Geology of the Smith and Morehouse-South Fork Area, Utah

The writer wishes to express his appreciation to Norman C. Williams of the University of Utah, for his supervision and assistance in the field and in the compilation of the manuscript. Thanks are due ViJilliam Lee Stokes of the University of Utah, for his effort in the identification of fossil specimens. A. J. Eardley, F. W. Christiansen and P. J. Shenon of the University of Utah, have assisted with the manuscript.

OP SOUTH PORK b y W a r r e n H o o p er t h e s i s s u b m i t t e d t o t h e f a c u l t y t he U n i v e r s i t y U t a h i n p a r t i a l f u l f i l l m e nt o f t h e r e q u i r e m e n t s f o r t h e d e g r e e of MASTER o f SCIENCE D e p a r t m e n t G e o l o gy A p p r o v e d : C h a i r m a n , T h e s i s C o m m i t t ee 1 9 5 1 GEOLOGY OF THE SMITH AND MOREHOUSE-SOUTH FORK AREA, UTAH by Warren G. Hooper A thesis submitted to the faculty of the University of Utah in partial fulfillment of the requirements for the degree of W~STER of SCIENCE Department of Geolqgy Approved: ~ .-<~. Chairman, Thesis Com.rnittee of Utah 1951 UNlVERS1TY Of UT f.H UBRARY ACKNOWLEDGEMENTS w r i t e r w i s h e s t o e x p r e s s h i s a p p r e c i a t i o n to W i l l i a m s t h e U n i v e r s i t y U t a h , f o r h is s u p e r v i s i o n a s s i s t a n c e i n t h e f i e l d i n t he c o m p i l a t i o n t h e m a n u s c r i p t . a r e W i l l i a m Lee S t o k e s t h e U n i v e r s i t y U t a h , f o r h i s e f f o r t i n t he i d e n t i f i c a t i o n f o s s i l s p e c i m e n s . J . E a r d l e y , C h r i s t i a n s e n P . J . t h e U n i v e r s i t y U t a h, h a v e a s s i s t e d w i t h t h e m a n u s c r i p t. « 2 8 1 6 3 2 i i ACKNOWLEDGE~$NTS The writer wishes to express his appreciation to Norman C. Williams of the University of Utah, for his supervision and assistance in the field and in the compilation of the manuscript. Thanks are due ViJilliam Lee Stokes of the University of Utah, for his effort in the identification of fossil specimens. A. J. Eardley, F. W. Christiansen and P. J. Shenon of the University of Utah, have assisted with the manuscript. .·li· 28:1632 ii \ OP CONTESTS P a g e INTRODUCTION 1 L o c a t i o n . . . . . . . T o p o g r a p h y P u r p o s e and S c o p e . I4. P r e v i o u s G e o l o g i c Work 5 STRATIGRAPHY P r e - C a m b r i a n Rocks 7 Red P i n e s h a l e 6 C a m b r i a n F o r m a t i o n s 10 P i n e V a l l e y q u a r t z i t e 11 D e v o n i a n F o r m a t i o n s . . . . . . 12 M i s s i s s i p p i a n F o r m a t i o n s llj- M a d i s o n l i m e s t o n e . . . . . 17 B r a z e r f o r m a t i o n 19 Lower Member 20 U p p e r Member . . . . . . . . . . . . 21 B l a c k s h a l e 2l\. P e n n s y l v a n i a n F o r m a t i o n s 27 M o r g a n f o r m a t i o n 28 W e b e r q u a r t z i t e 29 P e r m i a n Rocks 30 P a r k C i t y f o r m a t i o n 30 M e s o z o i c S y s t e m s 33 T r i a s s i c F o r m a t i o n s 33 W o o d s i d e s h a l e 33 i i i \. \ ' TABLE OF CO:NTEXTS Page INTRODUCTION . • • • • 1 Location • • 2 Topography • • • 2 Purpose and Scope • • • • • 4 Previous Geologic Work • • 5 STRATIGRAPHY • • • • • • • • • • 7 Pre-Cambrian Rocks • • Red Pine shale • • 8 Cambrian Formations • • • • • 10 Pine Valley quartzite • • 11 Devonian Formations • • • • 12 Mississippian Formations • • • • • • 14 Madison limestone • • • • 17 Brazer formation • • • 19 Lower Member • 20 Upper Member • • • • 21 Black shale • • • 24 Pennsylvanian Formations • • • • • 27 Morgan formation • • • • 28 Weber quartzite • • • • • 29 Permian Rocks • • • • • • • 30 Park City fornation • • • 30 Mesozoic Systems • • • • • 33 Triassic Formations • • 33 Woodside shale • • • 33 iii i v P a g e T h a y n e s l i m e s t o n e 3k- A n k a r e h s h a l e 35 S h i n a r u m p c o n g l o m e r a t e 3& C h i n l e f o r m a t i o n 37 J u r a s s i c F o r m a t i o n s 37 N u g g e t s a n d s t o n e 37 Twin C r e e k l i m e s t o n e s 3& P l e i s t o c e n e R e c e n t • STRUCTURE I4.O G e n e r a l S t r u c t u r e LLO R e g i o n a l s t r u c t u r e . . . . . [j_0 F a u l t i n g l\.0 N o r t h F l a n k f a u l t I4.O U n c o n f o r m i t i e s I4.I P r e - C a m b r i a n - C a m b r i a n U n c o n f o r m i t y . . . . I4.I P o s t - D e v o n i a n U n c o n f o r m i t y . I4.3 M e s o z o i c U n c o n f o r m i t e s lj_3 . T i n o r S t r u c t u r e s IL3 J o i n t i n g I4.3 F o l d Axes ijij. GEO MO RP HO LO GY Ij-5 <0 $2 $\ Thaynes limestone Ankareh shale • • iv Shinarump conglomerate . . . . . . . . Chinle format'ion · . . . . · . · . . . . . · . · . . . . . · . . . . . · . . . . Jurassic Formations • • • · . . . . . . . . Nugget sandstone • • • • • • • · . . . . . Twin Creek limestones · . . . . . QUARTERNARY FORMATIONS · . . . . · . . . Pleistocene • • • · . . . . . . · . . . Recent . . . . . . · . . STRUCTURE • . . . General Structure · . . . . . . . . Regional structure ••• · . . · . . . Faul ting . . .. .............. . North Flank fault · . . · . . . Unconformities ••••••••••••••••• Pre- Cambrian- Cambrian Unconformity •••• Post- Devonian Unconformity •• Mesozoic Unconformites •••••• . . . · . . . Ninor Structures • • • Jointing ••• • Fold Axes ••• · . . . . . ~ . . . . . • • · . . . . · . . . . . . . GEOMORPHOLOGY • • . . . · . . . . · . . · . . GEOLOGIC HISTORY . . . . . . . . . . . . . . . . . CONCLUSIONS • • • • • · . · . . . . · . • • • • • BIBLIOGRAPHY . . . . . . . . . . · . . . . . . Page 34 35 36 37 37 37 38 39 39 39 40 LI·O 40 40 40 41 41 43 43 43 43 44 45 50 52 54 P a g e F i g u r e U n c o n f o r m i t y b e t w e e n p r e - C a m b r i a n and C a m b r i a n s t r a t a , Q F i g u r e D i a g r a m s h o w i n g r e l a t i o n s h i p D e v o n i an s t r a t a w i t h C a m b r i a n M I s s i s s i p p i an s e d i m e n t s i n t h e West W a l l c l i f f s . . ' llj. F i g u r e 3 - R o c k s l i d e i n S o u t h F o r k 3$ F i g u r e II - F e n c e d i a g r a m s h o w i n g a n g u l a r u n c o n f o r m i ty b e t w e e n p r e - C a m b r i a n P i n e and C a m b r i a n P i n e V a l l e y ; p o s t - D e v o n i a n - p r e - M a d i s o n u n c o n f o r m i t y l\.2 F i g u r e 5 - C l i f f s c a r r o c k s l i d e i n S o u t h F o rk C a n y o n I4.9 P l a t e G e o g r a p h i c s k e t c h s h o w i n g l o c a t i o n of S m i t h M o r e h o u s e - S o u t h F o r k A r e a , U t a h. P l a t e D r a i n a g e S m i t h M o r e h o u s e - S o u th F o r k A r e a , U t a h. P l a t e I I I G e o l o g i c p o r t i o n n o r t h w e s t e rn U i n t a M o u n t a i n s , U t a h. P l a t e C o l u m n a r s e c t i o n t h e n o r t h w e s t e r n U i n ta M o u n t a i n s . v ILLUSTRATIONS Page Figure 1 - Unconformity between pre-Cambrian and Cambrian strata • • • • • • • • • • • 9 Figure 2 - Diagram showing relationship of Devonian strata with Cambrian and I',,!ississinnian sedim.ents'in the 'Hest Wall cliffs" -. • 14 Figure 3 - Rockslide in South Fork Canyon • • • • • 38 Figure 4 - Fence diagram showing angular unconformity between pre-Cambrian Red Pine and Cambrian Pine Valley; post-Devonian­pre- Madison unconformity ••• • • • Figure 5 - Cliff scar of rockslide in South Fork Canyon •• • • • • • • • • • • • • • 49 Plate I - Geographic sketch map - showing location of Smi th and Morehouse-South Fork Area, Utah. Plate II - Drainage map of Smith and Morehouse-South Fork Area, Utah. Plate III - Geologic map of portion of northwestern Uinta Mountains, Utah. Plate IV - Columnar section of the northwestern Uinta Mountains. v T h i s r e p o r t t r e a t s t h e a r e a l g e o l o g y b e t w e e n S m i th a n d M o r e h o u s e S o u t h P o r k C a n y o n s t h e w e s t p a r t of t h e n o r t h f l a n k t h e U i n t a M o u n t a i n s. R o c k s t h e a r e a c o n s i s t p r e - C a m b r i a n p u r p le q u a r t z i t e s a r g i l l i t e s , b u f f q u a r t z i t e s m i c a c e o us s h a l e s , m i c a c e o u s s h a l e s s a n d s t o n e s ; C a m b r i an q u a r t z i t e s s h a l e s ; ^ D e v o n i a n m i c a c e o u s s h a l e s d o l o - m i t i c l i m e s t o n e s ) ; M i s s i s s i p p i a n l i m e s t o n e s s h a l e s; P e n n s y l v a n i a n l i m e s t o n e s , s a n d s t o n e s q u a r t z i t e s ; P e r m i a n l i m e s t o n e s , s a n d s t o n e s and p h o s p h a t i c s h a l e s . The T r i a s s i c i s r e p r e s e n t e d by r e d s h a l e s , a r e n a c e o u s l i m e s t o n e s, p e b b l y c o n g l o m e r a t e s , s i l t s t o n e s m u d s t o n e s . C r o s s - b e d d ed s a n d s t o n e s and l i m e s t o n e s and s h a l e s c o m p r i s e t h e J u r a s s ic r o c k s mapped i n t h e a r e a . Upper J u r a s s i c , C r e t a c e o u s and T e r t i a r y r o c k s w e r e n o t s t u d i e d i n d e t a i l and w e r e mapped o n l y a s u n d i f f e r e n t i a t e d u n i t s . P l e i s t o c e n e and r e c e nt s e d i m e n t s c o n s i s t of m o r a i n e s , t e r r a c e s , l a n d s l i d e s and a l l u v i a l f a n s. INTRODUCTION This report treats the areal geology between Smith and Morehouse and South Fork Canyons on the west part of the north flank of the Uinta Mountains. Rocks of the area consist of pre-Cambrian purple quartzites and argillites, buff quartzites and micaceous shales, and micaceous shales and sandstones; Cambrian quartzi tes and shales; mevonian micaceous shales and dolo-mi tic limestones!'; Mississippian limestones and shales; Pennsylvanian limestones, sandstones and quartzites; Permian limestones, sandstones and phosphatic shales. The Triassic is represented by red shales, arenaceous limestones, pebbly conglomerates, siltstones and mudstones. Cross-bedded sandstones and limestones and shales comprise the Jurassic rocks mapped in the area. Up-per Jurassic, Cretaceous and Tertiary rocks were not studied in detail and were mapped only as undifferentiated units. Pleistocene and recent sediments consist of moraines, terraces, landslides and alluvial fans. 1 L o c a t i o n S m i t h M o r e h o u s e - S o u t h F o r k a r e a l i e s t he u p p e r ? / e b e r R i v e r , s i x m i l e s e a s t O a k l e y , U t a h i n Summit C o u n t y . It c o m p r i s e s a l l of T. 1 S . , R. ? E . p a r t of T. I N . , R. 7 E . , and e x t e n d s i n t o t h e n o r t h e r n t i e r of s e c t i o n s of T . 2 S . , R. 7 E . of t h e C o a l v i l l e q u a d r a n g l e , S. L. B . a n d M. A c c e s s i s g a i n e d o v e r U t a h H i g h w a y 2 1 3 w h i c h j o i ns U. S. Highway 1&9 n e a r O a k l e y , U t a h . Large p o r t i o n s of t he a r e a a r e a c c e s s i b l e o v e r F o r e s t S e r v i c e r o a d s i n u p p er W e b e r , S m i t h M o r e h o u s e , Red P i n e S o u t h F o r k c a n y o n s. The h i g h e r e l e v a t i o n s c a n be r e a c h e d o n l y by J e e p o r h o r se b a c k . C o n i f e r s , q u a k i n g a s p e n , m o u n t a i n m a h o g a n y and g r a s s e s c o m p r i s e t h e v e g e t a t i o n t h e a r e a . v e g e t a t i ve p a t t e r n , e s p e c i a l l y t h a t a s p e n s p i n e s , i s i n p l a c es i n d i c a t i v e g e o l o g i c c o n d i t i o n s w h i c h a r e o t h e r w i se o b s c u r e . T o p o g r a p h y p o s t - m a t u r e r e l i e f d e v e l o p e d t h e U i n t a M o u n t a i ns d u r i n g O l i g o c e n e o r M i o c e n e t i m e d e e p l y i n c i s e d by s t r e a m s t o p r o d u c e v e r y r u g g e d t o p o g r a p h y . P l e i s t o c e ne 2 Location The Smith and Morehouse-South Fork area lies on the upper Weber River, six miles east of Oakley, Utah in Summit County. It comprises all of T. 1 S., R. 7 E. part of T. 1 N., R. 7 E., and extends into the northern tier of sections of T. 2 S., R. 7 E. of the Coalville quadrangle, 8. L. B.and M. Access is gained over Utah Highway 213 which joins U. S. Highway 189 near Oakley, Utah. Large portions of the area are accessible over Forest Service roads in upper Weber, Smith and Morehouse, :qed Pine and South Fork canyons. The higher elevations can be reached only by Jeep or horse back. Conifers, quaking aspen, mountain mahogany and grasses comprise the vegetation of the area. The vegetative pattern, especially that of aspens and pines, is in places indicative of geologic conditions which are otherwise obscure. Topography A post-mature relief developed on the Uinta Mountains during Oligocene or Miocene time and was deeply incised by streams to produce a very rugged topography. In Pleistocene 3 P l a t e RICH MORGAN SALT LAKE W Y O M I N G U T A H DUCHESNE W A S A T C H U T A H 0 4 8 •6 24 miles G e o g r a p h i c S k e t c h M a p - s h o w i n g l o c a t i o n of S m i th 8 M o r e h o u s e - S o u t h F o r k A r e a , U t a h. SALT LAKE UTA H , I ~ .. - ~ .3 Platt I WYOMING ~-- UTAH 'SUMMIT ---- DU CHESNE ?!! ! !!!!!!!!~4iiiiiiiiiii8!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!i16iiiiiiiiiiiiiiiiiifii24 mile s Geographic Sketch Map- showing location of Smith 8 Morehouse- South Fork Area, Utah. h t i m e t h i s s u r f a c e was e x t e n s i v e l y m o d i f i e d by a l p i n e g l a c i a - t i o n . G l a c i a l f e a t u r e s s u c h as U - s h a p e d c a n y o n s , m o r a i n es a n d c i r q u e s s t i l l d o m i n a t e t h e l a n d s c a p e , a l t h o u g h p r e s e nt f l u v i a l p r o c e s s e s a r e a c t i v e l y m o d i f y i n g t h e g l a c i a l f o r m s. Many of t h e m o r a i n e s h a v e b e e n p a r t i a l l y o r w h o l l y d e s t r o y ed a n d s t r e a m c h a n n e l s a r e d e v e l o p i n g w i t h i n t h e U - s h a p ed c a n y o n s and c i r q u e s . The p r e s e n t d r a i n a g e I s i n t o t h e G r e at B a s i n v i a t h e Weber R i v e r. S e v e r a l s i n k - h o l e s g e i n d i c a t e t h a t an i n c i p i e n t k a r s t t o p o g r a p h y w a s , s t i l l b e d e v e l o p i ng o n some of t h e h i g h , o l d - a g e s u r f a c e s. N u m e r o u s l a n d s l i d e s r e c e n t r o c k s l i d e c o n ­s i d e r a b l e m a g n i t u d e i n d i c a t e t h a t m a s s - w a s t i n g i s a c t i ve e r o s i o n a l p r o c e s s I n t h e a r e a. r e l i e f 3 * ^ 3 9 f e e t e x i s t s b e t w e e n Hoyt P e a k ( 1 0 , 2 3 9 ) a n 0 ^ a p o i n t on t h e u p p e r Weber R i v e r a t t he m o u t h of S w i f t C r e e k ( 6 , 6 0 0 ). \ P u r p o s e and Scope i n v e s t i g a t i o n r e p o r t e d i n t h i s p a p e r i s of s e r i e s s t u d i e s b e i n g b y t h e U n i v e r s i t y U t ah G e o l o g y D e p a r t m e n t l e a d i n g t o c o m p r e h e n s i v e g e o l o g ic r e p o r t t h e C o a l v i l l e q u a d r a n g l e. 4 time this surface was extensively modified by alpine glacia­tion. Glacial features such as U-shaped canyons, moraines and cirques still dominate the landscape, although present fluvial processes are actively modifying the glacial forms. Many of the moraines have been partially or wholly destroyed and stream channels are developing within the U-shaped canyons and cirques. The present drainage is into the Great Basin via the i ~eb er River. Several sink-holes of unknown a ge indicate that an incipient karst topography was, and may still be , developing on some of the high, old-age surfaces. NQmerous landslides and a recent rockslide of con­siderable magnitude indicate that mass-wasting is an active erosional process in the area. A maximum relief of 3,639 feet exists between Hoyt Peak (10,239 ) and a point on the upper Weber River at the mouth of Swift Creek (6,600 ) . Purpose and Scope The investigation reported in this paper is one of a series of studies being made by the University of Utah Geology Department leading to a comprehensive geologic report on the Coalville quadrangle. 