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Show - 8 7 - U n i t Description Feet 30 Sandstone, l i g h t b r o w n ; f i n e - g r a i n e d ; 156 m e d i u m - t o t h i c k - b e d d e d ; i n t e r b e d d e d l i m e s t o n e , medium g r a y ; s a n d s t o n e 75% > l i m e s t o n e 2 5 $ ; f o r m s s m a l l l e d g e s and s l o p e. 29 Sandstone, l i g h t brown t o l i g h t g r a y ; 23 w e a t h e r s l i g h t brown and l i g h t g r a y ; f i n e g r a i n e d ; honeycomb w e a t h e r i n g common; much c r o s s - b e d d i n g ; forms l e d g e s. 28 Limestone, g r a y ; f i n e l y - c r y s t a l l i n e ; t h i n - 18 b e d d e d . 27 Sandstone, l i g h t b r o w n ; w e a t h e r s l i g h t b r o w n ; 45 t h i n - t o t h i c k - b e d d e d ; some h o n e y c o m b w e a t h e r i n g and c r o s s - b e d d i n g ; forms l e d g e s. 26 Sandstone, l i g h t brown t o c r e a m w i t h some 189 t h i n , m a r o o n b e d s ; f i n e - g r a i n e d ; medium-t o t h i c k - b e d d e d. 25 Limestone, medium g r a y and l i g h t b r o w n ; 25 w e a t h e r s l i g h t g r a y and t a n ; f i n e l y s a n d y; m e d i u m - t o t h i c k - b e d d e d. 24 Q u a r t z i t e , l i g h t b r o w n ; f i n e - g r a i n e d w i t h 29 some g r a y , l i m e s t o n e i n t e r b e d s. 23 Limestone, medium g r a y ; f i n e l y c r y s t a l l i n e ; 128 f i n e l y s a n d y ; m e d l u m - t o t h i c k - b e d d e d; c a l c i t e n o d u l e s ; forms a s l o p e. 22 Sandstone, l i g h t b r o w n , some m a r o o n ; f i n e - 38 g r a i n e d ; c a l c a r e o u s ; forms l e d g e s. 2 1 Limestone, medium g r a y ; w e a t h e r s l i g h t g r a y ; 11 f i n e l y c r y s t a l l i n e ; m e d i u m - b e d d e d ; forms a s l o p e . 20 Q u a r t z i t e , l i g h t brown and g r a y ; w e a t h e r s 173 l i g h t b r o w n ; c a l c a r e o u s ; f i n e - g r a i n e d; o c c a s i o n a l t h i n , s a n d y , g r a y l i m e s t o n e; p a r t l y c o v e r e d. 19 Limestone, medium g r a y ; w e a t h e r s l i g h t g r a y ; 45 f i n e l y c r y s t a l l i n e ; m e d i u m - t o t h i c k - b e d d e d; c h e r t n o d u l e s , c a l c i t e n o d u l e s. - 8 8 - U n l t Description Feet 18 Sandstone, l i g h t b r o w n ; w e a t h e r s l i g h t 138 b r o w n and l i g h t y e l l o w - b r o w n ; d e s e rt v a r n i s h ; f i n e - g r a i n e d ; c a l c a r e o u s ; t h i n - t o m e d i u m - b e d d e d ; o c c a s i o n a l brown and l i g h t b r o w n , b e d d e d c h e r t ; w e a t h e r s w i th a m a r o o n s u r f a c e. 17 Dolostone and s a n d s t o n e ; d o l o s t o n e i s l i g h t 51 g r a y - b r o w n ; f i n e l y c r y s t a l l i n e ; w e a t h e rs t a n and b r o w n . S a n d s t o n e i s l i g h t b r o w n; f i n e - g r a i n e d . 16 Limestone, medium g r a y ; w e a t h e r s medium 4 g r a y ; m e d i u m - c r y s t a l l i n e ; t h i c k - b e d d e d; f o r m s a l e d g e. 15 Dolostone, l i g h t g r a y - b r o w n ; f i n e l y c r y s - 47 t a l l i n e ; w e a t h e r s l i g h t brown and b r o w n; m e d i u m - b e d d e d ; s t e p - l i k e s l o p e. 14 Sandstone, medium g r a y ; m e d i u m - g r a i n e d ; 6 r o u n d e d g r a i n s ; s l i g h t l y c a l c a r e o u s; t h i c k - b e d d e d ; l e d g e* 13 Sandstone, p a l e m a r o o n and l i g h t b r o w n ; 407 f i n e - g r a i n e d ; t h i n - b e d d e d ; p l a t y w e a t h e r i n g ; m a r o o n and l i g h t brown " r i n g s t r u c t u r e" o n e x p o s e d b e d d i n g s u r f a c e s ; d e n d r i t es common; m a r o o n and l i g h t brown c h e r t. 12 Sandstone, l i g h t b r o w n ; f i n e - g r a i n e d ; i n t e r - 235 l a y e r e d l i m e s t o n e , y e l l o w i s h b r o w n; d e t r i t a l ; s a n d s t o n e 50% - l i m e s t o n e 50%. 1 1 Limestone, l i g h t b r o w n ; medium brown and 70 y e l l o w b r o w n ; w e a t h e r s l i g h t brown and m a r o o n ; t h i n - t o m e d i u m - b e d d e d ; some t h in b e d s of f i n e - g r a i n e d , l i g h t brown s a n d s t o n e ; m o s t l y c o v e r e d s l o p e. 10 Sandstone, l i g h t b r o w n ; f i n e - g r a i n e d ; t h i n - 131 t o m e d i u m - b e d d e d ; i n t e r b e d d e d w i t h s a n d s t o n e , g r a y ; f i n e g r a i n e d ; m e d i u m - b e d d e d. O c c a s i o n a l bed of g r a y d o l o s t o n e 2-3 f e et t h i c k i n u p p e r 20 t o 30 f e e t ; forms s l o p e. D e s c r i p t i o n Pe S a n d s t o n e , l i g h t b r o w n ; w e a t h e r s l i g h t 1 b r o w n and c r e a m ; d e s e r t v a r n i s h ; h o n e y comb w e a t h e r i n g ; f i n e - g r a i n e d ; medium-t o t h i c k - b e d d e d ; forms l e d g e s. S a n d s t o n e , g r a y ; f i n e - g r a i n e d ; s l i g h t ly c a l c a r e o u s ; c a p p e d w i t h 6 - f o o t d o l o s t o ne l e d g e ; c h e r t, D o l o s t o n e , medium g r a y and l i g h t b r o w n; a r g i l l a c e o u s ; w e a t h e r s t a n ; m e d i u m - b e d d e d. S a n d s t o n e , l i g h t g r a y - b r o w n ; w e a t h e r s g r a y 1 a n d l i g h t b r o w n ; f i n e - g r a i n e d ; g r a y c h e rt n o d u l e s ; m e d i u m - b e d d e d ; few t h i n l i m e s t o ne l a y e r s ; f o r m s a s l o p e. S a n d s t o n e and l i m e s t o n e , s a n d s t o n e , t a n ; 1 w e a t h e r s l i g h t brown t o b r o w n , f i n e - g r a i n ed a n d s l i g h t l y f r i a b l e . L i m e s t o n e , medium g r a y ; some i s b i o c l a s t i c ; g r a y , l i g ht b r o w n , and o r a n g e c h e r t ; i n d i v i d u a l s a n d s t o n e and l i m e s t o n e u n i t s 6 t o 8 f e e t t h i c k. A c o n g l o m e r a t e bed i n t h e u p p e r 30 t o 40 f e et h a s l i m e s t o n e and s a n d s t o n e c o b b l e s 6 t o 8 i n c h e s i n d i a m e t e r , most a r e 1 t o 3 i n c h e s . L i m e s t o n e , medium g r a y ; w e a t h e r s medium g r a y; s a n d y , g r a y c h e r t. S a n d s t o n e , l i g h t b r o w n - g r a y ; w e a t h e r s y e l l o w, l i g h t b r o w n , b r o w n ; some l a y e r s q u a r t z i t i c; c o n c h o i d a l f r a c t u r e , f l a t t e n e d , g r a y and l i g h t brown c h e r t n o d u l e s. S a n d s t o n e , medium g r a y ; w e a t h e r s medium g r a y; t h i c k - b e d d e d ; m e d i u m - g r a i n e d ; some g r a i ns h i g h l y r o u n d e d and f r o s t e d , c a l c a r e o u s; n u m e r o u s c a v i t i e s f i l l e d w i t h w h i t e c h e r t. Top of O q u i r r h F o r m a t i on S a n d s t o n e , b r o w n - g r a y ; w e a t h e r s l i g h t b r o w n , 2 g r a y y e l l o w ; f i n e - g r a i n e d ; c a l c a r e o u s ; t h i n - t o m e d i u m - b e d d e d ; q u a r t z i t i c i n some l a y e r s. T o t a l t h i c k n e s s of unnamed f o r m a t i on - 9 0 - Age and C o r r e l a t i on The u p p e r m o s t b e d s of t h e O q u i r r h F o r m a t i o n i n t he C e d a r M o u n t a i n s a r e d a t e d a s L e o n a r d ( ? ) , on t h e b a s i s of f u s u l i n i d s . F o s s i l c o l l e c t i o n s made by t h e w r i t e r have n o t y i e l d e d e v i d e n c e f o r s p e c i f i c d a t i n g of t h e G r a n d e ur Member of t h e P a r k C i t y F o r m a t i o n b u t i t i s c o n s i d e r e d to b e of L e o n a r d a g e a t most l o c a l i t i e s ( D u n b a r e t a l , I 9 6 0 ). T h e " P e r m i a n unnamed f o r m a t i o n " i s p r o b a b l y L e o n a r d i a n s i n ce t h e r e i s e v i d e n c e t h a t t h e b e d s a b o v e and b e l o w i t i n t he C e d a r M o u t a i n s a r e p r o b a b l y L e o n a r d i a n . No s i g n i f i c a nt f o s s i l c o l l e c t i o n s w e r e o b t a i n e d from t h e " u n n a m e d f o r m a t i o n" i n t h e C e d a r M o u n t a i n s . While i n v e r t e b r a t e s , e s p e c i a l ly b r a c h i o p o d s , a r e n u m e r o u s i n s e v e r a l of t h e l i m e s t o n e and d o l o s t o n e l a y e r s t h e y do n o t w e a t h e r o u t r e a d i l y and a re v e r y d i f f i c u l t t o s e p a r a t e from t h e m a t r i x. T h e " P e r m i a n unnamed f o r m a t i o n " o f t h e C e d a r M o u n t a i ns i s c o r r e l a t e d w i t h t h e " u n n a m e d f o r m a t i o n " o f l i k e age in t h e G r a s s y M o u n t a i n s ( D o e l l i n g , 1 9 6 4 ) . Both of t h e s e u n i ts o c c u p y t h e same s t r a t i g r a p h i c p o s i t i o n and a r e of s i m i l ar l i t h o l o g i e s o A c o n c e n t r a t i o n of c h e r t n o t e d by t h e w r i t er a t t h e b a s e of t h e unnamed u n i t i n t h e C e d a r M o u n t a i n s and a l s o by D o e l l i n g ( 1 9 6 4 , p . 227) I n t h e G r a s s y M o u n t a i n s may b e s i g n i f i c a n t f o r c o r r e l a t i o n . There i s n o t as g r e a t a c o n c e n t r a t i o n of c h e r t i n t h e b a s a l b e d s of t h e ? T u n n a m e d f o r m a - - 9 1 - t i o n " i n t h e C e d a r M o u n t a i n s as i n t h e G r a s s y M o u n t a i n s where D o e l l i n g ( 1 9 6 4 , p . 227) d e s c r i b e d b e d d e d m a s s e s . A c o a r se c o n g l o m e r a t e i n t h i s s e q u e n c e i n t h e C e d a r M o u n t a i n s s u g g e s t s a t i m e l a p s e b e t w e e n t h e C q u i r r h F o r m a t i o n and t he o v e r l y i n g " u n n a m e d f o r m a t i o n ." C o r r e l a t i o n i s a l s o made w i t h t h e A r c t u r u s F o r m a t i on i n t h e C o n f u s i o n Range (Hose a n d R e p e n n i n g , 1 9 5 9 ) . S i m i l a r i t y of c o l o r , g r a i n s i z e , c e m e n t i n g m a t e r i a l and i n d u r a t i on a s w e l l a s t h e r a t i o of c a r b o n a t e t o s a n d s t o n e s t r a t a a re b a s i s f o r c o r r e l a t i o n i n a d d i t i o n t o s i m i l a r s t r a t i g r a p h ic p o s i t i o n . The P e r m i a n unnamed u n i t i s c o r r e l a t e d a l s o w i th p a r t or a l l of t h e Diamond C r e e k - L o r a y ? i n t e r v a l of S t i f el ( 1 9 6 4 ) i n t h e T e r r a c e M o u n t a i n s . It r e s e m b l e s L o r a y ? more c l o s e l y t h a n t h e Diamond C r e e k. The m e d i u m - s i z e d , r o u n d e d , and f r e q u e n t l y f r o s t e d q u a r tz g r a i n s w h i c h a p p e a r f i r s t i n b e d s a b o v e t h e O q u i r r h F o r m a t i on may p r o v e i m p o r t a n t f o r c o r r e l a t i o n . They a l s o i m p l y t he a p p e a r a n c e of a new e r o s i o n a l s o u r c e m a t e r i a l i n t h e p a l e o g e - o g r a p h i c s e t t i n g . In a d d i t i o n t o m e n t i o n i n t h e p r e s e nt s t u d y , t h e s e d i s t i n c t i v e c l a s t s h a v e b e e n d e s c r i b e d by Hose a n d R e p e n n i n g ( 1 9 5 9 , p . 2175) and S t i f e l ( 1 9 6 4 , p 0 5 1 ). The P e r m i a n unnamed f o r m a t i o n may be e q u i v a l e n t t o t he Diamond C r e e k i n t h e s o u t h e r n W a s a t c h M o u n t a i n s ( B a k e r, 1 9 4 7 ) . - 9 2 P a r k C i t y , P h o s p h o r i a , and G e r s t e r F o r m a t i o ns I n t r o d u c t i o n P e r m i a n s t r a t a y o u n g e r t h a n t h e " P e r m i a n unnamed format i o n " i n t h e C e d a r M o u n t a i n s c o m p r i s e p a r t s of t h r e e f o r m a t i o n s ; t h e P a r k C i t y , t h e P h o s p h o r i a , and t h e G e r s t e r . The w r i t e r h a s u s e d , as f a r as p o s s i b l e , t h e s y s t e m of nomenc l a t u r e p r o p o s e d by McKelvey (McKelvey e t a l , 1956) i n t he d e s c r i p t i o n of c e r t a i n s t r a t a w h o l l y o r p a r t l y e q u i v a l e nt t o t h e P h o s p h o r i a F o r m a t i o n . This s y s t e m r e c o g n i z e s t h r ee f o r m a t i o n s f o r t h e a s s o c i a t i o n of t h e s t r a t a w h i c h h a ve b e e n p r e v i o u s l y r e f e r r e d t o a s t h e P a r k C i t y - P h o s p h o r ia Complex ( D u n b a r and o t h e r s , I 9 6 0 , p . 1 7 7 4 ) . Park C i ty F o r m a t i o n r e f e r s t o t h e s e q u e n c e of c a r b o n a t e r o c k and s a nd s t o n e w h i c h i s t y p i c a l of t h e c o m p l e x i n n o r t h - c e n t r a l Utah P h o s p h o r i a F o r m a t i o n r e f e r s t o t h e c h e r t , m u d s t o n e , p h o s p h o r i t e a s s o c a t i o n i n s o u t h e a s t e r n I d a h o w h e r e i t was f i r s t named by R i c h a r d s and M a n s f i e l d ( 1 9 1 2 , p 0 6 8 4 ). M c K e l v e y and o t h e r s i n t r o d u c e d a new n a m e , S h e d h o r n S a n d s t o n e , f o r t h e s a n d s t o n e s of P h o s p h o r i a age i n n o r t h w e s t e rn Wyoming and a d j a c e n t p a r t s of M o n t a n a . A member of one f o r m a t i o n may o c c u r a t one l o c a l i t y w i t h a member of a n o t h e r f o r m a t i o n . For e x a m p l e , t h e Meade P e a k Member of t h e P h o s p h o r i a F o r m a t i o n o c c u r s i n t h e C e d a r M o u n t a i n s w i th t h e G r a n d e u r Member of t h e P a r k C i t y F o r m a t i o n, - 9 3 - P a r k C i t y F o r m a t i on G r a n d e u r Member D i s t r i b u t i o n and T h i c k n e ss The G r a n d e u r Member f o r m s a s t r i p of o u t c r o p b e t w e en t h e U. S. C o a s t and G e o d e t i c S u r v e y C e d a r t r i a n g u i a t i on s t a t i o n , and H a s t i n g s P a s s , a n o r t h - s o u t h d i s t a n c e of a b o ut e l e v e n m i l e s . Over m o s t of t h i s d i s t a n c e , i t i s t h e most p r o m i n e n t r o c k u n i t of an e a s t - f a c i n g e s c a r p m e n t . The e s c a r p m e n t h a s t h e g r e a t e s t r e l i e f ( 6 0 0 ' - 8 0 0 ' ) n e a r i ts s o u t h e r n l i m i t o p p o s i t e S u l p h u r S p r i n g . S e v e r a l p o i n ts a l o n g t h e m o u n t a i n c r e s t i n t h i s a r e a r i s e s l i g h t l y a b o ve 7 , 6 0 0 f e e t and a r e t h e h i g h e s t s u m m i t s i n t h e C e d a r M o u n t a i n s . The o u t c r o p a r e a of t h e G r a n d e u r Member b r o a d e n s to t h e n o r t h w h e r e i t i s t h e s u r f a c e f o r m a t i o n on e i t h e r s i de o f t h e a x i a l t r a c e of t h e C e d a r A n t i c l i n e . I n l i e r s of " P e r m i a n unnamed f o r m a t i o n " a r e e x p o s e d i n t h i s a r e a w h e re e r o s i o n h a s r e m o v e d t h e G r a n d e u r . A m e a s u r e d s e c t i o n in t h e c l i f f s w e s t of S u l p h u r S p r i n g showed t h e u n i t t o be 419 f e e t t h i c k . The t h i c k n e s s d o e s n o t a p p e a r t o v a r y s i g n i f i c a n t l y o v e r i t s e x t e n t i n t h e c e n t r a l and n o r t h e r n C e d ar M o u n t a i n s . There a r e a l s o s e v e r a l s m a l l o u t c r o p s of t he G r a n d e u r Member a l o n g t h e w e s t e r n b a s e of Lone M o u n t a in a b o u t s i x m i l e s w e s t of t h e n o r t h e r n C e d a r M o u n t a i n s. - 9 4 - L i t h o l o g y L i m e s t o n e , d o l o m i t i c l i m e s t o n e , and d o l o s t o n e a r e t he p r i n c i p a l r o c k c o n s t i t u e n t s of t h e G r a n d e u r Member* Chert i s v e r y a b u n d a n t i n many h o r i z o n s and i t i s p r e s e n t i n m i n or p r o p o r t i o n s i n a l m o s t a l l t h e o t h e r u n i t s . Much of t he c h e r t i s l i g h t brown and s h a d e s of g r a y b u t t h e r e a r e a l so l i g h t e r c o l o r s . Pink and c r e a m c o l o r s a r e e s p e c i a l ly n o t i c e a b l e i n t h e u p p e r l a y e r s of t h e G r a n d e u r Member„ The m o s t common t e x t u r e s a r e f i n e l y c r y s t a l l i n e and b i o c l a s t i c . Where t h e G r a n d e u r Member h a s e r o d e d t o form s t e e p e s c a r p m e n t s , i t p r e s e n t s two m a s s i v e c l i f f s s e p a r a t e d by a r e l a t i v e l y t h i n , s l o p e - f o r m i n g u n i t composed of d o l o s t o n e and c h e r t ( P i g . 