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ANNALS NEW YORK ACADEMY OF SCIENCES 



western and especially the southwestern areas than in any of the other 

 districts in which the fonnation occurs. According to Lupton (1914, 3), 

 the McElmo is over 1,000 feet thick near Green Eiver, Utah; in the 

 Telluride quadrangle, according to Cross (1899, 3), it varies from 400 

 to 900 feet; in McElmo Canyon it is between 400 and 500 feet; in the 

 Grand Eiver Valley, at various points between Grand Junction and the 

 Colorado-Utah line, it is about 700 feet thick ; in the region south of the 

 Uinta Mountains the formation is about 650 feet thick ; in the region of 



e^ j gy^^^ 



i^v;;.v- 





Fig. 80. — Sections of the Morrison formation shoivinp decrease in thickness from western 



Colorado eastward. 



A. Mack, Colorado, thickness about 700 feet ; B. Canon City, Colorado, thickness about 

 325 feet ; C. Red Rocks Canyon, Colorado, thickness about 140 feet. Scale, 250 feet to 1 

 inch. 



the Owl Creek and Bighorn Mountains the formation is usually between 

 300 and 250 feet thick; in the Great Falls region of Montana, about 100 

 feet thick. It must be remembered in this connection that some of the 

 Kootenie of this area may be Morrison. In the Shoshone Eiver region 

 the formation is 580 feet thick; in the Encampment district, in southern 

 Wyoming, the thickness is about 400 feet; at Como Bluff and in the 

 Freezeout Hills about 200 feet ; and in the Black Hills usually less than 

 100 feet, in one locality disappearing completely. In central Colorado 

 the thickness is about 450 feet; near Canon City, between 350 and 400 