5 m a i n p u r p o s e i s t o p r e s e n t t h e a r e a l g e o l o g y and s t r a t i g r a p h y t h e a r e a b e t w e e n S m i t h M o r e h o u s e and S o u t h F o r k C a n y o n s t h e n o r t h f l a n k t h e w e s t e r n U i n ta M o u n t a i n s • s p e c i a l s i g n i f i c a n c e i s c o n c e p t t he d i v i s i o n t h e p r e - C a m b r i a n t h e C a m b r i a n r o c k s , and t h e f i r s t r e c o g n i t i o n of d e f i n i t e D e v o n i a n s t r a t a. F i e l d w o r k was b e g u n d u r i n g t h e summer of 1 9 ^ 9 * a n <^ c o m p l e t e d d u r i n g t h e 1950* Mapping d o n e on a e r i a l p h o t o g r a p h s t h e d a t a t r a n s f e r r e d t o p l a n i m e t r i c c o m p i l e d f r o m S o i l C o n s e r v a t i o n a e r i al m o s a i c 6 0 , U t a h , F o r e s t S e r v i c e Maps. P r e v i o u s G - e o l o g i c Work U i n t a M o u n t a i n s h a v e l o n g b e e n i n t e r e s t to g e o l o g i s t s . C l a r e n c e K i n g I 8 7 6 ) , J . P o w e l l ( I 6 7 6 ), S . F . 1 9 0 7 ) , F . 1 9 0 7 ) , C P . B e r k ey 1 9 0 7 ) W. W. I 9 0 9 ) w e r e among t h e f i r s t i n ­v e s t i g a t o r s t h e r e g i o n . J. B o u t w e l l 1 9 1 2 ) , R. S c h u l t z 1 9 1 9 ) , B r a d l e y 1 9 3 i j - - 3 £ ) , J . F o r r e s t er 1 9 3 7 ) , J- W i l l i a m s 1 9 3 9 a n d I9I4.3), J . E a r d l ey (I9kh)> J - Huddle F . ( I 9 I 4 . 7 ) , B a k e r, J . H u d d l e K i n n e y ( I 9 L 9 ) a r e t h e a u t h o r s more 5 The main purpose is to present the areal geology and stratigraphy of the area between Smith and Morehouse and South Fork Canyons on the north flank of the western Uinta Mountains. Of special significance is a new concept of the division of the pre-Cambrian and the Cambrian rocks, and the first recognition of definite Devonian strata. Field work was begun during the summer of 1949, and completed during the summer of 19.50. 'Mapping was done on aerial photographs and the data was transferred to a planimetric map compiled from U. S. Soil Conservation aerial mosaic No. 60, Utah, and Forest Service Maps. Previous Geologic Work The Uinta Mountains have long been of interest to geologists. Clarence King ( 1876), J. W. Powell (1676), s. F. Emmons ( 1907), F. B. Weeks ( 1907), C. P. Berkey ( 1907) and ~N. w. Atwood ( 1909) were a'11ong the first in­vestigators of the region. M. Boutwell ( 1912), A. R. Schultz ( 1919), W. H. Bradley ( 1934-35), J. D. Forrester ( 1937) J J. S. 'Nilliams ( 1939 and 19t:-3) J A. J. Eardley (194ljJ, J. iN. Huddle and F. T. McCann (1947), A. A. Baker, J. W. Huddle and D. M. Kinney (1949) are the authors of more 6 r e c e n t w o r k s r e l a t i n g t o t h i s a d j a c e n t a r e a s. I n f o r m a t i o n , y e t u n p u b l i s h e d , e m e r g i n g f r om t he U n i v e r s i t y U t a h g e o l o g i c s t u d y t h e C o a l v i l l e q u a d r a n g le a v a i l a b l e t o t h e a u t h o r f a c i l i t a t e d t h e e a r l y s t a g es o f t h e w o r k. 6 recent works relating to this and adjacent areas. Information, as yet unpublished, emerging from the University of Utah geologic study of the Coalville quadrangle was available to the author and facilitated the early stages of the work. P r e - C a m b r i a n Rocks c o r e t h e U i n t a M o u n t a i n s i s r o c ks o f p r e - C a m b r i a n a g e . ( I 6 7 6 ) , P o w e l l ( I 6 7 6 ) , Weeks ( 1 9 0 7 ) , B e r k e y ( 1 9 0 9 ) , L e i t h H i s e ( 1 9 0 9 ) , and B u t l e r ( 1 9 2 0 , p i . h a v e s t u d i e d t h e s e d e " o o s i t s . King f i r s t a s s i g n e d t h e m t o t h e C a r b o n i f e r o u s b e l i e v ed t h e m t o p r e - C a m b r i a n . B e r k e y B u t l e r t h e m as C a m b r i a n , L e i t h H i s e a p p l i e d t h e U i n ta S e r i e s a s s i g n e d A l g o n k i a n t o t h e r o c k s . More r e c e n t l y H i n d s 193&* P« 9^) s t a t e s t h a t t h e U i n t a M o u n t a i ns Q u a r t z i t e i s U n c o m p a h g r a n i n a g e . w r i t e r s e s t i m a te 1 2 , 0 0 0 f e e t of s e d i m e n t s i n t h e U i n t a S e r i e s , and F o r r e s t er 1 9 3 7 , p . 6 3 7 ) e x t e n d s t h e e s t i m a t e t o 1 5 , 0 0 0 f e e t. T h e u p p e r m o s t p r e - C a m b r i a n r o c k s e x p o s e d c o n s i s t of s e r i e s m i c a c e o u s s h a l e s s a n d s t o n e s , r e p r e s e nt t h e y o u n g e s t p r e - C a m b r i a n r o c k s e x p o s e d i n t h e a r e a . These c o n f o r m a b l y o v e r l i e s e q u e n c e i n t e r b e d d e d b u f f c o l o r ed q u a r t z i t e s b r o w n m i c a c e o u s s h a l e s , t h e s e i n t u rn c o n f o r m a b l y o v e r l i e g r e a t t h i c k n e s s p u r p l e and r ed STRATIGRAPHY Pre-Cambrian Rocks The core of the Uinta Mountains is composed of rocks of pre-Cambrian age. King (1876), Powell (1676), Weeks (1907), Berkey (1909), Leith and Van Rise (1909), and Butler (1920, pl. V) have studied these deposits. King first assigned them to the Carboniferous and Weeks believed them to be pre-Ca~brian. Berkey and Butler mapped the~ as Cambrian, and Leith and Van Hise applied the name Uinta Series and assigned an Algonkian age to the rocks. gore recently Hinds (1936, p. 92) states that the Uinta Mountains Quartzite is Uncomp~~gran in age. These writers estimate 12,000 feet sediments in the Uinta Series, Forrester ( 1937, p. 637) extends the estimate to 15,000 feet. The uppermost pre-Cambrian rocks exposed consist of a series of micaceous shales and sandstones, and represent the youngest pre-Cambrian rocks exposed in the area. These conformably overlie a sequence of interbedded buff colored quartzites and brown micaceous shales, and these in turn conformably overlie a great thickness of purple fu~d red 7 q u a r t z i t e s o l d e r r o c k s w h i c h w e r e n o t s t u d i e d. H i n t z e (193i[-* p - 166) b e l i e v e s u n c o n f o r m i ty e x i s t s a t t h e t o p t h e p u r p l e r e d q u a r t z i t e s ( l o w e st s e q u e n c e a b o v e ) i n S m i t h a n d M o r e h o u s e C a n y o n . w r i t e r , h o w e v e r , m a p p i n g t h e d i v i s i o n s c o u l d d e t e c t e v i d e n ce t o s u p p o r t t h i s s u g g e s t i o n. P i n e s h a l e . 1 - P i n e s h a l e is a p p l i e d t o t h e s e q u e n c e m i c a c e o u s s h a l e s s a n d s t o n e s, w h i c h c o n s t i t u t e t h e y o u n g e s t p r e - C a m b r i a n r o c k s t he w e s t e r n U i n t a M o u n t a i n s. T h e P i n e s h a l e c o n s i s t s m i c a c e o u s , g r a y to g r e e n , m o t t l e d t o d a r k c o l o r e d s h a l e s i n t e r b e d d ed s a n d s t o n e s . f ew r e s i s t a n t b e d s m a s s i v e s h a l e o u t c r op a n d f o r m r i d g e s ; b r o w n i s h - g r a y q u a r t z i t i c a p p r o x i ­m a t e l y f e e t t h i c k , i s p r e s e n t n e a r t h e m i d d l e t h e f o r m a ­t i o n . f o s s i l w e r e f o u n d i n t h e P i n e s h a l e . In P i n e C a n y o n , t h i s f o r m a t i o n i s a p p r o x i m a t e l y 2 0 0 0 f e et t h i c k . F o r r e s t e r t e n t a t i v e l y c o r r e l a t e d t h i s s e q u e n c e w i th t h e O p h i r s h a l e t h e O q u i r r h M o u n t a i n s t h e L o d o re s h a l e t h e e a s t e r n U i n t a s l i t h o l o g i c s i m i l a r i t y and ^ - W i l l i a m s , H o o p e r , n a m e . M a n u s c r i pt i n p r e p a r a t i o n .) 8 quartzites and older rocks which were not studied. Hintze (1934, p. lS6) believes an unconformity exists at the top of the purple and red quartzites (lowest sequence above) in Smith and Morehouse Canyon. The writer, however, upon mapping the divisions could detect no evidence to support this suggestion. Red Pine shale~l- The name Red Pine shale is applied to the sequence of micaceous shales and sandstones, which constitute the youngest pre-Cambrian rocks of the western Uinta Mountains. The Red Pine shale consists of micaceous, gray to green, mottled brown to dark colored shales and interbedded sandstones. A few resistant beds of massive shale outcrop and form ridges; a brownish-gray quartzitic member, approxi-mately 20 feet thick, is present near the middle of the forma-tion. No fossil forms were found in the Red Pine shale. In Red Pine Canyon, this formation is approximately 2000 feet thick. Forrester tentatively correlated this sequence with the Ophir shale of the Oquirrh Mountains and the Lodore shale of the eastern Uintas on lithologic Similarity and l.Williams, N. C. and Hooper, W. G. (New name. Manuscript .in preparation.) b e c a u s e i t s c o n f o r m i t y w i t h t h e o v e r l y i n g C a m b r i a n q u a r t ­z i t e . r e f e r e n c e t o t h i s s t r u c t u r a l r e l a t i o n s h i p he s t a t e s t h a t " C o n f o r m a b l y o v e r l y i n g t h e O p h i r s h a l e I s a q u a r t z i t e . 5 5 C a r e f u l m a p p i n g , h o w e v e r , i n d i c a t e s t h e o v e r l y i ng q u a r t z i t e t r u n c a t e s t h e Red P i n e s h a l e ( P i g . 1 ) . An a n g u l ar u n c o n f o r m i t y of 15 t o 20 d e g r e e s may a l s o be s e e n i n t he w e s t w a l l S o u t h P o r k B a s i n b e t w e e n t h e C a m b r i a n q u a r t z i te a n d t h e u n d e r l y i n g s h a l e s e q u e n c e . F o r r e s t e r o b s e r v ed t h i s u n c o n f o r m i t y , i t i s d o u b t f u l t h a t h e w o u l d h a v e a s s i g n ed t h e s h a l e s e q u e n c e t o t h e C a m b r i a n . h e d i d n o t s t u dy t h e u p p e r S o u t h F o r k a r e a i s a c k n o w l e d g e d h i m ( 1 9 3 7* p . 61+2) . F i g u r e 1 . U n c o n f o r m i t y b e t w e e n p r e - C a m b r i a n and C a m b r i a n s t r a t a. 9 because of its conformity with, the overlying Cambrian quart-zite. In reference to this structural relationship he states that !lConformably overlying the Ophir shale is a quartzite. II Careful mapping, however, indicates the overlying quartzite truncates the Red Pine shale (Fig . 1). An angular unconformity of 15 to 20 degrees may also be seen in the west wall of South Fork Basin between the Cambrian quartzite and the underlying shale sequence. Had Forrester observed this unconformity, it is doubtful that he would have assigned the shale sequence to the Cambrian. That he did not study the upper South Fork area is acknowledged by him (1937, p. 642). Figure 1. Unconformity between pre-Cambrian and Cambrian strata. C a m b r i a n F o r m a t i o ns t h r e e f o l d d i v i s i o n C a m b r i a n f o r m a t i o n s is r e c o g n i z e d t h r o u g h o u t U t a h . T h r e e d i s t i n c t l i t h - o l o g i e s a r e p r e 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 ; T i n t ic q u a r t z i t e a t t h e b a s e , t h e O p h i r s h a l e i n t h e m i d d l e , and t h e M a x f i e l d l i m e s t o n e a t t h e t o p . G i l l u l y ( 1 9 3 2 , p . 7 - 2 0) n o t e s s i m i l a r t h r e e f o l d C a m b r i a n l i t h o l o g y i n t h e O q u i r rh M o u n t a i n s , C a l k i n s B u t l e r (19^-3* P» i n t he C o t t o n w o o d - A m e r i c a n F o r k d i s t r i c t . T h i s n o r m a l C a m b r i a n s e q u e n c e h a s n o t b e e n r e c o g n i z ed b y p r e v i o u s i n v e s t i g a t o r s i n t h e U i n t a M o u n t a i n s . B a k e r, H u d d l e K i n n e y C 19^4-9* P» l l 6 8 ) n o t e a d i s s i m i l a r i t y in t h e C a m b r i a n s e c t i o n t h e S o u t h f l a n k s t a t e: C a m b r i a n r o c k s a l o n g t h e s o u t h f l a n k of t h e U i n t a M o u n t a i n s . • . b e a r l i t t l e l i t h o l o g ic r e s e m b l a n c e t o t h e C a m b r i a n r o c k s i n t h e W a s a t ch a n d O q u i r r h M o u n t a i n s. t h e n o r t h w e s t e r n f l a n k t h e U i n t a M o u n t a i ns l o w e r C a m b r i a n i s r e p r e s e n t e d t h e P i n e V a l l e y q u a r t z i t e, s i m i l a r t o t h e T i n t i c B r i g h a m q u a r t z i t e s t h e W a s a t c h - O q u i r r h M o u n t a i n s , i s t e n t a t i v e l y c o r r e l a t e d w i t h t h e m. N e a r t h e t o p , t h i s f o r m a t i o n c o n t a i n s z o n e i n t e r b e d d e d, b r o w n , m i c a c e o u s s h a l e , b e e q u i v a l e n t t o t h e O p h ir 10 Cambrian Pormations A threefold division of Cambrian formations is recognized throughout much of Utah. Three distinct lith-ologies are present in the Wasatch Mountains; The Tintic quartzite at the base, the Ophir shale in the middle, and the Maxfield limestone at the top. Gilluly (1932, p. 7-20) notes a similar threefold Cambrian lithology in the Oquirrh 1.1ountains, as do Calkins and Butler (19L1-3, "p. 16) in the Cottonwood-American Fork district. This nO~illal Cambrian sequence has not been recognized by previous investigators in the Uinta Mountains. Baker, Huddle and Kinney (1949, p. 1160) note a dissimilarity in the Cambrian section of the South flank and state: The Cambrian rocks along the south flank of the Uinta Mountains ••• bear little lithologic resemblance to the Cambrian rocks in the Wasatch and Oquirrh TlJountains. On the northwestern flank of the Uinta Mountains lower Cambrian is represented by the Pine Valley quartzite, similar to the Tintic and Brigham quartzites of the Wasatch- Oquirrh Mountains, and is tentatively correlated with them. Near the top, this formation contains a zone of interbedded, brown, micaceous shale, and may be equivalent to the Ophir 1 1 s h a l e . C a r b o n a t e r o c k s u p p e r C a m b r i a n a g e w e r e n ot r e c o g n i z e d I n t h e a r e a. P i n e V a l l e y q u a r t z i t e . - - l o w e r C a m b r i a n is r e p r e s e n t e d by t h e P i n e V a l l e y q u a r t z i t e named by F o r r e s t er ( 1 9 3 7 * P- 6 3 8 ) s t a t e s : . . . C o n f o r m a b l y o v e r l y i n g t h e O p h i r s h a l e i s t he s o - c a l l e d Qgden O r d o v i c i a n ) q u a r t z i t e W e e k s. t y p e i s known t o o l d e r r o c k s r e ­p e a t e d f a u l t i n g . A l t h o u g h f o s s i l s w e re f o u n d i n t h i s f o r m a t i o n , i t i s t h o u g h t t o b e of C a m b r i a n a g e . B e c a u s e i t s e x p o s u r e in P i n e V a l l e y n e a r S t e w a r t s ' t h e P r o vo R i v e r , t h e P i n e V a l l e y i s h e r e p r o p o s e d . . .. P i n e V a l l e y q u a r t z i t e l a r g e l y r e m o v e d e r o s i on d u r i n g p o s t - D e v o n i a n - p r e - M a d i s o n t i m e i s p r e s e n t o n ly i n a r e a s w h i c h e s c a p e d t h i s e r o s i o n . g r e a t e s t c o n t i n u o us e x p o s u r e t h e P i n e V a l l e y i s a l o n g l i n e p r o m i n a n t, v e r t i c a l , c l i f f s w h i c h m a r k t h e w e s t b o u n d a r y of S o u t h F o r k B a s i n P l a t e I I I ) . W a l l c l i f f s" i s s u g g e s t e d u s e d i n r e f e r e n c e t o t h i s l o c a l i t y . The P i n e V a l l e y c a n o b s e r v e d t o t h i c k e n f r o m e d g e a t t he m o u t h ? / e l c h C r e e k t o maximum o f a p p r o x i m a t e l y f e et i n t h e W a l l c l i f f s . t h e l a t t e r l o c a l i t y i t i s o v e r ­l a i n D e v o n i a n s t r a t a w h i c h a l s o e s c a p e d p o s t - D e v o n i a n - p r e - M a d i s o n e r o s i o n , i t i s a p p a r e n t t h a t f e e t h e re r e p r e s e n t s t h e t h i c k n e s s j u s t b e f o r e D e v o n i a n d e p o s i t i o n. S m a l l e r , d i s c o n t i n u o u s l e n s e s a r e p r e s e n t In unnamed 11 shale. Carbonate rocks of upper Cambrian age were not recognized in the area. Pine Valley quartzite.