1 1 ). The l o w e r c o n t a c t of t h e G r a n d e u r i s w e l l e x p o s ed w h e r e t h e member f o r m s s t e e p c l i f f s west of S u l p h u r S p r i ng a n d was c h o s e n a t t h e b a s e of a m e d i u m - g r a y , b i o c l a s t ic l i m e s t o n e c o n t a i n i n g g r a y and l i g h t brown c h e r t . The c o n t a c t i s c o n f o r m a b l e . The u p p e r c o n t a c t i s g r a d a t i o n a l i n to t h e Meade P e a k Member of t h e P h o s p h o r i a F o r m a t i o n and was s e l e c t e d w h e r e t h e l i m e s t o n e b e d s became t h i n - t o medium-b e d d e d a b o u t 20 f e e t b e l o w t h e p h o s p h a t i c s h a l e , c h e r t - c a r b o n a t e b e d s of t h e Meade P e a k Member. Age and C o r r e l a t i on The G r a n d e u r Member was named by Cheney ( i n McKelvey - 9 5 - F i g . 11 - P h o t o g r a p h s h o w i n g t h e " P e r m i a n unnamed f o r m a t i o n " a n d t h e G r a n d e u r Member of t he P a r k C i t y F o r m a t i o n . Note t he p r o m i n e n t d o u b l e c l i f f d e v e l o p e d on t he G r a n d e u r Member. View i s t o w a r d t he n o r t h . - 9 6 - a n d o t h e r s , 1 9 5 9 , p . 12) f o r t h e e x p o s u r e a b o u t one m i le s o u t h w e s t of G r a n d e u r P e a k i n t h e c e n t r a l W a s a t c h M o u n t a i n s. W i l l i a m s ( i n McKelvey and o t h e r s , 1 9 5 9 , p . 36) s t a t e d t h at t h e a g e of t h e G r a n d e u r i s i n f e r r e d t o be L e o n a r d i a n , b a s ed o n a f a u n a c o l l e c t e d f o r t y - t w o m i l e s from t h e t y p e l o c a l i t y. Y o c h e l s o n ( 1 9 6 8 , p . 624) h a s r e p o r t e d t h a t t h e f a u n a r e f e r r e d t o by W i l l i a m s w h i c h c o n t a i n s i n p a r t i c u l a r S q u a m a r la i v e s i h a s b e e n f o u n d a t t h e t y p e l o c a l i t y and e l s e w h e r e in t h e v i c i n i t y of S a l t Lake C i t y , U t a h . Dunbar ( D u n b a r and o t h e r s , I 9 6 0 ) a l s o i n d i c a t e d a L e o n a r d i a n age f o r t he G r a n d e u r Member and r e p o r t e d t h a t i t i s c o r r e l a t i v e w i t h t he K a i b a b L i m e s t o n e . S t o k e s ( p e r s o n a l c o m m u n i c a t i o n ) s t u d i ed a n d i d e n t i f i e d f o s s i l s of t h e f o l l o w i n g c o l l e c t i o n s from t he G r a n d e u r Member made by t h e w r i t e r . He n o t e d t h e f a u n al s i m i l a r i t y t o t h a t of t h e K a i b a b L i m e s t o n e: F 2 4 5 P e n l c u l a r i s s p. S t o k e s r e m a r k e d , "More l i k e K a i b a b ." F 2 5 2 Composita p a r va C h o n e t e s p h o s p h o r ! e n s is D e r b y i a s p. F 3 5 6 Rugata p a r a i n d i s c us b r a c h i o p o d u n i d e n t i f i ed S t o k e s r e m a r k e d , "More l i k e K a i b a b ." F 4 3 3 O r b i c u l o i d e a s p. C o m p o s i t a p a r va B a t h y m o n i a n e v a d e n s i s (?) - 9 7 - S i m i l a r l i t h o l o g y , t h i c k n e s s and s t r a t i g r a p h i c p o s i t i on j u s t i f y c o r r e l a t i o n of t h e G r a n d e u r Member of t h e C e d ar M o u n t a i n s w i t h t h e K a i b a b L i m e s t o n e of t h e C o n f u s i o n Range. A l t h o u g h t h e r e i s a r a t h e r r e m a r k a b l e i n c r e a s e i n t h i c k n e ss n o r t h w a r d t o t h e T e r r a c e M o u n t a i n s , 1 , 1 9 0 f e e t ( S t i f e l, 1 9 6 4 , p . 55) and t h e G r a s s y M o u n t a i n s w h e r e a s i m i l a r t h i c k n e s s i s e s t i m a t e d by D o e l l i n g ( 1 9 6 4 , p„ 2 3 0 ) , t h e G r a n d e ur Member of t h e C e d a r M o u n t a i n s i s c o r r e l a t e d w i t h p a r t or a ll o f t h e G r a n d e u r a t e a c h of t h e s e l o c a l i t i e s . B e c a u s e of t he s i m i l a r i t y of t h e s t r a t i g r a p h i c s e q u e n c e as w e l l as s i m i l a r i t y of l i t h o l o g y and t h i c k n e s s , c o r r e l a t i o n i s a l s o made w i t h t h e G r a n d e u r Member of t h e P a r k C i t y F o r m a t i o n a t i ts t y p e l o c a l i t y i n t h e c e n t r a l W a s a t c h M o u n t a i n s. P h o s p h o r i a F o r m a t i on Meade P e a k Member D i s t r i b u t i o n and T h i c k n e ss O u t c r o p s of t h e Meade P e a k Member a r e q u i t e c l o s e ly a s s o c i a t e d w i t h e x p o s u r e s of t h e G r a n d e u r Member of t h e P a rk C i t y F o r m a t i o n and a r e w h o l l y c o n f i n e d t o t h e a r e a b e t w e en t h e U. S. C o a s t and G e o d e t i c S u r v e y C e d a r T r i a n g u l a t i on S t a t i o n and H a s t i n g s C a n y o n . The e a s i l y e r o d e d s e d i m e n t a ry b e d s of t h e Meade P e a k Member f o rm a s l o p e b e t w e e n t he m a s s i v e c l i f f s of t h e G r a n d e u r and t h e l e d g e - f o r m i ng - 9 8 m e m b e r s of t h e l o w e r G e r s t e r F o r m a t i o n . A s m a l l i s o l a t ed e x p o s u r e of b l a c k s h a l e s of t h e Meade P e a k Member o v e r l i es t h e G r a n d e u r i n SW 1/4 s e c . 2 2 , T1S, R10W. T h i c k n e s s of t h e Meade P e a k Member was m e a s u r e d i n t h e S 1/2 of s e c . 1 5 } T 3 S , R10W a n d d e t e r m i n e d t o be 141 f e e t. L i t h o l o g y The Meade P e a k Member i s composed of e a s i l y e r o d ed s t r a t a i n w h i c h t h e b e d s a r e n o t u s u a l l y more t h a n t h r e e or f o u r i n c h e s t h i c k . O u t c r o p s a r e m o s t l y c o v e r e d . The l o w e r 20 f e e t of t h e member i s s l a b b y - w e a t h e r i n g g r a y d o l o s t o n e and c h e r t g r a d i n g u p w a r d i n t o b l a c k , s h a l y , p h o s p h a t - i c r o c k w i t h i n t e r b e d d e d c h e r t and d o l o s t o n e . Black o o l i t i c , p h o s p h a t i c l a y e r s c o m p r i s e some of t h e s h a l e b e d s. L a y e r s r i c h i n b r a c h i o p o d s , v e r t e b r a t e t e e t h , and s k e l e t al f r a g m e n t s o c c u r a l s o i n t h e s h a l y b e d s . Channel s a m p l es o f m e a s u r e d i n t e r v a l s w e r e t a k e n f o r a p o r t i o n of t h e Meade P e a k Member i n NW 1 / 4 , s e c . 1 7 , T 3 S , R10W t o d e t e r m i n e t he c o n c e n t r a t i o n of ?2®5° A t a b u l a t i o n of t h e r e s u l t s f o l l o ws U n i t Thickness ( f e e t ) % ?2°5 9 6 0.14 8 3.5 0.11 7b 1.5 0.26 7 a 4.5 0.19 6 2.0 0.32 5 4.5 11.30 4 4.0 22.50 3 3.0? 0.64 2 3.0 4.00 1 2.0 25.52 A p p r o x i m a t e T o t a l 34\ 0 T h i c k n e s s At t h e o u t c r o p i t a p p e a r s t h a t a s m a l l r e v e r s e f a u l t r e p e a ts p a r t of t h e l o w e r s a m p l e d s e c t i o n so t h a t u n i t s 1 a n d 4, w h i c h show f a i r l y h i g h P 2 0 ^ c o n c e n t r a t i o n , a c t u a l l y r e p r e s e nt o n l y one b e d . A c h e m i c a l a n a l y s i s of an o o l i t i c , p h o s p h a t ic s a m p l e c o l l e c t e d from a b e d a b o u t one and o n e - h a l f f e et t h i c k n e a r t h e b a s e of t h e Meade P e a k Member a t a b o u t t he c e n t e r of N 1 / 2 , s e c . 3 , T 2 S , R10W i n d i c a t e d a P 2 ° 5 c o n t e nt o f 2 7 . 8 3 $. The b a s e of t h e Meade P e a k Member was c h o s e n w h e r e t he l i m e s t o n e and d o l o s t o n e b e d s a b o v e t h e G r a n d e u r became much t h i n n e r - b e d d e d and a d a r k e r g r a y c o l o r e These b e d s w e a t h er t o s l a b b y c o b b l e s c o m p a r e d w i t h t h e b l o c k y t a l u s w h i c h forms on o u t c r o p s of t h e u p p e r G r a n d e u r Member. The l o w e s t u n it o f t h e o v e r l y i n g G e r s t e r F o r m a t i o n i s a l e d g e - f o r m i n g b r o w n - g r a y d o l o s t o n e u n i t w h i c h c o n t r a s t s s h a r p l y w i t h t h e l i t h o l - o g y of t h e Meade P e a k Member. The c o n t a c t i s c o n f o r m a b l e. Age and C o r r e l a t i on M c K e l v e y ( 1 9 5 6 , p . 2845) named t h e p h o s p h a t i c s h a le member of t h e P h o s p h o r i a F o r m a t i o n f o r e x p o s u r e s n e a r Meade P e a k w h i c h i s a b o u t 2 1/2 m i l e s s o u t h of t h e t y p e l o c a l i ty o f t h e P h o s p h o r i a F o r m a t i o n a t P h o s p h o r i a G u l c h , B e a r Lake C o u n t y , I d a h o . S p e c i a l i s t s s t u d y i n g v a r i o u s f a u n a l e l e m e n ts o f t h e Meade P e a k Member c o n c l u d e d t h a t i t s age i s i n t he L e o n a r d - W o r d r a n g e . Y o c h e l s o n ( 1 9 6 8 , p . 622) r e p o r t s t h at - 1 0 0 - s t u d i e s of t h e c e p h a l o p o d s i n d i c a t e a L e o n a r d a g e , w h e r e as t h e b r a c h i o p o d s s u g g e s t c o r r e l a t i o n w i t h t h e Word F o r m a t i on o f West T e x a s . C e r t a i n o t h e r f o s s i l g r o u p s s u c h as p e l e - c y p o d s and f i s h f r a g m e n t s h a v e n o t y e t b e e n s t u d i e d in d e t a i l . One c o l l e c t i o n ( F 4 3 7 ) from an o o l i t i c p h o s p h o r i te b e d n e a r t h e b a s e of t h e Meade P e a k Member n e a r Q u i n cy S p r i n g was e x a m i n e d by S t o k e s ( p e r s o n a l c o m m u n i c a t i o n ) who i d e n t i f i e d H e l i c o p r i o n s p . The w r i t e r h a s a l s o n o t i c ed l i n g u l o i d b r a c h i o p o d m o l d s i n t h i s same h o r i z o n a t d i f f e r e nt l o c a t i o n s . Y o c h e l s o n ( 1 9 6 8 , p . 622) r e p o r t e d t h a t t h e Meade P e a k Member i n t e r t o n g u e s w i t h t h e l o w e r F r a n s o n Member of t h e P a r k C i t y F o r m a t i o n i n n o r t h e a s t e r n U t a h a n d a d j a c e nt a r e a s and t h a t t h e b a s a l Meade P e a k may a l s o be e q u i v a l e n t to t h e u p p e r m o s t p a r t of t h e G r a n d e u r Member. T h e r e f o r e t he Meade P e a k Member i n t h e C e d a r M o u n t a i n s i s c o r r e l a t e d w i th t h e Meade P e a k Member a n d p a r t of t h e o v e r l y i n g c a r b o n a te f o r m a t i o n of n e a r b y l o c a l i t i e s . Some p a r t i c u l a r a r e a s i n c l ud ed i n t h i s c o r r e l a t i o n a r e : the G r a s s y M o u n t a i n s , ( D o e l l i n g, 1 9 6 4 ) , t h e T e r r a c e M o u n t a i n s ( S t i f e l , 1 9 6 4 ) , t h e c e n t r al W a s a t c h M o u n t a i n s ( B a k e r and o t h e r s , 1 9 4 9 , p . 1 1 8 8 ) . The Meade P e a k Member i n t h e C e d a r M o u n t a i n s i s a l s o c o n s i d e r e d t b e c o r r e l a t i v e w i t h t h e P l y m p t o n F o r m a t i o n of t h e C o n f u s i on R a n g e . G e r s t e r F o r m a t i on - 1 0 1 - D i s t r i b u t i o n and T h i c k n e ss The G e r s t e r F o r m a t i o n h a s t h e same g e n e r a l o u t c r op p a t t e r n as t h e G r a n d e u r and Meade P e a k M e m b e r s , i n t h e c e n t r al C e d a r M o u n t a i n s b e t w e e n t h e l a t i t u d e of U. S. C o a s t and G e o d e t i c S u r v e y C e d a r T r i a n g u l a t i o n S t a t i o n and H a s t i n g Summit. The o u t c r o p a r e a of t h e G r a n d e u r and Meade P e a k Members t o g e t h e r w i t h t h e G e r s t e r F o r m a t i o n i s e s t i m a t e d as 26 s q u a r e m i l e s ( T a b l e 1 ) . E x p o s u r e s of t h e G e r s t e r F o r m a t i on a c c o u n t f o r most of t h i s a r e a . The G e r s t e r F o r m a t i o n forms t h e c a p r o c k of a h o m o c l i n e w h i c h i s a c t u a l l y t h e w e s t e r n, m o r e g e n t l y d i p p i n g l i m b of C e d a r A n t i c l i n e o v e r s e v e r al m i l e s of i t s o u t c r o p . The w i d t h of o u t c r o p n a r r o w s n e ar H a s t i n g s Summit a s t h e d i p s t e e p e n s t o as much a s 45 d e g r e e s. A s m a l l o u t c r o p of t h e G e r s t e r a l s o a p p e a r s on t h e e a s t e rn l i m b of C e d a r A n t i c l i n e i n t h i s a r e a . This o u t c r o p i s o v e r r i d d e n s o u t h w a r d by b e d s of t h e l o w e r O q u i r r h F o r m a t i on w h i c h h a v e b e e n r a i s e d a l o n g t h e r e v e r s e f a u l t b o r d e r i n g t he m o u n t a i n f r o n t. L i t h o l o g y The G e r s t e r F o r m a t i o n i s p r e d o m i n a n t l y l i m e s t o n e. The c o l o r v a r i e s t h r o u g h l i g h t e r s h a d e s of brown and g r a y, f r e q u e n t l y w i t h a p i n k i s h c a s t . The l a y e r s a r e medium and t h i n - b e d d e d , f r e q u e n t l y w e a t h e r i n g t o p a r t l y c o v e r e d , s l a b b y, - 1 0 2 - s t e e p , r o u g h s l o p e s . Gray, c r e a m , and p i n k c h e r t n o d u l e s a re common i n many of t h e u n i t s . S e v e r a l b e d s h a v e v u g s 2 t o 4 i n c h e s i n d i a m e t e r , p a r t l y t o c o m p l e t e l y f i l l e d w i t h c a l c i t e. A f ew b e d s a r e b i o c l a s t i c b u t most a r e c r y s t a l l i n e , r a n g i ng f r om f i n e - t o m e d i u m - g r a i n e d . Sand and s i l t a r e v e r y m i n or c o n s t i t u e n t s of t h e c a r b o n a t e b e d s i n t h i s f o r m a t i o n. S e v e r a l b e d s a r e h i g h l y f o s s i l i f e r o u s , w i t h b r a c h i o p o d s most commonly p r e s e r v e d , and w i t h p e l e c y p o d s and g a s t r o p o d s. S i n c e t h i s c a r b o n a t e s e q u e n c e l i e s a b o u t midway b e t w e e n i ts c o r r e l a t i v e s , t h e F r a n s o n Member of t h e P a r k C i t y F o r m a t i on i n t h e c e n t r a l W a s a t c h M o u n t a i n s , and t h e G e r s t e r F o r m a t i on i n t h e Deep C r e e k M o u n t a i n s , t h e r e h a s b e e n some q u e s t i o n as t o t h e n o m e n c l a t u r e w h i c h s h o u l d be a p p l i e d . This s e c t i o n, h o w e v e r , seems t o r e s e m b l e t h e G e r s t e r F o r m a t i o n l i t h o l o g - i c a l l y , as d e s c r i b e d i n t h e Gold H i l l Q u a d r a n g l e ( N o l a n, 1 9 3 5 , p . 39) and t h e C o n f u s i o n Range (Hose and R e p e n n i n g, 1 9 5 9 , p . 2184) much more c l o s e l y t h a n t h e F r a n s o n Member ( C h e n e y , 1 9 5 7 , p . 22) of t h e W a s a t c h M o u n t a i n s a r e a. Age and C o r r e l a t i on The G e r s t e r F o r m a t i o n was named by N o l a n ( 1 9 3 5 , p . 