446 GEOLOGY OF NORTHWESTERN TEXAS. 



"The production in 1888 was about two thousand barrels."* 



In the Carboniferous and Permian formations in Northwestern Texas are 

 numerous salt springs and wells, and at Colorado City, at a depth of eight 

 hundred and fifty feet a bed of rock salt was found in boring for water. 



The condition for the deposition of salt seems to have been peculiarly fa- 

 vorable during the latter Permian period. There was evidently an enclosed 

 continental sea that followed the Carboniferous epoch, and that was for a 

 long time very shallow. The red saliferous clays are in places several hun- 

 dred feet thick and extend over large areas. 



All the rivers and streams that have their origin in these clays and sandy 

 shales, or that pass through them, are highly impregnated with salt, and 

 many springs and small lakes in the region are completely saturated with it. 



The Colorado, Salt, and Double Mountain Forks of the Brazos, Big Wichita 

 Pease, Prairie Dog Town, and Salt Forks of Red River all have their source 

 in or pass through the Red Beds of the Triassic and Permian, and with their 

 lateral streams are more or less impregnated with salt, the Salt Fork of the 

 Brazos and the Salt Fork of the Red River carrying more than any of the 

 others. 



From the confluence of the Salt Fork and the Double Mountain Fork of 

 the Brazos River the Salt Fork is, at a low stage of water, almost brine. The 

 least evaporation of the water along the margins of the river results in the 

 precipitation of the salt. For miles and miles at such times the brinks of 

 the river are as white as a bank of snow. About one mile above the junc- 

 tion of Salt Croton Creek with the Salt Fork of the Brazos there is a fall of 

 four feet in Croton Creek. At this place the rocks above the falls and along 

 bluff are all incrusted with salt. Some of the party went bathing in the 

 deep pool below the falls, and such was the density of the water they found 

 it almost impossible to sink in it without great effort. A few miles above 

 that is Salt Flat, an open, level piece of land, caused by the erosion of the 

 overlying strata, about two hundred acres in extent. In the midst of this 

 level area is a bold running spring of several thousand gallons of water per 

 hour. This water carries so much salt that at the least evaporation of the 

 water the salt is precipitated, and lies in sheets along the banks of the stream 

 below in such quantities that it is easily gathered up in masses sometimes an 

 inch or two thick. It has been the custom of the stockmen and other per- 

 sons within reach of this place to send their wagons there during a dry time 

 and in a day or two collect a load of the salt left by solar evaporation. There 

 is no place in the State where salt could be so cheaply manufactured as at 

 this place, and it only awaits the advent of cheap transportation to make this 

 a great salt producing locality. 



* J. S. Newberry in Transactions of the New York Academy of Science, November, 1889. 



