LAKES OF THE LAHONTAN BASIN. 55 



their bases. These deposits are unlike the greater part of the old tufa 

 strvictures occurring abundantly in the same basin, especially in the neigh- 

 borhood of Pyramid Lake, but agree in form and structure with the rings 

 and domes now forming about many subaerial hot springs; thus indicating 

 that the deposits in question are of post-Lahontan date. The presence of 

 siliceous sinter also indicates that these deposits were of subaerial origin, as 

 no precipitates of this nature from sublacustrine springs are known. 



LAKES. 



At present there are seven lakes in the Laliontan basin. These are 

 Honey Lake, California; Pyramid, Winnemucca, Humboldt, North Carson, 

 South Carson, and Walker lakes, Nevada. To these we may add the two 

 Soda lakes near Ragtown, Nevada, as occurring in the same basin, but 

 these are of a decidedly different character from those enumerated above, 

 and will receive special attention. These lakes are of assistance to the 

 geologist in interpreting the history of the great lake which formerly 

 flooded all their valleys ; we shall, therefore, describe them somewhat 

 minutely, 



HONEY LAKE. 



Honey Lake Valley was occupied by the western arm of Lake Lahon- 

 tan, and became deeply filled with lake sediments. At present it is a broad, 

 level-floored, sage-brush-covered plain, with fruitful areas on its western and 

 northern borders where water is available for irrigation, and has an abso- 

 lutely barren plaj-a of considerable extent on its eastern margin near Fish 

 Spring. The lake occupies a shallow depression in the western part of the 

 valley, and may be classed as a playa lake, as it is without outlet and be- 

 comes completely desiccated during seasons of unusual aridity. It is sup- 

 plied principally by Susan River, which enters it from the northwest ; but it 

 receives some tribute during the rainy season from Long Valley. The hot 

 springs along its northern border also furnish considerable quantities of 

 water. The area of the lake varies with the seasons, as well as from year 

 to year, as is common with all inclosed lakes. As mapped by the survey 

 in charge of Captain Wheeler, in 1867 it covered an area of approximately 



