GEOLOGY OF THE LARAMIE PLAINS 



The surface of the plains generally consists of two to three ter- 

 races, the higher one often flat on summit and with scant grass. 



Most of the terraces are sandy and frequently are strewn with 

 water-worn pebbles. The valleys along the streams are wide 

 and often slope up gently to the terraces above. Grass abounds 

 on the valleys, and, with Judicious irrigation, can furnish plenty 

 of hay and also good grazing. Most of the valleys of the tribu- 

 taries of both the Platte and the Laramie may be considered 

 as valuable for grazing purposes. 



The "sagebrush" is common, growing on good soil. The 

 "grease wood" is rather common on alkali soils. Cactus abounds 

 on the dry slopes. Along the running streams are willows, 

 Cottonwood and birch. Pines abound on the mountains and 

 also occur in the valleys of the hills. 



The Medicine Bow Mountains are clothed with a dense 

 growth of pines, chiefly P. Contorla. In many places the 

 ground may be covered with a dense mass of fallen logs, often 

 apparently one-fourth as many as are standmg. High up on the 

 mountains the pme gives place to the spruce, growing large and 

 very straight. In wet mountain valleys, the quaking aspen 

 abounds. Cedar is also common. 



The Dakota sandstone, along the Front Range in Colorado 

 and New Mexico, forms the prominent "hog-back" ridge. On 

 Rock Creek it affords excellent beds for building purposes. 

 The other Cretaceous groups above are mostly shaly; the 

 Fox Hills everywhere is easily recognized. 



The following named fossils were collected, all of them 

 mollusca: Helicoceras vespeieones, Ancylocevas uncum, j4. 

 annulatum, A . Jenneyi, Scaphiits nodosus var. plenus, ^acu- 

 lites ovatus, ^. compressus, Hammea minor, H. occiden- 

 talis, T-*seudobuccinum [AC'^brascense, Fasciolaria cretacea, 



