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Show 36 l i m e s t o n e a p p r o x i m a t e l y 1,134 f e e t of s t r a t a c o u l d be a s s i g n e d to t h e O p h i r f o r m a t i o n. R e g a r d i n g the S t o c k t o n - F a i r f i e i d a r e a , G i l l u l y (1932, p . 9) s t a t e s t h a t the T i n t i c - O p h i r c o n t a c t i s t r a n s i t i o n a l and t h a t: " T h e b o u n d a r y s e l e c t e d in m a p p i n g was t h e b a se of t h e l o w e s t ' s h a l e 1 bed whose t h i c k n e s s e x c e e ds one f o o t . This ' s h a l e ' b e d , which i s r e a l l y a s c h i s t, i s e a s i l y t r a c e a b l e and i d e n t i f i a b l e a b o v e the q u a r t z i t e o u t c r o p s and was s e l e c t e d f o r t h i s r e a s o n, a l t h o u g h it i s p o s s i b l e t h a t the top of t h e t r a n s i t i o n al b e d s would be an e a s i e r h o r i z o n to i d e n t i f y u n d e r g r o u n d ." A l s o , in t h e S t o c k t o n - F a i r f i e i d a r e a , the u p p e r b o u n d a r y of t h e O p h ir f o r m a t i o n Uke the l o w e r i s a r b i t r a r y but with l e s s t r a n s i t i o n a l m a t e r i a l. G i l l u l y ( 1 9 3 2 , p . 11) s t a t e s t h a t , " T h e b o u n d a r y b e t w e e n t h i s f o r m a t i on a n d the H a r t m a n n l i m e s t o n e i s d r a w n at t h e top of t h e h i g h e s t s h a le b e d in t h i s p a r t of the s e c t i o n " . The S h e e p r o c k s e c t i o n c a n be d i v i d ed s i m i l a r l y b e t w e e n the t o p of t h e T i n t i c q u a r t z i t e and t h e b a s e of the l i m e s t o n e m e m b e r of the S w a s e y l i m e s t o n e ( s e e F i g u r e 3) a n d is r e p r e s e n t e d by a p p r o x i m a t e l y 1,134 feet of O p h i r s t r a t a c o m p a r e d to 320 f e e t of s t r a t a f o r the S t o c k t o n - F a i r f i e i d a r e a. In t h e C a n y o n R a n g e ( C h r i s t i a n s e n , ( 1952, p . 723) c o n s i d e r s the b a s a l O p h i r f o r m a t i o n a s the b o t t om of a f u c o i d a l 5 5 - f o o t unit of i n t e r b e d d e d s a n d s t o n e and s h a l e , w h e r e a s the u p p e r c o n t a c t i s t h e top of a s h a l e s e q u e n c e about 200 f e e t t h i c k which l i e s a b o v e 225 f e et of l i m e s t o n e s . This c h o i c e of c o n t a c t s g i v e s a t o t a l of 975 f e e t of s t r a t a f o r t h e O p h i r f o r m a t i o n . If a s i m i l a r c h o i c e of b o u n d a r i es SHEEPROCK MTS. Ct COMPARISON OF SHEEPROCK AND EAST TINTIC SECTIONS SHEEPROCK MTS. et i'y»,'-f.w.' y COMPARISON OF SHEEPROCK AND OQUIRRH SECTIONS SHEEPROCK MTS. CANYON RANGE i : 177 7i I I II COMPARISON OF SHEEPROCK AND CANYON RANGE SECTIONS R E G I O N A L 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 O F B A S A L C A M B R I A N C A R B O N A T ES •Cw = WHEELER FM., €h = HARTMANN LS.,-Cmt« TEUTONIC LS. , Cmu • CAMBRIAN UNDIFF. (€8= SWASEY LS. , -Cc • CON DOR FM. , €d = DOME LS. , €bc •= BURNT CAN. FM., Cm* MILLARD FM. , € b 1 BUSBY FM.,€p * PIOCHE SH., Co » OPHIR FM. , €t "TINTIC QTZT. ) F I G U R E 3 w e r e m a d e in t h e S h e e p r o c k a r e a , the O p h i r f o r m a t i o n would be r e p r e s e n t e d by t h e i n t e r v a l b e t w e e n the top of t h e T i n t i c q u a r t z i te a n d the b a s e of t h e l i m e s t o n e m e m b e r of t h e S w a s e y l i m e s t o n e and would be 1, 134 f e e t t h i c k. No p r o b l e m of l i t h o l o g i c c o r r e l a t i o n e x i s t s b e t w e e n the P i o c he a n d O p h i r s h a l e s but p a i e o n t o l o g i c a l i y a g r e a t g a p i s r e a d i l y a p p a r e n t. E v e n though it i s p r o p e r to d i s r e g a r d t i m e when c o r r e l a t i n g l i t h o l o g ic u n i t s , the w r i t e r b e l i e v e s the " d i s r e g a r d " s h o u l d h a v e s o m e l i m i t s. • Without l i m i t s , it i s c o n c e i v a b l e t h a t f a r out on t h e C a m b r i a n shelf a r e a s t h e P i o c h e s h a l e m a y c o n f o r m a b l y u n d e r l i e the L y n c h o r the Ajax d o l o m i t e o r o t h e r u p p e r C a m b r i a n f o r m a t i o n s . A b a s a l q u a r t z i te m a y h a v e g r e a t e r s i g n i f i c a n c e than t h e o v e r l y i n g s h a l e b e c a u s e the q u a r t z i t e c a n n o t o t h e r w i s e be a d e q u a t e l y d a t e d ; w h e r e a s , the o v e r l y i ng s h a l e s c a n usualLy be d a t e d by f o s s i l s . The b a s a l s h a l e s of t h e d e e p er b a s i n s h a v e b e e n n a m e d ' P i o c h e 1 ; w h e r e a s , t h o s e in m o r e s h e l v i ng a r e a s , r e l a t i v e to t h e C a m b r i a n g e o s y n c i i n e , a r e c a l l e d O p h i r. P i o c h e s h a l e h a s a l o w e r C a m b r i a n c o n n o t a t i o n while O p h i r s h a le i m p l i e s M i d d l e C a m b r i a n . To c o r r e l a t e P i o c h e with O p h i r without s p e c i f i c m e n t i o n t h a t the c o r r e l a t i o n i s only l i t h o l o g i c i s p r o b a b ly c o n f u s i n g to m o s t g e o l o g i s t s ; to t h e s t u d e n t s of C a m b r i a n s t r a t i g r a p hy p o s s i b l y no p r o b l e m e x i s t s. 38 W h e e l e r (1948, p . 25) s t a t e s: " T h e ' O p h i r 1 and ' C a b i n ' s h a l e s of w e s t e r n Utah a r e a m o n g t h e s y n o n y m s of t h e P i o c h e ." The w r i t e r b e l i e v e s t h a t f o r the H o u s e R a n g e s e c t i o n ( P l a t e XI) t h e O p h i r s h a l e i s not only a s y n o n y m of t h e P i o c h e but a l s o the B u s b y , the M i l l a r d ( L y n d o n - C h i s h o i m - P e a s i e y ) , the B u r r o w s , B u r nt C a n y o n , Dome, and the C o n d o r m e m b e r of t h e S w a s e y . In t h e Deep C r e e k M o u n t a i n s ' O p h i r ' t i m e i s r e p r e s e n t e d by t h e C a b i n s h a l e, t h e B u s b y q u a r t z i t e and m u c h of t h e l o w e r p o r t i o n of the A b e r c r o m b ie f o r m a t i o n . C o r r e l a t i o n s to s e c t i o n s west of t h e S h e e p r o c k M o u n t a i n s i s b o th p a l e o n t o l o g i c and l i t h o l o g i c ; w h e r e a s t h e t i e with ' t y p e ' O p h i r to the e a s t i s m a i n l y by l i t h o l o g y. T h e w r i t e r p r o p o s e s t h a t the t e r m s ' O p h i r s h a l e ' and ' O p h ir f o r m a t i o n ' be r e s t r i c t e d to t h e a r e a s in which t h e y h a v e b e e n a p p l i e d. A u t h o r s of v a r i o u s r e p o r t s do not s e e m to b e in a g r e e m e n t c o n c e r n i ng t h e b o u n d a r i e s of t h e O p h i r f o r m a t i o n ; h o w e v e r , the b o u n d a r i es d e s c r i b e d m a r k s h a r p l i t h o l o g i c c h a n g e s and p o s s e s s a h i g h d e g r e e of u t i l i t y within t h e l i m i t s of t h e a r e a of e a c h r e p o r t . The d i f f e r e nt c r i t e r i a u s e d to d e p i c t a t r a n s i t i o n a l c o n t a c t a s d i s c u s s e d in t h e f o r e g o i n g p a r a g r a p h s , t o g e t h e r with the p r e s e n c e of t h r e e d i s t i n c t f a u n al h o r i z o n s within t h e O p h i r of t h e S h e e p r o c k a r e a and a r e c o g n i t i on of m a n y H o u s e R a n g e i i t h o i o g i e s , h a s p r e s e n t e d a p r o b l e m which is b e s t r e s o l v e d by e l e v a t i n g the O p h i r f o r m a t i o n to g r o u p s t a t u s . In 39 t h i s way f u t u r e i n v e s t i g a t o r s m a y u s e O p h i r g r o u p a s a l u m p t e rm o r m a y s u b d i v i d e it if t i m e , l i t h o l o g y , and f a u n a p e r m i t. L i m i t s - The O p h i r g r o u p a s d e s c r i b e d h e r e c o m p r i s e s a l l the s t r a t a f r o m the top of t h e P r o s p e c t M o u n t a i n q u a r t z i t e t h r o u g h the C o n d o r m e m b e r of t h e S w a s e y l i m e s t o n e ( P l a t e s X, XI, and XVII). A c c o r d i n g to t h e C o m m i t t e e on S t r a t i g r a p h i c N o m e n c l a t u r e ( A s h l ey et a l . , p . 437, 1933), a g r o u p i s a l o c a l o r p r o v i n c i a l s u b d i v i s i on of a s y s t e m b a s e d on l i t h o l o g y . It c o m p r i s e s two o r m o r e f o r m a t i o n s. I n a s m u c h a s t h e t o p c o n t a c t of t h e p r o p o s e d O p h i r g r o u p i s p l a c e d at t h e t o p of t h e C o n d o r m e m b e r of t h e S w a s e y l i m e s t o n e , it i s n e c e s s a ry to r e d e f i n e the C o n d o r a s a f o r m a t i o n to a v o i d p l a c i n g a g r o u p c o n t a ct w i t h i n a f o r m a t i o n. T h e O p h i r g r o u p c o m p r i s e d t h e f o l l o w i n g f o r m a t i o n s o r t h e ir e q u i v a l e n t s : P i o c h e s h a l e , B u s b y q u a r t z i t e , M i l l a r d l i m e s t o n e, B u r r o w s l i m e s t o n e , B u r n t Canyon l i m e s t o n e , Dome l i m e s t o n e , and t h e C o n d o r f o r m a t i o n (new n a m e ) . Although m a n y of t h e f o r m a t i o ns m a y h a v e p r i o r i t y in p u b l i s h e d w o r k s ^ t h e t e r m O p h i r i s a p p l i e d b e c a u s e of i t s u s a g e and w i d e s p r e a d r e c o g n i t i o n on o r n e a r t h e ' W a s a t ch l i n e ' w h e r e t h e d i s c o v e r y and e x p l o i t a t i o n of t r e m e n d o u s a m o u n t s of b a s i c m e t a l s h a s s t i m u l a t e d and f o s t e r e d m a n y g e o l o g i c i n v e s t i g a t i o n s. B a s i c a l l y , the p r o b l e m i s one c o n c e r n i n g the m e r g i n g of t h e ' b a s i n or t r o u g h ' C a m b r i a n s t r a t a with t h e ' s h e l f C a m b r i a n b e d s . To a v o id p r e s e n t i n g a s e r i e s of n e w f o r m a t i o n s , an a t t e m p t h a s b e e n m a d e to 40 s i m p l i f y the s i t u a t i o n . S t r i c t a d h e r e n t s of e i t h e r ' b a s i n 8 o r ' t r o u g h' t e r m i n o l o g y m o s t l i k e l y c a n n o t b e s a t i s f i e d ; but, it i s h o p e d t h a t t h is p r e s e n t a t i o n m a y r e s o l v e m a n y u n c e r t a i n t i e s. C o n c l u s i o n s - No r e a s o n a b l e p a i e o n t o i o g i c c o m p a r i s o n b e t w e en t h e t y p e a r e a of t h e O p h i r s h a l e and t h o s e a r e a s d i r e c t l y c o r r e l a t ed with t h e ' t y p e ' s e c t i o n c a n b e r e l i a b l y m a d e . To a v o i d f u r t h e r c o n f u s i o n s the w r i t e r , wishing to r e c o g n i z e O p h i r a s a d e s i g n a t i o n for a r o c k u n i t , h a s c h o s e n to e l e v a t e t h e O p h i r to g r o u p s t a t u s f o r p u r p o s es of d i s c u s s i o n of t h e S h e e p r o c k s e c t i o n . S e v e r a l d i s t i n c t f a u n u l e s f a ll w i t h i n t h e b o u n d a r i e s of t h e O p h i r f o r m a t i o n a s do s e v e r a l i i t h o l o g i e s. A p r o p o s a l s u c h a s t h e f o r e g o i n g i s b o u n d to b e c h a l l e n g e d by m e m b e r s of t h e g e o l o g i c a l p r o f e s s i o n e s p e c i a l l y c o n c e r n e d with s t r a t i g r a p h i c n o m e n c l a t u r e . If c r i t i c s d i s a g r e e with t h i s p r o p o s al t h e n t h e y m u s t a u t o m a t i c a l l y s u p p o r t a s u b d i v i s i o n of O p h i r in the S h e e p r o c k M o u n t a i n s e i t h e r by m e m b e r s o r by n e w f o r m a t i o n s with n e w n a m e s . This m a y be t h e p r o p e r a p p r o a c h but p r o b a b l y only an i n t e r m e d i a t e s t e p to what h a s b e e n p r o p o s e d . It i s i n t e n d e d by u se of t h e " g r o u p " c o n c e p t to s i m p l i f y the d i s c u s s i o n of t h e C a m b r i an s y s t e m within t h e S h e e p r o c k M o u n t a i n s. P i o c h e s h a le D i s t r i b u t i o n and t h i c k n e s s - The P i o c h e s h a l e i s b e s t e x p o s e d in an e a s t - w e s t b a n d a l o n g the s o u t h s i d e of L o o k o u t (Red P i n e ) M o u n t a i n. 41 The b e s t e x p o s u r e s a r e on t h e n o r t h s i d e s of w e s t - t r e n d i n g Log C a n y o n a n d a l ow t r i b u t a r y of the e a s t d r a i n i n g E a s t G o v e r n m e nt C r e e k . Other e x p o s u r e s a r e in a b e l t t r e n d i n g w e s t e r l y f r o m the west s i d e of N o r t h Oak B r u s h C a n y o n to t h e h e a d of W e s t O a k B r u sh d r a i n a g e a c r o s s t h e d i v i d e. T h e P i o c h e s h a l e was m e a s u r e d in t h r e e p l a c e s and found to be 175, 299, and 342 f e e t t h i c k . The 1 7 5 - f o o t m e a s u r e m e n t was i n a c o v e r e d a r e a w h e r e c o n t a c t s a r e q u e s t i o n a b l e . It i s s o u t h a n d e a st of t h e o t h e r s e c t i o n s . The w e s t e r n m o s t m e a s u r e m e n t was 342 f e et i n Log C a n y o n w h e r e a s the 2 9 9 - f o o t s e c t i o n i s on t h e d i v i d e along t h e s a m e o u t c r o p about two m i l e s e a