3 9) f o r e x p o s u r e s i n t h e Deep C r e e k M o u n t a i n s . He r e p o r t e d t h at t h e f o r m a t i o n c o n t a i n e d t h e S p i r i f e r i n a p u l c h r a f a u n a c h a r a c t e r i s t i c of t h e u p p e r c a r b o n a t e u n i t of t h e P a r k C i ty F o r m a t i o n i n c e n t r a l U t a h . D u n b a r , e t a l . ( I 9 6 0 ) i n d i c a t es - 1 0 3 - a G u a d a l u p i a n a g e f o r t h e G e r s t e r F o r m a t i o n . C o l l e c t i o ns made by t h e w r i t e r i n t h e C e d a r M o u n t a i n s s e r v e t o e s t a b l i sh t h e p r e s e n c e of t h e S p i r i f e r i n a p u l c h r a f a u n a and t o c o n f i rm a G u a d a l u p i a n age f o r t h e U n i t . I d e n t i f i c a t i o n s f o r t he c o l l e c t i o n s a r e a s f o l l o w s: F 2 3 7 Composita s p. S p i r i f e r i n a p u l c h ra F 3 3 9 Muirwoodia m u l t l s t r l a ta E c h i n a u r i s s u b h o r r l da F 2 4 0 L i n g u l o d l s c i n a s p. F 4 5 3 Muirwoodia m u l t l s t r l a ta B a t o s t o m e l l a s p. R h y n c o p o r a t a y l o ri F e n e s t e l l a s p. The a b o v e c o l l e c t i o n s w e r e i d e n t i f i e d by S t o k e s ( w r i t t en c o m m u n i c a t i o n ) . F 2 8 0 Muirwoodia ( ? ) s p. W e l l e r e l l a ( ? ) s p. S a d l i c k ( w r i t t e n c o m m u n i c a t i o n ) i d e n t i f i e d t h e a b o ve f o r m s and r e p o r t e d t h a t t h e y i n d i c a t e a G u a d a l u p i a n a g e. B e c a u s e of t h e i n t e r t o n g u i n g n a t u r e of t h e u p p e r c a r b o n a t e b e d s of t h e P a r k C i t y F o r m a t i o n , t h e w r i t e r c o n s i d e rs t h e G e r s t e r F o r m a t i o n e q u i v a l e n t t o f o r m a t i o n s i n s u r r o u n d i n g a r e a s w h i c h h a v e t h e S p i r i f e r i n a p u l c h r a fauna and a l so p r o b a b l y t o p o r t i o n s of t h e u n d e r l y i n g p h o s p h a t i c s h a l e b e d s. C o r r e l a t i o n s t o s p e c i f i c l o c a l i t i e s a r e : G e r s t e r and P l y m p - t o n F o r m a t i o n s of t h e C o n f u s i o n Range (Hose and R e p e n n i n g ,. 1 9 5 9 ) j G e r s t e r and Meade P e a k F o r m a t i o n of t h e G r a s sy - 1 0 4 - M o u n t a i n s ( D o e l l l n g , 1 9 6 4 ) , F r a n s o n Member of t h e P a r k C i ty F o r m a t i o n and t h e Meade P e a k Member of t h e P h o s p h o r i a F o r m a t i o n of t h e T e r r a c e M o u n t a i n s ( S t i f e l , 1 9 6 4 ) ; a l s o t he G e r s t e r F o r m a t i o n of t h e Gold H i l l Q u a d r a n g l e i n t h e Deep C r e e k M o u n t a i n s ( N o l a n , 1 9 3 5 ) , and t h e F r a n s o n and Meade P e a k Members of t h e P a r k C i t y and P h o s p h o r i a F o r m a t i o ns r e s p e c t i v e l y i n t h e W a s a t c h M o u n t a i n s a r e a ( M c K e l v e y , 1 9 5 6 ). M e a s u r e d S e c t i o n : So. 1 / 2 , s e c . 1 5 , T 3 S , R10W N o r t h Horn ( ? ) F o r m a t i on U n c o n f o r m i t y U n i t Description Feet 26 Limestone, l i g h t g r a y , w e a t h e r s l i g h t 3 g r a y , f i n e l y c r y s t a l l i n e , n u m e r o us p a t c h e s of c o a r s e l y c r y s t a l l i n e , w h i te c a l c i t e . 25 Limestone, g r a y and p i n k i s h g r a y , a p h a n - 27 i t i c t o v e r y f i n e l y c r y s t a l l i n e , t h i n - b e d d e d , f o r m s a s l o p e. 24 Limestone, g r a y t o l i g h t b r o w n , a p h a n - 11 i t i c t o v e r y f i n e l y c r y s t a l l i n e , t h i n - b e d d e d , many v u g s f i l l e d w i t h w h i t e c a l c i t e c r y s t a l s. 23 Dolostone, l i g h t g r a y , w e a t h e r s g r a y and 14 l i g h t b r o w n , a p h a n i t i c , t h i n - b e d d e d . , many w a l n u t - s i z e d c h e r t n o d u l e s. 22 Chert, l i g h t b r o w n , b e d d e d , w e a t h e r s 21 t o k n o b b y , brown s l o p e , s e v e r a l w h i te c a l c i t e s e a m s. 21 Limestone, l i g h t g r a y , f i n e l y c r y s t a l l i n e 35 t o a p h a n i t i c , much i n t e r l e n s e d g r a y c h e r t, t h i n - t o m e d i u m - b e d d e d , forms a s l o p e. - 1 0 5 - U n i t Description Feet 20 Limestone, g r a y w i t h p i n k i s h - b r o w n s p e c k s , 67 w e a t h e r s l i g h t g r a y , f i n e l y c r y s t a l l i n e, n u m e r o u s t h i n l a y e r s of f i n e f o s s i l d e b r is ( b r y o z o a , c r i n o i d s , b r a c h i o p o d s ) , makes a s e r i e s of 2-3 f o o t l e d g e s , c h e r t n o d u l es common i n some l a y e r s. 19 Limestone, l i g h t g r a y t o p i n k i s h - g r a y , v e r y 109 f i n e t o f i n e l y c r y s t a l l i n e , t h i n - b e d d e d, n u m e r o u s g r a y and p i n k c h e r t n o d u l e s, f o r m s a s l o p e. 18 Limestone, g r a y t o l i g h t b r o w n - g r a y , med- 4 i um c r y s t a l l i n e , l i g h t brown l a m i n a t i o n s, f o r m s a l e d g e. 17 Limestone, y e l l o w - b r o w n , w e a t h e r s t o 12 y e l l o w , s i l t y s u r f a c e , g r a y and w h i t e lami n a t e d c h e r t n o d u l e s , p l a t y f r a g m e n t s form s l o p e , b r a c h i o p o d f r a g m e n t s n u m e r o u s. 16 Limestone, l i g h t y e l l o w - b r o w n , p l a t y - w e a t h - 40 e r i n g , some f r a g m e n t s h a v e brown d e s e rt v a r n i s h . 15 Covered. 59 14 Dolostone, l i g h t y e l l o w - b r o w n , t h i n t o 20 m e d i u m - b e d d e d , o c c a s i o n a l c h e r t n o d u l e s, v u g s f i l l e d w i t h w h i t e c a l c i t e c r y s t a l s, F 4 2 9 n e a r t h e t o p. 13 Limestone, l i g h t p i n k - g r a y , f i n e l y c r y s t a l - 5 l i n e . 12 Dolostone, l i g h t b r o w n - g r a y , w e a t h e r s l i g h t 84 g r a y t o l i g h t b r o w n , f i n e l y c r y s t a l l i n e. Top of Meade Peak Member 1 1 Dolostone, c h e r t , p e l l e t a l and b l a c k s h a l y 121 p h o s p h a t i c r o c k ; b a s a l l a y e r i s t h i n - b e d d e d; p h o s p h a t i c r o c k l e s s t h a n 2 f e e t t h i c k ; much t a n and g r a y c h e r t w i t h t h i n - b e d d e d , d a rk g r a y d o l o s t o n e upward t o t h e m i d d l e of t h e u n i t. U p p e r h a l f p r e d o m i n a n t l y t h i n - b e d d e d d o l o s t o n e; s h a l y p h o s p h a t i c r o c k f l o a t i n u p p e r h a l f ; u n it i s a m o s t l y c o v e r e d s l o p e. - 1 0 6 - U n i t Description Feet 10 Dolostone and c h e r t , t h i n - t o m e d i u m - b e d d e d , 18 f o r m s c l i f f b e l o w p h o s p h a t i c b e d. 9 Limestone, g r a y , t h i n - b e d d e d . 2 Top of G r a n d e u r Member 8 Limestone, medium g r a y , w e a t h e r s medium 16 g r a y , m e d i u m - c r y s t a l l i n e , t h i n t o medium-b e d d e d , c h e r t y , s l o p e. 7 Limestone, medium g r a y , w e a t h e r s medium 6 g r a y , m e d i u m - c r y s t a l l i n e , m e d i u m - b e d d e d, f o r m s a c l i f f. 6 Limestone, l i g h t b r o w n - g r a y , f i n e l y c r y s t a l - 74 l i n e , s i l t y , g r a d e s i n t o s l i g h t l y - c a l c a r e o us s i l t s t o n e i n u p p e r h a l f , l i g h t b r o w n , w e a t h e rs t a n , c h e r t i n s t r i n g e r s and n o d u l e s. 5 Dolostone, l i g h t b r o w n - g r a y , w e a t h e r s l i g h t 142 g r a y , b i o c l a s t i c ( c r i n o i d , b r y o z o a n , b r a c h i o - p o d , p e l e c y p o d d e b r i s ) , m a t r i x f i n e t o medi u m - c r y s t a l l i n e , g r a y c h e r t w i t h t a n r i m s in s t r i n g e r s and n o d u l e s , forms a p r o m i n e n t c l i f f. 4 Dolostone and c h e r t , l i g h t g r a y i s h - b r o w n 55 d o l o s t o n e , w e a t h e r s medium g r a y , a p h a n i t ic t o v e r y - f i n e l y c r y s t a l l i n e , c h e r t - d o l o s t o ne r a t i o a p p r o x . 25%/75%3 forms s l o p e b e t w e en t w o l a r g e c l i f f s. 3 Limestone, d o l o m i t i c , l i g h t g r a y , w e a t h e r s 80 l i g h t g r a y , b i o c l a s t i c , m a t r i x i s f i n e ly c r y s t a l l i n e , q u i t e v u g g y , some v u g s p a r t ly f i l l e d w i t h c a l c i t e c r y s t a l s , f o r m s l o w e r, d i s t i n c t c l i f f. 2 Dolostone and d o l o m i t i c l i m e s t o n e w i t h 34 n u m e r o u s t a n c h e r t n o d u l e s. 1 Limestone, medium g r a y , w e a t h e r s l i g h t g r a y , 12 f i n e l y c r y s t a l l i n e , much b i o c l a s t i c m a t e r i a l, t h i c k - b e d d e d , g r a y and l i g h t brown c h e rt n o d u l e s i n l o w e r p a r t , l e d g e - f o r m e r. G r a n d e u r Member 419 - 1 0 7 - T e r t i a r y S y s t em N o r t h Horn ( ? ) F o r m a t i on D i s t r i b u t i o n and T h i c k n e ss O u t c r o p s of t h e N o r t h Horn ( ? ) F o r m a t i o n a r e c o n f i n ed t o t h e w e s t e r n f o o t h i l l s b e t w e e n H a s t i n g s Canyon and Q u i n cy S p r i n g . There a r e s e v e r a l s m a l l , p o o r l y e x p o s e d o u t c r o p s in v a l l e y b o t t o m s i n t h e n o r t h e r n p a r t of t h i s a r e a . A n a r r ow b a n d of N o r t h Horn ( ? ) F o r m a t i o n t r e n d s n o r t h f o r a b o u t two m i l e s a l o n g t h e b a s e of t h e u p t h r o w n b l o c k of t h e Cedar T h r u s t from t h e l a t i t u d e of Q u i n c y S p r i n g . C o n g l o m e r a t e and s a n d s t o n e b e d s a r e e x p o s e d a l o n g t h i s s c a r p . North Horn ( ?) F o r m a t i o n i s a l s o e x p o s e d a l o n g t h e b a s e of t h e k l i p p e j u st n o r t h of Q u i n c y S p r i n g. The t o t a l a r e a of N o r t h Horn ( ? ) o u t c r o p s i s a b o u t one s q u a r e m i l e . The t h i c k n e s s was n o t m e a s u r e d i n t h e f i e ld b e c a u s e of l a c k of good e x p o s u r e s . However, m a p p i n g i n t he v i c i n i t y of s e c t i o n 2 9 , T 2 S , T 2 S , R10W i n d i c a t e s t h a t s e v e r al h u n d r e d f e e t of t h e f o r m a t i o n a r e p r e s e n t. L i t h c l o g y and S t r a t i g r a p h i c R e l a t i o ns The N o r t h Horn ( ? ) F o r m a t i o n i s p r e d o m i n a n t l y v a r i o us s h a d e s of r e d , t h e c o l o r b e i n g c o n c e n t r a t e d i n t h e c e m e n t i ng m a t e r i a l . Gray, l i g h t b r o w n , d a r k b r o w n , and o l i v e g r e en l a y e r s a r e a l s o r a t h e r common. B e d d i n g r a n g e s from t h i n to m a s s i v e w i t h t h i c k e r t y p e s most common. It i s a l m o s t t o t a l ly - 1 0 8 - a c l a s t i c or c o n g l o m e r a t e u n i t w i t h s i z e r a n g e from c l a y to b o u l d e r s 18" i n d i a m e t e r . The c l a s t s a r e l o c a l l y d e r i v ed a n d c o m p r i s e s a n d s t o n e , l i m e s t o n e and c h e r t w h i c h r e s e m b le l i t h o l o g i e s of P a l e o z o i c b e d s of t h e Upper O q u i r r h and o v e r l y i n g f o r m a t i o n s . T h e i r a n g u l a r i t y s u g g e s t s a s h o r t d i s t a n c e of t r a n s p o r t a t i o n . P e b b l e c o n g l o m e r a t e , s a n d s t o n e, s i l t s t o n e , and m u d s t o n e p r e d o m i n a t e i n t h e s o u t h e r n e x p o s u r e s n e a r Q u i n c y S p r i n g w h i l e c o a r s e c o n g l o m e r a t e a re a b u n d a n t i n t h e m i d d l e and n o r t h e r n r e g i o n of t h e N o r t h Horn ( ? ) e x p o s u r e s. T h e c o n t a c t r e l a t i o n s h i p of N o r t h Horn ( ? ) and t he u n d e r l y i n g G e r s t e r F o r m a t i o n i s one of a n g u l a r u n c o n f o r m i t y. A d i v e r g e n c e i n d i p of 25 t o 30 d e g r e e s i s i n d i c a t e d i n t he West H a s t i n g s Canyon a r e a b u t d e c r e a s e s s o u t h w a r d . T h i c k n e s s of t h e G e r s t e r F o r m a t i o n b e t w e e n N o r t h Horn ( ? ) and t h e Meade P e a k Member d e c r e a s e s from a r o u n d 500 f e e t i n t he n o r t h e r n e x p o s u r e s t o z e r o n e a r Q u i n c y S p r i n g. T h e N o r t h Horn ( ? ) i s o v e r l a i n i n most p l a c e s by Q u a t e r n a r y s a n d s and g r a v e l . The u p p e r b o u n d a r y i n t he e x t r e m e n o r t h e r n and s o u t h e r n o u t c r o p a r e a s i s a t h r u s t f a u lt c o n t a c t w h e r e s u p e r j a c e n t b e d s a r e l a t e P a l e o z o i c f o r m a t i o n s. Age a n d C o r r e l a t i on Two f o s s i l c o l l e c t i o n s ( 3 6 1 , F 4 4 3 ) w e r e made f r om t he l o w e r 100 t o 150 f e e t of t h e N o r t h Horn ( ? ) F o r m a t i o n and - 1 0 9 - t h e s e , a l o n g w i t h F635 w h i c h was c o l l e c t e d from t h e 1 f T e r t i a ry u n n a m e d f o r m a t i o n , " w e r e e x a m i n e d by L a R o c q u e ( w r i t t e n comm u n i c a t i o n ) . His i d e n t i f i c a t i o n of t h e f o s s i l forms and c o m m e n t s f o l l o w: F 3 6 l G y r a u l u s s p. F 4 4 3 G y r a u l u s s p. F 6 3 5 Physa c f . P. b r i d g e r e n s i s (Meek) V l v i p a r u s t r o c h i f o r m i s ("Meek and Hayden) S p h a e r i u m s p. " A l l of t h e s e r e p r e s e n t a l a c u s t r i n e , f r e s h w a t e r e n v i r o n m e n t . In a g e , t h e y a r e c e r t a i n l y C e n o z o i c , most p r o b a b l y l a t e P a l e o c e ne o r E o c e n e ." Red c l a s t i c u n i t s s i m i l a r t o t h e N o r t h Horn ( ? ) h a v e b e en r e c o g n i z e d a t v a r i o u s l o c a l i t i e s i n c e n t r a l and n o r t h w e s t e rn U t a h . These u n i t s o v e r l i e t h e y o u n g e s t P a l e o z o i c b e d s u n c on f o r m a b l y and u n d e r l i e t h e o l d e s t v o l c a n i c s . They o c c u p y a s t r a t i g r a p h i c p o s i t i o n s i m i l a r t o t h a t of t h e N o r t h Horn (?) F o r m a t i o n i n t h e C e d a r M o u n t a i n s . To t h e w r i t e r ' s knowl e d g e , no a g e s b a s e d on f o s s i l c o l l e c t i o n s from t h e s e u n i ts i n w e s t e r n U t a h h a v e b e e n r e p o r t e d i n t h e l i t e r a t u r e . Corr e l a t i o n of t h e N o r t h Horn ( ? ) F o r m a t i o n of t h e Cedar M o u n t a i n s i s t h u s made w i t h t h e f o l l o w i n g l o c a l i t i e s on t he b a s i s of s i m i l a r 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: S t a n s b u r y M o u n t a i n s , ( R i g b y , 1 9 5 7 , p . 5 2 ) ; Deep C r e e k Mount a i n s , ( N o l a n , 1 9 3 5 , p . 4 2 ) ; Goose C r e e k M o u n t a i n s , (Heylmun 1 9 6 5 , p . 1 0 ) ; S h e e p r o c k M o u n t a i n s , ( C o h e n o u r , 1 9 5 9 , p . 9 7 ); - 1 1 0 - E a s t T I n t i c M o u n t a i n s ( M o r r i s , 1 9 5 7 , p . 2 6 ) ; Long R i d ge ( M u e s s i g , 1 9 5 1 ) ; O q u i r r h M o u n t a i n s ( T o o k e r and R o b e r t s, 1 9 6 1 , p . 3 2 ). " T e r t i a r y Unnamed F o r m a t i o n" D i s t r i b u t i o n and T h i c k n e ss An unnamed e a r l y T e r t i a r y f o r m a t i o n o u t c r o p s i n a few s m a l l a r e a s on t h e e a s t s i d e of t h e C e d a r M o u n t a i n s b e t w e en H a s t i n g s Canyon and R e d l am S p r i n g . The t o t a l o u t c r o p a r ea i s a b o u t o n e - q u a r t e r s q u a r e m i l e . The l a r g e s t and b e st e x p o s u r e i s i n s e e s . 30, 3 1 , T 1 S , R9W i n H a s t i n g s Canyon w h e r e t h e "unnamed f o r m a t i o n " h a s b e e n p r o t e c t e d by a c a p p i n g of b a s a l t ( F i g . 1 2 ) . About t h r e e h u n d r e d f e e t of t he f o r m a t i o n a r e e x p o s e d . Two o t h e r s m a l l e x p o s u r e s a r e in d r y w a s h e s a s h o r t d i s t a n c e n o r t h e a s t of R e d l am S p r i n g . The t h i c k n e s s was n o t m e a s u r e d i n t h e f i e l d b u t c a l c u l a t i o ns u s i n g map i n f o r m a t i o n i n d i c a t e t h a t a maximum of t h r e e h u n d r ed f e e t of t h e " T e r t i a r y unnamed f o r m a t i o n " o u t c r o p i n t h e Ceda r M o u n t a i n s. L i t h o l o g y and S t r a t i g r a p h i c R e l a t i o ns The " T e r t i a r y unnamed f o r m a t i o n " i s c o m p o s e d m o s t l y of m e d i u m - t o t h i c k - b e d d e d s a n d s t o n e . O u t c r o p s a r e r o u n d e d and e v e n on f a i r l y s t e e p s l o p e s t e n d t o become c o v e r e d w i t h a t h i n l a y e r of w e a t h e r e d m a t e r i a l . Some of t h e u n i t s n e ar - 1 1 1 - F i g . 