COLORADO 39U 



Photographed by J. F. Kemp, Columbia University, New York, New York 

 5 by 8 inches 



411 . View of mount Sopris, western Colorado, from the Spring Gulch coal mines 



across Jerome park. The point of view is on the Laramie. The inter- 

 vening upturned strata are Mesozoic and Paleozoic. 



412. The Sunshine coal mines, Jerome park, northwestern Colorado. The Lara- 



mie sandstones show in section on the right, dipping westward. 



Photographed by G. K. Gilbert 

 5 by 8 inches. Negatives in United States Geological Survey 



413. Group of Tepee buttes north of Nepesta, Pueblo county, Colorado (No. 859.) 



414. Tepee butte; core not exposed; 2 miles northeast of Boone, Colorado (No. 



940). 



415. Exposed core of a Tepee butte north of Nepesta, Colorado (No. 941). 



416. The Great Plains. Characteristic landscape on broad upland between the 



Platte and Arkansas rivers, Colorado (No. 942). 



417. The Great Plains, Colorado. Spring issuing from the " Tertiary grit" (Hay) 



irrigates a few acres and affords water for cattle (No. 943). 



418. Haystack butte, Pueblo county, Colorado. A typical mesa butte. Geolog- 



ically an outlier of the Niobrara limestone protecting upper Benton shales. 

 Lakelet basin in foreground, hollowed by wind erosion (No. 944). 



419. End view of South Rattlesnake butte, an outlier of Niobrara limestone, 



Huerfano county, Colorado (No. 860). 



420. Side view of North Rattlesnake butte, Huerfano county, Colorado. A rem- 



nant of Niobrara limestone capping a pyramid of upper Benton shale. 

 The trees are juniper, from 10 to 12 feet high (no negative). 



421. Typical water-pocket near Thatcher, Colorado. Timpas creek has here 



made a canyon 50 feet deep in Dakota sandstone (No. 945). 



422. The Greenhorn formation, Middle Benton, exposed in an arroyo near 



Thatcher, Colorado. The upland at the right is capped by Niobrara 

 limestone. The formation consists of a rapid alternation of limestone 

 and shale, indicating a rhythm in the conditions of sedimentation (No. 

 946). 



423. A cliff determined by a fault, Las Animas county, Colorado. The hard rock 



at the right is Dakota sandstone, originally covered by Benton shale. The 

 plain at the left consists of Benton shale underlain by Dakota sandstone. 

 The fault line follows base of cliff, and the block at the left stands about 

 200 feet lower than the block at the right. The country has been greatly 

 degraded since the faulting, and the cliff results immediately from the 

 unequal erosion of soft shale and hard sandstone (No. 947). 



424. Modern rain-prints, natural size. Dried mud from Great Plains, Colorado. 



Animal tracks also shown (No. 948). 



425. Ant hill, Pueblo, Colorado (No. 949). 