s t of t h e L o g C a n y o n s e c t i o n. A s s u m i n g c o n t a c t s w e r e t o l e r a b l y c i o s e , t h e P i o c h e s h a l e i s t h i n n i ng to the s o u t h e a s t at a b o u t 20 f e e t p e r m i l e. T o p o g r a p h i c e x p r e s s i o n - The P i o c h e s h a l e i s well m a r k ed by t h e r e s i s t a n t d a r k m a r o o n q u a r t z i t e s of t h e P i o c h e - B u s b y c o n t a ct z o n e . T h e s e f o r m a d i s t i n c t i v e l e d g e o r r i d g e u n i t which i s e a s y to r e c o g n i z e . The l o w e r half of t h e f o r m a t i o n w e a t h e r s to f o r m l e d g e s. L i t h o l o g y - The b a s e of t h e P i o c h e s h a l e i s a r b i t r a r i l y p l a c ed w h e r e s h a l e s c o m p r i s e m o r e t h a n o n e - t h i r d of t h e s t r a t a . S t r a ta a s s i g n e d to t h e P i o c h e s h a l e a r e b e s t d e s c r i b e d a s s h a i y q u a r t z i t e s. The q u a r t z i t e c o m p r i s e s b e t w e e n one half and two t h i r d s of the f o r m a t i o n . The q u a r t z i t e s of t h e l o w e r half of t h e f o r m a t i o n s r a n ge f r o m two i n c h e s to s i x f e e t in t h i c k n e s s , a r e m e d i u m - g r a i n e d , and 42 a r e g e n e r a l l y d a r k e r s h a d e s of i v o r y and d i r t y g r e e n . C r o s s - b e d d i ng i s e v i d e n t in m a n y of the g r e e n i s h b e d s . The i n t e r b e d d e d s h a l es c o m p r i s e a p p r o x i m a t e l y one t h i r d of the s t r a t a . Shales a r e m i c a c e o us and f u c o i d a l ( P l a t e IX), and a b o u t 40 f e e t above t h e b a s e 5 t r i l o b i t e ( ?) t r a c k s w e r e found c r o s s i n g f u c o i d a l e x p r e s s i o n s. A 9 0 - f o o t s t r a t u m of d a r k p u r p l i s h - g r e e n , t h i c k - b e d d e d , c r o s s - b e d d e d q u a r t z i t e o v e r l i e s t h e i n t e r b e d d e d q u a r t z i t e and s h a l e zone 175 f e e t a b o v e t h e b a s e of t h e f o r m a t i o n . The top 75 f e e t of t h e f o r m a t i on i s t h i n - to m e d i u m - b e d d e d q u a r t z i t e c o n t a i n i n g m a n y s h a l e p a r t i n g s. S c o l i t h e s a r e p r o m i n e n t in t h i s z o n e. T h e b a s e of t h e P i o c h e s h a l e i s w h e r e s h a l e i s p r o m i n e n t and a g g r e g a t e s at l e a s t one t h i r d of t h e s t r a t a . The o u t c r o p s a r e d o m i n a n t ly d a r k e r b r o w n s and g r e e n t i n t s. T h e top of t h e f o r m a t i o n was t e n t a t i v e l y p l a c e d at t h e b a s e of a d o l o m i t e which r a n g e s f r o m 30 t o 60 f e e t in t h i c k n e s s . This d o l o m i te w e a t h e r s to a s a n d p a p e r y t e x t u r e and i s e a s i l y m i s t a k e n f o r s a n d s t o ne on c a s u a l e x a m i n a t i o n. F i e l d i d e n t i f i c a t i o n - The P i o c h e s h a l e i s e a s i l y r e c o g n i z e d by t h e p r e s e n c e of f u c o i d s . The Swan P e a k q u a r t z i t e , with which it m i g h t be c o n f u s e d , i s f u c o i d a l n e a r the b a s e but d o e s not c o n t a i n as m u c h of t h e m i c a c e o u s m a t e r i a l t h a t i s t y p i c a l of t h e P i o c h e . The q u a r t z i t e s of t h e Swan P e a k a r e p u r e r and w h i t e r t h a n t h o s e of the PLATE I! Figure 2 Fucoids from the Pioche shale (transgressive conditions). 43 P i o c h e . S t r a t a s i m i l a r in c o l o r and with i d e n t i c a l t e x t u r e and b e d d i n g f e a t u r e s a s t h e P i o c h e a r e p r e s e n t i n t h e P r e c a m b r i a n, h o w e v e r , they a r e not f u c o i d a l. Age and c o r r e l a t i o n - The P i o c h e s h a l e in e a s t e r n N e v a d a and w e s t e r n U t a h i s the t r a n s i t i o n a l u n i t b e t w e e n the b a s a l C a m b r i an q u a r t z i t e s and the o v e r l y i n g c a r b o n a t e s ( P l a t e s X and X I ). F o s s i l s p r e s e n t in t h e P i o c h e f a c i e s i n c l u d e f u c o i d a l m a r k i n gs and a s i n g u l a r t r i l o b i t e t r a c k . The t r a c k was found 40 f e e t above t h e b a s e of the P i o c h e and i s i d e n t i c a l with t h o s e found by McKee ( P l a t e 7, 1935) n e a r t h e top of t h e T a p e a t s s a n d s t o n e in t h e G r a nd C a n y o n r e g i o n. T h e P i o c h e i s t h e l i t h o g e n i c e q u i v a l e n t of t h e b a s a l u n i t s of t h e O p h i r s h a l e o r f o r m a t i o n s in t h e O q u i r r h ( G i l l u l y , 1932), W a s a t c h ( C a l k i n s , 1943), and t h e E a s t T i n t i c M o u n t a i n s ( L o u g h i i n, 1919), and t h e C a n y o n R a n g e ( C h r i s t i a n s e n , 1952). The P i o c he s h a l e i s t h e l i t h o g e n i c e q u i v a l e n t of, but i s p r o b a b l y y o u n g e r t h a n, t h e P i o c h e in the H o u s e R a n g e ( W a l c o t t , 1908), the D e e p C r e ek M o u n t a i n s ( N o l a n , 1935), and t h e b a s a l s h a l e of the P i o c h e d i s t r i ct ( W a l c o t t , 1 9 0 8 a ) . The P i o c h e i s t h e a p p r o x i m a t e age and l i t h o g e n ic e q u i v a l e n t to t h e P i o c h e s h a l e in the P r o m o n t o r y R a n g e ( O l s o n , 1956), t h e b a s a l O p h i r in t h e L a k e s i d e M o u n t a i n s (Young, 1955), and the S c o l i t h u s zone in t h e top of t h e B r i g h a m q u a r t z i t e in t h e Logan q u a d r a n g l e , Utah ( W i l l i a m s , 1948). P L A T E X (NEoluarne,k eat, aNl,e v1a9da56 ) G(oNldo lHani,ll , 19U3t5a)h Sheepr(otchkis Rpaanpgeer), Utah (MEoarsrti s,T ipneticrs .M cotmnsm., .,U 1ta9h55 ) 5 Long Ridge, Utah Ajax dolomite 221 Opex dolomite 120 Cole Canyon doL5o3m3 ite Bluebird doLomite 124 Herkimer limestone 237 \Dagmar limestone 46/- Teutonic limestone 281 Ophir formation 277 Tintic quartzite /VAWVAWAMAM, I N D E X MAP C O R R E L A T I O N O F C A M B R I A N S Y S T E M I N E A S T E R N N E V A D A A N D W E S T E R N U TA 44 B u s b y q u a r t z i te D i s t r i b u t i o n and t h i c k n e s s - The B u s b y q u a r t z i t e h a s a d i s t r i b u t i o n s i m i l a r to t h a t of t h e P i o c h e s h a l e and l i k e w i s e i s p r e s e n t but p o o r l y e x p o s e d a l o n g t h e n o r t h e r n f l a n k of t h e r a n g e f r om N o r t h Oak B r u s h to W e s t Oak B r u s h C a n y o n s . The b e s t e x p o s u r es a r e in t h e Log Canyon d r a i n a g e s o u t h of L o o k o u t P e a k. The B u s b y was m e a s u r e d in s e v e r a l p l a c e s and i s f r om 65 to 146 f e e t t h i c k w h e r e c o n t a c t s a r e b e s t e x p o s e d. T o p o g r a p h i c e x p r e s s i o n - The B u s b y i s c o i n c i d e n t in r e l i ef wit h t h e u n d e r l y i n g P i o c h e and s i m i l a r l y w e a t h e r s a s l e d g e s and r i d ge f o r m e r s . The s o f t e r r o c k s of the o v e r l y i n g M i l l a r d f o r m a t i o n a re m o r e e a s i l y e r o d e d , a l l o w i n g the t o p m o s t b e d s of t h e B u s b y q u a r t z i te t o s t a n d a s r i d g e c r e s t s o r p r o m f n e n t l e d g e s (PLate X I I ). L i t h o l o g y - The B u s b y q u a r t z i t e i s about one half q u a r t z i t e and one half c a r b o n a t e . The l o w e r 60 f e e t i s c a r b o n a t e and t h e b a s al 30 t o 45 f e e t of t h i s zone i s a b r o w n - w e a t h e r i n g , g r a y s a n d y d o l o m i t e. The r e m a i n d e r of the unit i s c a l c a r e o u s s a n d s t o n e and s a n d y l i m e s t o n e. T h e f a u n a of t h e A l b e r t e l l a z o n e (Howell et a l . , 1944) was found 40 f e e t a b o v e t h e b a s e of t h e B u s b y q u a r t z i t e in a r e l a t i v e l y p u r e l i m e s t o n e . The f a u n a was found only by b r e a k i n g a l a r g e q u a n t i t y of r o ck f r o m a l e d g e t e n f e e t above t h e u n d e r l y i n g d o l o m i t e. The u p p e r half of t h e B u s b y i s t y p i c a l l y a q u a r t z i t e v e r y s i m i l ar to t h e p u r p l e q u a r t z i t e of t h e u p p e r m o s t u n i t s of t h e u n d e r l y i n g P i o c h e. Figure I View to north from head of Spring Canyon section exposed from the Tintic quartzite to the Swasey limestone on the skyline. Figure 3 Hand specimen of sandy limestone from Busby formation. Sandy and quaHzitic layers weathers in relief. 45 H o w e v e r , t h e s e q u a r t z i t e s a r e not c o n s i s t e n t in t h i c k n e s s along s t r i k e . They t h i n s l i g h t l y to t h e e a s t a l l o w i n g a t h i c k e n i n g of the u n d e r l y i n g b a s a l c a r b o n a t e s . The y o u n g e s t s t r a t u m of t h e B u s by i s a c a l c a r e o u s s a n d s t o n e which in p l a c e s b e c o m e s a s a n d y l i m e s t o n e . This u n i t w e a t h e r s t a n , i s m a s s i v e , and m i c a i s p r e s e n t in s o m e p o r t i o n s. T h e b a s e of t h e B u s b y i s t h e b a s e of t h e s a n d y , b r o w n - w e a t h e r i ng d o l o m i t e or, m o r e s p e c i f i c a l l y , t h e b a s e of t h e f i r s t c a r b o n a t e above the T i n t i c q u a r t z i t e. T h e top of the B u s b y i s the t o p of a s a n d y l i m e s t o n e o r c a l c a r e o us q u a r t z i t e b e l o w a p i s o l i t i c b l u e - g r a y l i m e s t o n e ( P l a t e X I I ). F i e l d i d e n t i f i c a t i o n - The b r o w n w e a t h e r i n g d o l o m i t e i s the l o w e s t c a r b o n a t e in t h e s e c t i o n and the only d o l o m i t e n e a r t h e b a s e of t h e C a m b r i a n s y s t e m . The n e x t d o l o m i t i c s t r a t a in t h e s e c t i o n a re 1, 600 f e e t a b o v e. Age and c o r r e l a t i o n - F o s s i l s w e r e c o l l e c t e d f r o m two l o c a l i t i es i n t h e B u s b y f o r m a t i o n ( A p p e n d i x B and P l a t e I I I ) . L o c a l i t y C - 2 1 is n e a r the m o u t h of Log C a n y o n . Here t h e f a u n a i s i n a s a n d y l i m e s t o ne a p p r o x i m a t e l y 40 f e e t above t h e b a s e of t h e f o r m a t i o n . L o c a l i t y C - 30 i s 6 | m i l e s e a s t of C - 2 1 and i s n e a r the m o u t h of N o r t h Oak B r u sh C a n y o n . F a u n a of l o c a l i t y C - 3 0 was c o l l e c t e d 75 f e e t above the b a se i n a s a n d y l i m e s t o n e. 46 M r . R. C. B r i g h t r e p o r t s t h e f o l l o w i n g: C - 2 1 C a b o r c e l i a cf. C. A r r o j o s e n s i s L o c h m an K o o t e n i a s p p. Q n c h o c e p h a l u s ? s p. P t a r m i g a n i a or P t a r m i g a n o i d e s s p. B r a c h i o p o d f r a g m e n ts H e l c i o n e l l a s p. P e l a g i e l i a - l i k e g a s t r o p od S c e n e l l a s p. C - 3 0 D o l i c h o m i t o p s i s s p. K o c h a s p i s s p. T h e type s e c t i o n f o r the B u s b y q u a r t z i t e i s in t h e Gold H i l l m i n i ng d i s t r i c t at t h e n o r t h end of t h e D e e p C r e e k M o u n t a i n s . Nolan (1935, p . 7) a p p l i e d t h e n a m e to t h e s t r a t a b e t w e e n t h e u n d e r l y i n g P i l o t ( P i o c h e) s h a l e and t h e o v e r l y i n g A b e r c r o m b i e f o r m a t i o n . Type B u s b y i s 450 f e e t t h i c k and c o n s i s t s m a i n l y of m a s s i v e q u a r t z i t e s and a f ew s h a l e s. In t h e H o u s e R a n g e , s o u t h of t h e D e e p C r e e k M o u n t a i n s , W h e e l er ( 1 9 4 8 , p. 28) a s s i g n e d the t e r m ' B u s b y q u a r t z i t e ' to 150 f e e t of b e ds n a m e d T a t o w l i m e s t o n e by D e i s s ( 1 9 3 8 ) . D e i s s h a d s u p p l a n t e d the L a n g s t o n of W a l c o t t (1908) c a l l i n g it t h e T a t o w l i m e s t o n e . The Bus.by of t h e H o u s e R a n g e i s a c a l c a r e o u s , c o a r s e - g r a i n e d , r e d d i s h - b r o wn s a n d s t o n e with l e n s e s of a r e n a c e o u s s h a l e s . In t h e S h e e p r o ck M o u n t a i n s t h e B u s b y q u a r t z i t e c o m p r i s e s 146 f e e t of b e d s b e i ng O l e n o i d e s s p. O r y c t o e e p h a l i t e s s p . cf. O. r e s s e r i R a s e t ti L o c a l i t y C - 2 1 i s a s s i g n e d a l o w e r A l b e r t e l l a age on t h e b a s i s of t h e Qnchoc e p h a l u s ? s p. L o c a l i t y C - 3 0 i s A l b e r t e l l a a g e. 47 m a i n l y q u a r t z i t e s , s a n d s t o n e s , and s a n d y l i m e s t o n e s. W h e e l e r (1943, p . 