-- The lower Cambrian is represented by the Pine Valley quartzite named by Forrester (1937, p. 635) who states: ••• Conformably overlying the Ophir shale is the so-called Ogden ( Ordovician) quartzite of Weeks. The type Ogden is now knovm to be older rocks re­peated by faulting_ Although no fossils were found in this formation, it is thought to be of Cambrian age. Because of its good exposure in Pine Valley near Stewarts' Ranch on the Provo River, the name Pine Valley is here proposed •••• The Pine Valley quartzite was largely removed by erosion during post-Devonian-pre-Madison time and is now present only in areas which escaped this erosion. The greatest continuous exposure of the Pine Valley is along a line of prominant, vertical, unnamed cliffs which mark the west boundary of South Fork Basin ( Plate III). The name "West Wall cliffsH is suggested and used in reference to this locality. The Pine Valley can be observed to thicken from an edge at the mouth of Welch Creek to a maximQm of approximately 300 feet in the West Wall cliffs. At the latter locality it is over-lain by Devonian strata which also escaped post-Devonian-pre- - Madison erosion, and it is apparent that 300 feet here r~presents the thickness just before Devonian deposition. Smaller, discontinuous lenses are present in an unnamed v a l l e y t r i b u t a r y t o S o u t h P o r k m i l e s o u t h P u l l C r e e k . P r i s m a t i c j o i n t i n g and s e p a r a t i o n a l o n g b e d d i ng p l a n e s i s c h a r a c t e r i s t i c of t h e P i n e V a l l e y q u a r t z i t e . Near t h e b a s e i s a 2 t o 3 f o o t member c o m p o s e d of q u a r t z i t ic p e b b l e s , o n e - h a l f t o i n c h i n d i a m e t e r , i n a p u r p l e t o b u f f q u a r t z i t i c g r o u n d m a s s . P i n e V a l l e y p r o ­d u c e s w h i t e , a n g u l a r t a l u s b l o c k s a t t h e b a s e t h e s h e ar c l i f f s i n S o u t h F o r k B a s i n. N e a r t h e t o p t h e P i n e V a l l e y q u a r t z i t e i s zone o f b r o w n , s i l t y t o m i c a c e o u s s h a l e s . A l t h o u g h , o n l y n o n ­d i a g n o s t i c t r i l o b i t e f r a g m e n t s h a v e b e e n f o u n d , I t i s t e n t a ­t i v e l y c o r r e l a t e d w i t h t h e O p h i r s h a l e s c e n t r a l and w e s t e r n U t a h. d e m o n s t r a t i o n u n c o n f o r m i t y a t t h e b a s e of t h e P i n e V a l l e y q u a r t z i t e , t h e d i s c o v e r y t r i l o b i t e - b e a r i n g s h a l e zone a t t h e t o p of t h e q u a r t z i t e b r i n g s t he U i n t a M o u n t a i n C a m b r i a n s e c t i o n i n t o h a r m o n y w i t h t h e g e n e r al C a m b r i a n s e q u e n c e i n U t a h. D e v o n i a n F o r m a t i o ns D e v o n i a n s t r a t a w e r e n o t d e f i n i t e l y r e c o g n i z e d by F o r r e s t e r ( 1 9 3 7 ) * o r by H u d d l e and McCann (191+7) o r by e a r l ie 12 valley tributary to South Fork one mile south of Pull em Creek. Prismatic jointing and separation along bedding planes is characteristic of the Pine Valley quartzite. Near the base is a 2 to 3 foot member composed of quartzitic pebbles, one-half to one inch in diameter, embedded in a purple to buff quartzitic groundmass. The Pine Valley 9ro­duces white, angular talus blocks at the base of the shear cliffs in South Fork Basin. Near the top of the Pine Valley quartzite is a zone of brown, silty to micaceous shales. Although, only non­diagnostic trilobite fragments have been found, it is tenta­tively correlated with the Ophir shales of central and western Utah. The demonstration of an unconformity at the base of the Pine Valley quartzite, and the discovery of a trilobite­bearing shale zone at the top of the quartzite brings the Uinta l!ountain Cambrian section into harmony with the general Cambrian sequence in Utah. Devonian Formations Devonian strata were not definitely recognized by Forrester (1937), or by Huddle and IvTcCann (1947) or by earlier 13 i n v e s t i g a t o r s of t h e U i n t a M o u n t a i n s . t h e s o u t h f l a nk o f t h e U i n t a M o u n t a i n s , B a k e r , H u d d l e K i n n e y (1914-9* p . 1171) n o t e d a w e a t h e r e d s a n d s t o n e u n i t a t t h e b a s e of t h e M a d i s o n l i m e s t o n e w h i c h t h e y t e n t a t i v e l y c o r r e l a t e w i th t h e J e f f e r s o n (?) d o l o m i t e t h e b a s i s l i t h o l o g y and s t r a t i g r a p h i c p o s i t i o n. I n t h e West W a l l c l i f f s S o u t h F o r k B a s i n , l o w er s h a l e and an u p p e r d o l o m i t i c l i m e s t o n e a r e p r e s e n t b e t w e en l o w e r M i s s l s s i p p i a n and t h e P i n e V a l l e y q u a r t z i t e . The l o w e r p a r t c o n s i s t s of a d r a b b r o w n , t h i n l y b e d d e d , s l i g h t ly m i c a c e o u s , f o s s i l i f e r o u s s h a l e , 10 i n c h e s t o 2 f e e t t h i c k, r e s t i n g u p o n t h e u p p e r s h a l e and q u a r t z i t e zone of t h e P i ne V a l l e y q u a r t z i t e . F o s s i l s c o l l e c t e d w e r e i d e n t i f i e d by W i l l i a m Lee S t o k e s , 2 as f i s h t e e t h and p l a t e f r a g m e n t s, a n d C y r t o s p i r i f e r s p . The f i s h t e e t h and p l a t e f r a g m e n ts w e r e i d e n t i f i e d b e i n g o l d e r t h a n D e v o n i a n . The C y r t o s p i r i f e r s p . a r e e q u i v a l e n t t o t h o s e t h e U p p er J e f f e r s o n (v) d o l o m i t e p r o b a b l y , i n p a r t , t h e f a u n a of t h e T h r e e F o r k s s h a l e H o l l a n d , J a n u a r y , 1 9 5 1 * P« 1 2 8 ). The l o w e r s h a l e i s t o o t h i n t o be shown on t h e s c a le o f t h e g e n e r a l g e o l o g i c P l a t e I I I ) . i s i n d i c a t e d In t h e d e t a i l F i g . 2) w h e r e i t i s p r e s e n t , o v e r l y i n g t he P i n e V a l l e y q u a r t z i t e and m i c a c e o u s s h a l e s. 2 P e r s o n a l c o m m u n i c a t i o n. 13 investigators or the Uinta JI!~ountains. On the south rlank or the Uinta IVlountains, Baker, Huddle and Kinney (1949, p. 1171) noted a weathered sandstone unit at the base of the Madison limestone which they tentatively correlate with the Jefferson dolomite on the basis of lithology and stratigraphic position. In the ~est Wall cliffs of South Fork Basin, a lower shale and an upper dolomitic limestone are present between lower Mississippian and the Pine Valley quartzite. The lower part consists of a drab bro'lm, thinly bedded, slightly micaceous, fossiliferous shale, 10 inches to 2 feet thick, resting upon the upper shale and quartzite zone of the Pine Valley quartzite. Fossils collected were identified by William Lee Stokes,2 as fish teeth and plate fragments, and Cyrtosnirifer sp. The fish teeth and plate fragments were identified as being no older than Devonian. The Cyrtospirifer sp. are equivalent to those of the Upper Jerferson (,~) dolomite and probably, in part, the fauna of the Three Forks shale ( Holland, January, 1951, p. 128). The lower shale is too thin to be shown on the scale of the general geologic map ( Plate III). It is indicated in the detail map ( Fig. where it is present, overlying the Pine Valley quartzite and micaceous shales. 2Personal co~~unication. I k MISS. I I I I I | Madison limestone 1 1 . 1 1 . 1 J -J- ' ^ DEVONIAN 1 / I / 1 / I /I 1 / 1 / 1 1 J 1 • x I- ± 1 iI dolomitic limestone i i i ii I I / I / 1 1 1 / 1 / 1 1 II 1 1 1 / 1 / - - micaceous shale - fossiliferous - - - - CAMBRIAN -'--shale - fossiliferous-thought to'be Ophir'- - - - - Figure 2. Diagram showing relationship of Devonian strata with Cambrian and Mississippian sediments in the West Wall cliffs. •m • ' *$' - ^ ji '•• ' u p p e r d o l o m i t i c l i m e s t o n e i s c o m p o s e d a l i g h t b l u e - g r a y , d o l o m i t i c l i m e s t o n e , s e v e r a l i n c h e s to f e e t t h i c k w h i c h , t h o u g h f o s s i l s w e r e f o u n d , is c o n f o r m a b l e w i t h t h e u n d e r l y i n g s h a l e i s a c c o r d i n g ly a l s o t h o u g h t o l a t e D e v o n i a n i n a g e. S t r u c t u r a l e v i d e n c e i n t h e w e s t e r n U i n t a M o u n t a i ns a l s o i n d i c a t e s l a t e D e v o n i a n f o r t h e f o r m a t i o n. M i s s i s s i p p i a n F o r m a t i o ns G e n e r a l d e s c r i p t i o n . - - r o c k s t h e M i s s i s s i p p i an - --- ._-- - ~.~?-. "'_';j:!iL:~· i I I I I I I I I I 1 . ! 1 I I i il , - i I I ~ I I I / I I L I I I 1 I I I ! I I / I 1 I I I J 1 1 " I I I L 1 L - - - - - - - - - - - - - - - - - - '- - I - - - - - - - j ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - --- shale'~ f <.> s'~ i I! fe'~o'u~'-: th?~gh! to' be Ophir - ---- , 0' Pine Valley quartzite :'l ~\!l;l ... :~ Devon iari' i cliffs. l ____ .;~~_ ~ ___ " ___ ~_. _ ~_~. The upger dolomitic limestone is composed of a light blue-gray, dolomitic limestone, several inches to 10 feet thick which, though no fossils were found, is conformable with the underlying shale and is accordingly also though to be late Devonian in age. Structural evidence in the western Uinta Mountains also indicates late Devonian age for the formation. Mississippian Formations General description.-- The rocks of the Ilfississippian Ora inage Map of Smith a Mo0ouse South Fork Area, Utah . ,l . • i. ,I, .~ ,\, ,I, ,\, .\, For explanation of numbered sections see text o I mi. .t: :::: =~t:I: :======IP Cr. HOYT PEAK 8 (4 ) (2 ) (11 (10) # ~ (I -c tl> 16 s y s t e m a r e m o s t l y of m a r i n e o r i g i n and a r e r e p r e s e n t e d by t h r e e f o r m a t i o n s t h e M a d i s o n , B r a z e r and s o - c a l l e d " B l a ck s h a l e . " The M a d i s o n l i m e s t o n e c o n s i s t s of f o s s i l i f e r o u s, d a r k g r a y l i m e s t o n e i n t h i n t o m a s s i v e b e d s . It f o r m s s t e ep c l i f f s a l o n g t h e s t r i k e v a l l e y of S o u t h P o r k a n d Red P i ne C a n y o n s . The M a d i s o n i s o v e r l a i n by t h e B r a z e r f o r m a t i on w h i c h , i n t h i s r e g i o n , can b e d i v i d e d i n t o l o w e r and u p p er m e m b e r s . The l o w e r member i s a r e n a c e o u s , f o s s i l i f e r o u s, b u f f t o g r a y l i m e s t o n e w h i c h l o c a l l y c o n t a i n s z o n e s of c h e r t n o d u l e s . It g r a d e s i n t o t h e u p p e r member w h i c h is e s s e n t i a l l y a r e n a c e o u s , b r e c c i a t e d l i m e s t o n e t h a t w e a t h e rs l i g h t o r t a n . c o n t a c t b e t w e e n t h e l o w e r and u p p er I s g e o m o r p h i c b o u n d a r y. l o w e r t h e B r a z e r f o r m a t i o n i s g e n e r a l ly c o n f i n e d t o t h e b a c k s l o p e s t h e M a d i s o n c l i f f s . u p p er i s t h e s u r f a c e f o r m a t i o n i n t h e a r e a s i n c i p i e nt k a r s t t o p o g r a p h y . d i s t i n c t l i t h o l o g i c c h a n g e i s o b s e r v ed w h e r e t h e u p p e r g i v e s t o o v e r l y i n g b l a ck s h a l e . b l a c k s h a l e u n i t c o n s i s t s b l a c k f i s s i l e s h a l es i n t e r b e d d e d w i t h b u f f c o l o r e d d e n s e l i m e s t o n e s , is d o m i n a n ^ n t l y s l o p e m a k e r. A t o t a l t h i c k n e s s of a p p r o x i m a t e l y 2 6 0 0 f e e t of M i s s i s s i p p i a n s t r a t a m e a s u r e d i n t h e a r e a . B r a c h i o p o d s, g a s t r o p o d s c o r a l s w e r e t h e f o s s i l j ^ forms f o u n d . 16 system are mostly of marine origin and are renresented by three formations the Madison, Brazer and so-called "Black shale." The Madison limestone consists of fossiliferous, dark gray limestone in thin to massive beds. It forms steep cliffs along the strike valley of South Fork and Red Pine Canyons. l'he Madison is overlain by the Brazer formation which, in this region, can be divided into lower and upper members. The lower member is arenaceous, fossiliferous, buff to gray limestone which locally contains zones of chert nodules. It grades into the upper member which is essentially an arenaceous, brecciated limestone that weathers light brown or tan. The contact between the lower ~d upper members is mapped on a geomorphic boundary. The lower member of the Brazer formation is generally confined to the back slopes of the Madison cliffs. The upper member is the surface formation in the areas of incipient karst topography. A distinct lithologic change is observed where the upper member gives way to an overlying black shale. The black shale unit consists of black fissile shales interbedded with buff colored dense limestones, and is dominanmttly a slope maker. A total thickness of approximately 2800 feet of Mississippian strata was measured in the area. Brachiopods, gastropods and corals were the most common fossill forms found. 17 M a d i s o n L i m e s t o n e . - M a d i s o n l i m e s t o n e m e a s u r ed 7 3 0 f e e t t h i c k i n t h e P i n e - P u l l e m C r e e k a r e a P l a t e I I, 1 ) . f o r m a t i o n f i r s t d e s c r i b e d P e a l e ( I 8 9 3) i n t h e t y p e l o c a l i t y of t h e M a d i s o n M o u n t a i n s , M o n t a n a. M a n s f i e l d ( 1 9 2 7 ) r e c o g n i z e d t h e M a d i s o n l i t h o l o g y i n I d a h o, a n d R i c h a r d s o n ( 1 9 2 0 ) h a s mapped i t i n n o r t h e r n U t a h. F o r r e s t e r ( 1 9 3 7 ) e x t e n d e d t h e f o r m a t i o n on t h e b a s i s of l i t h o l o g y , i n t o t h e U i n t a M o u n t a i n r e g i o n. The M a d i s o n l i m e s t o n e h a s b e e n p r o v i s i o n a l l y a s s i g n ed t o t h e M i d d l e and U p p e r K i n d e r h o o k l a n and O s a g i a n s e r i e s by W e l l e r , e t . a l . ( F e b r u a r y , I9I4.8). It i s a f o s s i l i f e r o u s, l i g h t t o d a r k g r a y , l i m e s t o n e c o n t a i n i n g c a l c i t e s t r i n g e rs a n d c h e r t h o r i z o n s t o w a r d t h e t o p . A p e t r o l i f e r o u s o d or i s n o t e d i n some f r e s h l y b r o k e n s p e c i m e n s. I n t h e a r e a of t h e n o r t h f l a n k of t h e U i n t a M o u n t a i ns t h e M a d i s o n c o n t a i n s two d i s t i n c t members d i v i s i b l e on t he b a s i s b e d d i n g e r o s i o n a l c h a r a c t e r i s t i c s . l o w er m e m b e r , c o m p r i s i n g t h e b o t t o m t h i r d t h e f o r m a t i o n , is d o m i n a n t l y t h i n b e d d e d ; t h e u p p e r i s m a s s i v e. J o i n t i n g i s c o n s p i c u o u s t h r o u g h o u t t h e M a d i s o n and i t Is d o m i n a n t l y c l i f f m a k e r , g e n e r a l l y f o r m i n g n e a r ly v e r t i c a l c l i f f s s e p a r a t e d s h o r t s l o p e b e t w e e n. E u o m p h a l u s I s g a s t r o p o d t h e M a d i s o n and 17 'Madison Limestone. -- The ~/radison limestone measured 730 feet thick in the Red Pine-Pullem Creek area ( Plate II, No. 1). The formation was first described by Peale (1893) in the type locality of the ~~adison Mountains, Montana. Mansfield (1927) recognized the lV;adison lithology in Idaho, and Richardson (1920) has mapped it in northern Utah. Forrester (1937) extended the formation on the basis of lithology, into the Uinta IVTountain region. The Madison limestone has been provisionally assigned to the Middle and Upper Kinderhookian and Osagian series by Weller, et. ale (February, 194-6). It is a fossiliferous, light to dark gray, limestone containing calcite stringers and chert horizons toward the top. A petroliferous odor is noted in some freshly broken specimens. In the area of the north flank of the Uinta rv~ountains the Madison contains two distinct members divisible on the basis of bedding and erosional characteristics. The lower member, comprising the bottom third of the fo~nation, is dominantly thin bedded; the upper member is massive. Jointing is conspicuous throughout the Madison and it is dominantly a cliff maker, generally forming two nearly vertical cliffS separated by a short slope between. Euomphalus is a common gastropod of the Madison and s m a l l h o r n c o r a l s a r e a b u n d a n t . C o l o n i a l c o r a l s a r e p r e s e nt n e a r t h e t o p t h e f o r m a t i o n . S p i r i f e r s p . , C h o n e t es a n d P r o d u c t i d s a r e t h e most common b r a c h i o p o d s. On t h e w e s t s i d e of S o u t h P o r k C a n y o n , t h e M a d i s on l i m e s t o n e r e s t s u n c o n f o r m a b l y u p o n D e v o n i a n s h a l e s and d o l o ­m i t i c l i m e s t o n e s . E l s e w h e r e i n t h e a r e a t h e M a d i s o n l i es u n c o n f o r m a b l y u p o n t h e P i n e s h a l e. 7 P u l l e m C r e e k : S e c t i o n I p , ' T . 