52 GEOLOGICAL HISTORY OF LAKE LAHONTAN. 



the total outflow could be obtained. At a number of points the tempera- 

 ture of the water approxiuiateh; to tlie boiling point, and, on cooling, depos- 

 its a limited quantity of calcareous tufa. A qualitative examination indi- 

 cates that these springs have about the same chemical composition as the 

 water of Schaffer's Spring, an anah^sis of which is given above. 



High Rock Spring, situated 5 miles eastward of the group described in 

 the last paragraph, occurs at the base of large tufa crags of Lahontan date, 

 and has a temperature of 100° F. Its waters are used for irrigation, and 

 are inhabited by both fish and mollusks. This spring is evidently of consid- 

 erable antiquity, as the tufa crags deposited from its waters are coated with 

 heavy layers of calcium carbonate that have a dendritic structure and were 

 without question deposited from the lake waters which once flooded the 

 valley. 



None of the numerous springs on t-he western border of Smoke Creek 

 Desert are remarkable for their high temperatures, but a immber are ther- 

 mal, and nearly all bear indications of having been hot springs at some 

 former time There is no evidence that any of these springs were in exist- 

 ence during the time when Lake Lahontan covered the desert 



On the border of the desert at the eastern end of Granite Mountain a 

 group of circular basins filled with heated waters fi'om a subterranean source 

 covers a considerable area. A number of these basins furnish water of won- 

 derful transparency, which overflows to the eastward, and on evaporating 

 leaves a saline incrustation that covers many acres. Others occur in the 

 tops of low mounds and are caldrons of boiling mud that occasionally erupt 

 and discharge their tenacious contents to a distance of 30 or 40 feet. This 

 group is known as the Mud Springs. 



The most copious outflow of hot water in the Lahontan basin occurs 

 in a small embayment of the ancient lake a, few miles nortli of Granite 

 Mountain This is a group of springs several acres in extent which fill cir- 

 cular basins in the tops of low mounds that have been formed to some 

 extent by spring deposits, but are largely composed of vegetable growths 

 mingled with aeolian sand and dust. These springs vary through all degrees 

 of temperature, from 50° to (iO° F. up to that of boiling water, and their 

 discharge forms a creek ot heated water of considerable size that pours into 