1812 and 1948, p. 29) r e c o g n i z e s the B u s by q u a r t z i t e at C h e r r y C r e e k , N e v a d a , and in t h e Wah Wan R a n g e of s o u t h w e s t e r n Utah. T h e age of t h e B u s b y f o r m a t i o n in t h e S h e e p r o c k a r e a i s l o w er M i d d l e C a m b r i a n with s t r o n g i n d i c a t i o n s t h a t it m a y h a v e b e en d e p o s i t e d only v e r y s l i g h t l y a f t e r e a r l y C a m b r i a n t i m e. T h e B u s b y f o r m a t i o n i s t h e a p p r o x i m a t e age e q u i v a l e n t of t h e B u s by q u a r t z i t e of N o l a n (1935) in t h e D e e p C r e e k M o u n t a i n s , Utah; t h e B u s by q u a r t z i t e of W h e e l e r (1948) in t h e H o u s e R a n g e , Utah; the l o w e r p a rt of t h e E l d o r a d o d o l o m i t e of N o l a n , M e r r i a m and W i l l i a m s (1956) in t h e v i c i n i t y of E u r e k a , N e v a d a ; t h e l o w e r p a r t of m e m b e r A of the P o l e C a n y o n l i m e s t o n e of D r e w e s and P a l m e r (1957) of t h e s o u t h e rn Snake R a n g e , N e v a d a ; t h e u p p e r p a r t of t h e P i o c h e s h a l e in t h e V i r g in M o u n t a i n s , N e v a d a ; the l o w e r p o r t i o n s of t h e O p h i r s h a l e of G i l l u ly (1932) in t h e O q u i r r h M o u n t a i n s , Utah; and t h e l o w e r half of L a n g s t on f o r m a t i o n of W a l c o t t (1908) in t h e b l a c k s m i t h F o r k a r e a of n o r t h w e s t e r n U t a h . The B u s b y l i t h o l o g y h a s b e e n r e c o g n i z e d by t h e w r i t er i n the S i m p s o n M o u n t a i n s and the Keg M o u n t a i n s (McDowell M o u n t a i n s) of w e s t - c e n t r a l U t a h . T h e s e s e c t i o n s a r e c o r r e l a t e d with t h e B u s b y of t h e S h e e p r o c k R a n g e. 48 M i l l a r d f o r m a t i on G e n e r a l - The n a m e M i l l a r d f o r m a t i o n i s s u b s t i t u t e d f o r M i l l a rd l i m e s t o n e of t h e H o u s e R a n g e s e c t i o n . The M i l l a r d f o r m a t i o n in the S h e e p r o c k M o u n t a i n s i s a t h r e e - f o l d unit c o m p o s e d of l i m e s t o n e - s h a l e - l i m e s t o n e . These s u b d i v i s i o n s a r e s i m i l a r to t h e M i l l a rd e q u i v a l e n t s of w e s t e r n G r a n d C a n y o n , the Wan Wan R a n g e , Utah, and t h e P i o c h e d i s t r i c t , Nevada; n a m e l y , the Lyndon l i m e s t o n e , C h i s h o lm s h a l e , and t h e P e a s l e y l i m e s t o n e . L i t h o g e n i c a l l y t h e M i l l a r d f o r m a t i on i s i n c l u d e d a m o n g o t h e r f o r m a t i o n s within the c o n f i n e s of t h e O p h ir f o r m a t i o n of t h e ' t y p e ' O p h i r at S t o c k t o n , T i n t i c , and in t h e Canyon R a n g e . It w a s d e c i d e d t h a t s i n c e a " b a s i n " t e r m i n o l o g y was to be a p p l i e d to t h e S h e e p r o c k s e c t i o n it would be r i s k y to b r i n g a n a me s u c h a s O p h i r i n t o a r e l a t i v e l y c l e a r c u t H o u s e R a n g e s e c t i o n . The t e r m ' O p h i r ' s h o u l d b e r e s t r i c t e d to the m o r e e a s t e r l y f a c i e s w h e re c o r r e l a t i o n i s m a i n l y on l i t h o l o g y. D i s t r i b u t i o n and t h i c k n e s s - The M i l l a r d f o r m a t i o n c r o p s out on t h e s p u r s a l o n g t h e n o r t h f l a n k of t h e r a n g e f r o m H a r k e r Canyon t o t h e h e a d of W e s t Oak B r u s h C a n y o n on t h e west f l a n k . Lion H i l l, a p r o m i n e n t n o r t h - e a s t t r e n d i n g d i s p l a c e d m a s s s e p a r a t i n g the h e ad of H a r k e r d r a i n a g e f r o m N o r t h Oak B r u s h Canyon, c o n t a i n s the M i l l a r d f o r m a t i o n along the b a s e of i t s s o u t h m a r g i n f r o m n e a r the h e a d of t h e H a r k e r Canyon e a s t w a r d to t h e s p u r e a s t of t h e m o u t h of t h e c a n y o n . The b e s t e x p o s e d s e c t i o n s a r e in a b a n d a l o n g t h e s o u th 49 s i d e of L o o k o u t P e a k f r o m the m o u t h of L o g Canyon to t h e d i v i d e. T h e M i l l a r d f o r m a t i o n i s f r o m 245 to 355 f e e t t h i c k w h e re m e a s u r e d . The s h a l e u n i t v a r i e s c o n s i d e r a b l y in t h i c k n e s s but a l w a y s at the e x p e n s e of t h e u n d e r l y i n g l i m e s t o n e. T o p o g r a p h i c e x p r e s s i o n - The s h a l e unit of t h e M i l l a r d w e a t h e rs to f o r m s a d d l e s and s l o p e s and i s g e n e r a l l y m a s k e d by d e b r i s f r om t h e o v e r l y i n g l i m e s t o n e s. L i t h o l o g y - The M i l l a r d i s d i v i s i b l e i n t o t h r e e d i s t i n c t m e m b e r s . The b a s a l m e m b e r r a n g e s f r o m 150 to 207 f e e t in t h i c k n e s s . The l o w e r m o s t u n i t i s c o n s i s t e n t l y a p i s o l i t i c , b l u e - g r a y , m e d i u m - b e d d e d l i m e s t o n e . P i s o i e s a r e d a r k g r a y to b l a c k and r a n g e f r o m one f o u r t h to n e a r l y one i n c h in d i a m e t e r . This u n i t i s 15 o r m o r e f e e t t h i c k and i s o v e r l a i n by a b l u e - g r a y , f i n e - g r a i n e d , t h i n - b e d d e d l i m e s t o n e with s i l t y s t r e a k s b e t w e e n o n e - to t w o - i n c h l i m e s t o n e b e d s . The b a n d ed u n i t v a r i e s f r o m 80 to 174 f e e t in t h i c k n e s s. T h e m i d d l e u n i t i s a g r e e n s h a l e which m e a s u r e s f r o m 50 t o 120 f e e t t h i c k . This i s t h e G l o s s o p l e u r a zone of the S h e e p r o c k C a m b r i a n. The s h a l e i s p l a t y and s o m e w h a t f i s s i l e but t h i s f i s s i l i t y i s not p a r a l l el with t h e b e d d i n g s o t h e r o c k i s e s s e n t i a l l y a s l a t e . This u n i t i s only l o c a l l y f o s s i l i f e r o u s . It p o s s e s s e s a c h a r a c t e r i s t i c light g r e e n c o l or at e a c h o b s e r v e d l o c a l i t y . F o s s i l s and o t h e r f o r e i g n m a t t e r a r e d a rk g r e e n a s a r e m i n u t e n e t w o r k f r a c t u r e s which a r e p r e s e n t in t h e s h a l e. 50 T h e u p p e r unit i s a p i s o l i t i c l i m e s t o n e of v a r i a b l e t h i c k n e ss which a v e r a g e s about 40 f e e t ( P l a t e X I I I ). T h e b a s e of t h e M i l l a r d i s at t h e t o p of t h e c a l c a r e o u s s a n d s t o ne of t h e c o n f o r m a b l y u n d e r l y i n g B u s b y q u a r t z i t e . P i s o l i t e s a re c h a r a c t e r i s t i c of t h e b a s e of t h e M i l l a r d. T h e top of t h e M i l l a r d f o r m a t i o n , though m o r e a r b i t r a r i l y p l a c e d, i s t h e top of t h e p i s o l i t i c l i m e s t o n e o v e r l y i n g the s h a l e u n i t. F i e l d i d e n t i f i c a t i o n - The s h a l e unit of t h e M i l l a r d i s t h e m o st d i s t i n c t i v e of any s h a l e in t h e e n t i r e S h e e p r o c k R a n g e . It c a n r e a d i ly be r e c o g n i z e d by the p r e s e n c e of d a r k g r e e n p a t c h e s of a n e t w o r k of f r a c t u r e s and s p o t s on a l i g h t b l e a c h e d g r e e n b a c k g r o u n d of t h e u n a l t e r ed s h a l e . The c l o s e - p a c k e d p i s o l i t e s of t h e u p p e r and l o w e r u n i t s a l so s e r v e to d i s t i n g u i s h the f o r m a t i o n. Age .and c o r r e l a t i o n - F o s s i l s w e r e c o l l e c t e d f r o m ten l o c a l i t i es in t h e M i l l a r d f o r m a t i o n ( A p p e n d i x B a n d P l a t e III); a l l e x c e p t two c o l l e c t i o n s w e r e f r o m the s h a l e m e m b e r . The two c o l l e c t i o n s , C - 2 8, n e a r the h e a d of L o g C a n y o n , and C - 3 1 , n e a r the m o u t h of N o r t h Oak B r u s h C a n y o n , a r e f r o m the l o w e r l i m e s t o n e m e m b e r of t h e M i l l a rd f o r m a t i o n . Mr. R. C. B r i g h t s t u d i e d the c o l l e c t i o n s and r e p o r t s . t h e f o l l o w i n g: C - 2 8 K o o t e n i a s p. H e l c i o n e l l a s p. C - 3 1 H e I c i o n e l l a s p. Figure I Flat pill-like pebbles from basal unit of the upper member of the Millard formation in Log Canyon. Figure 2 Pisolites or algal balls from the upper member of the Millard formation on Lion Hill. 51 C h r i s t i n a L o c h m a n B a l k e x a m i n e d s e v e r a l s p e c i m e n s f r om C - 2 8 and r e p o r t e d: P a c h y a s p i s ( ? ) s p. T h e r e m a i n i n g e i g h t c o l l e c t i o n s w e r e e x a m i n e d by R. C. B r i g h t, A. R. P a l m e r , and t h e w r i t e r . All c o n t a i n e d G l o s s o p l e u r a s p. L o c a l i t y C - l , s t u d i e d by A. R. P a l m e r , y i e l d e d the f o l l o w i n g: C - l E h m a n i e l l a s p. G l o s s o p l e u r a s p. P o l y p l e u r a s p i s s p. One s p e c i m e n f r o m C - 3 2 , i d e n t i f i e d by R. C. B r i g h t , was G l o s s o p l e u r a p r o d u c t a H a i l and W h i t f i e l d. No f o s s i l s w e r e c o l l e c t e d f r o m the u p p e r l i m e s t o n e m e m b e r of the M i l l a r d f o r m a t i o n . The f a u n a i n d i c a t e s t h a t the M i l l a r d f o r m a t i o n is m e d i a l M i d d l e C a m b r i a n in a g e. T h e M i l l a r d f o r m a t i o n i s t h e a p p r o x i m a t e age e q u i v a l e n t to the M i l l a r d l i m e s t o n e of W h e e l e r (1948) in t h e H o u s e R a n g e , Utah; the l o w e r p o r t i o n of t h e A b e r c r o m b i e f o r m a t i o n of N o l a n (1935) in the D e e p C r e e k M o u n t a i n s ; m e m b e r s A, B, and C io£ ifee P o l e Canyon l i m e s t o n e of D r e w e s and P a l m e r (1957) i n the s o u t h e r n Snake R a n g e, N e v a d a ; p a r t of the E l d o r a d o d o l o m i t e of N o l a n , M e r r i a m and W i l l i a m s (1956) in t h e v i c i n i t y of E u r e k a , Nevada; the L y n d o n l i m e s t on C h i s h o l m s h a l e , and p a r t of t h e P e a s l e y l i m e s t o n e of M c N a i r (1951) in t h e V i r g i n M o u n t a i n s , N e v a d a ; the L y n d o n l i m e s t o n e , C h i s h o l m s h a le 52 a n d the P e a s l e y l i m e s t o n e of W h e e l e r (1939 and 1948) of t h e P i o c he d i s t r i c t , Nevada; p a r t of t h e L a n g s t o n f o r m a t i o n , the S p e n c e s h a l e, a n d the l o w e r p o r t i o n of the U t t e l i m e s t o n e of W a l c o t t (1908) and D e i s s (1938) in t h e B l a c k s m i t h F o r k a r e a of n o r t h - e a s t e r n Utah; p a r t of t h e O p h i r f o r m a t i o n of G i l l u l y (1932) i n t h e O q u i r r h M o u n t a i n s, Utah; p a r t of t h e O p h i r s h a l e of L o u g h l i n (1919) of t h e T i n t i c d i s t r i c t, Utah; p a r t of t h e O p h i r s h a l e of C a l k i n s (1943) of the Cottonwood A m e r i c a n F o r k d i s t r i c t , Utah; p a r t of the O p h i r f o r m a t i o n of C h r i s t i a n s e n (1952) in t h e C a n y o n R a n g e , Utah. B u r r o w s l i m e s t o ne G e n e r a l - The B u r r o w s l i m e s t o n e i s not c l e a r l y r e c o g n i z e d in t h e S h e e p r o c k a r e a . However, on b a s i s of g r a i n s i z e , the b a s al 21 f e e t of t h e B u r n t C a n y o n l i m e s t o n e m a y r e p r e s e n t the B u r r o w s . F o r p u r p o s e s of t h i s r e p o r t , B u r r o w s l i t h o l o g y i s a b s e n t but B u r r o w s t i m e i s p r o b a b l y r e p r e s e n t e d in the b a s a l B u r n t Canyon l i t h o l o g y . W h e e l e r (1940 a n d 1943) n o t e d u n c o n f o r m i t i e s a b o v e and b e l o w t h e B u r r o w s l i m e s t o n e in t h e P i o c h e d i s t r i c t , N e v a d a , but l a t e r (1948, p . 