12 - P h o t o g r a p h s h o w i n g " T e r t i a r y unnamed f o r m a t i o n" i n e a s t H a s t i n g s Canyon o v e r l a i n by b a s a lt c a p r o c k . View i s w e s t w a r d, - 1 1 2 - R e d l am S p r i n g a r e t u f f a c e o u s . Clay i s t h e c h i e f c e m e n t i ng m a t e r i a l a t a l l e x p o s u r e s of s a n d s t o n e and t u f f e x a m i n e d. One l i g h t - g r a y f r e s h w a t e r l i m e s t o n e bed a b o u t a f o o t t h i ck was o b s e r v e d a t t h e t o p of t h e o u t c r o p i n H a s t i n g s C a n y o n. About e i g h t y t o n i n e t y p e r c e n t of t h e p a r t i c l e s of t h e "unnamed f o r m a t i o n " a r e s u b - r o u n d e d t o s u b - a n g u l ar q u a r t z g r a i n s . A f ew of t h e q u a r t z g r a i n s a r e n e a r l y s p h e r i c a l and f r o s t e d . C h e r t , s a n d s t o n e , and q u a r t z i t e c l a s ts f o rm a s m a l l f r a c t i o n of l a r g e r g r a i n s . All t h e s e c o n s t i t u e n t s of t h e n u n n a m e d f o r m a t i o n " r e s e m b l e v e r y c l o s e l y t he u p p e r O q u i r r h , " P e r m i a n unnamed f o r m a t i o n , " a n d t h e G r a n d e ur Member of t h e P a r k C i t y F o r m a t i o n and p r o b a b l y had t h e ir s o u r c e i n t h e s e f o r m a t i o n s . M a g n e t i t e g r a i n s compose two t o f o u r p e r c e n t of t h e s a n d s t o n e. T u f f a c e o u s s a n d s t o n e b e d s o c c u r i n t h e o u t c r o p s n e ar R e d l am S p r i n g . B l a d e d and b r a n c h i n g s h a r d s w h i c h r e t a i n a v i t r e o u s a p p e a r a n c e c o m p r i s e s l i g h t l y l e s s t h a n f i v e p e r c e nt o f t h e r o c k . L i g h t g r a y c l a y i n c l u s i o n s - o n e o r two m i l l i m e t e r s on t h e l o n g e s t a x i s a r e common and may r e p r e s e nt o r i g i n a l f e l d s p a r g r a i n s. T h i s f o r m a t i o n u n c o n f o r m a b l y o v e r l i e s s t r a t a of t he u p p e r O q u i r r h F o r m a t i o n i n H a s t i n g s C a n y o n . The c o n t a ct w i t h u n d e r l y i n g b e d s i s n o t e x p o s e d i n t h e o u t c r o p s n e ar R e d l am S p r i n g . A d i s c o n f o r m i t y s e p a r a t e s t h e T e r t i a r y u n - - 1 1 3 - named f o r m a t i o n from o v e r l y i n g b a s a l t i n H a s t i n g s Canyon. Age and C o r r e l a t i on Heylmun ( 1 9 6 5 ) r e v i e w e d t h e T e r t i a r y s e d i m e n t a r y r o c ks o f w e s t e r n U t a h and d i s c u s s e d t h e s e as r e l a t e d t o v a r i o us r o c k s e q u e n c e s a s f o l l o w s: L a t e P l i o c e n e - P l e i s t o c e n e S e q u e n ce M i d d l e V o l c a n i c S e q u e n ce L a t e M i o c e n e - E a r l y P l i o c e n e S e q u e n ce Lower V o l c a n i c S e q u e n ce Lower L a c u s t r i n e S e q u e n ce B a s a l C o n g l o m e r a t es Red b a s a l c o n g l o m e r a t e s h a v e b e e n d e s c r i b e d i n s e v e r al o f t h e G r e a t B a s i n r a n g e s as w e l l as i n t h e C e d a r M o u n t a i ns ( t h i s r e p o r t ) . Heylmun ( 1 9 6 5 , p . 10) s t a t e d t h a t v a r i o us w o r k e r s h a v e r e p o r t e d a g e s f o r t h e c o n g l o m e r a t e s r a n g i ng f r om L a t e C r e t a c e o u s t o P l i o c e n e . These s t r a t a a r e p r o b a b ly n o t t h e same a g e a t a l l l o c a l i t i e s . However, t h e p r i n c i p al w e i g h t of t h e e v i d e n c e i n d i c a t e s an e a r l y T e r t i a r y Age. The n e x t y o u n g e r Lower L a c u s t r i n e S e q u e n c e i s r e p r e s e n t e d by o n ly o n e f o r m a t i o n , t h e W h i t e Sage F o r m a t i o n i n t h e Deep C r e ek M o u n t a i n s w h i c h was d e s c r i b e d by N o l a n ( 1 9 3 5 , p . 4 2 ). Heylmun ( 1 9 6 5 , p . 12) r e p o r t e d t h a t t h e W h i t e Sage F o r m a t i on c o u l d be a c o r r e l a t i v e , at l e a s t i n p a r t , w i t h t h e S h e e p P a ss F o r m a t i o n , an e a r l y T e r t i a r y l a c u s t r i n e u n i t of e a s t e rn N e v a d a . He a l s o m e n t i o n e d i n t h i s c o n n e c t i o n an o u t c r o p of w h i t e t u f f a c e o u s l i m e s t o n e i n C i t y C r e e k Canyon w h i c h m i g ht - 1 1 4 - b e of l a t e E o c e n e Age. S t r u c t u r a l and s t r a t i g r a p h i c r e l a t i o n s h i p s t o g e t h er w i t h two g a s t r o p o d c o l l e c t i o n s h e l p t o e s t a b l i s h t h e age o f t h e T e r t i a r y unnamed u n i t i n t h e C e d a r M o u n t a i n s . The F o r m a t i o n d i p s a b o u t 3 0 - 3 5 d e g r e e s e a s t i n t h e o u t c r o ps n e a r R e d l am S p r i n g . The r e v e r s e f a u l t i n g a l o n g t h e e a s t e rn f o o t of t h e C e d a r Range seems most l i k e l y t o h a v e p r o d u c ed t h i s p o s t - d e p o s i t i o n a l t i l t i n g . No l o c a l b l o c k f a u l t i n g is known w h i c h c o u l d h a v e p r o d u c e d t h i s a t t i t u d e . Any s u ch f a u l t i n g would h a v e had t o be n e a r b y s i n c e u n r e a s o n a b ly l a r g e d i s p l a c e m e n t s would be demanded i f t h e f a u l t were e v en a few m i l e s d i s t a n t . It seems p r o b a b l e t h a t t h e r e v e r se f a u l t i n g i s a p p r o x i m a t e l y c o n t e m p o r a n e o u s w i t h t h e Cedar T h r u s t . S i n c e t h e N o r t h Horn ( ? ) i s d e m o n s t r a b l y o l d e r t h an t h e C e d a r T h r u s t , i t i s t h e n p r o b a b l y o l d e r t h a n t h e " T e r t i a r y unnamed f o r m a t i o n . " The f a c t t h a t t h e " u n n a m e d f o r m a t i o n" c o n t a i n s t u f f a c e o u s u n i t s and t h e N o r t h Horn ( ? ) d o e s not a l s o s u g g e s t s a y o u n g e r age f o r t h e unnamed f o r m a t i o n . Foss i l c o l l e c t i o n F635 from t h e u p p e r p a r t of t h e e x p o s u r e in e a s t H a s t i n g s Canyon c o n t a i n e d t h e f o l l o w i n g f o r m s: P h y s a c f . P. b r i d g e r e n s l s (Meek) V i v i p a r u s t r o c h i f o r m i s ("Meek and Hayden) S p h a e r i u m s p. L a R o c q u e ( w r i t t e n c o m m u n i c a t i o n ) r e p o r t e d t h a t t h e s e forms t o g e t h e r w i t h two s m a l l e r c o l l e c t i o n s from t h e N o r t h Horn ( ?) - 1 1 5 - F o r m a t i o n i n d i c a t e d a l a c u s t r i n e , f r e s h w a t e r e n v i r o n m e nt a n d p r o b a b l y l a t e P a l e o c e n e or E o c e n e Age0 The a v a i l a b l e e v i d e n c e s u g g e s t s t h a t t h e " T e r t i a ry unnamed f o r m a t i o n " o f t h e C e d a r M o u n t a i n s i s p a r t of t he Lower L a c u s t r i n e S e q u e n c e ( H e y l m u n , 1965) and t h a t i t i s at l e a s t p a r t l y c o r r e l a t i v e w i t h t h e W h i t e Sage F o r m a t i o n of t h e Deep C r e e k M o u n t a i n s . Nolan ( 1 9 3 5 ) r e p o r t e d no r e c o g n i z a b l e t u f f u n i t s i n t h e W h i t e S a g e F o r m a t i o n b u t he ( 1 9 3 5 , p . 42) m e n t i o n e d t h a t t h e f o r m a t i o n c o n t a i n e d a r a t h er l a r g e amount of e x t r e m e l y f i n e c l a y and v a r y i n g a m o u n t s of q u a r t z . " The unnamed f o r m a t i o n may a l s o be r e l a t e d t o t he w h i t e t u f f a c e o u s l i m e s t o n e i n C i t y C r e e k Canyon. - 1 1 6 - QUATERNARY SYSTEM The o l d e s t Q u a t e r n a r y d e p o s i t s a r e a l l u v i a l s a n d and g r a v e l b e d s w h i c h f o rm a v e n e e r o v e r p e d i m e n t s on b o t h t he e a s t and w e s t s i d e s of t h e r a n g e , e s p e c i a l l y i n t h e a r ea n o r t h of Tabby P e a k . P a l e o z o i c b e d r o c k p r o t r u d e s t h r o u gh t h e s e l a y e r s i n n u m e r o u s low o u t c r o p s i n d i c a t i n g t h a t t h ey a r e no more t h a n a few t e n s of f e e t t h i c k i n t h e u p p e r a r ea o f t h e p e d i m e n t . The o l d e r a l l u v i a l d e p o s i t s a r e m o s t ly b e l o w t h e l e v e l of Lake B o n n e v i l l e w h i c h e r a s e d t h e ir o r i g i n a l s u r f a c e e x p r e s s i o n . Lake c l a y d e p o s i t s o v e r l ap t h e a l l u v i u m i n t h e b a s i n a r e a on t h e p e r i p h e r y of t h e Cedar R a n g e . S i n c e t h e r e a r e no known s t r a t a of m i d d l e or l a te T e r t i a r y a g e , i t i s n o t p o s s i b l e t o e s t a b l i s h p r e c i s e l y an o l d e r age l i m i t f o r t h e o l d e r a l l u v i a l d e p o s i t s . Because o f t h e l o w e r t o p o g r a p h i c e l e v a t i o n , s m a l l e r d r a i n a g e s y s t e m s , and p r o b a b l y a l s o t h e l a c k of d u r a b l e e a r l y P a l e o z o ic s o u r c e r o c k s , t h e r e a r e no l a r g e w e l l - d e f i n e d p r e - L a ke B o n n e v i l l e a l l u v i a l f a n s i n t h e C e d a r M o u n t a i n s . R e c e n t, s m a l l , a l l u v i a l f a n s a r e f o u n d i n a s s o c i a t i o n w i t h many of t h e p r e s e n t s t r e a m c h a n n e l s. T h i n - b e d d e d and l a m i n a t e d l a c u s t r i n e c l a y and s i l t b e d s of w h i t e and l i g h t brown c o l o r , s o m e t i m e s w i t h a s s o c i a t e d b e a c h g r a v e l s , a r e f o u n d i n s e v e r a l a r e a s on t h e m a r g in o f t h e C e d a r M o u n t a i n s . There a r e w e l l - e x p o s e d o u t c r o p s of - 1 1 7 - T a b l e 2. - E s t i m a t e d A r e a s of O u t c r o p of B e d r o c k U n i t s in t h e C e d a r M o u n t a i n s. G r e a t B l u e - Humbug F o r m a t i o n s M a n n i n g Canyon F o r m a t i on O q u i r r h F o r m a t i on U n i t 1 U n i t 2 U n i t 3 U n i t 4 U n i t 5 u n d i v i d e d T o t a l O q u i r rh P e r m i a n unnamed f o r m a t i on G e r s t e r F o r m a t i on P h o s p h o r i a F o r m a t i o n, Meade P e a k Member P a r k C i t y F o r m a t i o n, G r a n d e u r Member T e r t i a r y s e d i m e n ts I g n e o u s r o c ks S q u a r e m i l e s 8 P e r c e n t of t o t a l e x p o s e d b e d r o ck 3 14 45 35 25 8 130 15 26 1 27 1 7 21 17 12 4 "5*2 13 T o t a l a r e a of b e d r o ck o u t c r o p 209 - 1 1 8 - t h e c l a y i n t h e n o r t h e r n C e d a r M o u n t a i n s s o u t h of U. S. H i g h way 40 ( s e c . 1 9 , TIN, R9W) and a l o n g t h e s o u t h w e s t e r n and s o u t h e r n f l a n k of t h e r a n g e m o s t l y w i t h i n t h e l i m i t s of t he U. S. Army Dugway P r o v i n g G r o u n d s ( F i g s . 1 3 , 1 4 ) . Lag g r a v e l d e p o s i t s h a v e d e v e l o p e d on t h e n e a r l y f l a t g r a v el t e r r a c e s i n t h e s o u t h w e s t e r n C e d a r M o u n t a i n s w h e r e p e r s i s t e n t s o u t h w e s t e r l y t o s o u t h e r l y w i n d s e x e r t t h e i r g r e a t e st e f f e c t on t h e r a n g e ( F i g . 1 5 ). E o l i a n s a n d d e p o s i t s h a v e a c c u m u l a t e d i n s i z e a b le a r e a s of t h e s o u t h e r n , w e s t e r n , and n o r t h e r n C e d a r M o u n t a i n s. The d e p o s i t s can be c o n s i d e r e d t o be of two t y p e s , one of a c t i v e , w e l l - d e f i n e d d u n e s ( F i g . 16) and t h e o t h e r of s t a t i o n a r y d u n e s , p a r t i a l l y c o v e r e d by g r a s s and s a g e b r u s h, a n d l a c k i n g r e g u l a r t o p o g r a p h i c f o r m . C o m p o s i t i o n of b o th t y p e s i s a l m o s t t o t a l l y q u a r t z s a n d . Some c a r b o n a te g r a i n s a r e p r e s e n t p a r t i c u l a r l y i n t h e a r e a s of l o w e r e l e v a t i o n . The a c t i v e , w e l l - d e f i n e d d u n e s h a v e d e v e l o p e d i n a t r a c t a l i g n e d n o r t h - n o r t h w e s t a l o n g t h e s o u t h w e s t e r n b o r d er o f t h e r a n g e . In p a r t of t h e f i e l d s a n d i s so a b u n d a nt t h a t t h e s u r f a c e i s m a r k e d by t r a n s v e r s e , u n d u l a t i n g r i d g e s. W e l l - f o r m e d b a r c h a n s o c c u p y t h e m a r g i n a l a r e a s. Some of t h e s u r f i c i a l d e p o s i t s a l o n g t h e s o u t h e a s t e rn f l a n k of t h e C e d a r M o u n t a i n s seem t o be b e s t d e s c r i b e d as a m i x t u r e of s a n d and c l a y . These s e d i m e n t s m a i n l y o c c u py F i g . 13 - P h o t o g r a p h of P l e i s t o c e n e l a k e c l a y b e ds a b o u t 5 m i l e s s o u t h of Cane S p r i n g s in t h e s o u t h e r n C e d a r M o u n t a i n s. F i g . 14 - P h o t o g r a p h of l a k e c l a y and b e a c h g r a v el a s s o c i a t e d w i t h t h e P r o v o L e v e l a b o u t 2 m i l e s n o r t h of Wig M o u n t a i n . View is n o r t h w a r d . P i g . 15 - P h o t o g r a p h s h o w i n g l a g g r a v e l a b o u t 2 m i l e s n o r th o f Wig M o u n t a i n . N o t i c e t h e d e g r e e of d e f l a t i on a r o u n d g r a s s t u f t s and s a g e b r u s h . . View w e s t w a rd t o w a r d W i l d c a t M o u n t a i n s. F i g . 16 - P h o t o g r a p h of a c t i v e dune f i e l d a l o n g t h e s o u t h w e s t f l a n k of t h e C e d a r M o u n t a i n s . View is t o w a r d t h e s o u t h w e s t. STRUCTURAL GEOLOGY - 1 2 1 - T e c t o n i c S e t t i ng The C e d a r M o u n t a i n s a r e a was n e a r t h e e a s t e r n m a r g in o f t h e C o r d i l l e r a n M i o g e o s y n c l i n e d u r i n g l a t e P a l e o z o i c and e a r l y M e s o z o i c t i m e s . R e g i o n a l s t u d i e s of t h e l a t e P a l e o z o i c s e d i m e n t s h a v e d e t e r m i n e d t h a t c e r t a i n a r e a s of t he g e o s y n c l i n e were a c t i v e l y s u b s i d i n g b a s i n s w h i l e o t h e rs u n d e r w e n t o n l y s l i g h t s u b s i d e n c e o r , at t i m e s , u p l i f t. O r o g e n i c a c t i v i t y b e g a n i n t h e e a s t e r n s e c t o r of t he m i o g e o s y n c l i n e i n a b o u t m i d - M e s o z o i c t i m e . Misch ( i 9 6 0) d i s c u s s e d m o v e m e n t s w h i c h o c c u r r e d i n an a r e a b e t w e e n t he A n t l e r L a r a m i d e o r o g e n i c b e l t s i n w e s t e r n U t a h and e a s t e rn N e v a d a . He r e f e r r e d t o t h e o r o g e n y i n f o r m a l l y as t he " M i d - M e s o z o i c O r o g e n y " and d a t e d i t as d e f i n i t e l y p o s t - e a r l y T r i a s s i c t h r o u g h o u t and p r o b a b l y p r e - L a t e C r e t a c e o us m o r e o r l e s s t h r o u g h o u t ( i b i d . , p . 