GENEEAL EBPOET. XV 



but little above the level of the lake. The lake itself is for the most part 

 very shallow, in no place over fifty feet in depth, the waters a concen- 

 trated solution of salt. As with all these sheets of water the shore-line and 

 consequent area vary greatly in diiferent years. 



The intermediate ranges of the Basin are very similar to each other 

 in character. They vary in altitude from one to six thousand feet above 

 the valleys, culminating in occasional peaks scarcely ever so rugged that 

 they cannot be ascended from some direction upon mules. They are cut 

 up by numerous ravines or " canons," which are narrow, very rarely with an 

 acre of intervale or surface approaching to a level, the sides sometimes rocky 

 or precipitous, more frequently sloping to the summits of the lateral ridges. 

 In geological structure tliese ranges are more or less complicated, showing 

 rocks of all ages from the azoic to the glacial period, here metamorphic rocks, 

 quartzites, slate, and limestones, there an outburst of granite or syenite, vol- 

 canic rocks of often the most diverse and picturesque colors, or broad table- 

 lands of lava overflow. The erosion and decomposition of these various 

 rocks have filled the valleys to a monotonous level with a detritus of gravel, 

 sand, or silt, and given to them that accumulation of alkaline salts which is 

 so marked a peculiarity of the country. 



With few exceptions also these mountains are for most of the year 

 wholly destitute of water, with but small rivulets in the principal canons, 

 frequently with only scanty springs here and there at their bases, irri- 

 gating a few square yards of ground. Even where the mountain supply is 

 sufficient to send a stream into the valleys it is usually either soon entirely 

 evaporated, sinks into the porous soil, or becomes demoralized with alkali 

 and is " lost" in the mud of the plain. The lowest portion of nearly every 

 valley is occupied by some extent of alkah flat, where in the winter season 

 the water collects and the softened clay-like mud is bottomless and im- 

 passable. As the moisture evaporates under the heat of coming summer the 

 level naked surface becomes hard and pavement-hke, or covered with a 

 snowy incrustation or deposit of salt or carbonates. The springs and wells 

 even are often more or less saUne, and thermal springs are not rare. 



The chief exceptional ranges in northern Nevada, which from their 

 greater altitude receive heavier snowfalls in vs^inter, retained through the year 

 in greater or less quantity in the more sheltered depressions of the higher 

 peaks, and which in summer are subject to more abundant rains, are the 