36) s t a t e d , " . . . t h e s e b r e a k s now a p p e a r to be d i a s t e m s of l i t t l e s t r a t i g r a p h i c s i g n i f i c a n c e " . No u n c o n f o r m i t y was found at o r n e a r t h e b a s e of B u r n t Canyon l i t h o l o g y in t h e S h e e p r o c k. H o w e v e r , it i s p o s s i b l e t h a t one m a y be p r e s e n t which c o u l d a c c o u nt f o r the a b s e n c e of B u r r o w s l i t h o l o g y. 53 B u r n t C a n y o n f o r m a t i on D i s t r i b u t i o n a n d t h i c k n e s s - T h e B u r n t Canyon f o r m a t i o n c r o ps out a s t h e l o w e r m o s t l i m e s t o n e c l i f f s on t h e s o u t h s i d e of Lookout M o u n t a i n . The f o r m a t i o n d e f e n d s t h e s p u r e n d s a l o n g t h e n o r t h f l a nk of t h e m o u n t a i n s f r o m N o r t h Oak B r u s h C a n y o n to t h e d i v i d e. T h e f o r m a t i o n a g g r e g a t e s 178 f e e t of s t r a t a w h e r e m e a s u r e d on t h e n o r t h - s o u t h d i v i d e at t h e h e a d s of S p r i n g and Log C a n y o n s . Near t h e m o u t h of N o r t h Oak B r u s h C a n y o n , 2 2 1 f e e t of s t r a t a i s a s s i g n e d to the B u r n t C a n y o n f o r m a t i o n. T o p o g r a p h i c e x p r e s s i o n - The B u r n t C a n y o n f o r m a t i o n c r o p s out a s a c l i f f - f o r m i n g and s t e e p s l o p e u n i t. L i t h o l o g y - The s t r a t a c o m p r i s i n g the B u r n t C a n y o n f o r m a t i on a r e d o m i n a n t l y t h i n - b e d d e d , f i n e - to m e d i u m - g r a i n e d , b l u e - g r ay l i m e s t o n e s . T h r o u g h o u t the whole f o r m a t i o n a r e g r e e n s h a l e s which r a n g e in t h i c k n e s s f r o m 1 t o 25 f e e t . The g r e a t e r p a r t of t h e f o r m a t i on i s m a d e up of l i m e s t o n e b e d s about two i n c h e s t h i c k . These a re s e p a r a t e d by t a n a n d p i n k i s h s i l t y u n d u l a t o r y b a n d s which r a n g e up to one o r two i n c h e s in t h i c k n e s s . The f o r m a t i o n c h a n g e s p h y s i c al c h a r a c t e r a l o n g s t r i k e with s h a l e s l e n s i n g and t h i c k e n i n g . None of t h e s h a l e s a r e r e l i a b l e a s m a p u n i t s . The s h a l e s r a n g e f r o m g r e e n i s h - t a n to g r e e n and in m a n y l o c a l i t i e s a r e d e n s e and b l o c k y . The l i m e s t o n e s a b o v e and b e l o w a r e g r a d a t i o n a l with t h e s h a l e and a r e v e ry t h i n l y b e d d e d in t h e t r a n s i t i o n z o n e. 54 F i e l d i d e n t i f i c a t i o n - The B u r n t C a n y o n f o r m a t i o n i s r e c o g n i z ed by t h e b a n d e d a p p e a r a n c e c a u s e d by the m o r e s i l t y i n t e r b e d s . It m ay be c o n f u s e d with s o m e of t h e l i m e s t o n e s h i g h e r in t h e s e c t i o n s u c h as m a n y found in t h e M a r j u m f o r m a t i o n . The p r e s e n c e of g r e e n b l o c ky s h a l e f l o a t i s a g o o d i n d i c a t o r t h a t one i s s t r a t i g r a p h i c a l l y b e l ow t h e Dome l i m e s t o n e . The s h a l e i s not m a r k e d by t h e d a r k g r e en f r a c t u r e f i l l i n g s and f o s s i l f r a g m e n t s which c h a r a c t e r i z e the l o w er G l o s s o p l e u r a - b e a r i n g s h a l e s of t h e M i l l a r d f o r m a t i o n. Age and c o r r e l a t i o n - F o s s i l s c o l l e c t e d f r o m two l o c a l i t i es i n c l u d e only f r a g m e n t s of l i n g u l o i d b r a c h i o p o d s ( A p p e n d i x B and P l a t e I I I ) . H o w e v e r , the p o s i t i o n b e t w e e n the u n d e r l y i n g G l o s s o p l e u r a - b e a r i n g M i l l a r d f o r m a t i o n and t h e E l r a t h i n a f a u n a of t h e C o n d o r f o r m a t i o n l e a v e s l i t t l e doubt t h a t t h e B u r n t C a n y o n i s m e d i a l M i d d l e C a m b r i an i n a g e. T h e B u r n t C a n y o n f o r m a t i o n i s the a p p r o x i m a t e age e q u i v a l e nt of p a r t of t h e A b e r c r o m b i e f o r m a t i o n in t h e D e e p C r e e k M o u n t a i n s, Utah; a u n i t C of t h e H i g h l a n d P e a k l i m e s t o n e of W h e e l e r and L e m m on (1939) of the P i o c h e d i s t r i c t , N e v a d a ; of t h e O p h i r f o r m a t i o n in t he O q u i r r h M o u n t a i n s , Utah; and of p a r t of t h e O p h i r f o r m a t i o n in t he C a n y o n R a n g e , Utah. The b a s a l B u r n t C a n y o n f o r m a t i o n u n i t s a re probabLy e q u i v a l e n t in a g e to t h e B u r r o w s d o l o m i t e of W h e e l e r (1940) i n t h e H o u s e R a n g e , Utah. 55 Dome l i m e s t o ne D i s t r i b u t i o n and t h i c k n e s s - The Dome l i m e s t o n e c r o p s out along t h e s o u t h s i d e of t h e Lookout M o u n t a i n a s a c a p p i n g of t h e c l i f f s f o r m ed by the B u r r o w s - B u r n t Canyon f o r m a t i o n s t r a t a. T h e Dome r a n g e s f r o m 37 t o 81 f e e t in t h i c k n e s s on t h e d i v i d e s o u th of L o o k o u t P e a k. T o p o g r a p h i c e x p r e s s i o n - The s t r a t a of the Dome l i m e s t o n e a re m o r e r e s i s t a n t to e r o s i o n than the s h a i y b e d s of t h e o v e r l y i n g C o n d or f o r m a t i o n and i n v a r i a b l y s t a n d out a s c l i f f s and dip s l o p e s. L i t h o l o g y - The Dome l i m e s t o n e i s a t h i c k , m a s s i v e l y w e a t h e r i n g, t h i n - b e d d e d , f i n e - g r a i n e d , b l u e - g r a y l i m e s t o n e . The s t r a t a a re h o m o g e n e o u s and d e n s e . Abundant s e c o n d a r y c a l c i t e o c c u r s a s f r a c t u r e f i l l i n g s . Thin, wavy, g r a y l i m e s t o n e of the s a m e t e x t u r e a s t h e b l u e - g r a y b e d s s e r v e s to i m p a r t the v a g u e but p e r s i s t e n t t h i n - b e d d ed c h a r a c t e r to t h e r o c k. T h e b a s e of t h e Dome l i m e s t o n e i s g r a d a t i o n a l with t h e B u r nt C a n y o n f o r m a t i o n . It i s p l a c e d at a p o i n t w h e r e the b a s a l u n i t s of the Dome l i m e s t o n e w e a t h e r m a s s i v e and the b e d d i n g b e c o m e s t h i c k e r. F i e l d i d e n t i f i c a t i o n - The e a s i e s t m e t h o d of r e c o g n i t i o n of the Dome l i m e s t o n e i s by i t s p o s i t i o n r e l a t i v e to t h e G l o s s o p l e u r a - b e a r i ng s h a l e of t h e M i l l a r d f o r m a t i o n and t h e o v e r l y i n g C o n d o r f o r m a t i o n. The Dome l i m e s t o n e i s the u p p e r m o s t l i m e s t o n e unit a b o v e the 56 G l o s s o p l e u r a zone u s u a l l y f o r m i n g c l i f f - l i k e p r o m i n e n c e s. I m m e d i a t e l y o v e r l y i n g t h e Dome a r e t h e m o r e m i c a c e o u s s h a l es a n d t h i n - b e d d e d s i l t y l i m e s t o n e s of the C o n d o r f o r m a t i o n. Age and c o r r e l a t i o n - No f o s s i l s w e r e found in the Dome l i m e s t o n e . The Dome l i m e s t o n e , like t h e B u r n t C a n y o n f o r m a t i o n , is b e t w e e n f a u n a l z o n e s of the M i l l a r d f o r m a t i o n and of t h e C o n d or f o r m a t i o n and i s t h e r e f o r e of m e d i a l M i d d l e C a m b r i a n a g e. T h e Dome l i m e s t o n e i s t h e a p p r o x i m a t e age e q u i v a l e n t to p a rt of t h e A b e r c r o m b i e f o r m a t i o n in the D e e p C r e e k M o u n t a i n s , Utah; of u n i t s D a n d E of t h e H i g h l a n d P e a k l i m e s t o n e at P i o c h e , Nevada; p a r t of t h e O p h i r f o r m a t i o n in t h e C a n y o n R a n g e , Utah; a n d p r o b a b ly p a r t of t h e O p h i r f o r m a t i o n in the O q u i r r h M o u n t a i n s , S t o c k t o n - F a i r f i e i d a r e a , Utah. C o n d o r f o r m a t i on G e n e r a l - The S w a s e y l i m e s t o n e of t h e H o u s e R a n g e s e c t i on c o n s i s t s of 395 f e e t of s t r a t a d i v i s i b l e i n t o two p a r t s : the b a s a l 117 f e e t i s a t a n to g r a y , t h i n - b e d d e d , a r g i l l a c e o u s l i m e s t o n e and f i n e ly a r e n a c e o u s f o s s i l i f e r o u s s h a l e ( C o n d o r m e m b e r ) ; t h e u p p e r 278 f e et i s a d a r k to m e d i u m g r a y , f i n e - to m e d i u m - g r a i n e d , t h i c k - b e d d e d, a r g i l l a c e o u s l i m e s t o n e ( W h e e l e r , 1948, p . 39). A s i m i l a r d i v i s i on o c c u r s w i t h i n r o c k s r e f e r r e d to as S w a s e y l i m e s t o n e in t h e S h e e p r o ck M o u n t a i n s . H e r e the b a s a l u n i t s of t h e C o n d o r r a n g e f r o m 107 t o 135 f e et in t h i c k n e s s . The C o n d o r b e d s a r e a r e n a c e o u s s h a l e s and t h i n - b e d d ed 57 l i m e s t o n e s . Conformably o v e r l y i n g t h e s h a i y s e q u e n c e i s a cliff-, f o r m i n g u p p e r u n i t about 169 f e e t t h i c k c o m p o s e d e n t i r e l y of t h i c k - b e d d e d , d a r k b l u e = g r a y , m e d i u m - g r a i n e d l i m e s t o n e . The C o n d or m e m b e r i s r e c o g n i z e d t h r o u g h o u t the C a m b r i a n s e c t i o n s of w e s t e rn U t a h a n d e a s t e r n N e v a d a . R e c o g n i t i o n of the C o n d o r l i t h o l o g y in t h e S h e e p r o c k s and C a n y o n R a n g e s e c t i o n s i n d i c a t e s t h a t i t i s s u f f i c i e n t ly w i d e s p r e a d and d i s t i n c t to q u a l i f y a s a f o r m a t i o n . Steele ( p e r s o n al c o m m u n i c a t i o n , 1956) h a s found it to b e v e r y d i s t i n c t i v e in t h e U t a h - N e v a d a t e r r i t o r y and s t a t e s t h a t i t m a y p o s s i b l y be e l e v a t e d to f o r m a - t i o n a l s t a t u s . In d i s c u s s i n g t h e s t r a t i g r a p h y of t h e E a s t T i n t i c, O q u i r r h , and C a n y o n R a n g e s , L o u g h l i n , G i l l u l y , and C h r i s t i a n s e n, r e s p e c t i v e l y , c i t e t h a t t h e top of t h e O p h i r s h a l e i s t h e t o p of the u p p e r m o s t s h a l e in t h e s e q u e n c e (See O p h i r g r o u p , pp. 3 5 - 4 0 , t h is p a p e r ) . In t h e S h e e p r o c k M o u n t a i n s the t o p of t h e u p p e r m o s t s h a l e s in t h e s e q u e n c e a r e 950 f e e t a b o v e the t o p of t h e T i n t i c and 169 f e e t b e l ow t h e W h e e l e r s h a l e with i t s d i a g n o s t i c f a u n a . On t h e b a s i s of t h e f o r e g o i n g it i s o b v i o u s t h a t t h e C o n d o r m e m b e r of t h e S w a s e y h a s e i t h er b e e n i n c l u d e d in t h e O p h i r o r s h o u l d , by d e s c r i p t i o n of t h e u p p e r c o n t a c t , be i n c l u d e d within t h e O p h i r f o r m a t i o n . In t h i s r e p o r t the C o n d or m e m b e r of t h e S w a s e y l i m e s t o n e i s t r e a t e d a s the u p p e r m o s t u n i t of t h e ! O p h i r ' g r o u p and i s e l e v a t e d to f o r m a t i o n a l s t a t u s. 58 D i s t r i b u t i o n and t h i c k n e s s - The C o n d o r f o r m a t i o n c o n f o r m a b ly o v e r l i e s the Dome l i m e s t o n e and i s e x p o s e d a l o n g t h e s o u t h s i d e of L o o k o u t M o u n t a i n a n d on t h e d i v i d e w e s t of t h e m o u t h of T a l a w a g C a n y o n. T h e f o r m a t i o n r a n g e s f r o m 107 to 135 f e e t in t h i c k n e s s . The t h i c k e r s e c t i o n i s n e a r t h e m o u t h of L o g C a n y o n w h e r e a s the t h i n n er u n i t i s s e v e r a l m i l e s s o u t h of L o o k o u t P e a k on t h e m a i n d i v i d e . The s e c t i o n d e s c r i b e d i s well e x p o s e d on t h e s o u t h s l o p e of L o o k o ut M o u n t a i n on t h e d i v i d e. T o p o g r a p h i c e x p r e s s i o n - The C o n d o r f o r m a t i o n c o n s i s t s of s h a l e s and t h i n - b e d d e d s i l t y l i m e s t o n e s which a g g r e g a t e a t o t a l of 111 f e e t of b e d s . In p l a c e s m u c h of t h e f o r m a t i o n i s o b s c u r e d by d e b r is of t h e o v e r l y i n g s t r a t a . The C o n d o r c h a n g e s a p p e a r a n c e and c o m p o s i t i o n a l o n g s t r i k e ; the s o u t h e r n m o s t s e c t i o n i s of f i n e g r a d a t i o n ai u n i t s e a c h a b o u t 20 f e e t t h i c k , the l o w e r , m i d d l e , and u p p e r u n i ts b e i n g t h i n - b e d d e d (one to two i n c h e s ) , b l u e - g r a y , f i n e - g r a i n e d l i m e s t o n e s with t a n s i l t y p a r t i n g s . T h e s e l i m e s t o n e s w e a t h e r to f o rm i r r e g u l a r thin s l a b s . Shaiy u n i t s o c c u r b e t w e e n t h e l i m e s t o n e s . The s h a l e u n i t s c o n s i s t of m o r e t h i n l y b e d d e d l i m e s t o n e s and a r e n a c e o us g r e e n i s h s h a l e s with m u c h m i c a on b e d d i n g s u r f a c e s. The b a s e of t h e f o r m a t i o n l i e s on t o p of t h e m a s s i v e w e a t h e r i ng u n d e r l y i n g Dome l i m e s t o n e . The t o p i s at t h e b a s e of t h e b l u e - g r a y, t h i c k - b e d d e d , m a s s i v e w e a t h e r i n g l i m e s t o n e cliff c o m p r i s i n g the S w a s e y . 