.46 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



F 



part of the Forelle formation. The most extensive gypsum deposits 



region occur at Red Mountam, 25 miles 



volcanic asli/ bentonite,^ and soda.^ 



this 



On the track used by eastbound trains between Laramie and 



Hermosa 



Colores. 



Elevation 7,637 feet. 

 Omaha 5fi0 miles. 



formations 



by. The eastbound trains pass over these red rocks 

 for about 10 miles. The rocks contain water under 

 pressure, and many large springs issue from them 

 along the foothills. A spring near Colores furnishes water to fill 

 a 4-inch pipe. Another spring east of Laramie furnishes the city 

 supply— 3,000,000 gallons a day. About 4 miles south of the city 

 spring there is another large spring, which supplies a fish hatchery. 



Toward the southwest, across the Laramie Basin, good views are 

 obtained of the Medicine Bow Mountains, which constitute the north 

 end of one of the main ranges of the southern Rocky Mountains and 

 are so high that they are covered with snow during much of the year. 

 Jelm Mountain, the nearest of this group, is a mass of ancient schist 



» Beds of volcanic ash occur about 4 1 in the manufacture of dynamite. Other 



beda of beutouite occur farther west. It 

 ■pras fii-st mined in this region in 1888, but 

 "with the closing of the western paper 



mil 



They are 



formerly so active in the Rocky Mountain 

 region, but the location of the particular 

 volcanoes that furnished this ash ia not 

 known. The material is pure white, soft, 

 and fine grained. It occurs in beds that 

 are comparatively young— that is, Ter- 

 tiary or Quaternary. (See table on p. 2.) 

 Volcanic ash is sometimes used as an 

 abrasive, for scouring, polishing, or clean- 

 ing kitchen ware and other articles. 



^ About G miles west of Red Buttes, on 

 the northwest shore of Creighton I.oke, is 

 a bed of bentonite, 3 or 4 feet thick, 

 which appears as a white band in the 

 black Benton shale, from which bentonite 

 derives its name. Bentonite is a variety of 

 clay used chiefly to give body and weight 

 to paper, but to some extent in a dressing 

 for inflamed hoofs of horses, in antiphlo"^ 

 gistine (a proprietary remedial dressing), 

 aiid as an adulterant of candies and dni<^ 



power 



own 



of water. It absorbs twice as much 

 glycerine as can be absorbed by diatoma- 

 ceous earth, and for this reason has been 

 suggested as a substitute for thi^t mQforJoi 



mills m 1905 ita production practically 

 stopped. 



^ Soda lakes occur near the Union Pa- 

 cific line in Laramie Basin and at many 

 places farther west. The waters of these 

 lakes are strongly charged with sodium 

 sulphate, and along their edges lie thick 

 deposits of this salt that has been precip- 

 itated from the water. (See PI. VIII, B, 

 p. 44.) Three of these deposits were 

 worked prior to 1895. The lakes lie in 

 depressions in Cretaceous shale that con- 

 tains a variety of salts, some of which w^ere 

 derived from the sea water in wliich the 

 shale accumulated, 

 springs from this shale take the salts into 

 solution, and rain falling on the surface of 

 the shale dissolves them and carries them 

 into the lakes. Water can escape from 

 the depressions only by evaporation, so 

 the salts accumulate in them. The soda 

 deposits near Laramie have received more 

 attention than any similar deposits in 

 "Wyoming. They cover about 60 acres, 



Waters issuing as 



1 foot to 16 feet. 



thickness 