3 3 ) . The w e s t e r n l i m i ts o f L a r a m i d e m o u n t a i n - b u i l d i n g as w e l l a s t h e e a s t e r n l i m i ts o f M i s c h ' s " M i d - M e s o z o i c O r o g e n y " a r e y e t p o o r l y d e f i n e d. E a r d l e y ( 1 9 3 9 ) d e s c r i b e d two u p l i f t s a l o n g t h e e a s t e rn m a r g i n of t h e B a s i n and Range p r o v i n c e . The n o r t h e r n one was c e n t e r e d a t a b o u t t h e l o c a t i o n of A n t e l o p e I s l a n d and was named t h e N o r t h e r n U t a h H i g h l a n d . The s e c o n d u p l i ft - 1 2 2 - was c e n t e r e d a b o u t 60 o r 70 m i l e s e a s t - s o u t h w e s t and was d e s i g n a t e d t h e S h e e p r o c k U p l i f t . E a r d l e y ( 1 9 3 9 ) p o i n t e d out t h a t t h e s e u p l i f t s had a f f e c t e d t h e d e v e l o p m e n t of L a r a m i de f o l d s i n t h e r e g i o n . D o e l l i n g ( 1 9 6 4 ) f u r t h e r d e m o n s t r a t ed t h a t f o l d a x e s h a v e a c o n c e n t r i c a r r a n g e m e n t a r o u n d t he N o r t h e r n U t a h H i g h l a n d and s u g g e s t e d t h a t some f o l d s and t h r u s t f a u l t s m i g h t h a v e f o r m e d t h r o u g h g r a v i t y - s l i d i ng i n d u c e d by t h e s t r u c t u r a l g r a d i e n t away f r om t h e u p l i f t. On t h e b a s i s of u n c o n f o r m a b l e r e l a t i o n s b e t w e e n t he e a r l y T e r t i a r y v o l c a n i c s and u n d e r l y i n g P a l e o z o i c and M e s o z o i c s t r a t a , H a r r i s ( 1 9 5 9 ) d e f i n e d a m a j o r n o r t h e a s t - t r e n d i n g b e l t i n w e s t e r n and s o u t h w e s t e r n U t a h w h i c h became a c t i v e i n l a t e M e s o z o i c t i m e . He ( i b i d . , 1959) named t h is f e a t u r e t h e S e v i e r U p l i f t . The S h e e p r o c k U p l i f t of E a r d l ey ( 1 9 3 9 ) l i e s on t h e e a s t e r n b o r d e r of t h e S e v i e r U p l i f t as d e s i g n a t e d by H a r r i s and t h e C e d a r M o u n t a i n s a r e l o c a t e d 25 t o 30 m i l e s n o r t h of t h e S e v i e r U p l i f t. A r m s t r o n g ( 1 9 6 3 , 1968) d i s c u s s e d a more e x t e n s i ve o r o g e n i c b e l t , w h i c h i n c l u d e d t h e S e v i e r U p l i f t ( H a r r i s, 1 9 5 9 ) , and e x t e n d e d n o r t h e a s t w a r d t h r o u g h U t a h f r om t he s o u t h w e s t c o r n e r of t h e s t a t e . He ( 1 9 6 8 ) s t a t e d t h a t t he b e l t was c h a r a c t e r i z e d by e x t e n s i v e d e c o l l e m e n t t h r u s t s and s e v e r a l l a r g e f o l d s . He p r o p o s e d t h a t t h e m o u n t a i n - b u i l d i ng a l o n g t h i s b e l t s h o u l d be d i s t i n g u i s h e d as an o r o g e n y s e p a r a t e from t h e L a r a m i d e O r o g e n y t o t h e e a s t and t h e N e v a d an - 1 2 3 - O r o g e n y t o t h e w e s t and t h a t i t be c a l l e d t h e S e v i e r O r o g e n y. R o b e r t s ( R o b e r t s e t a l . , 1965) d i s c u s s e d t h e p o s t - d e p o s i t i o n a l s t r u c t u r e of t h e e a s t e r n B a s i n and Range P r o v i n c e and e x p r e s s e d t h e v i e w t h a t t h e l a t e M e s o z o i c and e a r l y C e n o z o i c o r o g e n y b e g a n i n t h e w e s t e r n p a r t of t he a r e a and p r o g r e s s e d e a s t w a r d t h r o u g h C r e t a c e o u s t i m e . The a c t i v i t y c u l m i n a t e d i n m a j o r t h r u s t s w h i c h e x t e n d e d t he b r e a d t h of w e s t e r n U t a h and j u x t a p o s e d d i f f e r i n g s e d i m e n - t a r u f a c i e s . It was p r o p o s e d t h a t t h e h i n t e r l a n d was an u p a r c h e d a r e a i n t h e v i c i n i t y of t h e S c h e l l C r e e k and S n a k e R a n g e s i n e a s t e r n Nevada w h i c h p r o v i d e d a g r a d i e nt f o r e a s t w a r d g l i d i n g of t h e t h r u s t p l a t e s ( R o b e r t s e t a l . , 1 9 6 5 , p . 1 9 5 1 ). The C e d a r M o u n t a i n s l i e a b o u t midway b e t w e e n t h e N o r t h e r n U t a h H i g h l a n d and t h e S h e e p r o c k U p l i f t and t o w a r d t he e a s t e r n m a r g i n of t h e G r e a t B a s i n a r e a i n v o l v e d i n l a te M e s o z o i c and e a r l y C e n o z o i c o r o g e n y. F o l l o w i n g a p e r i o d of e r o s i o n , and e x t r u s i v e and i n t r u s i v e a c t i v i t y , t h e e a s t e r n B a s i n and Range p r o v i n c e was a f f e c t e d by f o r c e s i n l a t e T e r t i a r y t i m e w h i c h b r o k e t he c r u s t i n t o a l a r g e number of f a u l t - b o u n d e d b l o c k s , t r e n d i ng r o u g h l y n o r t h - s o u t h , whose t i l t e d u p p e r e d g e s form many of t h e m o u n t a i n r a n g e s i n t h e G r e a t B a s i n t o d a y . Recent p i e d mont f a u l t s c a r p s i n d i c a t e b l o c k f a u l t i n g i s s t i l l a c t i v e. - 1 2 4 - W h i l e s u c h s c a r p s h a v e b e e n r e c o g n i z e d i n a r e a s a d j a c e n t to t h e s u b j e c t a r e a ( R i g b y , 1 9 5 7 ) none i s v i s i b l e t o d a y i n t he C e d a r M o u n t a i n s. The f o r m a t i o n s and s t r u c t u r e s mapped i n t h e C e d ar M o u n t a i n s add d e t a i l t o t h e r e g i o n a l p a t t e r n of s t r u c t u r es w o r k e d o u t by o t h e r g e o l o g i s t s , and p r o v i d e a d d i t i o n a l i n f o r m a t i o n f o r d a t i n g some of t h e e v e n t s. L o c a l S t r u c t u r es The s t r u c t u r a l f e a t u r e s of t h e C e d a r M o u n t a i n s can be c l a s s i f i e d as f o l d s , domal u p l i f t s , t h r u s t f a u l t s , h i g h - a n g l e r e v e r s e f a u l t s , s t r i k e - s l i p f a u l t s , t r a n s v e r s e f a u l t s, n o r m a l f a u l t s , and j o i n t s . F o l d s One l o n g , c u r v e d , a s y m m e t r i c a l a n t i c l i n e c o n s t i t u t es t h e b a s i c s t r u c t u r e of t h e C e d a r R a n g e . S i n c e t h e s o u t h e rn p a r t of t h e , f o l d t r e n d s a b o u t N45°W a n d t h e n o r t h e r n p a rt t r e n d s n o r t h - s o u t h and a l s o b e c a u s e t h e two p a r t s a r e c u t by a n i m p o r t a n t t r a n s v e r s e f a u l t , e a c h h a s b e e n named and d i s c u s s e d a s an i n d i v i d u a l s t r u c t u r e . The n o r t h e r n s t r u c t u r e is c a l l e d C e d a r A n t i c l i n e ( P I . I a , F i g . 17) and t h e s o u t h e rn o n e c a l l e d C o c h r a n V a l l e y A n t i c l i n e ( P I . I b , F i g . 1 7 ). The S o u t h e a s t R y d a l c h Canyon A n t i c l i n e ( P I . I b , F i g . 1 7 ), e x p r e s s e d a t t h e s u r f a c e i n t h e G r e a t B l u e F o r m a t i o n , is t r a n s i t i o n a l i n s i z e b e t w e e n t h e two m a j o r f o l d s and t he n u m e r o u s s m a l l e r o n e s on t h e p e r i p h e r y of t h e r a n g e. T h e r e a r e d i f f e r e n c e s o t h e r t h a n s i z e b e t w e e n t he l a r g e r and t h e s m a l l e r f o l d s of t h e C e d a r M o u n t a i n s . The l a r g e f o l d s a r e m a r k e d by g r e a t l i n e a r e x t e n t , f a i r l y u n c h a n g i n g f o r m , and b r o a d w a v e - l e n g t h . The s m a l l e r f o l ds a r e more c l o s e l y c o m p r e s s e d , t h e l i m b s commonly d i v e r g i ng a t a b o u t 90 d e g r e e s . The a x i a l t r a c e s of t h e s e f o l d s t e nd t o be s i n u o u s and may t e r m i n a t e a b r u p t l y . S m a l l - s c a le b u c k l i n g of b e d s , s u c h a s t h a t i n s e c . 1 2 , T 3 S , R10W may o c c u r i n t h e a r e a of t h e s m a l l e r f o l d s . The a x e s of two s m a l l e r f o l d s may m e r g e i n a m a n n e r w h i c h s u g g e s t s t h a t a f a u l t s e p a r a t e s t h e s t r u c t u r e s (SW 1/4 T2N, R9W). L a r g e r F o l ds C e d a r A n t i c l i n e forms t h e m a i n body of t h e r a n ge b e t w e e n Tabby Peak and H a s t i n g s S u m m i t , a d i s t a n c e of a b o ut s i x t e e n m i l e s . The f o l d a x i s t r e n d s n o r t h - s o u t h and v e e rs n o r t h w e s t w a r d n e a r H a s t i n g s Summit w h e r e n o r t h e r l y p l u n ge i n c r e a s e s t o 25 d e g r e e s . The f o l d t e r m i n a t e s as a s u r f a ce f e a t u r e a t t h e S o u t h H a s t i n g s T h r u s t F a u l t . Cedar A n t i c l i n e , named f o r t h e U n i t e d S t a t e s C o a s t and G e o d e t ic S u r v e y f i r s t o r d e r t r i a n g u l a t i o n s t a t i o n i n s e c . 2 2 , T3S, R10W i s a b r o a d , o p e n , a s y m m e t r i c a l f o l d . S t r a t a d ip - 1 2 6 - b e t w e e n 15 and 35 d e g r e e s a l o n g t h e w e s t f l a n k . Dips a re s o m e w h a t h i g h e r on t h e e a s t l i m b and s t e e p e n t o v e r t i c al a l o n g t h e m o u n t a i n f r o n t n o r t h w e s t of S u l p h u r S p r i ng ( P l a t e I I , s e c t i o n B-BT ). The a x i a l t r a c e of t h e f o l d i s d i s p l a c e d t o t h e e a st i n t h e a r e a w h e r e t h e e a s t l i m b s t e e p e n s s h a r p l y and t h is s e e m s t o be r e l a t e d t o t h e C e d a r T h r u s t F a u l t w h i c h c u ts t h e o p p o s i t e l i m b of t h e f o l d . Beds r a n g i n g from M i d d le P e n n s y l v a n i a n U n i t 3 of t h e O q u i r r h F o r m a t i o n t o e a r ly T e r t i a r y N o r t h Horn ( ? ) F o r m a t i o n h a v e b e e n i n v o l v e d i n f o l d i n g of t h e C e d a r A n t i c l i n e , A n g u l a r u n c o n f o r m i t y b e t w e en t h e N o r t h Horn ( ? ) F o r m a t i o n and t h e u n d e r l y i n g G e r s t er F o r m a t i o n i s a p p a r e n t i n t h e Q u i n c y S p r i n g a r e a w h e r e t he N o r t h Horn ( ? ) r e s t s on p r o g r e s s i v e l y o l d e r b e d s t o w a r d t he s o u t h . A d i s c o r d a n c e i n s u r f a c e d i p s of a b o u t 25 d e g r e es b e t w e e n t h e N o r t h Horn ( ? ) F o r m a t i o n , o b s e r v e d t o be as g r e a t as 27 d e g r e e s , p r o b a b l y f o r m e d l o c a l l y a t t h e t i m e of t h e C e d a r T h r u s t . The h i g h e s t p e a k i n t h e C e d a r M o u n t a i n s, a l i t t l e a b o v e 7 , 6 0 0 f e e t , i s n e a r t h e a x i a l t r a c e of C e d ar A n t i c l i n e a b o u t a m i l e s o u t h of Q u i n c y S p r i n g and r e s u l ts f r om t h e c o m p a r a t i v e l y g r e a t r e s i s t a n c e t o e r o s i o n of t he c l i f f - f o r m i n g G r a n d e u r Member of t h e P a r k C i t y F o r m a t i o n. C o c h r a n V a l l e y A n t i c l i n e i s t h e e x t e n s i o n of t he C e d a r A n t i c l i n e i n t h e s o u t h e r n C e d a r M o u n t a i n s . T r a n s - - 1 2 7 - v e r s e f a u l t i n g , v o l c a n i s m , and t h r u s t i n g on t h e w e s t l i mb h a v e d i s r u p t e d c o n t i n u i t y of t h e C o c h r a n V a l l e y - C e d ar A n t i c l i n e a l i g n m e n t and c h a n g e d i t s c h a r a c t e r i s t i c s somew h a t . The a x i a l t r a c e s h i f t s from n o r t h - s o u t h t o a b o ut N45°W s o u t h of R y d a l c h C a n y o n . The f o l d h a s a l i n e ar e x t e n t of a b o u t e i g h t m i l e s and i s t e r m i n a t e d i n t h e s o u t h e a s t q u a r t e r of T5S, R10W by W h i t e Rock Dome. The M a n n i ng C a n y o n i s t h e o l d e s t f o r m a t i o n e x p o s e d a l o n g t h e c r e s t of t h e f o l d , w h e r e i t a p p e a r s i n n u m e r o u s l o w , p o o r l y e x p o s ed o u t c r o p s . S o u t h e a s t R y d a l c h Canyon A n t i c l i n e ( P I . I b , P i g . 1 7 ), e x p r e s s e d i n t h e G r e a t B l u e F o r m a t i o n , i s of i n t e r e s t b e c a u s e of i t s r e l a t i o n t o t h e C o c h r a n S p r i n g A n t i c l i n e . It p r o b a b l y d e v e l o p e d p a r a l l e l w i t h t h a t s t r u c t u r e . Movement on t h e C o c h r a n S p r i n g F a u l t h a s s h i f t e d i t s a x i s w e s t w a rd a n d e l e v a t e d i t so t h a t i t i n t e r s e c t s t h e f a u l t a l o n g i ts s o u t h e r n e x t e n s i o n . The R y d a l c h Canyon F a u l t s e p a r a t e s t h is f o l d from i t s a p p a r e n t n o r t h e r n e x t e n s i o n i n t h e s o u t h e a st c o r n e r of T4S, R10W. S m a l l e r F o l ds An a n t i c l i n e and s y n c l i n e d e v e l o p e d i n U n i t 3 o f t he O q u i r r h F o r m a t i o n c o n s t i t u t e t h e s t r u c t u r e of S k u n k R i d ge n o r t h of U. S. Highway 4 0 . The a x e s of b o t h f o l d s t r e nd n o r t h e a s t and c a n be t r a c e d a b o u t two m i l e s . Both f o l ds - 1 2 8 - p l u n g e t o w a r d t h e n o r t h e a s t and d i s a p p e a r u n d e r Q u a t e r n a ry s e d i m e n t s i n t h a t d i r e c t i o n . The f o l d a x e s a r e a t an o b l i q u e a n g l e t o t h e t r e n d of Skunk R i d g e and e v i d e n t ly t e r m i n a t e a t t h e w e s t e r n m a r g i n of Skunk R i d g e a g a i n s t an e x t e n s i o n of t h e S t r a i g h t Canyon F a u l t . The e a s t e r l y t r e nd o f t h e Skunk R i d g e f o l d s a s w e l l as t h a t of t h e b r o a d s y n - c l i n e whose a x i s t r e n d s e a s t n e a r t h e m i c r o w a v e t o w er ( s e c . 2 0 , TIN, R9W) a p p e a r t o h a v e b e e n a f f e c t e d by s o u t h e r l y d i r e c t e d f o r c e s. S t r a t a of t h e u p p e r p a r t of U n i t 3 of t h e O q u i r r h Forma t i o n f o r m t h e Low S y n c l i n e i n s e c . 13 a n d 2 4 , TIN, R10W. The s t r u c t u r e t r e n d s e a s t - w e s t , and h a s b e e n o v e r t u r n e d as much a s 35 d e g r e e s t o w a r d t h e s o u t h . The a x i a l t r a ce t e r m i n a t e s e a s t w a r d a g a i n s t t h e S t r a i g h t Canyon F a u l t w h i le a b r o a d , open s y n c l i n e e x p r e s s e d i n U n i t 4 of t h e O q u i r rh F o r m a t i o n a b u t s a g a i n s t t h e Low S y n c l i n e e a s t of t h e f a u l t. T h e s e r e l a t i o n s a l o n g t h e S t r a i g h t Canyon F a u l t s u g g e s t a l e f t - l a t e r a l d i s p l a c e m e n t of as much a s a m i l e i n t he v i c i n i t y of Low S y n c l i n e. B e d s of t h e l o w e r O q u i r r h and M a n n i n g Canyon F o r m a t i o ns r e v e a l a number of s m a l l , d i s c o n t i n u o u s f o l d s i n t he p i e d m o n t a r e a b e t w e e n S u l p h u r S p r i n g and t h e e a s t e r n b a se o f t h e C e d a r M o u n t a i n s ( P I . I a , P I . I I ) . A t i g h t l y f o l d ed a n d s t e e p l y p l u n g i n g s m a l l a n t i c l i n e and c y n c l i n e i n SE 1 / 4, s e c . 1 2 , T3S, R10W i l l u s t r a t e f a i r l y w e l l t h e s c a l e and e x t e n t of t h e s m a l l e r f o l d s i n t h e a r e a . S u l p h u r S p r i ng S y n c l i n e l i e s on t h e e a s t e r n m a r g i n of t h e b e l t of e x p o s ed s t r u c t u r e s . The a x i s p l u n g e s s o u t h and t r e n d s a b o u t 15 d e g r e e s e a s t of n o r t h . S c a n t y e x p o s u r e s i n t h e p i e d m o nt a r e a n o r t h w a r d i n d i c a t e t h a t t h e b e d r o c k s t r u c t u r e as f ar n o r t h a s e a s t H a s t i n g s Canyon r e s e m b l e s t h a t w e s t of S u l p h u r S p r i n g. T h e r e a r e two c l o s e l y f o l d e d , n o r t h - t r e n d i n g a n t i c l i n e s and an i n t e r m e d i a t e s y n c l i n e a b o u t two t o f o u r m i l es w e s t of Q u i n c y S p r i n g ( P I . I a , P I . I I ) . Meager s u r f a ce e x p o s u r e s c o n f i r m b o t h f l a n k s of t h e w e s t e r n a n t i c l i ne w h i l e t h e w e s t e r n l i m b of t h e s e c o n d a n t i c l i n e i s i n f e r r ed i n o r d e r t o e x p l a i n t h e b r o a d s u r f a c e o u t c r o p of U n i t 3 of t h e O q u i r r h F o r m a t i o n . There i s v i r t u a l l y no t o p o g r a p h ic e x p r e s s i o n of t h e s t e e p l y i n c l i n e d b e d s of t h e s e f o l d s . A p e d i m e n t s u r f a c e b e v e l s t h e a r e a and i s m o s t l y c o v e r e d by Q u a t e r n a r y a l l u v i u m. The s t r u c t u r e s o u t h e a s t of W h i t e Rock Dome i n t he s o u t h e r n C e d a r M o u n t a i n s c o m p r i s e s a number of s m a l l , r a t h er j u m b l e d f o l d s and f a u l t b l o c k s . The s t r u c t u r e i n t h i s a r ea r e s e m b l e s more t h e " f o o t h i l l s t y p e " t h a n t h e m a j o r m o u n t a in f o l d s e v e n t h o u g h i t i s on t h e s o u t h e a s t e x t e n s i o n of C o c h r a n V a l l e y A n t i c l i n e . Post H o l l o w A n t i c l i n e e x e m p l i f i e s t h e t y p e of f o l d s i n t h e a r e a . It i s e x p r e s s e d a t t he s u r f a c e i n b e d s of U n i t 3 of t h e O q u i r r h F o r m a t i o n and i ts - 1 3 0 - a x i s i s i n f e r r e d t o e x t e n d u n i n t e r r u p t e d l y f o r a b o u t two m i l e s . D o m i c a l U p l i f ts W h i t e Rock Dome i s a r o u g h l y c i r c u l a r dome s i t u a t ed a l o n g t h e s o u t h e a s t e x t e n s i o n of t h e C o c h r a n S p r i n g A n t i c l i n e i n t h e n o r t h w e s t q u a r t e r of T 6 S , R9W. Manning C a n y o n F o r m a t i o n i s e x p o s e d on t h e v a l l e y f l o o r as a r e s u l t o f e r o s i o n of t h e s t r a t a a r c h e d u p w a r d by t h e i n t r u s i on o f t h e s m a l l r h y o l i t i c s t o c k ( P I . I b , P I . I I ) . The s u r r o u n d i n g c l i f f s a r e u n d e r l a i n by U n i t s 1 a n d 2 of t he O q u i r r h F o r m a t i o n . Three g r a y i s h - w h i t e r h y o l i t e m a s s es r i s e a b o v e t h e f l o o r of t h e a m p h i t h e a t e r and t h e l a r g e st h a s l o n g b e e n known a s W h i t e Rock ( K i n g , 1 8 7 7 , p . 