59 F i e l d i d e n t i f i c a t i o n - The C o n d o r f o r m a t i o n i s e a s y to r e c o g n i ze b e c a u s e of i t s p o s i t i o n b e l ow t h e c l i f f - f o r m i n g Swasey l i m e s t o n e. The s h a l e s and t h i n l y b e d d e d l i m e s t o n e s w e a t h e r to f o r m t a l us s l o p e s . The s h a l e s a r e d r a b g r e e n and v e r y s i l t y and m i c a c e o u s. The m i c a and g r i t t y f e e l s e r v e s to d i s t i n g u i s h the C o n d o r s h a l es f r o m o t h e r s h a l e s in t h e C a m b r i a n s e q u e n c e. Age and c o r r e l a t i o n - F o s s i l s w e r e c o l l e c t e d f r o m four l o c a l i t i es i n t h e C o n d o r f o r m a t i o n (Appendix B a n d P l a t e I I I ) . Two of the l o c a l i t i e s y i e l d e d only f r a g m e n t s of l i n g u l o i d b r a c h i o p o d s . L o c a l i t i es C - 2 3 and C - 3 4 y i e l d e d s p e c i m e n s i d e n t i f i e d by R. C. B r i g h t a s: C - 2 3 E h m a n i e l l a s p. A c r o t h e l e s p. C - 3 4 E h m a n i e l l a cf. E. b u r g e s s e n s i s R a s e t ti E l r a t h i n a ? sp. H y o l i t h e s cf. H. c e r c o p s W a l c o tt M i c r o m i t r a ? s p. I p h i c l e l l a s p. The f a u n a i n d i c a t e s a m e d i a l M i d d l e C a m b r i a n a g e , f o r the C o n d o r f o r m a t i o n. T h e C o n d o r f o r m a t i o n i s t h e a p p r o x i m a t e age e q u i v a l e n t of the l o w e r p a r t of t h e S w a s e y f o r m a t i o n d e s c r i b e d by W a l c o t t (1908) in the H o u s e R a n g e , Utah; the u p p e r p a r t of t h e A b e r c r o m b i e f o r m a t i o n in t h e D e e p Creek* M o u n t a i n s , Utah; u n i t F of t h e H i g h l a n d P e a k l i m e s t o ne of P i o c h e ; m e m b e r E of t h e P o l e C a n y o n f o r m a t i o n of D r e w e s and 60 P a l m e r (1957) in t h e s o u t h e r n Snake R a n g e , N e v a d a ; the u p p er p a r t s of t h e O p h i r in the T i n t i c d i s t r i c t , and in t h e C a n y o n R a n g e, U t a h . S w a s e y l i m e s t o ne G e n e r a l - R o c k s a s s i g n e d t o t h e S w a s e y l i m e s t o n e a r e r e s t r i c t ed t o t h e u p p e r p a r t of t h e S w a s e y l i m e s t o n e of p r e v i o u s w r i t e r s (See C o n d o r 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 s s - The S w a s e y l i m e s t o n e c o n f o r m a b ly o v e r l i e s the f l a g g y , t h i n - b e d d e d l i m e s t o n e s of t h e C o n d o r f o r m a t i on a n d f o r m the f i r s t p r o m i n e n t c l i f f s s o u t h of t h e h i g h e s t c l i f f s on L o o k out M o u n t a i n. T h e f o r m a t i o n f o r m s a h o m o g e n e o u s u n i t 169 f e e t t h i c k. T o p o g r a p h i c e x p r e s s i o n - The S w a s e y l i m e s t o n e i s a c l i f f - f o r m i n g u n i t which f o r m s the top of h o g b a c k s p u r s which e x t e nd f r o m the d i v i d e to p o i n t s low on t h e e a s t and west f l a n k s of Lookout M o u n t a i n . L i t h o l o g y - The d a r k b l u e - g r a y S w a s e y l i m e s t o n e i s i n d i s t i n c t ly t h i n - to t h i c k - b e d d e d . It f o r m s m a s s i v e a p p e a r i n g , n e a r l y v e r t i c al c l i f f s . The r o c k i s p r i n c i p a l l y f i n e - g r a i n e d , a n d f r a c t u r e s within the f o r m a t i o n f i l l e d with white s e c o n d a r y c a l c i t e f a p p a r e n t l y i m p a r t a s t r e n g t h to t h e u n i t ..which e n a b l e s it to s t a n d n e a r l y v e r t i c a l. F i e l d i d e n t i f i c a t i o n - The o v e r l y i n g W h e e l e r and t h e u n d e r l y i ng C o n d o r f o r m a t i o n f o r m s l o p e s and a c c e n t u a t e the s t e e p e r p r o f i le 61 of t h e S w a s e y l i m e s t o n e . If u n d e r l y i n g and o v e r l y i n g s h a i y u n i ts a r e not e x p o s e d the S w a s e y m a y be m i s t a k e n f o r e i t h e r the M a r j um o r the Dome l i m e s t o n e. Age and c o r r e l a t i o n - No f o s s i l s w e r e found in t h e S w a s e y l i m e s t o n e , but i t s p o s i t i o n b e t w e e n t h e f o s s i l i f e r o u s C o n d o r and W h e e l er f o r m a t i o n s n e c e s s i t a t e s an a g e a s s i g n m e n t s o m e w h a t above m e d i al M i d d l e C a m b r i a n. The S w a s e y l i m e s t o n e i s t h e a p p r o x i m a t e age e q u i v a l e n t of the u p p e r b e d s of t h e A b e r c r o m b i e f o r m a t i o n in t h e D e e p C r e e k M o u n t a i n s, Utah; the u p p e r l i m e s t o n e u n i t s of t h e S w a s e y f o r m a t i o n of D e i s s (1938) i n t h e H o u s e R a n g e , Utah; and of u n i t G of the H i g h l a n d P e a k l i m e s t o ne of t h e P i o c h e d i s t r i c t. W h e e l e r 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 s s - The W h e e l e r f o r m a t i o n i s e x p o s ed a l o n g t h e s o u t h s i d e of L o o k o u t P e a k , n e a r the c r e s t . It e x t e n d s f r om t h e v a l l e y f l o o r s on b o t h s i d e s of t h e m o u n t a i n . Small e x p o s u r e s a re p r e s e n t on t h e d i v i d e west of T a l a w a g C a n y o n and n e a r the c e n t er of L i o n H i l l , n o r t h of H a r k e r Canyon. T h e W h e e l e r a g g r e g a t e s a t o t a l of 429 f e e t of t h i n - b e d d e d s t r a t a, on t h e d i v i d e s o u t h of L o o k o u t P e a k. T o p o g r a p h i c e x p r e s s i o n ->' T h e W h e e l e r f o r m a t i o n f o r m s the b a se of t h e n o t c h of L o o k o u t P e a k which i s e v i d e n t at a d i s t a n c e f r o m Rush and Skull v a l l e y s . The m o r e e a s i l y e r o d e d l i m e s t o n e s c o m p r i s i n g the 62 f o r m a t i o n f o r m h i g h l e v e l s a d d l e s b e t w e e n t h e u p p e r m o s t l i m e s of t h e S w a s e y and t h e b a s a l u n i t s of the o v e r l y i n g M a r j u m f o r m a t i o n. C h a r a c t e r i s t i c a l l y , the W h e e l e r i s a s l o p e - f o r m i n g unit b e n e a th t h e M a r j u m c l i f f s . M a r k e d s t r i k e v a l l e y s h a v e d e v e l o p e d a l o n g i ts o u t c r o p on b o t h s i d e s of t h e m o u n t a i n. L i t h o l o g y - The W h e e l e r c o n s i s t s of d a r k b l u e - g r a y , f i n e g r a i n e d , t h i n - b e d d e d , flaggy l i m e s t o n e c h a r a c t e r i z e d by t h e s m o o t h n e s s and f l a t n e s s of the b e d d i n g p l a n e s . The s t r a t a w e a t h e r in s l a bs a n d b l o c k s u s u a l l y with s q u a r e e d g e s . Silty p a r t i n g s a f f o r d b r e a k a ge p l a n e s f o r the b e d s . T r i l o b i t e s s u c h a s E l r a t h i a s p . and P e r o n a s p is ( a g n o s t i d ) a r e p r e s e n t on b e d d i n g p l a n e s in t h e u p p e r one t h i r d of the f o r m a t i o n . The s i l t y p a r t i n g s a r e t a n to r e d d i s h - t a n and l i k e the l i m e s t o n e b e d s a r e r e m a r k a b l y s m o o t h . P y r i t e c u b e s ( a l t e r ed to i i m o n i t e ) a r e p r e s e n t a l o n g s o m e of t h e b e d d i n g p l a n e s. F i e l d i d e n t i f i c a t i o n - The f l a t f l a g g y c h a r a c t e r of t h e w e a t h e r ed W h e e l e r s t r a t a i s v e r y d i s t i n c t i v e , so m u c h s o a s to be u n i q u e and d i a g n o s t i c of t h e f o r m a t i o n in t h e S h e e p r o c k a r e a . T r i l o b i t e s , though not a b u n d a n t , a r e s u f f i c i e n t l y p l e n t i f u l to p r o v i d e a s u r e m e a n s for i d e n t i f i c a t i o n and in a l l p l a c e s w h e r e t h e W h e e l e r was o b s e r v ed E l r a t h i a was found. Age and c o r r e l a t i o n - F o s s i l s w e r e c o l l e c t e d f r o m five l o c a l i t i es ( A p p e n d i x B and P l a t e I I I ) . Mr. A. R. P a l m e r r e p o r t s: C - 3 E l r a t h i a ? s p. 63 C - 4 E l r a t h i n a ? sp. C - 1 0 Z a c a n t h o i d e s s p. C - 1 5 E l r a t h i a s p. M r . R. C. B r i g h t r e p o r t s: C - 2 4 E l r a t h i a s p. P e r o n o p s i s i n t e r s t r i c t u s (White) P r o t o s p o n g i a s p. T h e f a u n a i n d i c a t e s t h a t t h e W h e e l e r f o r m a t i o n i s of u p p e r Middle C a m b r i a n a g e. T h e W h e e l e r f o r m a t i o n i s t h e a p p r o x i m a t e age e q u i v a l e n t of the u p p e r u n i t s of t h e A b e r c r o m b i e f o r m a t i o n in t h e Deep C r e e k M o u n t a i n s. Utah; of u n i t s H a n d I ( ? ) of t h e H i g h l a n d P e a k l i m e s t o n e of W h e e l er a n d L e m m o n (1938) at P i o c h e . The W h e e l e r f o r m a t i o n h a s b e e n o b s e r v e d by M r . RB H. O l s o n in c o m p a n y with the w r i t e r in the P r o m o n t o r y R a n g e of n o r t h e r n Utah. M a r j u m f o r m a t i on G e n e r a l - The M a r j u m f o r m a t i o n i n c l u d e s t h e s t r a t a lying b e t w e e n the W h e e l e r f o r m a t i o n and C o l e Canyon d o l o m i t e . T e r m i n o logy of t h e T i n t i c m i n i n g d i s t r i c t i s a p p l i e d to t h e U p p e r C a m b r i an s t r a t a above the M a r j u m 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 s s - The M a r j u m f o r m a t i o n i s t h e m o st p r o m i n a n t l y d i s p l a y e d of a l l t h e C a m b r i a n f o r m a t i o n s in t h e S h e e p r o ck 64 M o u n t a i n s . It m a k e s up t h e h i g h e s t s t r a t a of L o o k o u t P e a k and c o m p r i s e s ail of t h e r o c k s on t h e n o r t h dip s l o p e s f r o m Lookout P e a k n o r t h w a r d to t h e s o u t h e r n l i m i t of t h e L o o k o u t H i l l s at t he d r a i n a g e s of E a s t and W e s t R e d P i n e C r e e k s. The M a r j u m f o r m a t i o n i s 1, 193 f e e t t h i c k b e t w e e n the top of t h e W h e e l e r f o r m a t i o n , about a q u a r t e r of a m i l e s o u t h of L o o k o u t P e a k , and a p o i n t on t h e s o u t h s i d e of the W e s t Red P i ne C r e e k . T o p o g r a p h i c e x p r e s s i o n - The m o r e r e s i s t a n t r o c k s of the M a r j u m f o r m a t i o n f o r m h o g b a c k s and f l a t i r o n s a l o n g t h e n o r t h - f a c i n g d i p s l o p e s of L o o k o u t M o u n t a i n . The whole n o r t h s l o pe s l i g h t l y s o u t h of L o o k o u t P e a k to t h e L o o k o u t H i l l s i s c o m p o s e d of s t r a t a of t h e M a r j u m f o r m a t i o n. L i t h o l o g y - The M a r j u m f o r m a t i o n i s c o m p o s e d of c a r b o n a t es a n d s o m e s h a l e s . The l o w e r 350 f e e t i s a b l u e - g r a y , t h i n - b e d d e d, f i n e - to m e d i u m - g r a i n e d l i m e s t o n e . Most of t h e u n i t s of t h is i n t e r v a l c o n t a i n t a n s i l t y l a m i n a t i o n s which a r e v e r y u n d u l a t o ry ( P l a t e X I V ) . Above the b a s a l u n i t s a r e a p p r o x i m a t e l y 50 f e e t of t a n, f i s s i l e s h a l e and s h a i y l i m e s t o n e s which y i e l d e d f r a g m e n t s of i n a r t i c u l a t e b r a c h i o p o d s . A f ew l i m e s t o n e b e d s a b o v e t h e s h a l e s a re i n t r a f o r m a t i o n a l and a r e o v e r l a i n by 210 f e e t of b l u e - g r a y , f i n e - to m e d i u m - g r a i n e d , t h i n - b e d d e d l i m e s t o n e , w h i c h , like t h e b a s a l s t r a t a, p o s s e s s e s t a n , s i l t y u n d u l a t o r y p a r t i n g s . A f ew b e d s in t h i s i n t e r v al PLATE XIV Figure I Marjum limestone near Lookout Peak showing undulatory bedding and tan silty laminations. Figure 2 Hand specimen of Marjum limestone showing an irregular bedding surface. 65 c o n t a i n bLack o o l i t e s up to one s i x t e e n t h of an i n c h in d i a m e t e r . The n e x t 340 f e e t i s m o s t l y d o l o m i t e With s o m e d o l o m i t i c l i m e s t o n e . The d o l o m i t e i s d a r k b l u e - g r a y to g r a y , m e d i u m - g r a i n e d , and i s t h i c k - b e d d e d to m a s s i v e . The d a r k e r b l u e v a r i e t i e s c o n t a i n s h o r t white c u r v e d r o d s of d o l o m i t e . A 2 0 6 - f o o t unit n e a r the top of t h i s s e q u e n ce b e c o m e s a m o r e n e u t r a l g r a y in i t s u p p e r half and t h e t o p m o s t 26 feet i s z e b r a - b a n d e d with white c o a r s e l y c r y s t a l l i n e d o l o m i t e c o m p r i s i ng t h e bandS/Which in a f ew i n c h e s f e a t h e r out a n d a r e a b s o r b e d in the g r a y of t h e c o u n t r y r o c , . The d o l o m i t e s s h o w i n g z e b r a - b a n d i ng a p p e a r to be s e c o n d a r y s i n c e t h e y h a v e i r r e g u l a r a r e a l d i s t r i b u t i on w i t h i n s h o r t d i s t a n c e s . This f e a t u r e i s m o s t l i k e l y t h e r e s u l t of s o l u t i o n s o p e r a t i n g in a n d n e a r the f a u l t zone and p e n e t r a t i n g i n to t h e m o r e p e r m e a b l e s t r a t a . The t o p m o s t u n i t i s a 1 2 2 - f o o t d a rk b l u e - g r a y l i m e s t o n e s i m i l a r to t h e b a s a l s t r a t a of t h e f o r m a t i o n. T h e top of the M a r j u m f o r m a t i o n i s a c h e r t zone f r o m 8 t o 12 i n c h e s t h i c k at t h e t o p of a 7 - f o o t , white w e a t h e r i n g , p i n k i s h - g r a y, a p h a n i t i c , l a m i n a t e d d o l o m i t e . This d o l o m i t e and o t h e r s h i g h e r in t h e C o l e Canyon d o l o m i t e r e s e m b l e the 'type* D a g m a r of t h e T i n t ic d i s t r i c t . T h e b a s e of t h e M a r j u m f o r m a t i o n i s at t h e b a s e of t h e cliff-f o r m i n g l i m e s t o n e s o v e r l y i n g the p l a t y W h e e l e r f o r m a t i o n. F i e l d i d e n t i f i c a t i o n - The M a r j u m l i t h o l o g i e s a r e e a s i l y m i s t a k en f o r t h o s e of m a n y f o r m a t i o n s , h o w e v e r , the t h i c k n e s s of the t h i n - b e d d ed 66 u n i t s i s m o s t