1 S . , R. 7 E . S.L.B. and M. U n i t Description Peet 6 Limestone; d e n s e b l a c k c o n t a i n i n g c h e r ty l e n s e s - - - - - - - - - - - - - - - - - - 61}. 7 Limestone; b l u e - g r a y , f o s s i l i f e r o u s , dom­i n a n t l y a t h i n b e d d e d f o s s i l i f e r o us member - - - - - - - - - - - - - - - - - - 96 C o n t a i n s H o r n c o r a ls S p i r i f e r c e n t r o n a t us E u o m p h a l u s u t a h e n s is S y r i n g o p o r a s p. Limestone; t o g r a y c o n t a i n i n g a b u n d a nt c h e r t c a l c i t e l e n s e s - - - - - - - - 69 5 v e r y d a r k g r a y , w e a t h e r s b a t t l e ­s h i p g r a y w i t h c h e r t b e d s n e a r t h e t o p 112 Ij. Limestone; l i g h t t o b u f f c o l o r e d, s l i g h t l y a r e n a c e o u s c o n t a i n i n g h o rn c o r a l s . a r e t o f o u r f e e t t h i c k 122 16 small horn corals are abundant. Colonial corals are present near the top of the formation. 3uirifer sp., Chonetes and Productids are the most common brachiopods. On the west side of South Fork Canyon, the Madison limestone rests unconformably upon Devonian shales and dolo-mitic limestones. Elsewhere in the area the Madison lies unconformably upon the Red Pine shale. '.J Pullem Creek: Section~,#T. 1 S., R. 7 E. S.L.B. and M. Unit Description S Limestonej dense black containing cherty lenses - - 7 Limestone; blue-gray, fossiliferous, dom­inantly a thin bedded fossiliferous Feet 64 member - - - - - - - - - - - - - - - - - - 98 Contains: Horn corals Spirifer centronatus Euomphalus utahensis Syringopora sp. 6 Limestonej brown to gray containing abundant chert and calcite lenses - 5 Limestone; very dark gray, weathers battle-ship gray with chert beds near the top - - 112 4 Limestonej light brown to buff colored, slightly arenaceous and containing horn corals. Beds are two to four feet thick - 122 1 9 U n i t 3 D e s c r i p t i o n L i m e s t o n e ; b r o w n , b u f f w e a t h e r i n g , d a rk g r a y , o c c u r r i n g i n b e d s t o s i x i n c h es t h i c k w i t h o c c a s i o n a l s h a l y p a r t i n g s o n e - h a l f t o one i n c h t h i c k - - - - - - - - - - P e e t 2 9 L i m e s t o n e ; w e a t h e r i n g , w i t h t h in s h a l y l i m e s t o n e b e d s . U n i f o r m b e d s two f o u r I n c h e s t h i c k , f o s s i l i f e r o u s , s l i g h t ly a r e n a c e o u s , d o m i n a n t l y s l o p e m a k e r b ut a t p l a c e s o u t c r o p s i n l e d g e s - - - - - - - L i m e s t o n e ; b l u e - g r a y i n b e d s t h r e e i n c h es t o t h r e e f e e t t h i c k , g r a y f r e s h f r a c ­t u r e s , c a v e r n o u s a t b a s e . C o r a l s p r e d o m ­i n a n t f o s s i l s - - - - - - - - - - - - - - R e s t s w i t h a n g u l a r d i s c o r d a n c e u p o n P i ne V a l l e y q u a r t z i t e C a m b r i a n a g e. T o t a l t h i c k n e ss B r a z e r f o r m a t i o n . - - The t e r m B r a z e r was f i r st 1 5 9 k e 7 3 1 a p p l i e d R i c h a r d s o n ( I 9 1 3 ) i n B r a z e r C a n y o n , R i c h C o u n t y, U t a h , a n d l a t e r u s e d W i l l i a m s ( I 9 k 3 ) E a r d l e y (I9I4I4-) f o r t h e U p p e r M i s s i s s i p p i a n f o r m a t i o n i n B l a c k s m i t h P o rk C a n y o n V a l l e y n o r t h e a s t M o r g a n , U t a h , r e s ­p e c t i v e l y . f o r m a t i o n i n t h e s e a r e a s c o n s i s t s 1 1 0 0 - 1 7 5 0 f e e t c a l c a r e o u s s a n d s t o n e s , a r e n a c e o u s l i m e s t o n e s, c h e r t l e n s e s b u f f t o d e n s e b l a c k , f i n e l y c r y s t a l l i n e, f o s s i l i f e r o u s l i m e s t o n e s . W i l l i a m s (I9I13* P* 5 9 5 ) and 19 Unit Description 3 Limestone; brown, buff weathering, dark gray, occurring in beds one to six inches thick with occasional shaly partings one- Feet half to inch thick - - - - - - - 29 2 Limestone; brown weathering, with few thin shaly limestone beds. Uniform beds two four inches thick, fossiliferous, slightly arenaceous, dominantly a slope maker but at places outcrops in ledges - - - - - 169 1 Limestone; blue-gray in beds three inches to three feet thick, gray on fresh frac­tures, cavernous at base. Corals predo~- inant fossils - - - - - - - - - - - Rests with angular discordance upon Pine Valley quartzite of Cambrian age. 48 Total thickness 731 / Brazer formation.-- The term Brazer was first applied by Richardson (1913) in Brazer Canyon, Rich County, Utah, and later used by Williams (1943) and Eardley (191.:4) for the Upper Mississippian formation in Blacksmith Fork Canyon and Round Valley northeast of ~;rorgan, Utah, res-pectively. The fornation in these areas consists of 1100- 1750 feet of calcareous sandstones, arenaceous limestones, chert lenses and buff to dense black, finely crystalline, fossiliferous limestones. TNilliams (1943, p. 595) and 2 0 E a r d l e y (I9I4I1-, p . 8 3 2 ) p l a c e t h e c o n t a c t b e t w e e n t h e M a d i s on a n d B r a z e r f o r m a t i o n s a t t h e b a s e b l a c k p h o s p h a t ic s h a l e and l i m e s t o n e s e r i e s . The U p p e r M i s s i s s i p p i a n h as b e e n d i v i d e d i n t o l o w e r a n d u p p e r members i n t h e O q u i r rh ( Q i l l u l y , 1 9 3 2 ) , and T i n t i c (Tower and S m i t h , I 6 9 9 ) m i n i ng d i s t r i c t s and t h e names D e s e r e t and Humbug, r e s p e c t i v e l y, a p p l i e d . C a l k i n s and B u t l e r 19^4-3) r e c o g n i z e d t h e f o r m a t i o ns i n t h e W a s a t c h M o u n t a i n s . Huddle and McCann I9J4.7), B a k e r, H u d d l e and K i n n e y [lQ^) apply t h e t e r m s D e s e r e t and Humbug o n t h e s o u t f l a n k t h e U i n t a M o u n t a i n s t h e b a s i s of l i t h o l o g y , b u t f o s s i l v e r i f i c a t i o n i s w a n t i n g . The D e s e r et a n d Humbug l i t h o l o g i e s a r e p r e s e n t t h e n o r t h f l a n k t he U i n t a s a s on t h e s o u t h f l a n k ( H u d d l e and McCann; B a k e r, H u d d l e K i n n e y ) , b u t d i a g n o s t i c f o s s i l s a r e a l s o w a n t i n g. A c c o r d i n g l y , p e n d i n g a m o r e p r e c i s e c o r r e l a t i o n , b a s e d upon a r e g i o n a l f a u n a l s t u d y of t h e D e s e r e t and Humbug f o r m a t i o n s, t h e s e f o r m a t i o n s a r e r e c o g n i z e d o n l y as p r o b a b l e c o r r e l a t i v es a n d t h e t e r m B r a z e r i s r e t a i n e d. T h e B r a z e r f o r m a t i o n m e a s u r e d i n P i ne C a n y o n a n d P u l l e m C r e e k , w h e r e t h e c o m b i n e d t h i c k n e s s t he t w o m e m b e r s i s I7I4-O f e e t P l a t e I I , 2 ) . Member D e s e r e t ( ? ) ) . - - l o w e r member c o n s i s t s of 660 f e e t a r e n a c e o u s , b l u e - g r a y , d e n s e to c o a r s e l y c r y s t a l l i n e , c h e r t y l i m e s t o n e w h i c h w e a t h e r s g r ay 20 Eardley (1944, p. 832) place the contact between the Madison and Brazer formations at the base of a black phosphatic shale and limestone series. The Upper J'I'rississippian has been divided into lower and upper members in the Oquirrh (Gilluly, 1932), and Tintic (Tower and Smith, 1899) mining districts and the names Deseret and Humbug, respectively, applied. Calkins and Butler (19L~3) recognized the formations in the Wasatch Mountains. Huddle and McCann (19L~7), Baker, Huddle and Kinney l1949) apply the terms Deseret and Humbug on the soute , flank of the Uinta Mountains on the basis of lithology, but fossil verification is wanting. The Deseret and Hu~bug lithologies are present on the north flank of the Uintas as the south flank Huddle Baker, Huddle and Kinney), but diagnostic 1'ossils are also wanting. Accordingly, pending more precise correlation, based upon regional faunal study the Deseret formations, these for.~ations are recognized only probable correlatives and the term Brazer is retained. The Brazer formation was measured in Red Pine Canyon and Pullem Creek, where the co~bined thickness of the two members is 1740 feet ( Plate II, No. 2). Lower Nember ( Deseret ('t)) .-- The lower :nember consists 01' 660 feet of arenaceous, blue-gray, dense to coarsely crystalline, cherty limestone which weathers gray 2 1 t o b r o w n . B l a c k w h i t e b a n d e d , z e b r a c h e r t " o c c u rs l o c a l l y i n t h i s member. The M a d i s o n - B r a z e r c o n t a c t i s g r a d a t i o n a l and c a n n ot b e e s t a b l i s h e d e x c e p t w i t h i n b r o a d l i m i t s . These l i m i ts a r e d e f i n e d z o n e t r a n s i t i o n a l l i t h o l o g y w e a t h e r ­i n g c h a r a c t e r i s t i c s . c o n t a c t i s p l a c e d a t t h e b a s e of b l a c k p h o s p h a t i c l i m e s t o n e a p p r o x i m a t e l y e i g h t t o t en f e e t t h i c k . T h i s l i m e s t o n e i s o v e r l a i n a r e n a c e o us l i m e s t o n e b e d c h a r a c t e r i z e d n u m e r o u s r e d c h e r t n o d u l es a n d l o s e s . c o n t a c t i s n o r m a l l y o b s c u r e d r o c k m a n t l e, b u t b e s e e n t o a d v a n t a g e i n t h e r o c k s l i d e s c a r in S o u t h F o r k a b o v e P u l l e m C r e e k P l a t e I I , 3 ) . F o s s i l s c o l l e c t e d f r o m t h e l o w e r member of t he B r a z e r w e r e e x a m i n e d W i l l i a m S t o k e s 3 r e p o r t ed t h e m a s b e i n g p o s t - M a d i s o n a g e . S p i r i f e r h a y d e n i a n u s, C h o n e t e s s p . and P r o d u c t i d s p . w e r e t h e most common b r a c h i o - p o d s . c o r a l s w e r e l e s s a b u n d a n t t h a n c o l o n i a l c o r a l s. B u o m p h a l u s a r e p r e s e n t b u t l e s s a b u n d a n t t h a n i n t h e Madison l i m e s t o n e . U p p e r Member ( v ) ) . - E i g h t h u n d r e d s i x ty f e e t t h e U p p e r Member t h e B r a z e r m e a s u r e d in s P e r s o n a l c o m m u n i c a t i o n. 21 to brown. Black and white banded, " zebra chert" occurs locally in this member. The Madison-Brazer contact is gradational and cannot be established except within broad limits. These limits are defined by a zone of transitional lithology and weather-ing characteristics. The contact is placed at the base of a black phosphatic limestone bed approximately eight to ten feet thick. This limestone is overlain by an arenaceous limestone bed characterized by numerous red chert nodules and leses. The contact is normally obscured by rock ~antle, but can be seen to good advantage in the rock slide scar in South Fork Canyon above Pullem Creek ( Plate II, No. 3). Fossils collected from the lower member of the Brazer were examined by William Lee Stokes3 who reported them as being of post-Madison age. Spirifer haydenianus., Chonetes sp. and Productid sp. were the most common brachio­pods. Horn corals were less abundant than colonial corals. -Euom-pha-lus are p- resent but less abundant than in the ~radison limestone. Upper ]\"'ember (Humbug ('i)) .-- Eight hundred and sixty feet of the Upper Uember of the Brazer was 'neasured in zPersonal co~munication. P u l l e m C r e e k P l a t e I I , 1L) . I t i s s e q u e n ce o f s a n d s t o n e l i m e s t o n e b r e c c i a s , s h a l e s , d e n s e, b l u e - g r a y l i m e s t o n e s n e a r t h e t o p . i s p r e s e n t b u t Is l e s s f r e q u e n t t h a n i n t h e l o w e r f o r m a t i o n s . T a l u s and v e g e t a t i o n o b s c u r e a r e a s . h o l e s a r e common g e o - m o r p h i c f e a t u r e s n e a r t h e c o n t a c t w i t h t h e l o w e r of B r a z e r f o r m a t i o n i n t h e u p l a n d a r e a s . s a n d s t o n e members a r e l e n t i c u l a r , medium g r a i n e d , b u f f c o l o r e d i n p a rt c a l c a r e o u s . L i m e s t o n e s a n d s t o n e b r e c c i a s a r e p r e s e nt t h r o u g h o u t . e s p e c i a l l y p r o m i n e n t , m a s s i v e b r e c c i a c o n ­t a i n i n g l i m e s t o n e s a n d s t o n e i n c l u s i o n s c h o s e n a s t he c o n t a c t b e t v / e e n t h e l o w e r and u p p e r m e m b e r s . The c o n t a ct i s n o r m a l l y o b s c u r e d by h e a v y v e g e t a t i o n and s o i l , b u t can b e s e e n i n t h e h e a d w a t e r s of P u l l e m C r e e k . The o v e r a ll c o n t a c t b e t w e e n t h e l o w e r and u p p e r members was mapped on a g e o m o r p h i c b o u n d a r y w h e r e t h e b a c k s l o p e s of t h e l o w er member j o i n t h e i n c i p i e n t k a r s t t o p o g r a p h y of t h e u p p er m e m b e r . C r i n o i d s t e m s S p i r i f e r s p . f r a g m e n t s w e r e t he o n l y f o s s i l f o r m s f o u n d i n t h e u p p e r member. L o w e r Member P u l l e m C r e e k : S e c t i o n 1 0 , S . , 7 E . , S . L . 3 . 