384 PROCEEDINGS OF WASHINGTON MEETING. 



1312 (30). Tepee butte ; core not exposed; two miles northeast of Boone, Colo- 



rado. 



1313 (37). Exposed core of a Tepee butte north of Nepesta, Colorado. 



1314 (24). The Great Plains. ' Characteristic landscape on broad upland between 



the Platte and Arkansas rivers, Colorado. 



1315 (26). The Great Plains, Colorado. Spring issuing from the "Tertiary grit" 



(Hay) irrigates a few acres and affords water for cattle. 



1316 (83). Haystack butte, Pueblo county, Colorado. A typical mesa butte. 



Geologically an outlier of the Niobrara limestone protecting upper 

 Benton shales. Lakelet basin in foreground, hollowed bj' wind 

 erosion. 



1317 (41). End view of South Rattlesnake butte, an outlier of Niobrara lime- 



stone, Huerfano county, Colorado. 



1318 (24). Side view of North Rattlesnake butte, Huerfano county, Colorado. A 



remnant of Niobrara limestone capping a pyramid of upper Benton 

 shale. The trees are juniper from 10 to 12 feet high. 



1319 (73). Typical water-pocket near Thatcher, Colorado. Timpas creek has here 



made a canyon 50 feet deep in Dakota sandstone. 



1320 (67). 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 lime- 

 stone and shale, indicating a rhythm in the conditions of sedimenta- 

 tion. 



1321 (50). 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. 



1322 (13). Modern rain-prints, natural size. Dried mud from Great Plains, Colo- 



rado. Animal tracks also shown. 



1323 (100). Anthill, Pueblo, Colorado. 



Twelve views presented by the U. S. Geological Survey ( Whitman Cross) 

 Size, 8 by 10 inches. Figures in parentheses are original numbers 



1324 (1). Eastern part of San Miguel mountains, Colorado. The sharp peak of 



mount Wilson (14,000 feet) is of diorite cutting up through Creta- 

 ceous and Eocene strata. 



1325 "(7). Mount Wilson group. San Miguel mountains, Colorado. The smooth 



slopes of middle ground are of Cretaceous shales. The canyon in 

 foreground is cut below the Dakota sandstone. 



1326 (8). Western portion of San Miguel mountains, Colorado. The sharper 



points are denuded laccoliths in Cretaceous shales. The plateau seen 

 extends westward into Utah. 



