h e T h r e e F o r k s f o r m a t i o n w a s . p l a c ed a t t h e b a s e of t h e f i r s t r e d s h a l e b e d a b o v e t h e b l a c k w e a t h - e r i n g e f f e r s o n l i m e s t o n e . u p p e r c o n t a c t , u s u a l l y c o v e r ed I n t e r b e d d e d s h a l e a n d l i m e s t o n e o m p r i s e t h e l o w e r p o r t i on 34 Jefferson formation (continued) 1. D'olomite: medium gray, weathers dark gray to black , medium crystalline , Thickness in feet medium bedded • • • • • • • • • • • • 10 Total J efferson fO~4tion Contact conformable Water Canyon formation Dolomite : medium gr ay, fin e" Co medium crystalline, weathers white, medium bedded Three Forks Formation 435 28 The Devonian Three Forks format ion is well exposed on the west s ide of Camp Kiesel Canyon 'tvhere it forms a distinct slope below t he very i mposing cliffs of Madison limestone. Interbedded shale and limestone c omprise the lower portion' of t he unit; t he shal es are r ed, green and chocolate brown. Two thin conglomer atic beds composed of r ed shale fragments_ interbedded in a calcareous matrix are conspicuous. Casts of halite crys t als a r e also common in t he lower unit. The upper portion of the formation, gener a lly poorly exposed, is predominately interbedded r eddish sandst one and gray, '#'calcareous shale. The lower contact of the Three Forks fo~tion · was. pl aced at the base of the first red shale bed above the black weath-ering J effer son lim~stone. The upper -contact, usually cove r ed b y d e b r i s f r o m t h e 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 , p l a c ed i m m e d i a t e l y b e l o w t h e f i r s t m a s s i v