22 Pull em Creek ( Plate II, No. 4). It is composed of a sequence of sandstone and limestone breccias, shales, and dense, blue-gray limestones near the top. Chert is present but is less frequent than in the lovler formations. Talus and vegetation obscure many areas. Sink holes are com~on geo-morphic features near the contact with the lower member of Brazer formation in the upland areas. The sandstone members are lenticular, mediu~ grained, buff colored and in part calcareous. Limestone and sandstone breccias are present throughout. An especially pro~nent, massive breccia con-taining limestone and sandstone inclusions was chosen as the contact between the lower upper members. contact is normally obscured heavy vegetation soil, but can be seen in the headwaters of Pullem Creek. The overall contact between the lower and upper members was mapped on geomorphic boundary where the back slopes the lower member join the incipient karst topography of the upper mel11ber. Crinoid ste~and Spirifer sp. frag~ents were the only fossil forms found in the upper member. Lower Member Pullem Creek: Section 10, T. 1 R. 7 E., S.L.B. and M. 2 3 U n i t Feet 5 f i n e g r a i n e d , c o n t a i n i n g c h e rt a n d c a l c i t e l e n s e s , p a s t e l p i n k , s h a ly l i m e s t o n e . I n t o a r e n a c e o u s l i m e ­s t o n e n e a r t h e t o p - - - - - - - - - - 75 It b l u e - g r a y , d e n s e 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 r s t o l i g h t g r a y , v e r y f o s ­s i l i f e r o u s , c o n t a i n i n g b r a c h i o p o d s , c o l o n ­i a l c o r a l s c r i n o i d s t e m s - - - - - no 3 c o v e r e d w i t h c o l l u v i u m d e n se v e g e t a t i o n - - - - - - - - - - - - - - - - j^o l i g h t m a s s i v e , s a n d y to q u a r t z i t i c , c o n t a i n s c h e r t c a l ­c i t e , f o s s i l i f e r o u s - - - - - - - - 130 S y r i n g o p o r a s p. B r a c h i o p o d s h o r n c o r a ls 1 b u f f c o l o r e d , s a n d y t o s h a l y, c o n t a i n i n g a b u n d a n t r e d , g r e e n " z e b r a" c h e r t w i t h s i x t o e i g h t f o o t of p h o s p h a t i c s h a l e a t t h e b a s e . C o n f o r m a b le w i t h M a d i s o n - - - - - - - - - - - - - 123 T o t a l t h i c k n e s s 878 y U p p e r Member P u l l e m C r e e k : S e c t i o n 1 0 , S . , E . S . L . 3 . 23 Unit Description 5 Limestone; fine grained, containing chert and calcite lenses, pastel pink, shaly limestone. Grades into an arenaceous lime- 4 stone near the top - - ~,- " }"-.>-{. *;} !.q\<,..~~-- ,; Light blue-gray, dense to coarsely crystal-line, weathers to a light gray, very fos­siliferous, containing brachiopods, colon- Feet 75 ial corals and crinoid stems - - - - - 110 3 Area covered with colluvium and dense vegetation - 2 Limestone; light brown massive, sandy to quartzitic, contains some chert and cal-cite, fossiliferous - - - - - - - - - Syringopora sp. Brachiopods and horn corals Limestone; buff colored, sandy to shaly, containing abundant red, green and ilzebra tl chert with a six to eight foot bed of phosphatic shale at the base. Confo rmable with Madison - - Total thickness Upper :'.~ember 440 130 123 Pullem Creek: Section 10, T. 1 S., R. 7 E. S.L.B. and M. 2k U n i t Description Feet 3 b l u e - g r a y t o g r a y , i n t e r b e d d e d, f i n e t o c o a r s e l y c r y s t a l l i n e , c o n t a i n i ng c a l c i t e s t r i n g e r s . I n t e r b e d d e d b u f f c o l o r ­e d , a r e n a c e o u s l i m e s t o n e , s a n d s t o n e and l e n s e s d o l o m i t i c l i m e s t o n e - - - - - 350 v e g e t a t i o n , c o l l u v i u m t a l us f r o m o v e r l y i n g f o r m a t i o n s - - - - - - - 300 b l u e - g r a y t o b u f f , c o a r s e ly c r y s t a l l i n e , f o s s i l i f e r o u s , a r e n a c e o u s, b r e c c i a t e d , d e n s e t o f i n e g r a i n e d , brown s a n d s t o n e a r e n a c e o u s l i m e s t o n e and l i m e y s h a l e s . C o n f o r m a b l e w i t h u n d e r l y i ng D e s e r e t f o r m a i o n s - - - - - - - - - - - 2l6 T o t a l t h i c k n e s s 866 G r a n d t o t a l t h i c k n e s s 17^1-5 1 B l a c k s h a l e T T . - - T h r e e h u n d r e d f o r t y - f i v e f e et o f b l a c k f i s s i l e s h a l e s , i n t e r b e d d e d w i t h b u f f c o l o r ed d e n s e l i m e s t o n e s w e r e m e a s u r e d i n B e a r T r a p H o l l o w P l a t e II N o . 5 ) » I t s p r e c i s e c o r r e l a t i o n b e i n g u n c e r t a i n , t h is f o r m a t i o n i s r e f e r r e d t o o n l y a s t h e B l a c k s h a l e . " I ts c o n t a c t w i t h t h e u n d e r l y i n g B r a z e r i s p l a c e d a t t h e b a se o f t h e f i r s t b l a c k s h a l e w h i c h o v e r l i e s t h e b l u e - g r ay l i m e s t o n e t h e u o o e r o f t h e B r a z e r f o r m a t i o n . The Unit Description 3 Limestone; blue-gray to gray, interbedded, fine to coarsely crystalline, containing calcite stringers. Interbedded buff color­ed, arenaceous limestone, sandstone and lenses of dolomitic limestone - - - 2 Covered by vegetation, colluvium and talus from overlying formations - - - - - - - 1 Limestone; blue-gray to buff, coarsely crystalline, fossiliferous, arenaceous, brecciated, dense to fine grained, brm'Vn sandstone and arenaceous limestone and limey shales. Conformable with underlying Deseret forma,t ions - Feet 350 300 216 Total thickness 866 ,,"'/ Grand total thickness 1745 ~ " Black shale lt .-- Three hundred and forty-five feet of black fissile shales, interbedded with buff colored dense limestones were ~easured in Bear Trap Hollow ( Plate II, No.5). Its precise correlation being uncertain, this formation is referred to only as the " Black shale." Its contact with the underlying Brazer is placed at the base of the first black shale which overlies the blue-gray limestone of the upper member of the Brazer fo~ation. The <i5 c o n t a c t i s d i s t i n c t r e a d i l y s e e n i n B e a r T r a p H o l l o w. E l s e w h e r e t h e c o n t a c t i s l e s s a p p a r e n t b u t i s m a r k e d a u n i t t h a t w e a t h e r s e a s i l y t o f o r m g e n t l e s l o p e s and s t r i ke v a l l e y s . 19^4-7) s i m i l a r u n i t on t h e s o u t h f l a n k . . G i l l u l y 1 9 3 2 ) a n d N o l a n 1 9 3 k ) a o p l y t he name Manning Canyon t o a b l a c k s h a l e f o r m a t i o n i n w e s t e r n, c e n t r a l and n o r t h e r n U t a h . They d e s c r i b e i t as a f o r m a t i on t h a t t r a n s g r e s s e s U p p e r M i s s i s s i p p i a n - L o w e r P e n n s y l v a n i an t i m e . Sharp ( 1 9 5 ° ) 4 n a s mapped a b l a c k s h a l e u n i t , w h i ch o c c u p i e 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 i n t h e C o t t o n ­wood a r e a , M i s s i s s i p p i a n i n a g e. F o s s i l s f r o m t h e B l a c k s h a l e " w e r e e x a m i n e d by W i l l i a m Lee S t o k e s 5 and f o u n d t o be n o n d i a g n o s t i c . However, s l i g h t l y f a s c i c u l a t e S p i r i f e r , w h i c h a c c o r d i n g t o S t o k e s, i s more s t r o n g l y s u g g e s t i v e of P e n n s y l v a n i a n t h a n of M i s s i s s i p p i a n age was c o l l e c t e d. P e n d i n g a m o r e t h o r o u g h r e g i o n a l s t u d y , t h e " B l a ck s h a l e " i s p l a c e d s t r a t i g r a p h i c a l l y b e t w e e n t h e U p p e r M i s s ­i s s i p p i a n and Lower P e n n s y l v a n i a n f o r m a t i o n s w i t h o u t age c o m m i t m e n t • 4 B y r o n S h a r p p e r s o n a l c o i m m u n i c a t i o n. 6 W i l l i a m S t o k e s , Op. c i t. 25 contact is distinct and readily seen in 3ear Trap Hollow. Elsewhere the contact is less apparent but is marked by a unit that weathers easily to form gentle slopes and strike valleys. Huddle and McCann (1947) mapped a similar unit on the south flank •. Gilluly ( 1932) and Nolan ( 1934) anply the name Manning Canyon to a black shale formation in western, central and northern Utah. They describe it as a fo~nation that transgresses Upper Mississippian-Lower Pennsylvanian time. Sha~ (1950)4 has mapped a black shale unit, which occupies the same stratigraphic position in the Big Cotton­wood area, as Mississippian in age. Fossils from the " Black shale" were exa-rnined by William Lee Stokes5 and found to be nondiagnostic. However, a slightly fasciculate Spirifer, which according to Stokes, is more strongly suggestive of Pennsylvanian than of Mississippian age was collected. Pending a more thorough regional study, the "Black shale" is placed stratigraphically between the Upper :Miss­issippian and Lower Pennsylvanian formations without age commi t,ment. 4Byron Sharp - personal communication. 5William Lee Stokes, Ope cit. 26 B l a c k S h a l e" B e a r T r a p C a n y o n : S e c t i o n D, S , , B. ? E . M, U n i t Feet f o o t o u t c r o p m a s s i v e l i m e s t o n e, b u f f c o l o r e d w i t h b r o w n w e a t h e r i n g b l o t c h e s. C o n t a i n s c o n g l o m e r a t e l e n s e s w i t h q u a r tz p e b b l e s l / t o i n c h e s i n d i a m e t e r . Lime­s t o n e i s r a t h e r d e n s e f i n e l y c r y s t a l ­l i n e t o c o n g l o m e r i t i c c h e r t y . Chert i s l i g h t g r e e n , b l u e , p i n k g r a y. C o n g l o m e r i t i c l i m e s t o n e I s b u f f t o l i g ht y e l l o w - - - - - - - - - - - - - - - - - - 3I4. 9 Limestone; b u f f o u t c r o p c o n t a i n i n g c a l c i te l e n s e s s m a l l c h e r t y n o d u l e s o r g r a n ­u l e s . g r a y f r e s h f r a c t u r e s , con­t a i n s r e d d i s h n o d u l e s a p p e a rs a s b r e c c i a t e d l i m e s t o n e - - - - - - - - 16 s l o p e c o v e r e d w i t h c o l l u v i u m 15 t o r e d d i s h b r o w n l i m e s t o n e w e a t h e r ­e d s u r f a c e , c o n t a i n i n g l e n s e s s h a ly l i m e s t o n e . O u t c r o p s r i d g e s o r l e d g es t w o t o t h r e e f e e t t h i c k - - - - - - - - - - 60 6 b l a c k f i s s i l e - - - - - - - - - 5 Limestone; g r a y w e a t h e r i n g , g r a y - b l u e on f r e s h s u r f a c e ; c o n t a i n s b r a c h i o p o d s, f e n e s t r a t e b r y o z o a n s c r i n o i d s . Lime­s t o n e v e r y b l a c k t h i n b e d d e d i n l e n s es o f m a s s i v e l i m e s t o n e - - - - - - - 70 26 " Black Shale" Bear Trap Canyon: Section 8, T. 1 S., R. 7 E. S.L.B. and M. Unit Description 10 Six foot outcrop of massive limestone, buff colored with brown weathering blotches. Contains conglomerate lenses with quartz pebbles 1/2 to 2 inches in diameter. Lime­stone is rather dense and finely crystal­line to conglomeritic and cherty. Chert is light green, blue, pink and gray. Conglomeritic limestone is buff to light yellow - - - - - - - - 9 Limestonej buff outcrop containing calcite lenses and small cherty nodules or gran­ules. Dark gray on fresh fractures, con­tains reddish brown nodules and appears as a brecciated limestone - 8 Shaly slope covered with colluvium - - - - 7 Buff to reddish broYfn limestone on weather­ed surface, containing lenses of shaly limestone. Outcrops as ridges or ledges Feet 16 two to three feet thick - - - - - - 60 6 Shale black fissile - - - - - - - - - S Limestonej gray weathering, gray-blue on fresh surfacej contains brachiopods, fenestrate bryozoans and crinoids. Lime­stone very black and thin bedded in lenses 7 of more massive limestone - - - - - - - - - 70 2 7 U n i t Feet ii. L i m e s t o n e ; o u t c r o p s a n d y , b u f f c o l o r e d, o n w e a t h e r e d s u r f a c e w i t h i n t e r b e d d e d, f i s s i l e b l a c k s h a l e s o n e - h a l f t o i n ch t h i c k - - - - - - - - - - - - - 66, 3 b u f f c o l o r e d , a r e n a c e o u s l i m e ­s t o n e o u t c r o p w i t h i n t e r b e d d e d f i s s i le b l a c k s h a l e s o n e - h a l f t o i n c h t h i c k - - 66 2 b l a c k s h a l e - - - - - - - - - s h a l y s o i l p a r t i c l e s c o n t a i n i ng f o s s i l s w i t h b u f f w e a t h e r i n g l i m e s t o n e. I n t e r b e d d e d s a n d y b u f f l i m e s t o n e b l a ck s h a l e s . F r e s h s u r f a c e i s d e n s e b l a c k. S l o p e s c o n s i s t s i x l i m e s t o n e o u t c r o ps i n t h e f o rm s m a l l l e d g e s a b o u t two f e et t h i c k w i t h i n t e r b e d d e d b l a c k f i s s i l e s h a l es i n l e n s e s o n e - h a l f i n c h t h i c k . C o n t a ct c o n f o r m a b l e w i t h t h e f o r m a t i o n - - 69 T o t a l P e n n s y l v a n i a n F o r m a t i o ns G e n e r a l d e s c r i p t i o n . - - r o c k s t h e P e n n s y l v an i a n s y s t e m a r e d i v i d e d i n t o f o r m a t i o n s , of t h r e e l i t h o l o g i c u n i t s , r e f l e c t t r a n s g r e s s i o n f r om g e o s y n c l i n a l t o s h e l f t y p e d e p o s i t i o n . b a s a l Morgan 27 Unit Description Feet 4 Limestone; outcrop of sandy, buff colored, on weathered surface with interbedded, fissile black shales one-half to one inch thick - - 66 ?, 3 Limestone; buff colored, arenaceous lime­stone outcrop with interbedded fissile black shales one-half to one inch thick Slope of black shale - - 1 Black shaly soil particles containing fossils with buff weathering limestone. Interbedded sandy buff limestone and black shales. Fresh surface is dense black. Slopes consist of six limestone outcrops in the form of small ledges about ~o feet thick with interbedded black fissile shales in lenses one-half inch thick. Contact conformable with the Humbug formation - Total Pennsylvanian Formations 66 8 General descrintion.-- The rocks of the Pennsylvan-ian system are divided into two formations, composed of three lithologic units, and reflect a transgression from geosynclinal to shelf type deposition. The basal Morgan f o r m a t i o n l o w e r u p p e r t h e o v e r ­l y i n g r e l a t i v e l y h o m o g e n e o u s q u a r t z i t e c o n s t i t u t e t he r o c k u n i t s t h e p e r i o d. M o r g a n f o r m a t i o n . - - f o r m a t i o n f i r st d e s c r i b e d B l a c k w e l d e r ( 1 9 1 0 , p . 5^9) i n t h e t y p e l o c a l i ty o f V a l l e y e a s t M o r g a n , U t a h , a s: . . . A n e a r t h y s a n d s t o n e , w h i c h i s r e l a t i v e l y s o f t. F r e s h f r a c t u r e s a r e g e n e r a l l y w h i t e o r p i n k , but u p o n w e a t h e r i n g t h e r o c k t u r n s b r i c k r e d . . .. W i l l i a m s (I9I1.3, p . 6 1 3 ) i n c l u d e s o n l y t h e a f o r e m e n t i o n ed u p p e r i n h i s d e s c r i p t i o n t h e Morgan f o r m a t i on a n d i n c l u d e s t h e l o w e r i n t h e B r a z e r l i m e s t o n e. E a r d l e y 19^4., p . 633) f o l l o w s t h e c l a s s i f i c a t i o n W i l l i a m s. H u d d l e (19^-7) r e c o g n i z e d t h e Morgan f o r m a t i on t h e S o u t h F l a n k t h e U i n t a M o u n t a i n s d i v i d e d it i n t o m e m b e r s : l o w e r c o n s i s t i n g c h i e f ly o f c h e r t y l i m e s t o n e u p p e r c o m p o s e d c h i e f ly o f r e d s a n d s t o n e s . F o r r e s t e r 1 9 3 7 . P« 6 3 9 ) m e n t i o n s i ts e x i s t e n c e , b u t d o e s n o t d e f i n e i t . t h e Morgan f o r m a t i o n a r e on t h e w e s t e r n n o r t h f l a n k t h e U i n t a M o u n t a i n s . l o w er c o n s i s t s a p p r o x i m a t e l y 200 f e e t d e n s e to 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 . c o n t a i n s l e n s e s of s i l t s t o n e s h a l e z o n e s r e d , w h i t e g r a y c h e rt 2b formation composed of lower and upper members and the over-lying relatively homogeneous Weber quartzite constitute the rock ~~its of the period. Morgan formation.