d i a g n o s t i c . The t a n , v e r y f i s s i l e s h a l e s b e a r i ng s c r a p s of i n a r t i c u l a t e b r a c h i o p o d s s e r v e to c o n f i r m the i d e n t i f y of t h e f o r m a t i o n. Age and c o r r e l a t i o n - F o s s i l s c o l l e c t e d f r o m t h r e e l o c a l i t i es ( A p p e n d i x B a n d P l a t e III) in t h e M a r j u m f o r m a t i o n w e r e m a i n l y s c r a ps of l i n g u l o i d b r a c h i o p o d s and t r i l o b i t e s . Mr. A. R. P a l m e r e x a m i n ed t h e m a t e r i a l and r e p o r t e d: C - 1 2 I n d e t e r m i n a t e t r i l o b i t e cf. M e t e o r a s p i s o r M o d o c ia T h e one i d e n t i f i a b l e f o s s i l i s not s u f f i c i e n t l y d i a g n o s t i c to a c c u r a t e ly d e t e r m i n e the a g e of the f o r m a t i o n . However, the s t r a t i g r a p j ^ i c p o s i t i on of t h e M a r j u m f o r m a t i o n , t o g e t h e r with the s u g g e s t i o n t h a t it c o n t a i ns M i d d l e C a m b r i a n f o r m s , l e a v e s l i t t l e doubt t h a t it i s u p p e r Middle C a m b r i a n in a g e . No f o s s i l s w e r e found in t h e u p p e r half of the f o r m a t i o n , a n d it i s p o s s i b l e t h a t p a r t of t h e M a r j u m m a y s t r a d d le t h e M i d d l e - U p p e r C a m b r i a n b o u n d a r y. The M a r j u m f o r m a t i o n i s the a p p r o x i m a t e age e q u i v a l e n t of the T r i p p e l i m e s t o n e in the D e e p C r e e k M o u n t a i n s , Utah, and of u n i t s J and K of the H i g h l a n d P e a k l i m e s t o n e at P i o c h e . The r e c o g n i t i o n of C o l e C a n y o n d o l o m i t e f a c i e s in t h e S h e e p r o c k s e c t i o n i m m e d i a t e ly o v e r l y i n g the M a r j u m l i m e s t o n e s u g g e s t s t h a t the M a r j u m c o r r e l a t es with t h e B l u e b i r d d o l o m i t e and t h e H e r k i m e r l i m e s t o n e of L o u g h l in (1919) of the T i n t i c m i n i n g d i s t r i c t , Utah. 67 C o l e C a n y o n d o l o m i te D i s t r i b u t i o n and t h i c k n e s s - The C o l e C a n y o n d o l o m i t e c r o ps out low on t h e n o r t h f l a n k of L o o k o u t M o u n t a i n s o u t h of W e s t Red P i n e C a n y o n and e x t e n d s o v e r a h a l f a m i l e n o r t h w a r d in t h e West L o o k o u t H i l l s . R e v e r s e and n o r m a l f a u l t s r e s t r i c t i t s e x t e n t to onl y a f ew f e e t in t h e E a s t L o o k o u t H i l l s . An e a s t - w e s t t h r u s t fault a l o n g the n o r t h b a s e of L o o k o u t M o u n t a i n h a s e l i m i n a t e d an unknown t h i c k n e s s of the C o l e C a n y o n s t r a t a . T e r t i a r y c o n g l o m e r a t e s o v e r l ie a d o w n - f a u l t e d g r a b e n - l i k e b l o c k which s e p a r a t e s t h e L o o k o u t H i l ls i n t o e a s t e r n and w e s t e r n e l e m e n t s . The c o n g l o m e r a t e o b s c u r e s a c o n s i d e r a b l e p o r t i o n of the a r e a b e t w e e n L o o k o u t M o u n t a i n and Lookout P a s s , s e v e r a L m i l e s to the n o r t h. C o l e C a n y o n l i t h o l o g y was t e n t a t i v e l y i d e n t i f i e d in t h e n o r t h e rn p a r t of t h e S i m p s o n M o u n t a i n s. S t r a t a of t h e C o l e C a n y o n f o r m a t i o n t o t a l 899 f e e t w h e r e m e a s u r ed at t h e s o u t h end of t h e W e s t L o o k o u t H i l l s. T o p o g r a p h i c e x p r e s s i o n - The C o l e C a n y o n , like a l l t h e f o r m a t i o n s n o r t h of L o o k o u t P e a k , o c c u p i e s an a r e a of low r e l i e f due to f a u l t i n g and a s h a l l o w n o r t h e r l y d i p . The C o l e C a n y o n w e a t h e rs to f o r m low r i d g e s with r o u n d e d c r e s t s . The o u t c r o p s a r e f e w er t h a n t h e u n d e r l y i n g f o r m a t i o n s and m u c h m o r e c o l l u v i um m a s ks t h e t e r r a n e. L i t h o l o g y - The C o l e C a n y o n d o l o m i t e c o n s i s t s of n e a r l y equal 68 p a r t s of d o l o m i t e and l i m e s t o n e . L i m e s t o n e i s m o s t c o m m o n in the l o w e r half w h e r e a s t h e u p p e r half c o n s i s t s p r i n c i p a l l y of d o l o m i t e s. U n i t s r a n g e f r o m 5 t o o v e r 200 f e e t in t h i c k n e s s . The d o l o m i t e s t e nd t o w a r d g r a y s while t h e l i m e s t o n e s a r e m a i n l y b l u e - g r a y . The l i m e s t o n e s a r e c h a r a c t e r i s t i c a l l y t h i n - b e d d e d with g r a y , tan, or p i n k i st s i l t y p a r t i n g s which a r e u n d u l a t o r y but h a v e a l o n g e r " w a v e l e n g t h" t h a n t h e p a r t i n g s of t h e u n d e r l y i n g M i d d l e C a m b r i a n f o r m a t i o n s . Some of t h e l i m e s t o n e s c o n t a i n n o d u l e s of s i l t and in a l l c a s e s the s i l t y b a n ds a r e of a l i g h t e r c o l o r than t h e l i m e s t o n e s ( P l a t e XV). Most of the d o l o m i t e s in t h e l o w e r p a r t of t h e f o r m a t i o n a r e g r a y , f i n e - g r a i n e d, a n d l a m i n a t e d. The b a s e of t h e f o r m a t i o n i s a r b i t r a r i l y p l a c e d at t h e t o p of a t h i n b l a c k c h e r t zone in a l a m i n a t e d d o l o m i t e of c o n f o r m a b l y u n d e r l y i n g M a r j u m f o r m a t i o n. F i e l d i d e n t i f i c a t i o n - The C o l e C a n y o n d o l o m i t e i s c o m p o s e d of t h i n a n d t h i c k u n i t s of d o l o m i t e and l i m e s t o n e which a r e l a m i n a t e d on a l a r g e s c a l e . The f i n e l y l a m i n a t e d light g r a y w e a t h e r i n g d o l o m i t e s a re t y p i c a l of t h i s f o r m a t i o n a s well a s of s t r a t a in t h e S i l u r i a n and D e v o n i a n s y s t e m s . However, the u n i t s in t h e C o l e C a n y o n a re u s u a l l y l e s s t h a n t e n f e e t t h i c k , w h e r e a s t h o s e of o t h e r s y s t e ms a r e 30 o r m o r e f e e t t h i c k . The b a n d e d l i m e s t o n e s of t h e C o le C a n y o n w e a t h e r to s m o o t h e r o u t l i n e s and t h e b e d d i n g p l a n e s a re not a s wavy a s t h o s e of the l i m e s t o n e s of t h e Middle C a m b r i a n f o r m a t i o n s. 69 Age and c o r r e l a t i o n - No f o s s i l s w e r e found in t h e C o le C a n y o n d o l o m i t e . F o r m s found in t h e b a s a l u n i t s of t h e o v e r l y i ng Opex f o r m a t i o n a r e of l o w e r U p p e r C a m b r i a n a g e . The top of the C o l e C a n y o n d o l o m i t e i s t e n t a t i v e l y c o n s i d e r e d to b e the top of the M i d d l e C a m b r i a n. T h e C o l e C a n y o n d o l o m i t e i s the a p p r o x i m a t e age e q u i v a l e nt of t h e L a m b d o l o m i t e and t h e l o w e r p a r t of t h e H i c k s f o r m a t i on d e s c r i b e d by N o l a n (1935) in the D e e p C r e e k M o u n t a i n s , Utah; m o st of t h e H a m b u r g d o l o m i t e of N o l a n , M e r r i a m and W i l l i a m s (1956) of t h e E u r e k a d i s t r i c t , N e v a d a ; the u p p e r p a r t of t h e M a r j u m l i m e s t o ne i n t h e H o u s e R a n g e , Utah; the u p p e r p a r t of t h e B l o o m i n g t o n f o r m a t i o n of W a l c o t t (1908) in t h e B l a c k s m i t h F o r k a r e a , Utah; t h e u p p er p a r t of t h e H i g h l a n d P e a k l i m e s t o n e and t h e l o w e r p a r t of t h e Mendha f o r m a t i o n of the P i o c h e d i s t r i c t ; and t o p a r t of t h e L y n c h d o l o m i t e of G i l l u l y (1932) in t h e O q u i r r h M o u n t a i n s , Utah. Opex 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 s s - The Opex f o r m a t i o n i s p r i n c i p a l ly l i m e s t o n e . It c r o p s out in a b e l t n e a r l y 2, 600 f e e t wide in the s o u t h e r n end of t h e E a s t and West L o o k o u t H i l l s . N o r t h - t r e n d i ng n o r m a l f a u l t s s l i g h t l y o f f s e t the s t r a t a on the w e s t e r n end. T h e Opex was m e a s u r e d in t h e Wrest L o o k o u t H i l l s a s a c o n t i n u a t i o n of the l i n e of t h e C o l e C a n y o n s e c t i o n . At t h i s l o c a l i ty i t i s 938 f e e t t h i c k. 70 T o p o g r a p h i c e x p r e s s i o n - The Opex w e a t h e r s like t h e u n d e r lying C o l e C a n y o n s t r a t a a s r o u n d e d h i l l s e a p p e d with c o n s i d e r a b le a l l u v i a l c o v e r. L i t h o i o g y - The Opex f o r m a t i o n i s m a i n l y l i m e s t o n e and d o l o m i te with f i s s i l e s h a l e c o m p r i s i n g the r e m a i n d e r . The l i m e s t o n e s a re m e d i u m - to f i n e - g r a i n e d , t h i n - b e d d e d with p i n k i s h , s i l t y p a r t i n g s, and w e a t h e r a s r o u g h f l a g s . I n t r a f o r m a t i o n a l c o n g l o m e r a t e s a re c o m m o n . The l o w e s t s h a l e i s a 1 0 - f o o t u n i t 120 f e e t a b o v e the b a s e . It is light g r e e n in c o l o r and i s e x t r e m e l y f i s s i l e ; i t s p r e s e n c e i s d e t e c t ed only by f l o a t . O v e r l y i n g the s h a l e a r e a d d i t i o n a l l i m e s t o n e s a g g r e g a t i n g n e a r l y 200 f e e t in t h i c k n e s s , w h i c h in t u r n a r e c a p p e d by 32 f e e t of s h a l e c o n t a i n i n g a 5-foot bed of l i g h t g r a y , l a m i n a t e d d o l o m i t e n e a r the c e n t e r . Above the u p p e r m o s t s h a l e i s 79 f e e t of l i m e s t o n e s of which the l o w e r 20 f e e t a r e o o l i t i c and p e b b l y . T r i l o b i te f r a g m e n t s w e r e found in t h i s z o n e . The n e x t o v e r l y i n g unit i s a 1 0 - f o o t b e d of b l u e - g r a y l i m e s t o n e which c o n t a i n s d i s p e r s ed i r r e g u l a r c h e r t m a s s e s . B r a c h i o p o d s w e r e c o l l e c t e d f r o m t h is u n i t . The t o p m o s t unit of the Opex f o r m a t i o n i s a b a n d e d , s i l ty l i m e s t o n e which w e a t h e r s b l o c k y . The b a n d s a r e v e r y f l a t and d i s p l a y s o m e l a m i n a t i o n , and t r i l o b i t e s c h a r a c t e r i s t i c of the C o n a s p i s zone a r e found on t h e s i l t y p a r t i n g s. 71 A f a u l t at t h e top of the C o l e C a n y o n f o r m a t i o n h a s cut out an u n known t h i c k n e s s of b a s a l O p e x . The m i s s i n g u n i t s p o s s i b l y r e p r e s e n t b e t w e e n 100 and 300 f e e t. F i e l d i d e n t i f i c a t i o n - The Opex f o r m a t i o n i s d i s t i n g u i s h e d by t h e b a n d e d l i m e s t o n e s of i t s t o p m o s t u n i t . The p r e s e n c e of a g r e at t h i c k n e s s of Ajax d o l o m i t e a b o v e , and t h e t h i c k d o l o m i t e s at t h e top of the C o l e C a n y o n b e l o w , a r e the b e s t m e a n s f o r i d e n t i f i c a t i o n . The top of t h e O p e x was found to be c o n s i s t e n t l y f o s s i l i f e r o u s. Age and c o r r e l a t i o n - F o s s i l s w e r e r e c o v e r e d f r o m s i x l o c a l i t i es i n t h e Opex f o r m a t i o n ( A p p e n d i x B a n d P l a t e I I I ) . A. R. P a l m e r i d e n t i f i e d t h e s p e c i m e n s f r o m l o c a l i t i e s C - 1 7 and C - 1 9 and r e p o r t e d: C - 1 7 C o n a s p i d t r i l o b i t e f r a g m e n ts B i l l i n g s e l l a s p. C o n o d o n t s A c r o t r e t i d s of U p p e r C a m b r i a n type P r o b l e m a t i c u m I - d e s c r i b e d by W e s t e r g a rd ( G e o l o g i s k a F o r e n i n g e n s I S t o c k h o lm F o r h a n d l i n g e r, B a n d 75, Heft 4, p . 