436 N. H. DARTON PALEOZOIC AND MESOZOIC OF WYOMING 



Feet 



Pink, massive, flne-graiued sandstones 24 



Reddish salmon-colored sandy shales 35 



White, flaggj- sandstone and red shales 45 



Massive, cross-bedded, fine-grained salmon sandstone 15 



Flaggy, white sandstone and reddish shales 20 



Massive, cross-bedded, fine-grained salmon sandstone 65 



Typical red shales and red flaggy sandstone 450 



Red gypsum, nearly pure 6 



Red shale 35 



Gypsum 3 



Red shale 10 



Gypsum 4 



Red shale 55 



Fine, banded, wavy, gypsiferous limestone 5 



Red, sandy shale (with aragonite crystals) 88 



Gypsum, pure, massive 67 



Total 1,133 



The iTpper limit of the formation is placed arbitraril_y at the base of a 

 l:)hie shale which lies below the lowest limestone containing Morrison 

 fresh-water fossils. This inchides in the upper part of the Chugwater 

 an alternation of about 200 feet of terra cotta, blue, and buff shales and 

 light colored sandstones, which are not typical and are absent in the re- 

 gion northeast, but they appear more likely to belong in the Chugwater 

 than in the Morrison formation. The gypsiferous member at the base of 

 the Chugwater formation is 273 feet thick in this section and consists of 

 alternations of gypsum, g_vpsiferous limestone, and red shales, and at the 

 base a massive bed of pure gypsum 67 feet thick Wing on supposed Forelle 

 limestone. In the red clay 20 feet above the gypsum there are numerous 

 crystals of aragonite which, according to Knight, are pseudomorphic after 

 hanksite. Above the gypsiferous measures are 450 feet of tj^pical red 

 shales and flaggy red sandstones, followed by 378 feet of massive, fine- 

 grainedj salmon colored sandstones, with a minor proportion of red shale. 

 These sandstones weather into "monuments" and walls similar to those 

 formed by the "monument" sandstones of the Casper formation. On 

 Sand creek near jSTorth Park road, where the gypsum is only from 2 to 4 

 feet thick, it is associated with and sometimes replaced by gj'psiferous 

 limestone lying on wavy-bedded gypsiferous limestone l^elieved to repre- 

 sent the Forelle limestone. Aragonite crystals occur in the overlying red 

 shales. Six miles southwest of Eed Buttes the gypsum appears to overlie 

 wavy, gypsiferous limestone, which can be traced northward with certainty 

 into the Forelle limestone which crosses the railroad at Forelle. North- 

 west of that place a well 333 feet deep is reported to be in red beds and 