-- The Morgan formation was first described by Blackwelder (1910, p. 529) in the type locality of Round Valley east of Horgan, Utah, as: ••• An earthy sandstone, which is relatively soft. Fresh fractures are generally white or pink, but upon weathering the rock turns brick red •••• Williams (194.3, p. 613) includes only the aforementioned upper member in his description of the Horgan formation and includes the lower member in the Brazer limestone. Eardley (1944, p. 833) follows the classification of Williams. Huddle and McCann (1947) recognized the ~lorgan formation on the South Flank of the Uinta Mountains and divided it into two members: (1) a lower member consisting chiefly of cherty limestone and (2) an upper member composed chiefly of red sandstones. Forrester ( 1937, p. 639) ~entions its existence, but does not define it. Two members of the I,1organ formation are mapped on the western north flank of the Uinta Mountains. The lower member consists of approximately 200 feet of dense to coarsely crystalline limestone. It contains lenses of siltstone and shale and zones of red, white and gray chert 2 9 a n d c h e r t y n o d u l e s . f o s s i l i f e r o u s h o r i z o n s , a p p r o x i ­m a t e l y f e e t t h i c k , a r e p r e s e n t i n t h e u p p e r p a r t t he m e m b e r . f o s s i l s w e r e e x a m i n e d P r o f e s s o r S t o k e s and r e p o r t e d t o c h a r a c t e r i s t i c L a t e P a l e o z o i c b u t n ot d i a g n o s t i c e a r l y P e n n s y l v a n i a n t i m e. F o s s i l s t h e l o w e r i n c l u d e P r o d u c t i d s, C o m p o s i t a s p . , G h o n e t e s s p . , many w e a t h e r e d b r y o z o a n s and G r i n o i d p l a t e s and s t e m s. O v e r l y i n g t h e l o w e r l i m e s t o n e i s s e r i e s of i n t e r c a l a t e d s a n d s t o n e s , s i l t s t o n e s , m u d s t o n e s l i m e ­s t o n e s a p p r o x i m a t e l y 2 6 5 f e e t t h i c k . d o m i n a n t c o l o r is r e d , b u t v a r i a t i o n s a r e c h a r a c t e r i s t i c l o c a l l y p r o d u ce v a r i e g a t e d a p p e a r a n c e . r e d , w h i t e g r a y c h e rt i s p r e s e n t t h r o u g h o u t . f o s s i l s w e r e f o u n d b u t S c h i zo p h o r a s p . i d e n t i f i e d S t o k e s . Morgan f o r m a t i on i s a p p r o x i m a t e l y I465 f e e t t h i c k b e s t e x p o s e d i n P u l l em C r e e k a n d B e a r T r a p H o l l o w ( P l a t e I I , N o s . I4. a n d 5 )* W e b e r q u a r t z i t e . - q u a r t z i t e named b y K i n g ( I 6 7 6 , p . I4.77-I4.79) i n Weber e a s t M o r g a n, U t a h . B a k e r , H u d d l e K i n n e y (19!i7> P» 1 1 6 2 ) it t h e S o u t h F l a n k t h e U i n t a s . B o u t w e l l ( 1 9 1 2 , p . h<) r e c o g n i z e d i t s l i t h o l o g i c s i m i l a r i t y , 12 m i l e s w e s t t he a r e a , 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 . t h e w e s t e rn 29 and cherty nodules. Two fossiliferous horizons, approxi-mately two feet thick, are present in the upper part of the member. The fossils were exa~ined by Professor Stokes and reported to be characteristic of Late Paleozoic but not diagnostic of early Pennsylvanian time. Fossils of the lower member include Productids, COmposita sp., Chonetes sp., many weathered bryozoans and Crinoid plates and ste~s. Overlying the lower limestone member is a series of intercalated sandstones, siltstones, mUdstones and lime­stones approximately 265 feet thick. The dominant color is red, but variations are characteristic and locally produce a variegated appearance. Some red, white and gray chert is present throughout. Few fossils were found but a Schizo­phora sp. was identified by Stokes. The Horgan formation is approximately 465 feet thick and best exuosed in Pullem Creek and Bear Trap Hollow Plate II, Nos. 4 and 5). Weber quartzite.-- The Weber quartzite was named by King (1876, p. 477-479) in 'ffeber Canyon east of Morgan, Utah. Baker, Huddle and Kinney (1947, p. 1182) mapped it on the South Flank of the Uintas. Boutwell (1912, p. 45) recognized its lithologic similarity, 12 miles west of the area, in the Park City mining district. On the western n o r t h f l a n k t h e U i n t a M o u n t a i n s t h e Weber q u a r t z i t e con­f o r m a b l y o v e r l i e s t h e Morgan f o r m a t i o n . The c o n t a c t is g r a d a t i o n a l , b u t t h e r e i s a n o t a b l e c h a n g e f r o m t h e r ed s a n d s t o n e t h e Morgan t o t h e b u f f c o l o r e d q u a r t z i t ic s a n d s t o n e t h e ?»reber i n r e l a t i v e l y f e e t. ( T h e W e b e r c o n s i s t s of 1^00 - 2 0 0 0 f e e t of w h i t e to r u s t c o l o r e d , q u a r t z i t i c s a n d s t o n e . f r e s h f r a c t u r e s it i s w h i t e c o n t a i n m i n u t e s p e c s f e r r u g i n o u s m a t e r i al w h i c h g i v e s i t s l i g h t r u s t c o l o r. T a l u s s l o p e s a r e e x t r e m e l y c h a r a c t e r i s t i c t he W e b e r a n d o b s e r v e d f o r g r e a t d i s t a n c e s . t a l us b l o c k s r a n g e f r o m s m a l l t o l a r g e a n g u l a r b l o c k s t o t en f e e t i n d i a m e t e r . i s r e s i s t a n t a p e r s i s t e n t r i d g e c l i f f f o r m e r t h r o u g h o u t t h e a r e a. f o s s i l s w e r e f o u n d i n t h e f o r m a t i o n. P e r m i a n Rocks P a r k C i t y f o r m a t i o n . - P e r m i a n p e r i o d i s r e p r e s ­e n t e d o n l y t h e P a r k C i t y f o r m a t i o n , c h a r a c t e r i z e d by v e r y h e t e r o g e n e o u s l i t h o l o g y . f o r m a t i o n i s c o r r e l a t ed f r o m i t s t y p e l o c a l i t y , m i l e s w e s t t h e a r e a , i n t he P a r k C i t y d i s t r i c t , w h e r e i t B o u t w e l l 1 9 1 2, p . [«.9) . R i c h a r d s o n (193k* p . kll\.) h i s s t u d y n o r t h - 30 north flank of the Uinta 1Fountains the 'Neber quartzite con­formably overlies the Morgan formation. The contact is gradational, but there is a notable change from the red sandstone of the Horgan to the buff colored quartzitic sandstone of the Weber in a relatively few feet. (The Weber consists of 1500 - 2000 feet of white to rust colored, quartzitic sandstone. On fresh fractures it is white but may contain minute specs of ferruginous material which gives it a slight rust color. Talus slopes are extremely characteristic of the Weber and can be observed for great distances. The talus blocks range from small to large angular blocks up to ten feet in dia>neter. The Weber is a resistant member and a persistent ridge and cliff former throughout the area. No fossils were found in the formation. Permian Rocks Park City formation.-- The Permian period is repres­ented by only the Park City formation, characterized by very heterogeneous lithology. The formation is correlated from its type locality, 12 miles west of the area, in the Park City district, where it was named by Boutwell ( 1912, p.49). Richardson ~193~, p. 414) in his study of north- 3 1 e a s t e r n U t a h , a p p l i e d t h e t e r m i n o l o g y s o u t h e r n I d a ho M a n s f i e l d , 1 9 ^ 7 . P- 7?) c o r r e l a t e d t h e P a r k C i t y w i th t h e P h o s p h o r i a . S c h u l t z (1919* P« 4-7) g e o l o g ic r e c o n n a i s s a n c e t h e U i n t a M o u n t a i n s w i t h r e f e r e n c e t o t he p h o s p h a t e c o n t e n t t h e P a r k C i t y f o r m a t i o n a n d c o n c u r r ed w i t h B o u t w e l l t h e b a s i s l i t h o l o g y . W i l l i a ms ( 1 9 3 9 * P» 6 2 - 1 0 0 ) r e c o g n i z e d t h r e e u n i t s i n t h e P a r k C i ty f o r m a t i o n , g r o u p e d t h e u p p e r i n t h e P h o s p h o r ia f o r m a t i o n , a p p l y i n g t h e t e r m s C h e r t P h o s p h a t i c s h a le t o t h e s e m e m b e r s . The lovsrest of t h e P a r k C i t y u n i t s he a s s i g n e d t o t h e f o r m a t i o n t h e b a s i s ? , f a u n al e v i d e n c e . " L a t e r , W i l l i a m s (1914-3* P« o l o ) became a w a r e of a n e r r o r I n h i s i d e n t i f i c a t i o n t h e f o r m a t i o n f r o m w h i ch h e c o l l e c t e d t h e f o s s i l s u s e d b a s i s f o r h i s c o n c e p t, a n d t u r n e d b a c k t o B o u t w e l l ' s c o n c e p t i n s t a t i n g t h a t: . . . . t h e e v i d e n c e . . . s e e m s t o i n d i c a t e t h a t t he P a r k C i t y f o r m a t i o n i s s t r a t i g r a p h i c u n i t . .. E a r d l e y X9I4J4-, p . 83k) loOO f e e t P a r k C i t y in W e b e r V a l l e y a b o v e M o r g a n , U t a h . McCann (X9^4-7) o b s e r v e d t h e P a r k C i t y f o r m a t i o n t h e s o u t h f l a n k t he U i n t a M o u n t a i n s , t o c o n s i s t of t h r e e d i s t i n c t m e m b e r s. B a k e r , H u d d l e K i n n e y (19^-1-9> P» 1 1 6 6 ) c o n c u r w i t h H u d d le a n d McCann. I n F r a n s o n P l a t e I I , o) t h e P a r k C i ty 31 eastern Utah, applied the terminology of southern Idaho ( Mansfield, 1927, p. 75) and correlated the Park City with the Phosphoria. Schultz (1919, p. 47) made a geologic reconnaissance of the Uinta Hountains with reference to the phosphate content of the Park City fo~ation and concurred with Boutwell on the basis of lithology. J. S. Williams (1939, p. 82-100) recognized three units in the Park City formation, and grouped the upper two in the Phosphoria formation, applying the terms Rex Chert and Phosphatic shale to these members. The lowest of the Park City units he assigned to the Weber formation on the basis of i1faunal evidence. It Later, Williams (1943, p. 616) became aware of an error in his identification of the formation from which he collected the fossils used as a basis for his concept, and turned back to Boutwell's concept in stating that: •••• the evidence ••• seems to indicate that the Park City formation is a stratigraphic unit ••• Eardley (19~lJ-, p. 834) mapped 1000 feet of Park City in Weber Valley above Morgan, Utah. Huddle and HcCann (1947) observed the Park City formation on the south flank of the Uinta ~':!ountains, to consist 0 f three distinct members. Baker, Huddle and Kinney (1949, p. lIdS) concur with Huddle and McCann. In Franson Canyon ( Plate II, No. 6) the Park City 32 i s 910 f e e t t h i c k , and c o n s i s t s of t h r e e s t r a t i g r a p h ic u n i t s . The l o w e r u n i t i s composed c h i e f l y of c a l c a r e o us s a n d s t o n e s , b u f f c o l o r e d on w e a t h e r e d s u r f a c e s and l i g ht b l u e on f r e s h f r a c t u r e s and a r e n a c e o u s l i m e s t o n e s u s u a l ly p o r o u s and f r i a b l e and c o n t a i n i n g c h e r t n o d u l e s . The c o n ­t a c t of t h e P a r k C i t y f o r m a t i o n w i t h t h e Weber q u a r t z i te i s i n d e f i n i t e , b u t i s p l a c e d a t t h e b a s e of a d i s t i n c t c a l c a r e o u s , b r e c c i a t e d s a n d s t o n e , w h i c h i n t h i s a r e a is o v e r l a i n 37 f o o t f r i a b l e r e d s a n d s , s h a l e s and s i l t s . m i d d l e t h e P a r k C i t y f o r m a t i o n is c o m p o s e d c h i e f l y b l a c k p h o s p h a t i c s h a l e s , s a n d s t o n e s and l i m e s t o n e s w h i c h c o n t a i n a b u n d a n t c h e r t c a l c i t e s t r i n g e r s. T h i s i s p r o b a b l y t h e d i s t i n c t i v e t h e P a r k C i ty f o r m a t i o n . T h e u p p e r c o n s i s t s m a i n l y d e n s e t o f i n e ly c r y s t a l l i n e c h e r t y g r a y l i m e s t o n e . i s u s u a l l y l i g h t g r ay t o b l u e I n c o l o r , t h i n l y t o m a s s i v e l y b e d d e d n e a r t h e t o p. C h e r t , c a l c i t e v u g s g e o d e s a r e common. P u n c t o s p i r i f e r s p . , S p i r i f e r s p . , C o m p o s i t a s p ., M y a l l n a s p . a r e t h e b r a c h i o p o d s f o u n d i n t h e P a rk C i t y f o r m a t i o n. 32 is 910 feet thick, and consists of three stratigraphic units. The lower unit is comoosed chiefly of calcareous sandstones, buff colored on weathered surfaces and light blue on fresh fractures and arenaceous limestones usually porous and friable and containing chert nodules. The con­tact of the Park City formation with the Weber quartzite is indefinite, but is placed at the base of a distinct calcareous, brecciated sandstone, which in this area is overlain by a 37 foot bed of friable red sands, shales and silts. The middle member of the Park City formation is composed chiefly of black phosphatic shales, sandstones and limestones which contain abundant chert and calcite stringers. This member is probably the most distinctive of the Park City formation. The upper member consists mainly of dense to finely crystalline cherty gray limestone. It is usually light gray to blue in color, thinly to massively bedded near the top_ Chert, calcite vugs and geodes are co~on. Punctospirifer sp., Spirifer sp., COmposita sp., Myalina sp. are the common brachiopods found in the Park City formation. • 33 M e s o z o i c S y s t e ms G e n e r a l S t a t e m e n t . - - D e t a i l e d s t u d y t h e M e s o z o ic r o c k s i s b e y o n d t h e s c o p e t h i s i n v e s t i g a t i o n . a re p r e s e n t t h e n o r t h e r n b o u n d a r y t h e a r e a , h o w e v e r , and a r e t h e g e o l o g i c a c c o m p a n y i n g t h i s r e p o r t . The M e s o z o i c s e d i m e n t s a r e b e i n g p r e s e n t l y s t u d i e d , p e n d i ng t h e r e s u l t s t h i s s t u d y a r e o n l y b r i e f l y d e s c r i b e d. T r i a s s i c F o r m a t i o ns W o o d s i d e s h a l e . - W o o d s i d e s h a l e r e p r e s e n t s t he b a s a l T r i a s s i c f o r m a t i o n i n t h e a r e a . B o u t w e l l 1 9 1 2 , p . £2) f i r s t d e s c r i b e d i t i n W o o d s i d e G u l c h t h e P a r k C i t y d i s t r i c t . I n F r a n s o n t h e W o o d s i d e m e a s u r e s 607 f e et t h i c k c o n f o r m a b l y o v e r l i e s t h e P a r k C i t y f o r m a t i on P l a t e I I , 7 ) . c o n t a c t w i t h t h e P a r k C i t y f o r m a ­t i o n i s d i s t i n c t . V e g e t a t i o n / i s g e n e r a l l y k e y t o t he c o n t a c t ; q u a k i n g a s p e n s p r e f e r t h e h i g h e r m o i s t u r e - r e t a i n i ng a b i l i t y t h e r e d b e d s t h e W o o d s i d e t o t h e l i m e s t o n e of t h e P a r k C i t y f o r m a t i o n. W o o d s i d e i s r e d d i s h - b r o w n s h a l e s i l t s t o ne f o r m a t i o n . i s c o m p r i s e d c h i e f l y t h i n b e d d e d s h a l es a n d s i l t s t o n e s w i t h t h e s i l t s t o n e s r e s i s t a n t t o e r o s i o n. 33 Mesozoic Systems General Statement.-- Detailed study of the ~esozoic rocks is beyond the scone of this investigation. They are present on the northern boundary of the area, however, and are shown on the geologic map accompanying this report. The r:~esozoic sediments are being -;>resently studied, and pending the results of this study are only briefly described. Triassic Formations Woodside shale.-- The Woodside shale represents the basal Triassic formation in the area. Boutwell ( 1912, p. 52) first described it in Woodside Gulch of the Park City district. In Franson Canyon the 7100dside measures 007 feet thick and conformably overlies the Park City formation ( Plate II, No. 7). The contact with the Park City forma­tion is distinct. Vegetationl is generally a key to the contact; quaking aspens prefer the higher moisture-retaining ability of the red beds of the Woodside to the limestone of the Park City formation. The Woodside is a reddish-brown shale and siltstone formation. It is comprised chiefly of thin bedded shales and siltstones with the siltstones more resistant to erosion. r e s i s t a n t t o f o o t member, t e n t a t i v e l y c a l l e d t he F r a n s o n M e m b e r , " s a p p e a r s 570 f e e t a b o v e t h e b a se a n d i s p r o n o u n c e d r i d g e m a k e r . W o o d s i d e s h a l e Is o t h e r w i s e s l o p e m a k e r. T h a y n e s l i m e s t o n e . - - T h a y n e s l i m e s t o n e i s w e ll e x p o s e d t h e s l o p e s u p p e r w h e r e i t m e a s u r es 7 f e e t t h i c k n e s s . B o u t w e l l ( 1 9 1 2 , p . 55) f i r s t named t h e f o r m a t i o n i n T h a y n e s i n t h e P a r k C i t y d i s t r i c t . I n t h e S o u t h F o r k - S w i f t C r e e k - F r a n s o n a r ea t h e T h a y n e s l i m e s t o n e i s d i v i d e d i n t o t h r e e P l a t e I I , N o . 