4 6 5 - 4 6 8 , 1953) f r om U p p e r C a m b r i a n b e d s in Sweden. C - 1 9 A c r o t r e t i d b r a c h i o p o d s of U p p e r C a m b r i a n type C o n o d o n t s P a l m e r s t a t e s: " C o l l e c t i o n s C - 1 7 and C - 1 9 a r e U p p e r C a m b r i an i n a g e . Although t h e y m a y c o m e f r o m a unit t h a t l i t h i c a l l y r e s e m b l e s the Opex, they c o n t a in f o s s i l s t h a t i n d i c a t e an a g e e q u i v a l e n c e to the Ajax d o l o m i t e . C o l l e c t i o n C - 1 7 i s of p a r t i c u l ar i n t e r e s t b e c a u s e , in a d d i t i o n to t h e p r e s e n c e of s i L i c i f i e d s p e c i m e n s of B i l l i n g s e i l a , a c h a r a c t e r i s t i c middLe U p p e r C a m b r i a n b r a c h i o p o d , it c o n t a i n s e x a m p l e s of C a m b r i a n c o n o d o n t s , and a s p e c i m e n of a p e c u l i a r t h r e e - p r o n g e d p r o b l e m a t i c um t h a t h a s b e e n d e s c r i b e d only f r o m U p p e r C a m b r i an b e d s in S w e d e n . C a m b r i a n c o n o d o n t s h a v e b e en r e c o g n i z e d in c o l l e c t i o n s f r o m the Dugway r a n ge i n r o c k s t h a t s e e m to r e s e m b l e t h o s e f r o m which c o l l e c t i o n C - 1 7 was o b t a i n e d . They a r e a l s o known f r o m Wyoming and c e n t r a l T e x a s . At a l l known l o c a l i t i e s they h a v e b e e n o b t a i n e d only f r o m h o r i z o n s e q u i v a l e n t to t h e C o n a s p i s zone of m i d d le F r a n c o n i a n age in t h e s t a n d a r d U p p e r C a m b r i an s e c t i o n . f l R. C. B r i g h t e x a m i n e d c o l l e c t i o n s f r o m l o c a l i t i e s C - 2 5 , C - 2 7 , and C - 3 5 ; t h e i d e n t i f i c a t i o n s a r e a s f o l l o w s: C - 2 6 , n e a r the b a s e of the Opex. C o o s e l l a s p p. K o r m a g n o s t u s cf. K. s i m p l e x ( R e s s e r) P s e u d a g n o s t u s p r o l o n g u s ( H a l l and Whitfield) S y s p a c h i c i u s ? s p. T r i e r e p i c e p h a l u s w a l c o t t i ( L o c h m a n) L i n g u i e l l a s p. H y o l i t h e s p r i m o r d i a l s i s (Hall) C - 2 7 , n e a r b a s e. T r i l o b i t e p y g i d i um a f f i n i t y U p p e r C a m b r i an C - 3 5 , n e a r top of Opex E l v i n i a m o n t i s R e s s er E l v i n a s p. C - 2 5 M a u s t o n i a s p. P a r a b o l i n o i d e s c o n t r a c t u s F r e d r i c k s on T a e n i c e p h a l u s cf. T. h y r u m e n s i s R e s s er T a e n i c e p h a l u s cf. T. h y r u m , e n s i s R e s s er T a e n i c e p h a l u s s h u m a r d i Hall T a e n i c e p h a l u s cf. T. s t r i a t u s R e s s er T a e n i c e p h a l u s n . s p. A c r o t r e t a cf. A. m i c r o s c o p i a W a l c o tt 73 C - 2 5 ( c o n t i n u e d) A c r o t r e t a o p h i r e n s i s W a i c o tt B i l l i n g s e i l a cf. B. e o l o r a d o e n s i s Waicott E o o r t h i s d e s m o p l e u r a Waicott L i n g u l e l l a s p. L i n g u i o i d b r a c h i o p o ds P e l a g i e l l a - l i k e g a s t r o p od T h e Opex f o r m a t i o n i s l o w e r and m i d d l e U p p e r C a m b r i a n in a g e . The b a s a l Opex i s r e p r e s e n t e d by f a u n a f r o m C - 2 6 which is of t h e u p p e r C e d a r i a zone o r the b a s a l C r e p i c e p h a l u s zone of the D r e s b a c h i a n s t a g e . F a u n a f r o m C - 3 5 r e p r e s e n t s the E l v i n i a z o n e. S p e c i m e n s f r o m l o c a l i t i e s C - 1 7 , C - 1 9 , and C - 2 5 n e a r the t o p of the Opex r e p r e s e n t the C o n a s p i s z o n e of t h e F r a n c o n i a n s t a g e. T h e Opex f o r m a t i o n i s t h e a p p r o x i m a t e age e q u i v a l e n t of the D u n d e r b e r g s h a l e of W a i c o t t (1908) of t h e E u r e k a d i s t r i c t , Nevada; t h e Nopah f o r m a t i o n of W h e e l e r and S t e e l e (1951) i n t h e H o u s e R a n g e, Utah; m o s t of t h e l o w e r half of t h e M e n d h a f o r m a t i o n at P i o c h e ; the Nounan a nd the l o w e r half of the St. C h a r l e s of W a i c o t t (1908) in t h e B l a c k s m i t h F o r k a r e a , Utah; the J o h n s W a s h l i m e s t o n e and t h e C o r s e t S p r i n g s h a l e of D r e w e s and P a l m e r (1957) in t h e Snake R a n g e , N e v a d a ; t h e u p p e r p a r t of t h e H i c k s f o r m a t i o n in t h e Deep C r e e k M o u n t a i n s , Utah. A j a x 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 s s - The Ajax f o r m a t i o n c r o p s out in a b e l t about 1, 000 f e e t wide at t h e s o u t h end of the E a s t L o o k o u t H i l ls 74 a n d s t r i k e s n o r t h of west to t h e W e s t L o o k o u t H i l l s w h e r e it is d i s p l a c e d n o r t h w a r d . Minor t h r u s t i n g h a s d e c r e a s e d the dip in t h e w e s t e r n p a r t of t h e o u t c r o p and the s t r i k e i s m o r e w e s t e r l y. No o t h e r d o l o m i t e s r e c o g n i z a b l e a s A j a x w e r e n o t e d on t h e r e st of t h e r a n g e o r in t h e e a s t e r n p a r t of t h e S i m p s o n M o u n t a i n s. T h e Ajax f o r m a t i o n was m e a s u r e d in t h e West L o o k o u t H i l ls a n d found to be 1, 012 f e e t t h i c k . No a p p a r e n t t h i n n i n g was n o t e d , but m u c h c o v e r in t h e e a s t e r n p a r t of t h e o u t c r o p a r e a r e n d e r s m e a s u r e m e n t t h e r e p r a c t i c a l l y i m p o s s i b l e. T o p o g r a p h i c e x p r e s s i o n - The Ajax f o r m a t i o n c r o p s out in r i d g es a n d s t e e p s l o p e s , being r e s i s t a n t enough to a f f o r d good e x p o s u r e s in m o s t of t h e o u t c r o p a r e a. L i t h o l o g y - The Ajax f o r m a t i o n i s c o m p o s e d e n t i r e l y of d o l o m i te •-ifr-th€^ShejBtpxock.„are.a.. The l o w e r 450 f e e t of s t r a t a a r e d a r k g r a y, m e d i u m - g r a i n e d d o l o m i t e s . Light and d a r k m o t t l e s a r e c o m m o n. B l a c k c h e r t n o d u l e s up t o e i g h t i n c h e s in l e n g t h a r e p r e s e n t in the b a s a l u n i t a s a r e w o r m y , g r a y c h e r t i n c l u s i o n s . The n e x t 150 f e et i s a l i g h t g r a y a n d s u g a r y t e x t u r e d d o l o m i t e which h a s b e e n c a l l ed t h e E m e r a l d m e m b e r a f t e r i t s c o r r e l a t i v e in the T i n t i c m i n i ng 4 i s i r i c t . The u p p e r u n i t s a g g r e g a t e o v e r 400 f e e t of s t r a t a , being m a i n l y a d a r k - g r a y to b l u e - g r a y , s u g a r - to m e d i u m - g r a i n e d d o l o m i t e. At s e v e r a l l o c a l i t i e s p i s o l i t e s w e r e n o t e d in t h e u p p e r p a r t of the Ajax ( P l a t e XVI). They a r e d i s t r i b u t e d in r a n d o m p o s i t i o n s and a re Figure I Hand specimen of the Ajax dolomite showing banding and laminations. This specimen is typical of the strata of the Simon-son dolomite. Pi Figure 2 Specimen of the Ajax dolomite with pisolitic structures dispersed in the medium-grained dolomite. 75 not in c l o s e c o n t a c t with e a c h o t h e r. T h e c o n t a c t b e t w e e n C a m b r i a n and O r d o v i c i a n i s c o n f o r m a b le a n d g r a d a t i o n a i . The t o p of t h e A j a x f o r m a t i o n i s a g r a y , flaggy d o l o m i t e , w h e r e a s t h e b a s a l s t r a t a of t h e o v e r l y i n g H o u s e l i m e s t o ne a r e n e a r l y 100 p e r c e n t i n t r a f o r m a t i o n a l and h a v e s i l t y p a r t i n g s. F i e l d i d e n t i f i c a t i o n - In t h e S h e e p r o c k M o u n t a i n s the Ajax f o r m a t i o n i s e n t i r e l y d o l o m i t e . The d a r k g r a y to b l a c k c o l o r of the u p p e r and l o w e r u n i t s i s v e r y c h a r a c t e r i s t i c a s i s t h e c r y s t a l i i n i t y. A few b e d s of s c a t t e r e d p i s o l i t e s a r e p r e s e n t in t h e u p p e r p a r t of the f o r m a t i o n . Near t h e m i d d l e of t h e A j a x i s 150 f e e t of white to light g r a y , c r y s t a l l i n e d o l o m i t e known a s the E m e r a l d m e m b e r of the A j a x f o r m a t i o n . Many v e r m i c u l a r and s l i g h t l y c u r v e d , r o d - l i ke b o d i e s o c c u r in the u p p e r p a r t of t h e l o w e r u n i t. Age and c o r r e l a t i o n - T h e Ajax d o l o m i t e i s d e v o i d of f o s s i l s. A M i d d l e U p p e r C a m b r i a n age i s i n f e r r e d for the f o r m a t i o n b e c a u se of i t s s t r i k i n g i i t h i c s i m i l a r i t y to t h e Ajax d o l o m i t e of t h e T i n t ic m i n i n g d i s t r i c t. T h e Ajax d o l o m i t e i s t h e age e q u i v a l e n t of t h e u p p e r half of the St. C h a r l e s f o r m a t i o n of t h e B l a c k s m i t h F o r k a r e a , Utah; t h e Notch P e a k f o r m a t i o n of W a i c o t t (1908) in t h e H o u s e R a n g e , Utah; p a r t of t h e C h o k e c h e r r y d o l o m i t e ( ? ) in t h e D e e p C r e e k M o u n t a i n s , Utah; the u p p e r p a r t of t h e M e n d h a f o r m a t i o n at P i o c h e ; and p a r t of an u n n a m ed l i m e s t o n e in t h e Snake R a n g e , N e v a d a. 7.6 C a m b r i a n c o r r e l a t i on C a m b r i a n s t r a t a of the S h e e p r o c k M o u n t a i n s p r e s e n t many p r o b l e m s in c o r r e l a t i o n . Though not s i n g u l a r l y r e s t r i c t e d to the S h e e p r o c k a r e a , the p r o b l e m s a r e e s p e c i a l l y s i g n i f i c a n t b e c a u s e of t h e g e o g r a p h i c p o s i t i o n of t h e S h e e p r o c k R a n g e r e l a t i v e to o t h er m e a s u r e d s e c t i o n s of C a m b r i a n s t r a t a in t h e O q u i r r h , E a s t T i n t i c, H o u s e , and D e e p C r e e k M o u n t a i n r e g i o n s. Many l o c a l i t i e s of m e a s u r e d C a m b r i a n s t r a t a w e r e p l o t t e d on F i g u r e 4 , a n d t h e known o r e s t i m a t e d t h i c k n e s s e s of C a m b r i a n s t r a ta above the b a s a l q u a r t z i t e w e r e i s o p a e h e d . The i s o p a c h o u s l i n es a i d in d e c i d i n g to which p r e v i o u s l y s t u d i e d s e c t i o n one m a y m o st p r o p e r l y and a c c u r a t e l y c o r r e l a t e n e w l y r e c o g n i z e d C a m b r i a n s t r a t a. The w r i t e r d o e s not i n f e r t h a t a l l s e c t i o n s lying with a c e r t a in i s o p a c h a r e c o r r e l a t i v e . F a c t o r s s u c h a s d i s t a n c e of t r a n s p o rt and s o u r c e of a d e t r i t a i f r a c t i o n t e n d to d i s r u p t a l i t h o l o g i c c o r r e l a - t i o n . C a r b o n a t e or c h e m i c a l f r a c t i o n s a r e m o s t l y l i k e l y to be c o r r e l a t i ve b o t h in t i m e and i i t h o l o g y . I n t r a - c a r b o n a t e a r e n a c e o u s s e d i m e n t s s u c h as W o r m C r e e k and the Swan P e a k q u a r t z i t e s l i k e w i s e a r e c o r r e l a t e d with e a s e b o t h iith9ger$.caiiy a n d f a u n a l l y . D e t r i t a i f r a c t i o n s , p a r t i c u l a r ly t h e b a s a l C a m b r i a n q u a r t z i t e s and s h a l e s , a r e l i t h o g e n i c a l l y c o r r e l a t i v e. B a s a l q u a r t z i t e s not u n d e r l a i n by a c c u r a t e l y d a t e d c a r b o n a t e s will m o st l i k e l y c r o s s t i m e l i n e s and, if a c c u r a t e l y e x a m i n e d , will be found to 77 c h a n g e l i t h o l o g i c a l l y f r o m one l o c a l i t y to a n o t h e r , t h o u g h in m a ny i n s t a n c e s , t h e d i f f e r e n c e s m a y be s m a l l . The c h a n g e in l i t h o l o g y, h o w e v e r s i g n i f i c a n t , is due to t h e c h a r a c t e r of t h e s o u r c e m a t e r i al a n d of t h e t r a n s p o r t i n g m e d i a . The l i t t o r a l p r o c e s s e s a l o n g the e d g e s of a t r a n s g r e s s i n g s e a a r e not a l w a y s c a p a b l e of l e a v i n g a b a s a l d e t r i t u s of l i k e l i t h o l o g y o v e r the f l o o r of an e n t i r e g e o s y n - c l i n e . As m e n t i o n e d p r e v i o u s l y , a l i m e s t o n e o r o t h e r c h e m i c al d e p o s i t p r e c i p i t a t e d d i r e c t l y f r o m s e a w a t e r m a y b e m o r e i d e a l ly c o r r e l a t i v e l i t h o l o g i c a l l y and f a u n a l l y . However, the w r i t e r d o e s not i m p l y t h a t a m a r i n e e n v i r o n m e n t would n e c e s s a r i l y be s o u n i f o rm c h e m i c a l l y a s to c a u s e d e p o s i t i o n of l i t h o l o g i c a l l y s i m i l a r l i m e s t o n e s o v e r the e n t i r e g e o s y n c l i n e , but at the s a m e t i m e he w i s h es to i n f e r t h a t d e p o s i t i o n of a l i t h o l o g i c a l l y s i m i l a r l i m e s t o n e o v e r a v e r y l a r g e a r e a i s p o s s i b l e . W e a t h e r , v e n t i l a t i o n of t h e s e a w a y s, o r g a n i s m s , and d e t r i t a i f r a c t i o n s a l l t e n d to m o d i f y o r r e s t r e c t a c h e m i c a l e n v i r o n m e n t. It s e e m s l o g i c a l to a s s u m e that if w a t e r c u r r e n t s w e r e s u f f i c i e n t ly c o m p e t e n t to c a r r y s i l t f a r i n t o t h e d e e p e r b a s i n o r b a s i n s and t h us f o r m s h a l e s , that t h e s e c o m p e t e n t c u r r e n t s would t e n d to f o l l ow d e s i g n a t e d c o u r s e s and t h a t a l o n g t h e c o u r s e s n e a r e r the s o u r c e, t h e r e s h o u l d be m o r e s h a l e . H e r e i n l i e s the d a n g e r of p r o j e c t i ng ' b a s i n * s h a l e u n i t s too f a r f r o m the t y p e l o c a l i t i e s . A b a s i n s h a le m a y be m a i n l y t h e m a n i f e s t a t i o n of a p a r t of a m o r e e x t e n s i v e s h a le 78 unit f a r t h e r r e m o v e d f r o m the b a s i n . The w r i t e r d o e s not a d h e re to t h e i d e a t h a t a b a s i n s h a l e m a y be an i s o l a t e d u n i t without a c o n n e c t i o n with a s o u r c e , but at t h e s a m e t i m e r e c o g n i z e s t h a t it m a y p o s s i b l y be t h