^2 COLORADO COLLEGE STUDIES. 



The sandstones of the Red Bluff are generally too 

 friable for building-stone ; but in some instances selected 

 portions have proved hard enough for such use and fairly 

 durable. 



A marked characteristic of most of these sandstones is 

 their unusually fine texture. When pulverized, or as seen 

 in soils that have been derived from them, they sometimes 

 seem like brick-dust. So light are some of their soils that, 

 walking over them, one may sink shoe-deep, as if walking 

 on the mellow ground of a well cultivated field. 



The sandstones are also porous and, especially where 

 overlaid not far away by Neocene sands, are often a source 

 of water. Their springs are rarely strong, being usually 

 seepage-springs, but their spring-waters are in some in- 

 stances nearly as sweet and soft as those coming directly 

 out of the Neocene sands themselves. Examples of perma- 

 nent springs of this sort are seen in Red Bluff sandstone at 

 the head of a north-side canyon of North Elk creek, on the 

 Medicine-Elk divide about five miles west of Sun City. 

 Wells dug in Red Bluff sandstone and which at first are 

 failures, or yield only a scanty supply of water, sometimes 

 become valuable wells after the lapse of a few years. The 

 water of such wells is hable to be more or less saline or 

 gypsum-tainted, but is frequently fresh enough to be palata- 

 ble and available for ordinary uses. 



The shales of the Red Bluff are rarely without some 

 admixture of fine arenaceous matter. 



The Red Bluff beds, once uncovered, yield rapidly to 

 subaerial erosion and their outcrops generally show a 

 rugged, canyon-cut relief which, in connection with their 

 bright-red color and their frequent setting-off with dark - 

 green cedars, makes some of their landscapes exceedingly 

 picturesque. The sandstones are frequently trimmed off 

 by stream-erosion in a long, straight, vertical wall that re- 

 sembles the face of a quarry. These and less regularly 

 cut exposures, where rendered conspicuous, have given rise 