6 ) ; t h e " l o w e r l i m e , " t h e " m i d d l e r e d " and " u p p e r l i m e ." The " l o w e r l i m e " g e n e r a l l y f o r m s p r o m i n e n t h o g b a c k s a l o ng t h e s l o p e s of Weber C a n y o n , S w i f t C r e e k and N o b l e t t C r e e k. I t c o n s i s t s c h i e f l y of b u f f c o l o r e d , a r e n a c e o u s l i m e s t o n es w i t h i n t e r b e d d e d , s a n d y s h a l e l e n s e s . s h a l e s d i s p l ay c r o s s b e d d i n g c o n t a i n f o s s i l f r a g m e n t s . l o w e r l i m e" w e a t h e r s t o d a r k b r o w n c o l o r i s 235 f e e t t h i c k . - It h a s p r o n o u n c e d p l a t y b e d d i n g p r i s m a t i c w e a t h e r i n g is c h a r a c t e r i s t i c . m i d d l e r e d " c o n s i s t s r e d d i s h , l a m i n a t ­e d , c a l c a r e o u s , f i n e g r a i n e d , t h i n l y b e d d e d s l i g h t ly 6 U n d e r t h e d i r e c t i o n Norman W i l l i a m s t he U n i v e r s i t y U t a G e o l o g y D e p a r t m e n t i s c o n d u c t i n g a s e r i e s s t u d i e s t h e g e o l o g y w i t h i n t h e C o a l v i l le q u a d r a n g l e • 34 A resistant 20 to 30 foot member~ tentatively called the " Franson Canyon Me'TI.ber~!TS appears 570 feet above the base and is a pronounced ridge maker. The Woodside shale is otherwise a slope maker. Thaynes limestone.-- The Thaynes limestone is well exposed on the slopes of upper Weber Canyon where it measures 714 feet in thickness. Boutwell 1912~ p. 55) first named the formation in Thaynes Canyon in the Park City district. In the South Fork-Swift Creek-Franson Canyon area the Thaynes limestone is divided into three members ( Plate II~ No.8); the "lower lime,!! the "middle redl! and !Tupper lime." The "lower lime!! generally forms prominent hogbacks along the slopes of Weber Canyon~ Swift Creek and Noblett Creek. It consists chiefly of buff colored, arenaceous limestones with interbedded, sandy shale lenses. The shales display crossbedding and contain fossil fragments. The " lower lime" weathers to a dark brown color and is 235 feet thick.. It has pronounced platy bedding and prismatic weathering is characteristic. The " middle red" member consists of reddish, larninat-ed, calcareous, fine grained, thinly bedded and slightly sUnder the direction of No~an C. Williams of the University of Uta.h Geology Department is now conducting a series of studies on the geology within the Coalville quadrangle. 35 m i c a c e o u s s a n d s t o n e . c o n t a c t b e t w e e n t h e l o w e r l i m e" a n d " m i d d l e r e d " I s a t t h e t o p d e n s e g r a y i sh l i m e s t o n e . m i d d l e r e d " m e a s u r e s 165 f e e t t h i c k and c o n t a i n s i n p l a c e s s i l i c e o u s l e n s e s. u p p e r l i m e " i s 29I4- f e e t t h i c k is m a i n l y i n t e r b e d d e d , d e n s e g r a y l i m e s t o n e , t h i n b e d d e d, b u f f c o l o r e d , a r e n a c e o u s l i m e s t o n e . c o n t a c t b e t w e e n t he " m i d d l e r e d " t h e u p p e r l i m e " i s g e n e r a l l y c o v e r e d by s o i l m a n t l e , b u t i s t r a n s i t i o n a l. A n k a r e h s h a l e . 2 - A n k a r e h s h a l e c o n f o r m a b ly o v e r l i e s t h e T h a y n e s l i m e s t o n e i n U p p e r C a n y o n , at w h i c h p o i n t i t i s fl^O f e e t t h i c k . The t y p e A n k a r e h i s in t h e P a r k C i t y d i s t r i c t w h e r e B o u t w e l l 1 9 1 2 , p . a s s i g n ed i t t o t h e l o w e r T r i a s s i c . A n k a r e h s h a l e c o n s i s t s p u r p l e t o b r i c k r e d, f i n e t o g r a i n e d , c a l c a r e o u s s i l t s t o n e s s h a l e s. c o n t a c t w i t h t h e u n d e r l y i n g T h a y n e s l i m e s t o n e i s m a r k ed 7 T h e t e r m s A n k a r e h , S h i n a r u m p C h i n l e a r e i n a c c o r d ­a n c e w i t h t e r m i n o l o g y b e i n g u s e d W i l l i a m s i n h is s t u d y t h e C o a l v i l l e q u a d r a n g l e a r e e q u a l t o t h e e n t i re A n k a r e h s e c t i o n C a l k i n s 1 9 1 6 ) o t h e r W a s a t c h M o u n t a i ns i n v e s t i g a t o r s , c o n s i d e r t h e S h i n a r u m p t h i s p a p e r "a b e d h a r d q u a r t z i t e " n e a r t h e m i d d l e t h e A n k a r e h f o r m a ­t i o n . t e r m i n o l o g y i s i n a c c o r d a n c e w i t h S t o k e s * (1950) c o n c e p t t h e S h i n a r u m p b e i n g m i d d l e T r i a s s i c d e p o s i ­t i o n , w i t h r e d b e d s b e l o w a s e a r l y T r i a s s i c r e d b e ds a b o v e a s l a t e T r i a s s i c. 35 micaceous sandstone. The contact between the " lower lime" and tlmiddle red tl is mapped at the top of a dense grayish limestone. The " middle red" measures Id5 feet thick and contains in places siliceous lenses. The " upper lime" member is 294 feet thick and is mainly interbedded, dense gray limestone, and thin bedded, buff colored, arenaceous limestone. The contact between the llmiddle red" and the " upper limeil is generally covered by a soil mantle, but is transitional. Ankareh shale. 1 The Ankareh shale conformably overlies the Thaynes limestone in Upper Weber Canyon, at which point it is 740 feet thick. type Ankareh is in the Park City district where Boutwell ( 1912, p. 59) assigned it to the lower Triassic. The Ankareh shale consists of purple to brick red, fine to medium grained, calcareous siltstones and shales. The contact with the underlying Thaynes limestone is ~arked 7The terms Ankareh, Shinarump and Chinle are in accord­ance with terminology being used by N. C. Williams in his study of the Coalville quadrangle and are equal to the entire Ankareh section of Calkins ( lg16) and other l!Jasatch r.1ountains investigators, who consider the Shinarump of this paper lIa bed of hard quartzite" near the ""!1iddle of the Ankareh forma­tion. This terminology is in accordance with Stokes' (1950) concept of the Shinarump as being of middle Triassic deposi­tion, with red beds below as early Triassic and red beds above as late Triassic. b y p u r p l i s h - r e d s i l t s t o n e i n t h e b a s e t h e A n k a r e h s h a l e. S h i n a r u m p c o n g l o m e r a t e . 3 - S h i n a r u m p c o n g l o m e r a te f o r m s p r o m i n e n t o u t c r o p s and i s an e x c e l l e n t m a r k e r bed a l o n g t h e w e s t e r n n o r t h f l a n k t h e U i n t a M o u n t a i n s . It o v e r l i e s t h e A n k a r e h s h a l e w i t h e r o s i o n a l u n c o n f o r m i t y. S h i n a r u m p v a r i e s i n t h i c k n e s s b u t i s 60 f e e t t h i c k n o r th o f S w i f t C r e e k P l a t e I I , 9 ). S h i n a r u m p c o n g l o m e r a t e c o n s i s t s f i n e to m e d i um g r a i n e d , l i g h t t o medium g r a y q u a r t z i t e c o n g l o m e r a t e. t h e s t r i k i n g f e a t u r e s i s t h e a b u n d a n c e of p e t r i f i e d wood. S t o k e s ( 1 9 5 ° * P» 91) s u g g e s t s: . . . T h e b u r i e d l o g s , l a t e r and b r o k e n b e f o r e r e b u r i a l In t h e f o r m a t i o n at o t h e r l o c a l i t i e s . . . p e t r i f i e d i s c o n f i n e d t o t h e b a s a l of t he f o r m a t i o n w h i c h i s m a i n l y d a r k b r o w n , s i l i c e o u s u n i t, v e r y r e s i s t a n t t o e r o s i o n. f o s s i l f o r m s , o t h e r t h a n p e t r i f i e d w e re f o u n d i n t h e S h i n a r u m p c o n g l o m e r a t e . S t o k e s b e l i e v e s t he S h i n a r u m p t o h a v e o r i g i n a t e d f r o m t h e p r o c e s s of p e d i m e n t - a t i o n s u g g e s t s t h a t i t r e p r e s e n t s M i d d l e T r i a s s i c t i me 1 9 5 0 , p . 9 7 ). 8 I b i d . by a purplish-red siltstone in the base of the Ankareh shale. Shinarump conglomerate.~- The Shinarump conglomerate forms prominent outcrops and is an excellent marker bed along the western north flank on the Uinta Mountains. It overlies the Ankareh shale with an erosional unconformity. The Shinarump varies in thickness but is 60 feet thick north of Swift Creek ( Plate II, No. 9). The Shinarump conglomerate consists of fine to medium grained, light to mediu.m gray quartzite conglomerate. One of the most striking features is the abundance of petrified wood. Stokes (1950, p. 91) suggests: ..• The wood was buried as logs, later exhumed and broken up before reburial in the same formation at other localities ••• The petrified wood is confined to the basal member of' the fo~ation which is ~ainly a dark brown, siliceous unit, very resistant to erosion. No fossil forms, other than petrified wood, were found in the Shinarump conglomerate. Stokes believes the Shinarump to have originated from the process pediment-ation and suggests that it represents Middle Triassic time ( 1950, p. 97). 8Ibid. 37 C h i n l e f o r m a t i o n . * C h i n l e i s v a r i e g a t ed m u d s t o n e s i l t s t o n e a p p r o x i m a t e l y 3 5 ° t o 3&0 f e e t t h i ck i n U p p e r C a n y o n . c o n t a c t i s a t t h e b a se o f p u r p l e q u a r t z i t i c - s i l t w h i c h c o n f o r m a b l y o v e r l i e s t he S h i n a r u m p c o n g l o m e r a t e . Madcracks r i p p l e m a r k s a re p r e v a l e n t p r i m a r y s t r u c t u r e s In t h e r e d d i s h - b r o w n m u d s t o n e s. C h i n l e g r a d e s c o n f o r m a b l y i n t o t h e o v e r l y i n g Nugget s a n d s t o n e • J u r a s s i c F o r m a t i o ns N u g g e t s a n d s t o n e . - N u g g e t s a n d s t o n e c o n s i s ts o f s a l m o n c o l o r e d , m a s s i v e , f i n e t o g r a i n e d c r o s s - b e d d e d s a n d s t o n e , i s w e a k l y c e m e n t e d . c o n t a c t w i th t h e C h i n l e i s g r a d a t i o n a l b u t i s p l a c e d a t t h e b a s e g r a y t o g r e e n i s h - g r a y s a n d s t o n e w h i c h i s n o r m a l l y p r e s e n t. s a l m o n r e d c o l o r c h a r a c t e r i z e s t h e N u g g e t e x c e p t n e a r t he t o p w h e r e i t i s w h i t e c o l o r e d n e a r t h e c o n t a c t w i t h t he C r e e k l i m e s t o n e. t y p e l o c a l i t y t h e N u g g e t s a n d s t o n e i s in N u g g e t S t a t i o n , V e a t c h , 1 9 0 7 ) . i s s t r a t i g r a p h i - c a l l y p l a c e d l o w e r J u r a s s i c b e t w e e n t h e C h i n l e u p p er 9 I b i d . 37 Chinle formation.§- The Chinle is a variegated mudstone and siltstone approximately 350 to 360 feet thick in Upper Weber Canyon. The contact is mapped at the base of a purple quartzitic-silt which confo~ably overlies the Shinarump conglomerate. 1~dcracks and ripple marks are prevalent primary structures in the reddish-brown mUdstones. The Chinle grades conformably into the overlying Nugget sandstone. Jurassic Formations Nugget sandstone.-- The Nugget sandstone consists of a salmon colored, massive, fine to medium grained cross­bedded sandstone, and is weakly cemented. The contact with the Chinle is gradational but is placed at the base of a gray to greenish-gray sandstone which is normally present. A salmon red color characterizes the Nugget except near the top where it is white colored near the contact with the Twin Creek limestone. The type locality of the Nugget sandstone is in .Nugget Station, Wyoming ( Veatch, 1907). It is stratigraphi­cally placed as lower Jurassic between the Chinle of upper 38 T r i a s s i c t h e C r e e k m i d d l e J u r a s s i c , N u g g et s a n d s t o n e i s u n f o s s i l i f e r o u s i s a p p r o x i m a t e l y 9 0 0 f e et t h i c k a t t h e j u n c t i o n S o u t h P o r k w i t h C a n y o n . The t e r m N u g g e t s a n d s t o n e i s u s e d i n n o r t h e r n U t a h a n d c o r r e l a t ed w i t h t h e N a v a j o s a n d s t o n e s o u t h e r n U t a h. C r e e k l i m e s t o n e . - u p p e r t he T w i n C r e e k l i m e s t o n e a p p e a r s f r e s h s u r f a c e s b l u e - g r a y t o g r a y l i m e s t o n e w i t h t h i n l y b e d d e d , g r e e n i s h - g r ay l e n s e s a r e n a c e o u s s h a l e . f o r m a t i o n w e a t h e r s a l m o st w h i t e . i s e s t i m a t e d t o 1 , 3 0 0 f e e t t h i c k c o n f o r m ­a b l y o v e r l i e s t h e N u g g e t s a n d s t o n e , V e a t c h 1 9 0 7 , , £6) f i r s t d e s c r i b e d t h e C r e e k i n s o u t h w e s t e r n Wyoming. P I g u r 3» R o c k s l i d e i n S o u t h P o r k C a n y o n. 38 Triassic and the Twin Creek of middle Jurassic . The Nugget sandstone is unfossiliferous and is approximately 900 feet thick at the junction of South Fork with Weber Canyon. The term Nugget sandstone is used in northern Utah and correlated with the Navajo sandstone of southern Utah . Twin Creek limestone.-- In upper Weber Canyon the Twin Creek limestone appears on fresh surfaces as a blue­gray to gray limestone with thinly bedded, greenish- gray lenses of arenaceous shale. The formation weathers almost white. It is estimated to be 1,300 feet thick and conform­ably overlies the Nugget sandstone. Veatch ( 1907, p . 56) first described the Twin Creek in southwestern ~Tyoming . Figur 3. Rockslide in South Fork Canyon . QUATERNARY FORMATIONS P l e i s t o c e n e P l e i s t o c e n e r o c k s c o n s i s t g l a c i a l d e b r i s, m o r a i n e s o u t w a s h p l a i n s , a r e p r e s e n t i n S m i t h and M o r e h o u s e u p p e r W e b e r C a n y o n s i n S o u t h F o r k B a s i n. S w i f t C r e e k F r a n s o n c o n t a i n m i n o r a m o u n t s. R e c e n t A l l u v i u m i s p r e s e n t t h r o u g h o u t a l l c a n y o n v a l l e ys a n d s e v e r a l l a n d s l i d e s a r e p r e s e n t i n t h e a r e a . A r e c e nt r o c k s l i d e c a n s e e n a t t h e j u n c t i o n W e l c h C r e e k w i th S o u t h F o r k Canyon ( P i g . 3 )• 3 9 QUATERNARY FORMATIONS Pleistocene The Pleistocene rocks consist of glacial debris, moraines and outwash plains, and are present in Smith and Morehouse and upper Weber Canyons and in S~:>uth Fork Basin. Swift Creek and Franson Canyon contain minor amounts. Recent Alluvium is present throughout all canyon valleys and several landslides are present in the area. A recent rockslide can be seen at the junction of 17elch Creek with South F'ork Canyon (Fig. 3). 39 G e n e r a l S t r u c t u re R e g i o n a l S t r u c t u r e . - - s t r u c t u r a l f e a t u r e s t he U i n t a M o u n t a i n s h a v e b e e n a d e q u a t e l y s u m m a r i z e d by F o r r e s t er ( 1 9 3 7 ) a s: . . . A b r o a d , o p e n a n t i c l i n e , o v e r t u r n e d and a r c u a t e t o t h e n o r t h . a x i s t r e n d s r o u g h l y e a s t - w e s t . . . a n d p i t c h e s s o u t h w e s t i n t o V a l l e y . .. t h e n o r t h w e s t e r n f l a n k t h e U i n t a M o u n t a i ns t h e s t r u c t u r e i s e s s e n t i a l l y h o m o c l i n e d i p p i n g n o r t h w e s t. A l o n g t h e w e s t e r n b o u n d a r y t h e a r e a t h e U i n t a a n t i c l i ne p i t c h e s i n t o Rhodes V a l l e y r e s u l t i n g i n g r a d u a l c h a n g e of s t r i k e t h e f o r m a t i o n s a r o u n d t h e n o s e t h e a n t i c l i n e. F a u l t i n g N o r t h F l a n k F a u l t . - - N o r t h F l a n k F a u l t m a r ks t h e n o r t h e r n b o u n d a r y t h e a r e a i n c l u d e d i n t h e s t u d y . The f a u l t i t s e l f i s n o t d i s c e r n a b l e , b u t i t s p o s i t i o n be e s t a b l i s h e d w i t h i n t h e v a l l e y t h e u p p e r Weber R i v e r f r om STRUCTURE General Structure Regional Structure.