4 6 2 ). O q u i r r h s t r a t a d i p away f r om t h e c e n t e r of u p l i f t i n a ll d i r e c t i o n s a l t h o u g h v o l c a n i c s c o v e r most of t h e s e d i m e n t a ry s t r a t a of t h e s o u t h w e s t e r n q u a d r a n t. W h i t e Rock Dome i s t h e b e t t e r e x p o s e d e x a m p l e of two s u c h f e a t u r e s i n t h e s o u t h e r n C e d a r M o u n t a i n s . The s e c o nd e x a m p l e w h i c h h a s n o t a c t u a l l y b e e n d e m o n s t r a t e d t o be a d o m a l u p l i f t i s i n s e c . 3 3 , T 4 S , R10W. It a l s o l i e s a l o ng t h e a x i a l r e g i o n of t h e C o c h r a n S p r i n g A n t i c l i n e . The w r i t e r h a s r e c o r d e d l o c a l s t r u c t u r a l v a r i a t i o n a t t h is l o c a t i o n w h i c h s u r r o u n d s a r h y o l i t i c mass i d e n t i c a l i n l i t h - o l o g y t o t h a t a t W h i t e Rock. - 1 3 1 - T h r u s t F a u l ts The w e s t e r n , more g e n t l y d i p p i n g l i m b of t h e Cedar A n t i c l i n e i s c u t by a t h r u s t f a u l t w h i c h r o u g h l y p a r a l l e ls t h e a x i a l t r a c e of t h e a n t i c l i n e a n d , a f t e r an o f f s e t in w e s t R y d a l c h C a n y o n , a p p e a r s t o c o n t i n u e f o r s e v e r a l m i l es i n t o t h e s o u t h e r n C e d a r M o u n t a i n s . The C e d a r T h r u s t can be r e c o g n i z e d f o r t w e n t y - o n e m i l e s b e f o r e i t s s u r f a c e t r a c e at e i t h e r end d i s a p p e a r s b e n e a t h Q u a t e r n a r y g r a v e l i n t h e p i e d mont a r e a s . A s m a l l t h r u s t a b o u t one and o n e - h a l f m i l es s o u t h w e s t of t h e w e s t e n t r a n c e t o H a s t i n g s Canyon may be a s m a l l b r a n c h of t h e C e d a r T h r u s t or a s m a l l e r r e l a t ed t h r u s t f a u l t . The f a u l t a p p e a r s t o h a v e a r a t h e r low d ip i n t h e n o r t h e r n C e d a r s , b e t w e e n 20 and 30 d e g r e e s w h e r e it was o b s e r v e d n e a r Q u i n c y S p r i n g . The a t t i t u d e s t e e p e n s to t h i r t y d e g r e e s or a l i t t l e more i n t h e a r e a of w e st R y d a l c h C a n y o n . A map m e a s u r e m e n t s o u t h of R y d a l c h Canyon i n d i c a t e d 30 d e g r e e s w e s t d i p . N o r t h of Q u i n c y S p r i n g, w h e r e t h e u p p e r p l a t e i s on t h e N o r t h Horn ( ? ) F o r m a t i o n, t h e l e a d i n g e d g e of t h e u p t h r o w n b l o c k i s m a r k e d by an e a s t - f a c i n g s c a r p w i t h r e d e l a s t i c s and c o n g l o m e r a t e a l o n g t he b a s e . One c a n f o l l o w t h e f a u l t v i s u a l l y f o r l o n g d i s t a n c es f r om h i g h v a n t a g e p o i n t s i n t h e n o r t h e r n C e d a r M o u n t a i n s. The o l d e s t s t r a t a e x p o s e d a l o n g t h e f a u l t a r e b e d s of U n i t 1 o f t h e O q u i r r h F o r m a t i o n and t h e y o u n g e s t a r e r e d c o n g l o m - - 1 3 2 - e r a t e s and o t h e r e l a s t i c s of t h e N o r t h Horn ( ? ) n o r t h w e st o f Q u i n c y S p r i n g . G a s t r o p o d s c o l l e c t e d by t h e a u t h o r from t h e N o r t h Horn ( ? ) F o r m a t i o n h a v e b e e n d a t e d as l a te P a l e o c e n e or E o c e n e and t h u s l i m i t t h e o l d e s t p o s s i b l e d a te o f f a u l t i n g . S t r a t i g r a p h i c d i s p l a c e m e n t i n c r e a s e s from a b o u t 5 , 5 0 0 f e e t n e a r Long Canyon i n t h e s o u t h w e s t Cedar M o u n t a i n s t o a b o u t 1 3 , 0 0 0 f e e t n o r t h of Q u i n c y S p r i n g . It s e e m s p l a u s i b l e t h a t t h e C e d a r T h r u s t may be a s o u t h e rn e x t e n s i o n of t h e C e d a r M o u n t a i n s ( ? ) - C a l c i t e T h r u st d e s c r i b e d by D o e l l i n g ( 1 9 6 4 , p . 2 9 8 ) . A s e c o n d t h r u s t , h e re d e s i g n a t e d t h e Lone M o u n t a i n T h r u s t , i s p o s t u l a t e d t o u n d e r l i e t h e s u r f a c e g r a v e l b e t w e e n s e c . 1 2 , T 2 S , R11W a n d s e c . 7, T 3 S , R10W. T h i s f a u l t seems t o be r e q u i r e d t o a d a p t s u r f a ce a t t i t u d e s and d i s t r i b u t i o n of f o r m a t i o n s w i t h m e a s u r e d f o r m a t i o n t h i c k n e s s e s i n p r e p a r i n g a s t r u c t u r e c r o s s - s e c t i on f o r t h i s a r e a ( P I . I a , P I . I I ) . The t r a c e of t h e S o u t h H a s t i n g s T h r u s t F a u l t h a s an a r c u a t e s u r f a c e e x p r e s s i o n and e x t e n d s w e s t - n o r t h w e s t for a b o u t f o u r m i l e s j u s t s o u t h of H a s t i n g s C a n y o n . It was n ot p o s s i b l e t o g e t p r e c i s e m e a s u r e m e n t s of t h e f a u l t a t t i t u de b u t t h e s u r f a c e t r a c e on t h e g e o l o g i c map and c o n t a c t r e l a t i o n s on a i r p h o t o s s u g g e s t t h a t t h e i n c l i n a t i o n i s r a t h er s t e e p . The d i p i s i n t e r p r e t e d as d e c r e a s i n g n o r t h w a r d . A t o p o g r a p h i c d e p r e s s i o n h a s b e e n e r o d e d on t h e d o w n t h r o wn - 1 3 3 - b l o c k p a r a l l e l t o t h e f a u l t t r a c e w h e r e t h e s h a l e s and t h i n - b e d d e d d o l o s t o n e s of t h e Meade P e a k Member o f t h e P h o s p h o r ia F o r m a t i o n o u t c r o p . T o p o g r a p h y r i s e s n o r t h of t h e f a u l t t r a ce o n t h e more r e s i s t a n t O q u i r r h s t r a t a of t h e u p p e r b l o c k. S t r a t i g r a p h i c d i s p l a c e m e n t i n t h e c e n t r a l a r e a of f a u l t o u t c r o p i s a p p r o x i m a t e l y 1 0 , 5 0 0 f e e t . South H a s t i n g s T h r u s t, a n d t h e R e d l am S p r i n g F a u l t . It i s o l d e r t h a n t h e t r a n s v e r s e f a u l t t h r o u g h H a s t i n g s C a n y o n . South H a s t i n g s T h r u st F a u l t i s I n t e r p r e t e d a s p r o v i d i n g t h e s o l e f o r d i f f e r e n t i al s o u t h w a r d d i s p l a c e m e n t of b e d s a l o n g t h e S t r a i g h t Canyon F a u l t . South H a s t i n g s T h r u s t F a u l t seems t o be s i m i l a r in c h a r a c t e r t o t h e N o r t h O q u i r r h T h r u s t F a u l t f i r s t mapped by W e l s h ( J a m e s , e t . a l . , 1 9 6 1 , p . 5 8 ). H i g h A n g l e R e v e r s e F a u l ts A h i g h a n g l e r e v e r s e f a u l t h e r e named t h e Redlam S p r i n g F a u l t , c u t s t h e e a s t l i m b of t h e C e d a r a n t i c l i n e in t h e n o r t h e r n C e d a r M o u n t a i n s e x t e n d i n g s o u t h w a r d from t he s o u t h e a s t q u a r t e r of s e c . 3 6 , T 1 S , R10W t o t h e w e s t h a l f of s e c . 1 3 , T3S, R10W. The f a u l t j u x t a p o s e s t h e Manning C a n y o n and G e r s t e r F o r m a t i o n s n e a r i t s n o r t h e r n l i m it i n d i c a t i n g a s t r a t i g r a p h i c d i s p l a c e m e n t of a b o u t 1 6 , 0 00 t o 1 7 , 0 0 0 f e e t . Dip of t h e f a u l t p l a n e i n t h i s a r e a is a b o u t 60 t o 70 d e g r e e s . The f a u l t i s c o v e r e d by p i e d m o nt g r a v e l i n p l a c e s a l o n g t h e m o u n t a i n f r o n t b u t n u m e r o us - 1 3 4 - e x p o s u r e s a r e v i s i b l e b e t w e e n R e d l am and S u l p h u r S p r i n gs w h e r e u n i t s of t h e l o w e r O q u i r r h F o r m a t i o n h a v e b e e n b r o u g ht i n f a u l t c o n t a c t a g a i n s t t h e " P e r m i a n unnamed f o r m a t i o n ". The O q u i r r h F o r m a t i o n r i s e s o v e r t h e Unnamed F o r m a t i o n at t h e m o u n t a i n f r o n t west of S u l p h u r S p r i n g and r e v e a l s t h at t h e d i p of t h e f a u l t p l a n e i s somewhat l e s s h e r e t h an n e a r H a s t i n g s C a n y o n . D i s p o s i t i o n of t h e R e d l am S p r i ng F a u l t s o u t h of S u l p h u r S p r i n g b e c o m e s much l e s s c e r t a i n. O b s e r v a b l e s t r u c t u r e i n t h e p i e d m o n t a r e a i s q u i t e e r r a t i c. T h r e e r e v e r s e f a u l t s a p p e a r i n t h e h i l l s s o u t h of S u l p h ur S p r i n g ( s e c . 3 1 , T 4 S , R9W a n d s e e s . 2, 4 , T 4 S , R10W) and t h e w e s t e r n m o s t one a p p e a r s t o be t h e s o u t h e r n e x t e n s i o n of t h e R e d l am S p r i n g F a u l t . Each of t h e f a u l t s h a s much l e ss s t r a t i g r a p h i c d i s p l a c e m e n t t h a n t h e n o r t h e r l y f a u l t and it a p p e a r s t h a t t h e d i s p l a c e m e n t of t h e n o r t h e r l y f a u l t is d i s t r i b u t e d among t h e t h r e e s o u t h of i t . Two of t h e t h r ee r e v e r s e f a u l t s d i s a p p e a r u n d e r a l l u v i a l m a t e r i a l n e a r e a st R y d a l c h Canyon b u t t h e w e s t e r n f a u l t c r o s s e s R y d a l c h Cany o n i n s e c . 2 7 , T4S, R10W a n d c o n t i n u e s s o u t h f o r a b o u t a m i l e . E f f o r t s t o e s t a b l i s h t h e r e l a t i o n s h i p b e t w e e n t he R y d a l c h Canyon T r a n s v e r s e f a u l t and t h e r e v e r s e f a u l t have s o f a r b e e n u n s u c c e s s f u l. The R e d l am S p r i n g F a u l t and a s s o c i a t e d f a u l t s p r o b a b ly f o r m e d a t a b o u t t h e same t i m e a s t h e C e d a r T h r u s t. - 1 3 5 - The C o c h r a n S p r i n g F a u l t f o l l o w s t h e w e s t e r n m a r g i n of t h e G r e a t B l u e F o r m a t i o n s o u t h e a s t of R y d a l c h C a n y o n , It e x t e n d s a b o u t t e n m i l e s i n s u r f a c e e x p o s u r e s . The f a u l t is n o w h e r e w e l l e x p o s e d b u t t h e s t r a i g h t s u r f a c e t r a c e i n d i c a t e s a s t e e p d i p . I t s s t r a t i g r a p h i c d i s p l a c e m e n t n e a r t he n o r t h e r n l i m i t i s a b o u t 2 , 5 0 0 f e e t but i n c r e a s e s t o a p p r o x i m a t e l y 4 , 0 0 0 f e e t n e a r i t s s o u t h e r n e n d . The C o c h r a n S p r i ng F a u l t c u r v e s t o s t r i k e n o r t h e a s t n e a r i t s s o u t h e r n end in P o s t H o l l o w and p r o b a b l y i s a t e a r f a u l t a t t h i s l o c a t i o n. The a g e of t h e f a u l t i s i n d e t e r m i n a t e i n t h e a r e a of i ts o u t c r o p b u t i t p r o b a b l y f o r m e d a t t h e same t i m e a s t he r e v e r s e f a u l t s f a r t h e r n o r t h. S t r i k e - S l i p F a u l ts S t r a i g h t Canyon F a u l t s o u t h of U, S. Highway 40 i n t he n o r t h w e s t C e d a r M o u n t a i n s h a s a n o r t h - s o u t h e x t e n t of a b o ut e i g h t m i l e s . It f o l l o w s S t r a i g h t Canyon i n i t s n o r t h e rn o u t c r o p s and i s o f f s e t i n t h e H a s t i n g s Canyon a r e a by n o r t h w e s t - t r e n d i n g f a u l t s . Dip of t h e f a u l t p l a n e , m e a s u r ed n e a r t h e U t a h C a l c i u m Company m i n e i n w e s t H a s t i n g s Canyon, r a n g e s from n e a r v e r t i c a l a few h u n d r e d y a r d s n o r t h of t he C a n y o n r o a d t o 70 d e g r e e s e a s t , s o u t h of t h e r o a d . This is i n t e r p r e t e d t o be a s t r i k e - s l i p f a u l t w h i c h h a s u n d e r g o ne l e f t - l a t e r a l d i s p l a c e m e n t . G r e a t e r r e l a t i v e s o u t h w a rd - 1 3 6 - d i s p l a c e m e n t of t h e w e s t e r n b l o c k h a s d i s p l a c e d f o l d a x e s a m i l e o r more and h a s p r o d u c e d two l o c a l i t i e s of t i g h t to o v e r t u r n e d l o c a l f o l d s . One of t h e f o l d s i s t h e low S y n c l i n e i n s e e s . 13 and 2 4 , TIN, R10W a n d t h e o t h e r i s a t t he m o u t h of west H a s t i n g s C a n y o n . G e o l o g i c r e l a t i o n s of t he S t r a i g h t Canyon F a u l t seem t o be s i m i l a r t o t h o s e d e s c r i b ed by R o b e r t s and T o o k e r ( 1 9 6 1 , p . 45) i n r e f e r e n c e t o t he G a r f i e l d F a u l t i n t h e n o r t h e r n O q u i r r h M o u n t a i n s. T r a n s v e r s e F a u l ts I m p o r t a n t t r a n s v e r s e f a u l t i n g o c c u r r e d i n t h e Cedar M o u n t a i n s a f t e r f o l d i n g on n o r t h - s o u t h a x e s , t h r u s t i n g from t h e w e s t , h i g h - a n g l e r e v e r s e f a u l t i n g , f o l d i n g on e a s t - w e st a x e s and s o u t h w a r d t h r u s t i n g . It o c c u r r e d b e f o r e m i n or r a n g e - m a r g i n n o r m a l f a u l t i n g . Net s l i p of t h e two i m p o r t a n t f a u l t s r e f e r r e d t o as t r a n s v e r s e f a u l t s b o t h a p p e a r to c o n t a i n s i g n i f i c a n t a m o u n t s of s t r i k e - s l i p as w e l l a s d i p - s l i p m o v e m e n t. The t r a c e of t h e H a s t i n g s Canyon F a u l t i s somewhat s o u t h of t h e r o a d a c r o s s t h e m o u n t a i n a t H a s t i n g s Canyon. The s t r a t i g r a p h i c d i s p l a c e m e n t n e a r t h e m o u n t a i n summit is e s t i m a t e d t o be a b o u t 6 , 5 0 0 f e e t and a r e l a t i v e l y s m a ll p o r t i o n of t h i s d i s p l a c e m e n t h a s come a b o u t s i n c e e x t r u s i on o f b a s a l t f l o w s o v e r t h i s r e g i o n . The b a s a l t r e m n a n t s w h i ch h a v e b e e n r o t a t e d down t o w a r d t h e s o u t h on t h e d o w n t h r o wn - 1 3 7 - b l o c k c o n s t i t u t e " L o u d e r b a c k s " , named by W. M. D a v i s ( D a v i s, 1 9 3 0 , p . 