CRKTACEOUS SYSTEiE 453 



Feet 



Dark shale 5 



Dark sbale, with several layers of bard, buff sandstone 



from 3 to 38 feet tbick 200 



Buff sandstone :', 



Black sbale no 



Light gray sandstone, massive and moderately bard '2'> 



Browu and gray, bard, fine-grained sandstone, slalihy I2r( 



Hard, gray shales and thin-bedded, fine-grained sandstones 



with fish scales (Mowry beds) 250 



Gray shales, containing near the middle 10 feet of bard. 



buff sandstone in two bodies separated by 20 feet of 



sandy sbale 700 



Sandy shale and slabby sandstone — brown, olive green, and 



rust color 125 



Total 1,648 



The 40-foot stratum of light gray, saudv shale ^veatllers to a light l)ufT 

 color, somewhat suggestive of the Niohrara formation in other regions;. 

 The top sandstone and possibly part of the adjoining shales, comprising 

 the strata down to and including the light gray sandy shale which 

 Mcathers to a light buff color, may represent the Niobrara formation. 

 The fossiliferous sandstone varies in thickness from 5 to 25 feet and is 

 persistent along both slo]ies of the uplift, rising as a low but sharp ridge 

 conspicuous in Owl Creek valley and near Dry and Muddy creeks. On 

 the east side of the syncline east of Dry creek the beds are vertical, and 

 this sandstone filled with fossils rises as a wall 5 to 30 feet high. S. W. 

 Williston" recently examined the upper beds of the Colorado formation 

 southeast of Lander and proposes the name "Hailey" shale for some dark 

 blue shales, 30 to 75 feet thick, yielding saurian remains. These shales 

 contain two thin but continuous beds, the upper one of white clay and 

 the lower of irony shale with numerous bones and fresh-water shells. 

 Thirty feet above the "Hailey" beds are sandstone with rare Ostrea, and 

 then about 600 feet of sandstone and shale with Pierre fossils, followed 

 by 2,000 or 3,000 feet of Pierre shale. These "Hailey" beds are believed 

 1o ])c Niobrara and may possibly represent the Belly Eiver series. 



XoiiJi ririttr hasin to Tlnrh Rirrr. — Tn the "Rattlesnake "AEountain up- 

 lift the Colorado fornmtion presents its usual I'calurcs. Tbe ]\r()wry l)cds 

 are prominent, but only almut SO r(^('( tbick. and lie ajiproximately TOO 

 feet above the base of the formation. .About 200 feet above the Clovcrly 

 sandstone is an 8-foot bed of gray sandstone. Toward the top of the 

 formation is the usual bed of' sandstone, 30 feet lliick, and in places there 



"Science, vol. xxil, October 20, lOO.'J, p. 504. 