i c k e r by p r o c e s s of s t a g n a t i o n and p o n d i n g. F u r t h e r t e m p o r a r y f a i l u r e in " c o m p e t e n c y ' m a y a l l ow c a r b o n a te d e p o s i t i o n to b u i l d a c o n s i d e r a b l e t h i c k n e s s of s t r a t a in an i n t e r i m b e t w e e n e p i s o d e s of s h a l e d e p o s i t i o n . Such w e a k e n i n g in c o m p e t e n c y m a y be due e i t h e r to f l u c t u a t i o n at t h e s o u r c e o r d i f f e r en t i a i s i n k i n g of t h e t e r r a i n , or to b o t h. S a l i e n t s o r s h o a l i n g a r e a s , as shown on t h e i s o p a c h o u s m a p, l i k e w i s e c a n n o t be c o m p l e t e l y c o r r e l a t e d with c l o $ e - l y i n g s e c t i o ns s i t u a t e d in t h e d e e p e r p o r t i o n s of t h e g e o s y n c l i n e . Only t h e s t r a ta which w e r e d e p o s i t e d at n e a r l y e q u a l r a t e s d u r i n g a s p e c i f i c t i me i n t e r v a l will be c o r r e l a t i v e . An e x a m p l e i s t h e U p p e r C a m b r i an s t r a t a of the S h e e p r o c k - E a s t T i n t i c a r e a . The M i d d l e C a m b r i an s t r a t a of t h e S h e e p r o c k r e g i o n c a n n o t be a c c u r a t e l y c o r r e l a t e d with s t r a t a of s i m i l a r age in t h e E a s t T i n t i c M o u n t a i n s b e c a u s e the E a st T i n t i c a r e a , though n e g a t i v e in M i d d l e C a m b r i a n t i m e s , was not s o n e g a t i v e a s the S h e e p r o c k a r e a d u r i n g t h e s a m e t i m e i n t e r v a l. T h i s c o u l d p o s s i b l y e r a s e any s e m b l a n c e of l i t h o g e n i c c o r r e l a t i o n s, but would not n e c e s s a r i l y d e s t r o y f a u n a i c o r r e l a t i o n s. T h e i s o p a c h m a p of C a m b r i a n s t r a t a a b o v e the b a s a l q u a r t z i te ( F i g u r e 4) w a s p r e p a r e d to s h o w t h e f e a t u r e s of t h e C a m b r i an I S O P A C H MAP OF CAMBRIAN SYSTEM EXCLUSIVE OF BASAL QUARTZITES FIGURE 4 TABLE 2 - SOURCES OF L o c a l i ty WYOMING S.W. Wind R i v e r M t n s. Author L o v e , J, D, IDAHO Soda S p r i n g s Armstrong, F , C Mink C r e ek UTAH S o u t h e r n Malad Range B l a c k s m i t h F o rk P r o m o n t o r y Range P r o m o n t o r y Range No, S i l v e r I s l a nd Range So, S i l v e r I s l a nd Range S o u t h e r n L a k e s i d e M t n s, Salt Lake (Cottonwood) L o d o r e O q u i r r h Mtns, Deep C r e ek M o u n t a i n s S h e e p r o ck M o u n t a i n s E a s t T i n t ic M o u n t a i n s K e l l e r C o u l t e r , H. W. W i l l i a m s , J. Stewart O l s o n , R. H. O l s o n , R. H. A n d e r s o n , W. L. P u b l i c a t i on Wyoming Geol. A s s o c. 5th Ann. F i e l d Conf. ( C h a r t ) , I n t e r m o u n t a in A s s o c . P e t . G e o l . , 4th Ann. F i e l d Conf. T h e s i s , Univ. of Utah I d a h o B u r e a u of Mines and G e o l . , P a m p h l e t 107 G . S . A . Bull. v. 59 Guidebook to G e o l . of Utah, No. 11 P r i v a t e c o m m u n i c a t i on T h e s i s , Univ. of Utah S c h a e f f e r , F . E . , J r . Private c o m m u n i c a t i on Young, J. C. G r a n g e r , A. E. U n t e r m a n n , G. E . and B. R. G i i l i i y , J a m es Nolan, T. B. Cohen our., R. E. L i n d g r e n , W., and L o u g h i i n , G. F . Utah G e o l . and M i n e r a l. S u r v e y , Bull. 56 Utah Geol. and M i n e r a l. S u r v e y , B u l l . 42 U. S. Geol. Survey, P r o f . P a p e r 173 U. S. Geol. Survey, P r o f . P a p e r 177 T h i s p a p er U. S. Geol. Survey, P r o f . P a p e r 107 Date 1950 1953 1952 1956 1948 1956 1957 1957 1957 1955 U. S. Geol. S u r v e y , C i r c . 296 1953 1954 1932 1935 1957 1919 N FOR CAMBRIAN SYSTEM ISOPACH MAP L o c a l i ty UTAH ( c o n t ' d .) Long Ridge Canyon Range House Range A u t h o r M u e s s i g , S i e g f r i e d , J. C h r i s t i a n s e n , F . W. W h e e l e r , H. E . and S t e e l e , Grant P u b l i c a t i on T h e s i s , Ohio S t a t e Univ. G e o l . Soc. A m e r i c a Bull, v. 63 Guidebook to t h e Geology of Utah, No. 6 Date 1951 1952 1951 (Well) El P a so N a t . Gas #1 P a c k s a d d le (Well) Stan. Oil of Calif, and C o n t i n e n t a l Oil (Well) South L a s t Chance (Well) P a c . W e s t e r n #1 T e a s d a le (Well) Hunt Oil (Well) N o k a i - S k e l l y) W e l l s , L e w i s F . I n t e r m o u n t a i n A s s o c . P e t. G e o l . , 5th Ann. F i e ld Conf. 1954 B e a v e r Dam M o u n t a i n s NEVADA Mountain City a r e a E u r e k a S o u t h e r n Snake Range P i o c h e V i r g i n Mtns, F r e n c h m a n Mountain CALIFORNIA Nopah A r ea M c N a i r , A. H. C o h e n o u r , R. E. Guidebook to the Geology of Utah, No. 7 1952 U. S. Atomic E n e r g y C o m m . Unpublished Nolan, T. B . , M e r r i a m , U. S. Geol, Survey C. W . , and W i l l i a m s , Prof. P a p e r 276 J . S. D r e w e s , H . , and P a l m e r , A. R. W h e e l e r , H. E. M c N a i r , A. H. M c N a i r , A. H. H a z z a r d , J. C. A m e r . A s s o c . P e t . G e o l ., B u l l . v. 41 Univ. of N e v a d a B u l l ., v . 34, n o . 8 A m e r . A s s o c . P e t . Geol, B u l l . v. 35 Guidebook t o t h e G e o l . of U t a h , No. 7 C a l i f . J o u r , of M i n e s & G e o l . , v. 33 1956 1957 1940 1951 1952 1937 79 g e o s y n c l i n e and a s an a i d to c o r r e l a t i o n . The S h e e p r o c k s e c t i on o c c u p i e s a p o s i t i o n within t h e d e e p e r p o r t i o n s of t h e t r o u g h a n d, f o r t h i s r e a s o n , the w r i t e r c o r r e l a t e d the S h e e p r o c k s t r a t a with the H o u s e R a n g e s e c t i o n . As i s a p p a r e n t , a m o r e l o g i c a l c o r r e l a t i on would h a v e b e e n with t h e D e e p C r e e k s e c t i o n ; h o w e v e r , the C a m b r i an of t h e Deep C r e e k M o u n t a i n s h a s not b e e n s u f f i c i e n t l y s u b d i v i d e d and d a t e d , and t h e r e f o r e , t e r m i n o l o g y f r o m that a r e a was not u s e d. The E a s t T i n t i c M o u n t a i n s and t h e O q u i r r h M o u n t a i n s s e c t i o n s both a p p e a r to be in a r e a s m a r g i n a l to t h e d e e p e r t r o u g h s . The s e c t i on i n t h e s o u t h e r n Snake R a n g e ( D r e w e s and P a l m e r , 1957) i n d i c a t e s that a s o u t h w e s t - to n o r t h w e s t - t r e n d i n g e l e m e n t m a y p a r a l l e l and d i v i de t h e d e e p e r t r o u g h b e t w e e n the P i o c h e and t h e H o u s e R a n g e s e c t i o n s. F u r t h e r , t h e r e a p p e a r s to be an e a s t - w e s t e l e m e n t f o r m i n g a s a s a l i e n t f r o m the W a s a t c h M o u n t a i n s a r e a a s an e x t e n s i o n of the e a s t - t o - w e s t t r e n d of the U i n t a M o u n t a i n s . The w r i t e r p r o p o s es t h a t t h i s p r o m i n e n c e be n a m e d the " S t a n s p u r y S a l i e n t " b e c a u s e of i ts d i r e c t i o n t h r o u g h S t a n s b u r y I s l a n d . The i s o p a c h o u s m a p of the O r d o v i c i a n q u a r t z i t e s ( F i g u r e 5) s u b s t a n t i a t e s t h e p r e s e n c e of the a f o r e m e n t i o n e d e l e m e n t s . The O r d o v i c i a n q u a r t z i t e s a r e d e e p e st i n a r e a s w h e r e the C a m b r i a n t r o u g h was b e s t d e v e l o p e d and a re c o n s i d e r e d to be a m a n i f e s t a t i o n of d i f f e r e n t i a l c o m p a c t i o n of the C a m b r i a n s t r a t a in a r e g i o n of s l i g h t e p i r o g e n i c u p l i f t. The c a r b o n a t e - s h a l e s e q u e n c e of the S h e e p r o c k R a n g e t o t a ls I S O P A C H MAP OF MIDDLE ORDOVICIAN Q U A R T Z I T ES FIGURE 5 80 5, 700 f e e t and shouLd c o n t a i n s t r a t a s i m i l a r to t h e s t r a t a of the d e e p e r p a r t s of t h e C a m b r i a n t r o u g h , n a m e l y the H o u s e and Deep C r e e k (Gold H i l l ) M o u n t a i n s s e c t i o n s . The C a m b r i a n c a r b o n a t es of the s o u t h e r n O q u i r r h M o u n t a i n s ( S t o c k t o n ) t o t a l 2, 250 + f e e t in t h i c k n e s s , w h e r e a s t h o s e r e p r e s e n t e d in t h e E a s t T i n t i c M o u n t a i ns ( T i n t i c d i s t r i c t ) a g g r e g a t e a p p r o x i m a t e l y 3, 260 f e e t . Both t h e S t o c k t on and T i n t i c s e c t i o n s a r e m o r e r e p r e s e n t a t i v e of t h a t p a r t of a b a s in n e a r e r the s h e l f a r e a , e s p e c i a l l y d u r i n g E a r l y and M i d d l e C a m b r i an t i m e . G i i l u i y (1932, p . 11) w r i t e s the f o l l o w i n g r e g a r d i n g age and c o r r e l a t i o n of the O p h i r f o r m a t i o n: " . . . F o s s i l s f r o m the O p h i r f o r m a t i o n , c o l l e c t ed f r o m s c h i s t o s e b e d s l e s s t h a n 50 f e e t a b o v e the b a s e, w e r e s u b m i t t e d to D r . C. E. R e s s e r of t h e S m i t h s o n i an I n s t i t u t i o n , who r e p o r t s a s f o l l o w s: L o c a l i t i e s 4 and 6 c o n t a i n a M i d d l e C a m b r i an f a u n a which i s c h a r a c t e r i z e d by D o l i c h o m e t o p us p r o d u c t u s . C o l l e c t i o n 5 s e e m s to h a v e a s p e c i m en of N e o l e n u s . Ail of t h i s O p h i r s h a l e g r o u p i s r e p r e s e n t e d in t h e n e a r b y W a s a t c h and e l s e w h e r e, o c c u p y i n g a p o s i t i o n b e l o w t h e m i d d l e of the M i d d l e C a m b r i a n. " W a i c o t t (1912, pp. 164, 165) l i s t s t h e f o l l o w i ng f o s s i l s f r o m the O p h i r f o r m a t i o n at O p h i r . About 75 f e e t above t h e q u a r t z i t i c s a n d s t o n e s of the C a m b r i a n : O b o l u s ( W e s t o n i a ) e i la C o n c r e t i o n a r y l i m e s t o n e about 100 f e e t above t h e q u a r t z i t i c s a n d s t o n e s of t h e C a m b r i a n: M i c r o m i t r a s p. M i c r o m i t r a ( P a t e r i n a ) l a b r a d o r i c a u t a h n e n s is O b o l u s ( W e s t o n i a ) .ella O l e n o i d e s ( ?) " T h e s e a r e all a s s i g n e d to t h e Middle C a m b r i a n, H o w e v e r , in d i s c u s s i n g the C a m b r i a n of Utah, W a i c o t t ( 1 8 9 1 , p. 319-320) s t a t e d: The s e c t i o n i n t h e O q u i r r h R a n g e above O p h ir C i t y h a s a q u a r t z l t e at t h e b a s e w i t h s h a le a b o v e it c a r r y i n g L i n g u i e l l a e l l a , O l e n e l l us g i l b e r t ! , and B a t h y u r i s c u s p r o d u c t a , as d e t e r m i n e d by the c o l l e c t i o n b r o u g h t in by the W h e e l e r S u r v e y . It i s p o s s i b l e , h o w e v e r , that a s i n the c a s e of t h e Big C o t t o n w o o d s e c t i o n, O l e n e l l u s g i l b e r t i o c c u r s at t h e b a s e of t h e s h a l e, a n d t h e o t h e r two s p e c i e s at a h i g h e r h o r i z o n. " . . . On t h i s b a s i s , the O p h i r f o r m a t i o n i s in p a rt L o w e r C a m b r i a n and In p a r t M i d d l e C a m b r i a n in a g e. D i l i g e n t s e a r c h d u r i n g t h i s s u r v e y f a i l e d to r e v e a l any s p e c i m e n s of O l e n e l l u s , so t h a t i t i s i m p o s s i b l e to s ay h ow m u c h i s L o w e r and h ow m u c h i s M i d d l e C a m b r i a n. The f o s s i l s a s c r i b e d to t h e M i d d l e C a m b r i a n by D r. R e s s e r w e r e c o l l e c t e d within 50 f e e t of t h e b a s e of t h e f o r m a t i o n so t h a t if L o w e r C a m b r i a n i s p r e s e n t, i t i n c l u d e s l e s s t h a n t h i s t h i c k n e s s of O p h i r b e d s. C a r e f u l s e a r c h f a i l e d to r e v e a l any s h a r p l i t h o i o g ic c h a n g e o r any u n c o n f o r m i t y within t h i s i n t e r v a l. T h e s c h i s t o s e m a t e r i a l d i s c u s s e d a b o v e e x t e n d s h i g h e r than t h i s , so t h a t the a b s e n c e of s c h i s t o s i t y in t h e t o p m o s t p a r t of t h e f o r m a t i on a n d i t s p r e s e n c e t o w a r d the b a s e c a n n o t be c o n s i d e r e d e v i d e n c e of a s i g n i f i c a n t d i f f e r e n c e in the a g e of t h e s e b e d s . A c c o r d i n g l y , e i t h e r s e d i m e n t a t i o n was h e r e c o n t i n u o u s b e t w e e n L o w e r and Middle C a m b r i a n t i m e , or O l e n e l l u s s u r v i v e d i n t o the Middle C a m b r i a n , as was s t a t e d by U l r i c h ( 1 9 1 1 , p . 619-620) to b e t r u e in t h e A p p a l a c h i a n r e g i o n . The only o t h e r p o s s i b l e i n t e r p r e t a t i o n i s t h a t an u n c o n f o r m i ty r e a l l y i s p r e s e n t but e s c a p e d o b s e r v a t i o n . If s o , it is not m a r k e d by n o t a b l e e r o s i o n , a n g u l a r d i s c o r d a n c e, o r s h a r p l i t h o i o g i c d i f f e r e n c e s , and the w r i t e r b e l i e v es i t i s e x c e e d i n g l y i m p r o b a b l e t h a t one e x i s t s ." |