299) f o r G e o r g e L o u d e r b a c k who f i r s t e m p l o y e d d i s p l a c e d v o l c a n i c s t r a t a i n t h e s t u d y of s t r u c t u r e i n t he B a s i n and Range P r o v i n c e. R y d a l c h Canyon F a u l t t r e n d s a b o u t N45°W a c r o s s R y d a l ch C a n y o n and i s m o s t l y n o r t h of t h e r o a d w h i c h c r o s s e s t he r a n g e a t t h i s l o c a l i t y . S t r a t i g r a p h i c d i s p l a c e m e n t i s e s t i m a t e d a t a b o u t 4 , 0 0 0 f e e t from o u t c r o p s n e a r t h e s u m m i t. C o n s i d e r a b l e b r e c c i a t i o n e v i d e n t l y a c c o m p a n i e d t h e f a u l t i n g. B l e a c h e d , s i l i c i f i e d , l i m e s t o n e b r e c c i a s of t h e O q u i r rh F o r m a t i o n , U n i t 3 , a r e e x p o s e d on t h e l o w e r s o u t h w a l l of e a s t R y d a l c h C a n y o n . Also B r o w n T s S p r i n g seems t o r e s u lt l a r g e l y from s e e p a g e downward a l o n g a b r e c c i a z o n e w h i c h can b e o b s e r v e d e a s t of t h e s p r i n g . The s p a r s e n e s s of v o l c a n i cs n o r t h of t h e f a u l t c o m p a r e d w i t h t h e l a r g e mass on t he s o u t h i n w e s t R y d a l c h Canyon i s a c c o u n t e d f o r by e r o s i o n of v o l c a n i c s from t h e u p t h r o w n b l o c k. N o r m a l F a u l ts T h e r e i s l i t t l e l o c a l e v i d e n c e t h a t b l o c k f a u l t s e x i st n e a r t h e m a r g i n s of t h e C e d a r M o u n t a i n s t o d a y . One s u ch f a u l t h a s b e e n i n f e r r e d i n t h e s o u t h e r n C e d a r M o u n t a i n s e a st o f t h e e x p o s u r e s of G r e a t B l u e F o r m a t i o n . This i s b a s e d on a s e i s m i c s t u d y by J o h n s o n and Cook ( 1 9 5 7 , p . 53) who r e p o rt t h a t s e i s m i c d a t a s u g g e s t a m a j o r n o r t h - n o r t h w e s t w a r d - t r e n d i n g B a s i n and Range f a u l t z o n e . A s i n g l e f a u l t of 6 , 7 50 - 1 3 8 - f e e t d i s p l a c e m e n t d i p p i n g 50 d e g r e e s n o r t h e a s t w o u l d s a t i s fy t h e g e o p h y s i c a l d a t a . Cook i n d i c a t e d more r e c e n t l y t h at t h e d i s p l a c e m e n t on t h i s f a u l t i s p r o b a b l y n o t as g r e a t as p r e v i o u s l y s t a t e d ( p e r s o n a l c o m m u n i c a t i o n , 1 9 6 6 ). The f a i r l y s t e e p r a n g e f r o n t a l o n g t h e w e s t f a c e of S k u n k R i d g e , c o n s i d e r e d w i t h t h e o b l i q u e o r i e n t a t i o n of f o ld a x e s , s u g g e s t s a b l o c k f a u l t w e s t of Skunk R i d g e . The s t r i k e - s l i p movement of t h e S t r a i g h t Canyon F a u l t c o u l d a c c o u n t f o r t h e t r u n c a t e d f o l d a x e s of Skunk R i d g e . However, i t seems l i k e l y t h a t l a t e r n o r m a l f a u l t d i s p l a c e m e n t d e v e l o p e d on a n o r t h e r n e x t e n s i o n of t h e S t r a i g h t Canyon F a u l t. The w r i t e r h a s n o t o b s e r v e d any e v i d e n c e t h a t w o u l d j u s t i fy e x t e n d i n g a r a n g e - m a r g i n n o r m a l f a u l t any f a r t h e r s o u th t h a n t h e m o u t h of w e s t H a s t i n g s Canyon. J o i n t s J o i n t i n g i s a p r o m i n e n t f e a t u r e of t h e v o l c a n i c s at t h r e e l o c a l i t i e s and t h u s d e s e r v e s i n c l u s i o n i n t h e d i s c u s s i o n of s t r u c t u r a l f e a t u r e s of t h e C e d a r M o u n t a i n s. T a b b y P e a k , l o c a t e d n o r t h of R y d a l c h P a s s , and M o r o n i ' s P o s t - p i l e show e x c e l l e n t c o l u m n a r j o i n t i n g and b o t h seem l i k e ly t o be v o l c a n i c p l u g s ( F i g s . 2 0 , 2 1 , 2 2 , 2 3 ) . These a r e d i s c u s s e d f u r t h e r u n d e r I g n e o u s R o c k s . An i g n e o u s o u t c r o p in S i x - H o r s e P a s s Canyon h a s v e r y w e l l - d e v e l o p e d h o r i z o n t al c o l u m n a r j o i n t i n g w h i c h i n d i c a t e s t h a t i t c o o l e d i n a v e r t - - 1 3 9 - I c a l f i s s u r e ( F i g . 2 4 ) . This d i k e and M o r o n i ' s P o s t P i le a r e w i t h i n t h e U . S . A r m y ' s Dugway P r o v i n g G r o u n d s R e s e r v a t i o n and c a n be v i s i t e d o n l y by o b t a i n i n g p e r m i s s i o n and a n e s c o r t a t t h e P r o v i n g G r o u n d s h e a d q u a r t e r s a t Dugway, U t a h . IGNEOUS ROCKS - l 4 l - I n t r o d u c t i o n B o t h i n t r u s i v e and e x t r u s i v e r o c k s o u t c r o p i n t h e Cedar M o u n t a i n s . The e x p o s u r e s a r e m o s t l y i n t h e s o u t h e r n p a rt o f t h e r a n g e and c o m p r i s e r h y o l i t e , b a s a l t i c a n d e s i t e , and b a s a l t . E r o s i o n of t h e v o l c a n i c s t r a t a i n t h e s o u t h e rn C e d a r M o u n t a i n s h a s r e s u l t e d i n a v e r y a n g u l a r r a n g e p r o f i le w h i c h c o n t r a s t s s h a r p l y w i t h t h e more r o u n d e d s u m m i ts d e v e l o p e d on t h e l a t e P a l e o z o i c s e d i m e n t a r y r o c k s i n t he n o r t h e r n p a r t of t h e r a n g e. A l l of t h e r h y o l i t e i s i n t r u s i v e and o c c u r s as two s m a l l s t o c k s . These b o d i e s a r e p o s t - o r o g r e n i c f e a t u r e s and w e r e e m p l a c e d a l o n g t h e c r e s t a l zone of t h e C o c h r a n V a l l ey A n t i c l i n e i n e a r l y T e r t i a r y t i m e . The r h y o l i t e i s p r o b a b ly t h e o l d e s t of t h e i g n e o u s r o c k s i n t h e C e d a r M o u n t a i n s. B a s a l t i c a n d e s i t e f l o w s , b r e c c i a s , a g g l o m e r a t e s , and t u f f s s o u t h of Tabby P e a k c o n s t i t u t e w e l l o v e r n i n e t y p e r c e n t of a l l i g n e o u s o u t c r o p s i n t h e r a n g e , w h i c h a r e e s t i m a t e d t o c o v e r a b o u t 27 s q u a r e m i l e s . The m a j o r o u t c r o ps a r e on t h e s o u t h and s o u t h w e s t f l a n k s of t h e r a n g e . These v o l c a n i c s w e r e d e p o s i t e d o v e r a d e e p l y e r o d e d l a n d s u r f a c e. A l o w e r f l o w , an i n t e r m e d i a t e t u f f , and an u p p e r f l o w u n it h a v e b e e n d i s t i n g u i s h e d and mapped n e a r Cane S p r i n g s . Pour - 1 4 2 - a n d e s i t e d i k e s h a v e b e e n mapped a l o n g t h e s o u t h w e s t m a r g in o f t h e r a n g e . Two v o l c a n i c n e c k s , Tabby P e a k and M o r o n i 's P o s t p i l e mark s o u r c e a r e a s w h i c h s u p p l i e d p a r t or a l l of t h e a n d e s i t e s e q u e n c e. T h e r e a r e s e v e r a l s m a l l b a s a l t o u t c r o p s i n t h e n o r t h e r n C e d a r M o u t a i n s b e t w e e n H a s t i n g s Canyon and R e d l am S p r i ng The f l o w s a r e e s t i m a t e d t o r e a c h a maximum t h i c k n e s s of 50 t o 100 f e e t and a r e made up of b o t h d e n s e a p h a n i t i c and s c o r i a c i o u s l a y e r s . The s o u r c e of t h e b a s a l t a p p e a r s to h a v e b e e n n e a r t h e p r e s e n t r e m n a n t s of t h e f l o w s . Movements on a m a j o r t r a n s v e r s e f a u l t h a v e t i l t e d t h e f l o w s i n H a s t i n g s Canyon a b o u t 10 t o 15 d e g r e e s t o w a r d t h e s o u t h. The C e d a r M o u n t a i n s a r e a i s i n t h e n o r t h e a s t e r n s e c t or o f t h e L a t i t e - M o n z o n i t e P r o v i n c e d e s c r i b e d by E a r d l e y ( 1 9 6 2) a n d j u s t o u t s i d e t h e n o r t h e a s t e r n b o u n d a r y of t h e I g n i m b r i te S u b p r o v i n c e . E r i c k s o n ( 1 9 6 3 ) h a s s t u d i e d t h e v o l c a n i c g e o l o g y of w e s t e r n J u a b C o u n t y , a b o u t 25 m i l e s s o u t h of t he C e d a r M o u n t a i n s , and h a s w o r k e d out a s e q u e n c e of v o l c a n ic e v e n t s f o r t h a t a r e a . A l t h o u g h i n c o m p l e t e i n t h e Cedar M o u n t a i n s , t h e s e q u e n c e i s s i m i l a r t o t h a t e s t a b l i s h e d by E r i c k s o n . The o l d e s t v o l c a n i c s of w e s t e r n J u a b C o u n t y a re made up of i g n i m b r i t e s and v i s c o u s f l o w s . Mackin ( I 9 6 0 ) d is c u s s e d t h e w i d e s p r e a d o c c u r r e n c e of i g n i m b r i t e v o l c a n i c s of p o s t - L a r a m i d e a g e i n t h e G r e a t B a s i n . He p r o p o s e d t h at - 1 4 3 - s t r u c t u r a l - s t r a t i g r a p h i c s t u d i e s of t h e s e r o c k s makes It p o s s i b l e t o work o u t t h e g e o m e t r y of b l o c k - f a u l t i n g not p o s s i b l e w i t h m e t h o d s u s e d p r e v i o u s l y. R h y o l i t e F i e l d R e l a t i o ns E x p o s u r e s of l i g h t g r a y p o r p h y r i t i c r h y o l i t e o c c ur a t two l o c a l i t i e s a l o n g t h e c r e s t a l zone of C o c h r a n V a l l ey A n t i c l i n e i n t h e s o u t h e r n C e d a r M o u n t a i n s . The f i r s t is a t W h i t e Rock and t h e s e c o n d a b o u t 8 m i l e s n o r t h w e s t in s e c . 33j T. 4 s . , R. 10 W. Both o u t c r o p s a r e w i t h i n t he t o p o g r a p h i c b o u n d a r i e s of t h e r a n g e b u t s t a n d a b o v e an imm e d i a t e l y a d j a c e n t l o w l a n d w i t h s e v e r a l h u n d r e d f e e t of r e l i e f . White Rock ( F i g . 18) i s t h e b e t t e r known of t he t w o f e a t u r e s . It m e a s u r e s a b o u t 2 , 0 0 0 f e e t a l o n g a n o r t h w e s t - s o u t h e a s t a x i s and t h e summit i s a b o u t 425 f e e t a b o ve t h e s u r r o u n d i n g p l a i n . It h a s l o n g b e e n a r a t h e r p r o m i n e nt l a n d m a r k and was d e s c r i b e d by g e o l o g i s t s of t h e F o r t i e th P a r a l l e l S u r v e y ( K i n g , 1 8 7 7 ) . Rain and m e l t w a t e r f r om snow d r a i n f r om t h e r h y o l i t e mass t o p r o d u c e W h i t e Rock S p r i ng w h i c h u s u a l l y c o n t a i n s w a t e r i n t h e s p r i n g and e a r l y summ e r . The r h y o l i t e a t W h i t e Rock and a l s o t h a t i n s e c . 33 9 T. 4 S o , R. 10 W. i s c o n s i d e r e d by t h e w r i t e r t o be F i g . 18 - P h o t o g r a p h of W h i t e Rock ( c e n t e r ) , p a r t of a r h y o l i t e s t o c k . Tabby P e a k i n t h e d i s t a n ce i m m e d i a t e l y n o r t h of W h i t e Rock. View Is n o r t h w a r d . F i g . 19 - P h o t o g r a p h s h o w i n g t h e t h r e e u n i t s of t h e b a s a l t ic s e r i e s a t Cane S p r i n g s. - 1 4 5 - i n t r u s i v e . ( P l a t e I I , S e c t i o n D - D T ) . The l o c a l d i p of b e ds o f t h e O q u i r r h F o r m a t i o n away f r om W h i t e Rock t o w a r d t he n o r t h w e s t , n o r t h e a s t , and s o u t h e a s t seems most s a t i s f a c t o r i l y e x p l a i n e d as a r e s u l t of i n t r u s i o n of t h e r h y o l i t e. The a x i s of C o c h r a n V a l l e y A n t i c l i n e h a s b e e n i n t e r r u p t e d by f o l d i n g of t h e dome a n d a p p a r e n t l y d e f l e c t e d 15 o r 20 d e g r e es t o w a r d t h e n o r t h e a s t . S e v e r a l s m a l l f a u l t s n e a r W h i t e Rock may h a v e b e e n f o r m e d a s a r e s u l t of t h e i n t r u s i v e a c t i o n. H o w e v e r , t h e r e a r e no e x p o s e d c o n t a c t s b e t w e e n t h e r h y o l i te a n d b e d s of t h e M a n n i n g Canyon o r O q u i r r h F o r m a t i o n s . No x e n o l i t h s of t h e c o u n t r y r o c k h a v e b e e n d i s c o v e r e d i n t he r h y o l i t e . It i s p o s s i b l e t h a t t h e r h y o l i t e i s e x t r u s i v e. The r h y o l i t e i s c o n s i d e r e d t o be o l d e s t of t h e i g n e o us r o c k s i n t h e C e d a r M o u n t a i n s . Based on t h e e v i d e n c e t h a t it I s i n t r u s i v e , t h e a n d e s i t e s t r a t a s o u t h w e s t of W h i t e Rock h a v e n o t b e e n I n v o l v e d i n t h e f o l d i n g a s s o c i a t e d w i t h i ts i n t r u s i o n and a r e t h e r e f o r e y o u n g e r t h a n t h e r h y o l i t e . The w r i t e r h a s n o t made o b s e r v a t i o n s w h i c h w o u l d d e f i n i t e ly e s t a b l i s h t h e r e l a t i v e age of t h e r h y o l i t e c o n s i d e r i n g t he a l t e r n a t i v e p o s s i b i l i t y t h a t i t may be e x t r u s i v e . Based on t h e a v a i l a b l e e v i d e n c e , t h e r h y o l i t e r e p r e s e n t s t h e e a r l i e st i g n e o u s a c t i v i t y i n t h e C e d a r M o u n t a i n s and h a s a p o s i t i on I n t h e i g n e o u s r o c k s e q u e n c e s i m i l a r t o t h e Keg M o u n t a i ns i g n i m b r i t e s and v i s c o u s f l o w s ( E r i c k s o n , p . 24) I n w e s t e rn - 1 4 6 - J u a b C o u n t y. L i t h o l o g y The r h y o l i t e I s l i g h t g r a y and p o r p h y r i t i c , w i t h an a p h a n i t i c g r o u n d m a s s . P h e n o c r y s t s of s a n i d i n e , q u a r t z , and b i o t i t e c o n s t i t u t e a b o u t 25 p e r c e n t of t h e r o c k . There is a n o c c a s i o n a l p r i s m of h o r n b l e n d e . Some s a n i d i n e c r y s t a ls r e a c h an I n c h a l o n g t h e l o n g e s t a x i s . Many a r e q u i te f r a c t u r e d and h a v e i r r e g u l a r m a r g i n s i n d i c a t i n g p a r t i al r e s o r p t i o n . The q u a r t z i s l e s s f r a c t u r e d and u s u a l l y has r o u n d e d e d g e s. I n t h i n s e c t i o n t h e g r o u n d m a s s i s s e e n t o be h o l o c r y - s t a l l i n e and t o c o n t a i n m o s t l y a m i c r o c r y s t a l l i n e I n t e r g r o w th o f q u a r t z and s a n i d i n e . A u g i t e c r y s t a l s w i t h c h a r a c t e r i s t i c a l l y s q u a r e o u t l i n e s a h a l f m i l l i m e t e r o r l e s s i n d i a m e t er a n d n o t r e c o g n i z a b l e i n h a n d s p e c i m e n s u s u a l l y o c c u r in s m a l l c l u s t e r s . The a u g i t e I s e s t i m a t e d t o c o m p r i s e o n ly a b o u t 1 p e r c e n t , or a l i t t l e m o r e , of t h e r o c k . Brown b i o t i t e f l a k e s a c c o m p a n i e d by n u m e r o u s m a g n e t i t e g r a i n s make up a b o u t 2 p e r c e n t of t h e r o c k . There a r e a few g r a i n s of a n d e s i n e ( A n - ^ - ^ O ). B a s a l t i c A n d e s i t e S e r i es O b s e r v a t i o n s of t h e v o l c a n i c s t r a t a of t h e C e d a r Moun- - 1 4 7 - t a i n s n o r t h of t h e Dugway P r o v i n g G r o u n d s d u r i n g t h e e a r ly p a r t of t h e f i e l d work l e a d t o t h e r e c o g n i t i o n of e x t e n s i ve a n d e s i t e o u t c r o p s e s p e c i a l l y i n t h e a r e a s o u t h of C o c h r an S p r i n g . L i g h t brown a n d e s i t e and d a c i t e c r y s t a l t u f f were a l s o n o t e d a t C o c h r a n S p r i n g and i n t h e e a s t R y d a l c h Canyon a r e a . However, t h e i n f o r m a t i o n g a i n e d from f i e l d o b s e r v a t i o n s seemed I n a d e q u a t e t o d i f f e r e n t i a t e more t h a n two v o l c a n i c u n i t s or t o d e t e r m i n e a s t r a t i g r a p h i c s e q u e n c e f or t h e v o l c a n i c u n i t s . In l a t e May, 1 9 6 6 , t h e w r i t e r o b t a i n ed p e r m i s s i o n f r om a u t h o r i t i e s a t Dugway P r o v i n g G r o u n d s to s p e n d t h r e e d a y s i n v e s t i g a t i n g t h e v o l c a n i c r o c k s i n t he a r e a b e t w e e n Dugway and M o r o n i ' s P o s t p i l e w h i c h i s l o c a t ed i n t h e NE 1 / 4 , T. 6 S . , R. 11 W. D u r i n g p a r t of t h is p e r i o d , t h e v o l c a n i c s e c t i o n i n t h e v i c i n i t y of Cane S p r i n gs was s t u d i e d and s e e n t o c o m p r i s e t h r e e m e m b e r s : a l o w er u n i t of a n d e s i t e f l o w s and a g g l o m e r a t e s , a m i d d l e t u f f , and a n u p p e r a n d e s i t e f l o w u n i t . These u n i t s w e r e mapped to t h e e x t e n t t h a t t i m e p e r m i t t e d. Lower B a s a l t i c A n d e s i t e F l o w s and A g g l o m e r a t es The l o w e r u n i t i s made up of d e n s e , b r o w n - g r a y , p o r p h y r - i t i c b a s a l t i c a n d e s i t e . It c o n t a i n s a c o n s i d e r a b l e amount o f a g g l o m e r a t e as w e l l a s f l o w u n i t s n e a r Cane S p r i n g s . The maximum t h i c k n e s s i n t h e a r e a mapped was e s t i m a t e d t o be b e t w e e n 250 and 300 f e e t u s i n g U. S. G e o l o g i c a l S u r v e y, - 1 4 8 - T a b b y P e a k SW, 7 . 