CARBOKIFEROUS SYSTEM 



423 



bright red sandstone underlain by gray sandstones over 100 feet thick. 

 At the big spring east of Laramie there is locally a 6-foot bed of pure 

 limestone at top of Casper formation which is extensively quarried. 

 In the southeastern portion of Laramie basin the limestones become a 

 deeper purple, more sandy and thinner bedded than they are farther north. 

 A short distance south of Laramie red shale and arkosic sandstone are the 

 prevailing rocks, and the limestones -which do not disappear persist as thin 

 beds in the arkose to the Colorado line. In the slopes south of Laramie 

 there is, about 350 feet below the top of the formation, a sandstone mem- 

 ber about 200 feet thick, divided into three ledges by thin limestone beds. 

 This sandstone is fine-grained, massive, cross-bedded, light red to salmon 

 colored and weathers into fantastic forms or monuments, some features 

 of which are shown in plate 26. The diminution in number and thick- 

 ness of the limestones to the southwest, as well as the thinning of the for- 

 mation in that direction, are shown in the following sections : 



Partial Section of Red Beds in the Vicinity of Pulpit Rock, on Sand Greek, 

 9 Miles East of Red Mountain, at Colorado State Line 



Casper. 



Wavy, gypsiferous limestone 

 Red shales with aragonite. 

 Wavy, gypsiferous limestone (Forelle ?) 

 ■ Light buff sandstones and shales. 



I Chugwater J 



Flaggy to massive, light colored sandstone 



Limestone (thins out) 



Massive, fine-grained, red, monumental sandstone. . 



Shale, arkosic sandstone, and conglomerate 



Heavy, blocky limestone ; forms slope in this vicinity. 



Sandstone, arkose sands, and conglomerates 



Sandstone 



Arkosic sandstones and conglomerates 



Limestone 



Arkosic sandstones and conglomerates 



Feet 



2 



100: 



4 



100: 



30 



1 



40 



40 



5 



170 



5 



80 



2 



25 



Total 604 



Section of Red Beds at Red Mountain {condensed from W. C. Knight's Section)' 



Chugwater . 



Red sandstone and shale 



Gray, wavy quartzite (gypsiferous limestone ?) 



Red shale and sandstone 



Red clay and gypsum, with aragonite crystals.., 

 Solid gypsum 



Feet 



675 



5 



100 



20 



50 



» Laramie Plains red beds and their age. Journal of Geology, vol. 10, 1902, pp. 418- 

 419. 



