PLEISTOCENE GEOLOGY. 269 



a slope of loess considerable accumulations of the coarser portions of the 

 formation will be found, the result of checking the carrying capacity of the 

 water flowing over the surface by the lessening of the slope on reaching 



level ground. East of Boxelder or Running Creek, sand dunes, tunned 

 by sand blown in from the east, make their appearance and increase in 

 magnitude as one goes east. In eastern Colorado in many places the loess 

 is concealed for miles by a deposit of whitish sand. 



Cloudbursts, i. e., the precipitation of a large body of water in a limited 

 area within the space of a few minutes, produce some extraordinary effects. 

 < hi a plain some distance from a stream lied and a mile from the mountain 

 from which the bowlders traveled, trains of stones have been found, some 

 weighing 25 pounds or over, resting directly upon tufts of water-swept 

 grass. Contrary to the proverbial inability of traveling stones to acquire 

 accumulations, some of these bowlders in passing over a surface of 

 argillaceous soil have acted as the nucleus for the formation of a hall of 

 earth over a yard in diameter. Deposits of alluvium of small extent 

 occupy the river beds below the level of the river-drift terraces. 



When the material transported by a local storm reaches some of the 

 dry stream beds of the plains, it is arrested by the absorption of its trans- 

 porting force, water, and in this way there are left in the stream lied 

 considerable deposits of sand, which when moistened occasionally form 

 extensive quicksands. Such a bed on Kiowa ('reek near Denver has so 

 successfully swallowed a locomotive that in spite of diligent search it has 

 never been found. 



ECONOMIC FEATURES OF THE PLEISTOCENE DEPOSITS. 



RIVER DRIFT. 

 PLACER GOLn. 



The small quantities of gold contained in the river drift have played 

 an important part in the early development of the city of Denver, and even 

 of the State of Colorado. It was in the Platte River drift, near the present 

 city hall, that one of the first discoveries of gold in the Rocky Mountain 

 region was made, and to this was due the location of the first town site, 

 originally known as Auraria. The richest grounds were found along the 