-- The structural features of the Uinta Mountains have been adequately sU1n-marized by Forrester (1937) as: ••• A broad" open anticline" somewhat overturned and arcuate to the north. The axis trends roughly east­west ••• and pitches southwest into Rhodes Valley ••• On the northwestern flank of the Uinta :r::ountains the structure is essentially a homocline dipping northwest. Along the western boundary of the area the Uinta anticline pitches into Hhodes Valley resulting in a gradual change of strike of the format1ons around the nose of the anticline. Faulting North Flank Fault.-- The North Flank Fault marks the northern boundary of the area included in the study. The fault itself is not discernable" but its position may be established within the valley of the upper 'Neber River from P r a z i e r H o l l o w t o e a s t of t h e mouth of S m i t h and M o r e h o u se C a n y o n . Near S m i t h and M o r e h o u s e Canyon g e n t l y d i p p i ng T e r t i a r y b e d s n o r t h of t h e Weber R i v e r a r e o p p o s i t e s t e e p ly d i p p i n g P a l e o z o i c and M e s o z o i c f o r m a t i o n on t h e s o u t h s i de o f t h e W e b e r ; o p p o s i t e S h i n g l e M i l l C r e e k , P a l e o z o i c f o r m a ­t i o n s a r e p r e s e n t w h i l e d i r e c t l y a c r o s s t h e Weber R i v er C r e t a c e o u s b e d s o u t c r o p . w i d t h t h e V a l l e y at t h i s p o i n t i s i n s u f f i c i e n t t o a c c o m m o d a t e t h e i n t e r v e n i ng s t r a t i g r a p h i c s e q u e n c e . s o u t h s i d e t h e N o r t h F l a nk F a u l t i s t h e u p t h r o w n b l o c k t h e s t e e p d i p of t h e f o r m a ­t i o n s a t t h e m o u t h S m i t h M o r e h o u s e i n p a rt b e d r a g . S e v e r a l s m a l l t r a n s v e r s e f a u l t s a r e p r e s e n t in t h e a r e a. U n c o n f o r m i t i e s P r e - C a m b r i a n - C a m b r i a n U n c o n f o r m i t y . E a r l i e r i n ­v e s t i g a t o r s h a v e b e e n c o n f r o n t e d w i t h t h e p r o b l e m of a c c u r a te s e p a r a t i o n p r e - C a m b r i a n C a m b r i a n f o r m a t i o n s . H i n t ze ( 1 9 3 k ) p r o p o s e d t h i s d i v i s i o n t h e t o p s e r i e s p u r pl a n d r e d q u a r t z i t e s i n S m i t h a n d M o r e h o u s e C a n y o n , w h e r e he b e l i e v e s u n c o n f o r m i t y e x i s t s . P i n e V a l l e y , F o r r e s t er 1 9 3 7 ) d e s c r i b e s c o n f o r m a b l e r e l a t i o n s h i p b e t w e e n t h e p r e - C a m b r i a n a n d C a m b r i a n s e d i m e n t s . p l a c e s t h e c o n t a c t at Frazier Hollow to east of' the mouth of Smith and Morehouse Canyon. Near Smith and ~~orehouse Canyon gently dinping Tertiary beds north of the Weber River are opposite steeply v dipping Paleozoic and Mesozoic f'ormation on the south side of the 'Heber; opposite Bhingle Mill Creek, Paleozoic forma­tions are present while directly across the Neber River Cretaceous beds outcrop. The width of the Weber Valley at this point is insufficient to accommodate the intervening stratigraphic sequence. The south side of the North Flank Fault is the upthrown block and the steep dip of' the forma­tions at the mouth of SmJth and Morehouse Canyon may in part be drag. Several small transverse faults are present in the area. Unconformities Pre~Cambrian-Camb£ian Unconformity.-- Earlier in­vestigators have been confronted with the problem of accurate separation of pre-Cambrian and Cambrian formations. Hintze 193L~) proposed this division at the top of a series of purple and red quartzites in Smith and Morehouse Canyon, where he believes an unconfo~nity exists. In Pine Valley, Forrester ( 1937) describes a conformable relationship between the pre- Cambrian and Cambrian sediments. He places the contact at t h e b a s e m i c a c e o u s s h a l e P i n e s h a l e t h i s p a p e r) b e c a u s e i t s l i t h o l o g i c r e s e m b l a n c e t o t h e C a m b r i a n O p h ir s h a l e W a s a t c h a n d O q u i r r h M o u n t a i n s . T h i s l i t h o l o g ic s e q u e n c e , p r e v i o u s l y s t a t e d , s o u t h a r m o n y w i t h t he u s u a l C a m b r i a n s e q u e n c e i n U t a h . S o u t h P o r k B a s i n 15 t o d e g r e e a n g u l a u n c o n f o r m i t y s e p a r a t e s t h e m i c a c e o us s h a l e f r om C a m b r i a n f o r m a t i o n s P i . Ij.). u n c o n f o r m i ty i s t h e o n l y l o g i c a l s e p a r a t i o n p r e - C a m b r i a n C a m b r i an s e d i m e n t s . u n c o n f o r m i t y i s u s u a l l y a p p a r e n t t he n o r t h f l a n k i n c a n y o n s w h i c h a r e n o r m a l t o h e s t r i k e , w h e r e a s, i n s t r i k e v a l l e y s i t i s u s u a l l y n o t e v i d e n t. the base of a micaceous shale (Red Pine shale of this paper) because of its lithologic resemblance to the Cambrian Ophir shale of Wasatch and Oquirrh Mountains. This lithologic sequence, as previously stated, i s out of harmony with the usual Cambrian sequence in Utah. In South Fork Basin a 15 to 20 degree angula r unconformity sepa rates the micaceous shale from Cambrian fo rmations ( Fi g . 4). The uncon fo rmity is the only logical separation of pre-Cambrian and Cambrian Figure 4 . Fence diagram showing an gular unc onformi ty be t ween pre-Cambrian Red Pine (p£rp) and Cambrian Pine Valley (£pv); po st-D evonian-pre-Madison unconformity. -- ---_. ___ :;w......-=.......= __ sediments. The unconformity is usually apparent on the north flank in canyons which are no rmal to t he strike, whereas, in strike valleys it is usually not evi dent. P o s t D e v o n i a n - ? r e - M a d i s o n U n c o n f o r m i t y *- t he West W a l l c l i f f s r e m n a n t s of l a t e D e v o n i a n and C a m b r i an s t r a t a a r e p r e s e n t . E l s e w h e r e i n t h e a r e a , t h e s e f o r m a t i o ns h a v e b e e n r e m o v e d by e r o s i o n p r i o r t o d e p o s i t i o n of t he M a d i s o n l i m e s t o n e . M a d i s o n s e e n t o r e s t upon p r e - C a m b r i a n , C a m b r i a n , D e v o n i a n s e d i m e n t s , w h i ch i n d i c a t e s u n c o n f o r m a b l e r e l a t i o n s h i p b e t w e e n l a te D e v o n i a n t h e M a d i s o n f o r m a t i o n. M e s o z o i c U n c o n f o r m i t i e s . - - u n c o n f o r m i t i es e x i s t w i t h i n t h e M e s o z o i c s y s t e m , b u t t h e i r s i g n i f i c a n c e is b e y o n d t h e s c o p e t h i s p a p e r . U n c o n f o r m i t i e s a r e n o t ed a t t h e b a s e t h e S h i n a r u m p , w i t h i n t h e C r e t a c e o u s , and a t t h e b a s e t h e T e r t i a r y . c o m p l e t e s t u d y M e s o z o ic s t r a t i g r a p h y i s u n d e r w a y , 7 t h e r e s u l t s w i l l in p u b l i s h e d f o r m a t e a r l y d a t e. L n o r S t r u c t u r es J o i n t i n g . - - J o i n t s a r e common i n t h e p r e - C a m b r i an f o r m a t i o n s , g e n e r a l l y s e t s a r e d e v e l o p e d . F o r r e s t er ( 1 9 3 7 , p . 6I4.6) s t a t e s: 7 N . W i l l i a m s , o p . c i t . , p . 2 6. 43 Post Devonian-Pre-TvIadison Unconformity.-- In the West Wall cliffs remnants of late Devonian and Ca~brian strata are present. Elsewhere in the area, these formations have been removed by erosion prior to deposition of the Madison limestone. The Madison can be seen to rest upon pre-Cambrian, Cambrian, and Devonian sediments, which indicates an unconformable relationship between late Devonian and the I.~adison formation. Meso.zoic Unconformities. -- Numerous unconformities exist within the }/[esozoic system, but their significance is beyond the scope of this paper. Unconformities are noted at the base of the Shinarump, within the Cretaceous, and at the base of the Tertiary. A complete study of Mesozoic stratigraphy is now underway,7 and the results will be in published form at an early date. i~inor Structures Jointing.-- Joints are CO.'11':1.0n in the pre-Cambrian formations, and generally two sets are developed. Forrester (1937, p. 646) states: 7N. C. Williams, Ope cit., p. 28. 1 I • • • j o i n t s a r e w e l l d e v e l o p e d • • . a n d m o s t . . . a re f o u n d i n m a s t e r s e t s . s e t r o u g h ly p a r a l l e l s t h e a x i s t h e r a n g e ; t h e o t h e r s et i s a p p r o x i m a t e l y a t r i g h t a n g l e s. F o l d A x e s . - - i s s i g n i f i c a n t t o n o t e t h a t two a n t i c l i n a l a x e s a r e p r e s e n t i n t h e a r e a t h e U i n t a Moun t a i n s , and a r e c l e a r l y o b s e r v a b l e i n t h e S o u t h F o r k B a s in a r e a : (l) a p r e - C a m b r i a n a x i s , (2) t h e a x i s of L a r a m i de f o l d i n g p r e - C a m b r i a n l a t e r f o r m a t i o n s . p r e - C a m b r i a n a x i s l i e s a b o u t m i l e s o u t h o f , r o u g h ly p a r a l l e l t o t h e L a r a m i d e a x i s i n t h e a r e a. ••• joints are well developed ••• and ~ost ••• are found in one of two master sets. One set roughly parallels the axis of the range; the other set is approximately at right angles. Fold Axes.-- It is significant to note that two anticlinal axes are present in the area of the Uinta Moun-tains, and are clearly observable in the South Fork Basin area: (1) a pre-Cambrian axis, (2) the axis of Laramide folding of pre-Ca'11brian and later formations. The pre- Cambrian axis lies about one mile sout,- of, and roughly parallel to the Laramide axis in the area. GE 0 MO RP HO LO.GY p o s t - m a t u r e t o p o g r a p h y d e v e l o p e d t h e U i n ta M o u n t a i n s d u r i n g O l i g o c e n e o r M i o c e n e t i m e G i l b e r t P e ak S u r f a c e B r a d l e y ) h a s b e e n d e e p l y i n c i s e d l a r g e ly d e s t r o y e d s u b s e q u e n t e r o s i o n w h i c h b e g a n a s t h e r e s u lt o f u p l i f t . r e m n a n t s t h e o l d s u r f a c e r e m a i n a b o ve t h e L a k e F l a t s " r e g i o n P l a t e I I I ) . c r e s t t he U i n t a M o u n t a i n s f o r m s t h e d r a i n a g e d i v i d e b e t w e e n t h e n o r th a n d s o u t h f l a n k s• S m i t h M o r e h o u s e S o u t h F o r k C a n y o n s a r e t he p r i m a r y s t r e a m v a l l e y s and a r e c l a s s i f i e d as c o n s e q u e nt s t r e a m s . T h e i r c o u r s e s w e r e a p p a r e n t l y e s t a b l i s h e d when c o n t i n e n t a l u p l i f t t i l t e d t h e n o r t h s l o p i n g G i l b e r t P e ak s u r f a c e . The s t r e a m s i n c i s e d t h e i r c h a n n e l s a c r o s s t h e s t r i ke o f t h e f o r m a t i o n s . P i n e C a n y o n , P u l l e m C r e e k t he m o u t h S o u t h F o r k d e v e l o p e d p a r a l l e l t o t h e r e g i o n ­a l s t r i k e i n t h e s o f t e r f o r m a t i o n s s u b s e q u e n t s t r e a m s. R e s e q u e n t , o b s e q u e n t i n s e q u e n t s t r e a m s a r e r e p r e s e n t ed b y n u m e r o u s s m a l l t r i b u t a r i e s t h e p r i m a r y s e c o n d a ry s t r e a m s . u p p e r R i v e r i s t h e m a j o r s t r e a m t he GEOMORPHOLOGY A post-mature topography developed on the Uinta Mountains during Oligocene or Miocene time ( Gilbert Peak Surface of Bradley) and has been deeply incised and largely destroyed by subsequent erosion which began as the result of uplift. Small remnants of the old surface remain above the "Mud Lake Flats" region ( Plate III). The crest of the Uinta Mountains forms the drainage divide between the north and south flanks. Smith and Morehouse and South Fork Canyons are the primary stream valleys and are classified as consequent streams. Their courses were apparently established when continental uplift tilted the north sloping Gilbert Peak surface. The streams incised their channels across the strike of the formations. Red Pine Canyon, Pullem Creek and the mouth of South Fork Canyon developed parallel to the region­al strike in the softer formations as subsequent streamS. Resequent, obsequent and insequent streams are represented by numerous small tributaries of the primary and secondary streams. The upper Weber River is the major stream of the 45 1^6 a r e a i t s c o u r s e i s m a i n l y c o n t r o l l e d t h e N o r t h F l a nk F a u l t a b o v e t h e c o n f l u e n c e of F r a z i e r H o l l o w ; b e l o w F r a z i er H o l l o w t h e u p p e r W e b e r R i v e r f o l l o w s t h e s t r i k e of t h e s o f t e r, m o r e e a s i l y w e a t h e r e d T r i a s s i c and Lower J u r a s s i c r e d b e d s. The d o m i n a n t l a n d f o r m s a r e h o g b a c k s , s t r i k e v a l l e y s, c l i f f s r e m n a n t o l d a g e e r o s i o n s u r f a c e . R e s i s t a nt r i d g e s b e t w e e n t h e s t r i k e v a l l e y s a r e g e n e r a l l y s y m m e t r i c al a n d f o r m h o g b a c k s . The M a d i s o n , T h a y n e s and Twin C r e ek l i m e s t o n e s a r e c h a r a c t e r i s t i c a l l y h o g b a c k f o r m e r s . S t r i ke v a l l e y s a r e c o n f i n e d t o t h e s o f t e r s h a l e , s i l t and s a nd f o r m a t i o n s . Lower S o u t h F o r k , N o b l e t t C r e e k , P u l l e m C r e e k and Red P i n e Canyon u s e e x a m p l e s of s t r i k e v a l l e y s common to t h e a r e a. P r o m i n e n t c l i f f s a r e p r e s e n t i n Red P i n e C r e e k, B e a r T r a p H o l l o w and S o u t h F o r k B a s i n . The P i n e V a l l ey q u a r t z i t e of S o u t h F o r k B a s i n f o r m s n e a r l y v e r t i c a l c l i f fs a p p r o x i m a t e l y 300 f e e t h i g h , w h i c h a r e r e f e r r e d t o i n t h is p a p e r a s t h e West W a l l c l i f f s. I n c i p i e n t k a r s t t o p o g r a p h y i s p r e s e n t i n t h e u p p er member of t h e B r a z e r f o r m a t i o n and i s e s p e c i a l l y n o t e d on Mud L a k e F l a t s , w h e r e many s i n k h o l e s a p p e a r I n t h e l i m e s t o ne P l a t e I I , 1 0 ). B r a d l e y ( 1 9 3 ^ - 3 5 ) n a s d e s c r i b e d an e r o s i o n a l s u r f a ce o f O l i g o c e n e M i o c e n e p r e s e n t t h r o u g h o u t t he 46 area and its course is mainly controlled by the North Flank Fault above the confluence of Frazier Hollow; below Frazier Hollow the upper Weber River follows the strike of the softer, more easily weathered Triassic and Lower Jurassic red beds. The dominant landforms are hogbacks, strike valleys, cliffs and a remnant of an old age erosion surface. Resistant ridges between the strike valleys are generally synnnetrical and form hogbacks. The Madison, Thaynes and Twin Creek limestones are characteristically hogback formers. Strike valleys are confined to the softer shale, silt and sand formations. Lower South Fork, Noblett Creek, Pullem Creek and Red Pine Canyon use examples of strike valleys common to the area. Prominent cliffs are present in Red Pine Creek, Bear Trap Hollow and South Fork Basin. The Pine Valley quartzite of South Fork Basin forms nearly vertical cliffs approximately 300 feet high, which are referred to in this paper as the West Wall cliffs. Incipient karst topography is present in the upper member of the Brazer formation and is especially noted on trud Lake Flats, where many sink holes appear in the limestone ( Plate II, No. 10). Bradley (1934-35) has described an erosional surface of Oligocene and Miocene age present throughout much of the U i n t a M o u n t a i n s e a s t t h i s a r e a , t o w h i c h a p p l i e d t he G i l b e r t P e a k S u r f a c e . s t