5 m i n u t e s h e e t f o r t o p o g r a p h i c c o n t r o l. P l a g i o c l a s e p h e n o c r y s t s h a v e a s u b - p a r a l l e l a l i g n m e nt i n t h e b r o w n - g r a y g r o u n d m a s s whose s l i g h t l y waxy a p p e a r a n ce i n d i c a t e s t h a t g l a s s c o n s t i t u t e s p a r t of t h e g r o u n d m a s s. P l a g i o c l a s e p h e n o c r y s t s p l u s an u n i d e n t i f i e d f e r r o m a g n e s i an m i n e r a l make up a b o u t 10 p e r c e n t of t h e r o c k. I n t h i n s e c t i o n l a b r a d o r i t e ( A n ^ _ g 0 ) I s s e e n t o comp o s e a b o u t 60 t o 75 p e r c e n t of t h e r o c k . Many of t h e p h e n o c r y s t s h a v e n o r m a l , z o n e d s t r u c t u r e . A u g i t e i n c r y s t a l s up t o a b o u t 0 . 5 mm f o r m s a b o u t 5 p e r c e n t of t h e r o c k . Glass f o r m s a b o u t 15 t o 20 p e r c e n t of t h e g r o u n d m a s s . Minute m a g n e t i t e g r a i n s a r e a m i n o r a c c e s s o r y . An o c c a s i o n a l f l a ke o f b i o t i t e i s s e e n w h i c h h a s b e e n a l m o s t c o m p l e t e l y a l t e r ed l e a v i n g a s m a l l c l u s t e r of m a g n e t i t e g r a i n s. C h e m i c a l a n a l y s i s of a s p e c i m e n from t h e l o w e r u n i t is shown i n t h e f o l l o w i n g l i s t: 1 2 3 4 5* 6* 7* 8* SIO 57.65 6 6 . 9 1 6 2 . 2 5 6 1 . 1 2 53-6 55.4 56.8 55.8 CaO 5.74 3.27 4.05 5.80 7.10 3*80 8.15 9.80 N a P 0 3.59 4.13 3.55 3»82 2.25 2.90 2.46 2.90 K2 0 4.39 2.50 2o44 1.72 2.08 3.60 3.22 2.28 1 . Average L a t i t e . D a l y , R. A . , 1 9 1 4 , I g n e o u s r o c k s and t h e i r o r i g i n , p . 2 3 . M c G r a w - H i l l , 2 . Average D a c i t e . Daly, R . A . , o p . c i t . , p . 2 5. 3* A v e r a g e M i c a - A n d e s i t e . Daly, R. A . , o p . c i t . , p . 26. - 1 4 9 - 4 . Average H o r n b l e n d e - A n d e s i t e . Daly, R. A . , o p . c i t . , p . 26 5 . A n d e s i t e from l o w e r u n i t i n t h e C e d a r M o u n t a i n s at Cane S p r i n g . U n s u r v e y e d , 3 m i l e s w e s t of SW 1 / 4, T. 5 S . , R. 9 W. 6 . A n d e s i t e t u f f ( l e a c h e d ) from m i d d l e u n i t i n t h e C e d ar M o u n t a i n s 2 m i l e s s o u t h e a s t of Cane S p r i n g s. 7 . A n d e s i t e from u p p e r u n i t i n t h e C e d a r M o u n t a i n s 2 m i l es s o u t h e a s t of Cane S p r i n g s. 8 . A n d e s i t e ( M o r o n i ' s P o s t p i l e ) 2 m i l e s n o r t h e a s t of Wig M o u n t a i n , e x t r e m e s o u t h w e s t p a r t of S o u t h e r n Cedar M o u n t a i n s G e o l o g i c Map. * C h e m i c a l a n a l y s e s made t h r o u g h t h e c o u r t e s y of t h e U t ah G e o l o g i c a l and M I n e r a l o g i c a l S u r v e y. M i d d l e T u f f U n it The m i d d l e t u f f u n i t a t Cane S p r i n g s i s a l i g h t g r a y, p o r o u s , a n d e s i t e , c r y s t a l t u f f . There i s a l s o l o c a l l y some d a c i t e . Many of t h e p l a g i o c l a s e p h e n o c r y s t s h a v e b e en a l t e r e d t o a c l a y m i n e r a l . T h e r e a r e o c c a s i o n a l b r o k e n p h e no c r y s t s of s a n i d i n e . Much of t h e u n i t a t t h i s l o c a l i t y is c o a r s e a g g l o m e r a t e w i t h c o b b l e s and b o u l d e r s a s l a r g e as 2 f e e t i n d i a m e t e r i n a f i n e g r a v e l m a t r i x . Water a t Cane S p r i n g s e m e r g e s f r om n e a r t h e b a s e of t h e t u f f w h i c h a p p e a rs t o be a n a q u i f e r a t l e a s t I n a s m a l l a r e a n e a r t h e s p r i n g s. About 2 m i l e s s o u t h e a s t of Cane S p r i n g s , t h e m i d d l e u n i t is a l m o s t c o m p l e t e l y I n d u r a t e d c r y s t a l t u f f . Inasmuch a s t h e re i s o n l y one t u f f u n i t i n t h e v o l c a n i c s e q u e n c e a t Cane - 1 5 0 - S p r i n g s , i t seems l i k e l y t h a t t h e d e n s e , l i g h t brown t o g r ay c r y s t a l t u f f b e d s I n t h e C o c h r a n S p r i n g - e a s t R y d a l c h Cany o n a r e a a r e c o r r e l a t i v e s of t h e m i d d l e t u f f u n i t . The m i d d l e t u f f u n i t i n t h e e a s t R y d a l c h Canyon a r e a d i r e c t ly o v e r l i e s t h e M a n n i n g Canyon F o r m a t i o n s u g g e s t i n g t h a t t he l o w e r b a s a l t i c a n d e s i t e u n i t d i d n o t e x t e n d t h a t f a r n o r t h w a r d . At Cane S p r i n g s , t h e m i d d l e t u f f u n i t i s e s t i m a t e d to b e a b o u t 100 t o 150 f e e t t h i c k. A p a r t i a l c h e m i c a l a n a l y s i s of a s p e c i m e n f r om t h^ m i d d l e t u f f u n i t i s shown w i t h t h e l i s t on p . 1^7. The comp a r a t i v e l y low CaO c o n t e n t and h i g h K2 0 s u g g e s t a r o ck n e a r e r l a t i t e i n c o m p o s i t i o n t h a n a n d e s i t e . However, a t h i n s e c t i o n from a r e l a t i v e l y f r e s h p o r t i o n of a s p e c i m en h a s t h e c h a r a c t e r i s t i c s of b a s a l t i c a n d e s i t e . It c o n t a i ns a l i t t l e more t h a n 50 p e r c e n t l a b r a d o r i t e ( A n g 0 _ g ^ ) . It h a s 2 - 3 p e r c e n t b i o t i t e and a b o u t 1 p e r c e n t a u g i t e . There i s an o c c a s i o n a l s a n i d i n e p h e n o c r y s t 3 t o 5 mm l o n g . T e x t u re o f t h e r o c k p a r t i c l e s i s h y a l o p l l i t i c . L e a c h i n g of t h e t u ff u n i t may h a v e a l t e r e d i t s c o m p o s i t i o n i n f a i r l y l a r ge s a m p l e s t o t h e e x t e n t t h a t t h e c h e m i c a l a n a l y s i s d o e s not r e p r e s e n t i t s o r i g i n a l c o m p o s i t i o n. U p p e r B a s a l t i c A n d e s i te At Cane S p r i n g s t h e u p p e r f l o w u n i t c o n s i s t s of b o th d a r k g r a y and m a r o o n a n d e s i t e . It h a s a c r u d e , v e r t i c al - 1 5 1 - c o l u m n a r j o i n t i n g a t p l a c e s a l o n g t h e o u t c r o p . The b o t t om f ew f e e t of t h e u n i t a r e c o n s p i c u o u s l y d a r k e r g r a y t h a n t he h i g h e r p a r t s of t h e u n i t . The d a r k e r c o l o r i s p r o b a b l y t he e f f e c t of a g r e a t e r amount of g l a s s h a v i n g b e e n formed w h e r e c o o l i n g r a t e was g r e a t e r n e a r t h e b o t t o m of t h e f l o w. The u p p e r u n i t i s e s t i m a t e d t o be a t l e a s t 500 f e e t t h i ck i n t h e a r e a n e a r Cane S p r i n g s. A r e p r e s e n t a t i v e hand s p e c i m e n of t h e u p p e r u n i t has d e n s e p o r p h y r i t i c a p h a n i t i c t e x t u r e . P h e n o c r y s t s a r e of p l a g i o c l a s e , h o r n b l e n d e and an o c c a s i o n a l b i o t i t e c r y s t al t h a t r e a c h e s a b o u t 1 mm i n l e n g t h . An o c c a s i o n a l s a n i d i ne c r y s t a l may r e a c h 1 cm i n l e n g t h . The s a n i d i n e c o n s t i t u t es o n l y 1 o r 2 p e r c e n t of t h e r o c k . In t h i n s e c t i o n t h e r o ck i s s e e n t o h a v e a g r o u n d m a s s t h a t i s a b o u t 20 p e r c e n t g l a ss a n d 70 t o 75 p e r c e n t l a b r a d o r i t e m i c r o l i t e s . There a r e s m a ll a m o u n t s of b o t h h o r n b l e n d e and a u g i t e . The h o r n b l e n d e has b e e n l a r g e l y r e p l a c e d by c l u s t e r s of m a g n e t i t e g r a i n s . The r o c k h a s a h y a l o p i l l t i c t e x t u r e . A p a r t i a l c h e m i c a l a n a l y s i s of a s p e c i m e n of t h e Upper P l o w U n i t i s shown i n t he l i s t on p . 1 4 7. T a b b y P e a k ( P i g . 2 0 , 2 1 ) , a b o u t a h a l f m i l e n o r t h of t h e summit i n R y d a l c h C a n y o n , and M o r o n i ' s P o s t p i l e ( F i g . 2 2, 2 3 ) a t t h e s o u t h w e s t edge of t h e r a n g e , a r e i n t e r p r e t e d to b e v o l c a n i c n e c k s . Both f e a t u r e s a r e c o m p o s e d of a n d e s i te - 1 5 2 - v e r y s i m i l a r t o t h a t of t h e l o w e r and u p p e r b a s a l t i c a n d e s i t e u n i t s and t h e y p r o b a b l y a r e t h e v e n t s w h i c h s u p p l i ed p a r t or a l l of t h e l a v a f o r t h e A n d e s i t e S e r i e s. The e x p o s u r e a t Tabby P e a k h a s v e r t i c a l c o l u m n a r j o i n ts w h i c h d i v e r g e o u t w a r d t o w a r d t h e b a s e w h i c h i s t y p i c a l of some v o l c a n i c n e c k s . Viewed from t h e t o p ( P i g . 2 1 ) , t he c o l u m n s a t Tabby P e a k h a v e a c o n s p i c u o u s c o n c e n t r i c p a t t e rn w h i c h p o s s i b l y s u g g e s t s some p o s t - c o n s o l i d a t i o n v e r t i c al m o v e m e n t . The w r i t e r h a s n o t e x a m i n e d t h e c o l u m n s and t h e i r c o n t a c t s i n p l a c e t o f u r t h e r t e s t t h i s i d e a. M o r o n i ' s P o s t p i l e a l s o h a s v e r t i c a l c o l u m n a r j o i n ts w h i c h d i v e r g e d o w n w a r d . A c h e m i c a l a n a l y s i s of a s p e c i m en f r om M o r o n i ' s P o s t p i l e shows i t s c h e m i c a l s i m i l a r i t y t o t he l o w e r and u p p e r u n i t s of t h e A n d e s i t e S e r i e s. P o u r d i k e s h a v e b e e n mapped a l o n g t h e s o u t h w e s t e r n b o r d e r of t h e r a n g e . The one i n S i x H o r s e Canyon ( P i g . 24) h a s a r o u g h l y e a s t - w e s t s t r i k e and I s on t r e n d n o r t h w e s t of t h e f a u l t w h i c h f o r m s t h e n o r t h e r n b o u n d a r y of t h e a n d e s i te s e r i e s n o r t h of Cane S p r i n g s . It h a s h o r i z o n t a l c o l u m n ar j o i n t i n g , w i t h t h e c o l u m n s o r i e n t e d n o r t h - s o u t h . It is a n d e s i t e w h i c h c o n t a i n s b o t h h o r n b l e n d e and a u g i t e . Some h o r n b l e n d e p h e n o c r y s t s r e a c h a c e n t i m e t e r i n l e n g t h . In t h i n s e c t i o n t h e h o r n b l e n d e , e s p e c i a l l y t h e s m a l l e r g r a i n s, h a s b e e n a l t e r e d l e a v i n g c l u s t e r s of m a g n e t i t e g r a i n s w h i le F i g . 21 - P h o t o g r a p h of Tabby P e a k s h o w i n g c o n c e n t r ic c o l u m n . View i s t o w a r d t h e s o u t h. P i g . 22 - P h o t o g r a p h s h o w i n g M o r o n i ' s P o s t p i l e as s e en f r om t h e e a s t . B o n n e v i l l e Lake l e v e l n e a r t he summit a t an e l e v a t i o n of a b o u t 5120 f e e t. P i g . 23 - P h o t o g r a p h s h o w i n g c o l u m n a r j o i n t i n g of M o r o n i ' s P o s t p i l e. t h e a u g i t e a p p e a r s r e l a t i v e l y u n c h a n g e d. The s t r a t a of t h e b a s a l t i c a n d e s i t e s e q u e n c e w e r e d e p o s i t e d o v e r a d e e p l y e r o d e d l a n d s u r f a c e whose minimum r e l i e f i n t h e a r e a of Cane S p r i n g s i s e s t i m a t e d t o h a v e b e en b e t w e e n 1200 and 1300 f e e t . Mapped c o n t a c t s and t o p o g r a p h i c c o n t r o l p r o v i d e d by t h e U. S. G e o l o g i c a l S u r v e y, T a b b y P e a k SW Q u a d r a n g l e , 7 . 5 m i n u t e s e r i e s map f o rm t he b a s i s f o r t h i s e s t i m a t e . Minimum r e l i e f i n t h e a r e a s o u th o f B r o w n ' s S p r i n g was a b o u t 900 f e e t. The age of t h e b a s a l t i c a n d e s i t i c s e r i e s can be e s t a b l i s h e d as y o u n g e r t h a n t h e E a r l y L a r a m i d e C o c h r a n S p r i ng A n t i c l i n e . It f o l l o w e d t h e E a r l y L a r a m i d e O r o g e n y by a p e r i o d l o n g e n o u g h t o p e r m i t d e e p e r o s i o n of t h e f o l d s . The s e r i e s i s o l d e r t h a n t h e R y d a l c h Canyon T r a n s v e r s e F a u lt w h i c h i s most p r o b a b l y of l a t e T e r t i a r y a g e. B a s a l t S e v e r a l s m a l l b a s a l t f l o w s a r e f o u n d i n H a s t i n g s Canyon a n d t h e a d j o i n i n g a r e a s o u t h w a r d t o w a r d R e d l am S p r i n g . One i s o l a t e d o u t c r o p of s c o r i a s p a n s t h e s o u t h e r n b o u n d a r y of s e c . 9. T. 2 S . , R. 10 W. The v a r i a t i o n s i n e l e v a t i o n of t h e b a s e s of s e v e r a l of t h e s m a l l b a s a l t m a s s e s s o u t h of H a s t i n g s Canyon I n d i c a t e s a t l e a s t a few h u n d r e d f e e t of t o p o g r a p h i c r e l i e f at t h e t i m e t h e l a v a was e x t r u d e d . The t h i c k e r f l o w s a r e i n H a s t i n g s Canyon and a r e e s t i m a t e d to b e b e t w e e n 50 and 100 f e e t i n t h i c k n e s s. One a p p a r e n t s o u r c e of t h e b a s a l t i s i n t h e c a n y o n w h i ch t r e n d s n o r t h t h r o u g h t h e n o r t h w e s t q u a r t e r of T. 2 S . , R. 9 W. w h e r e two b a s a l t o u t c r o p s w e r e l o c a t e d . These two e x p o s u r es a r e p r o b a b l y p a r t of one d i k e w h i c h f o r m e d as magma was I n j e c t e d a l o n g t h e p l a n e of t h e m a j o r r e v e r s e f a u l t a t t h at l o c a t i o n . The b a s a l t s t r a t a I n H a s t i n g s Canyon h a v e b e e n r o t a t ed 10 t o 15 d e g r e e s t o w a r d t h e s o u t h by movement on t h e H a s t i n gs C a n y o n T r a n s v e r s e F a u l t . They c o n s t i t u t e e x a m p l e s of L o u d e r b a c k s ( D a v i s , W. M., 1 9 3 0 , p . 299) w h i c h a r e l a v a - c a p p e d T e r t i a r y b l o c k s t h a t h a v e b e e n d i s p l a c e d from t h e ir o r i g i n a l o r i e n t a t i o n, D o e l l i n g ( 1 9 6 4 , p . 275) r e p o r t e d t h a t b a s a l t i c f l o ws h a v e b e e n d i s c o v e r e d In v a r i o u s a r e a s a r o u n d t h e m a r g i n of t h e G r e a t S a l t Lake D e s e r t and t h e s e h a v e g e n e r a l l y b e en d a t e d a s M i o c e n e - P l i o c e n e . This age seems f e a s i b l e f o r t he b a s a l t i c r o c k s I n t h e n o r t h e r n C e d a r M o u n t a i n s. P i g . 24 - P h o t o g r a p h s h o w i n g an a n d e s i t e d i k e i n S ix H o r s e Canyon w h i c h e x h i b i t s h o r i z o n t a l, c o l u m n a r j o i n t i n g. - 1 5 8 - GEOLOGIC HISTORY P a l e o z o i c Era D u r i n g e a r l i e s t M i s s l s s i p p i a n t i m e , t h e M a d i s o n L i m e s t o n e and I t s e q u i v a l e n t s w e r e d e p o s i t e d i n a s h a l l o w s ea o v e r a b r o a d a r e a of t h e C o r d i l l e r a n m l o g e o s y n c l i n e and t h e s h e l f a r e a t o t h e e a s t . F o l l o w i n g t h i s e p o c h , s h o r e l i n e s of t h e e a r l y M i s s l s s i p p i a n s e a r e c e d e d b o t h f r om t he n o r t h w e s t and t h e e a s t t o w a r d t h e O q u i r r h B a s i n of n o r t h w e s t e r n U t a h w h e r e l i m e s t o n e and s a n d s t o n e f o r m a t i o ns c o n t i n u e d a c c u m u l a t i n g ( W i l l i a m s , 1 9 6 3 ) . The Humbug F o r m a t i o n , o l d e s t e x p o s e d i n t h e C e d a r M o u n t a i n s , i s p r e d o m i n a n t l y f i n e s a n d s o n e and q u a r t z i t e and r e p r e s e n t s n e a r s h o re d e p o s i t i o n i n a b a s i n of m o d e r a t e l y a c t i v e s u b s i d e n c e . An e a s t e r n p h |
