WYOMING FORMATION. 55 



Following is an analysis of the upper limestone: 



Analysis [by I.. <;. EaJcins) of Upper Wyoming limestone from Morrison, Colo. 



Per i int. 



[nsoluble 5.32 



CaO 48.73 



MgO 2.95 



MnO 49 



AU0 3 53 



I •■ <»: 38 



I'o 032 



ll<> 11 



co. 11.71 



ioo. 252 



An illustration of the variation in stratigraphic range and lithologic 

 appearance to which the limestones are subject occurs at Willow Creek, 5 

 miles south of Platte Canyon. There are here lour distinct bands, one 

 1\ ing immediately upon tin- ( Ireamy sandstone, the others, respectively, .'lit, 

 60, ami 70 feel above. All arc white and crystalline. The lowest is 1 .', 

 feet thick, without banding, has an angular fracture, and contains abundant 

 calcite crystals in small irregular vugs, but ha- none of the minute black 

 mineral seen in the other hands. The second, "_' feet thick, is gray, faintly 

 banded, and contains grains of a black mineral. The third, 2 to 1 feet 

 thick, contains the black mineral and, in addition, the purple amorphous 



chert concretions; it also display.- the banded structure. Ten feet above 

 the third is the fourth limestone, the two being united hv intervening, 

 banded, calcareo-argillaceous beds. The upper layer is aboul '■> feet thick, 

 is banded a faint purple and white, and has a considerable amounl of fer- 

 ruginous matter through it. Banded strata of lime and mud succeed for a 

 few feet, when they are followed by the red clay shale which generally 

 closes this series. 



The strata above the limestone series become more and more arenace- 

 ous, though still retaining in large degree their shah" nature. About (HI tcct 

 up are a number of layers of fine-grained, compact, red sandstone, 2 to <> 

 inches thick, characteristically marked with sharply defined, white, circular 

 dots, one-eighth to one-half inch in diameter, which are sections of spherical 

 masses containing at the center minute undetermined bodies. These 



