RELATION OF LAKES TO CLIMATIC CONDITIONS. 85 



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highest points on the lini of a sliarply defined hydrographic basin. The 

 di"ainaofe from all directions tends towards the center and forms a lake 

 from which the ^\•aters escape only by evaporation. We can trace nearly 

 the entire bonndary line of the basin, for the reason that the slo[)es are so 

 plainly marked and the crest lines so sharply drawn, that there is no doubt 

 as to the direction that surface water would take. The courses of the 

 swift, bright stream descending the mountain can be followed from their 

 sources in melting snow-fields, down through deep caiions to where they 

 enter the lake. On the desert side of the basin, however, there are no 

 streams, and but indefinite traces of tlie dry beds of former water-courses. 

 There is no notch in the rim of the basin to suggest a former outlet. The 

 only possible point of discharge for the waters when the ancient beaches 

 scoring the inner slopes of the valley were formed, is far to the north, and 

 concealed from view. Apparently at our feet, but in reality a mile in 

 vertical descent below, lies the lake, a silent and motionless \)[^\\\ of blue. 

 Should the wind chance to be strong in the valley, however, its surface 

 would be ruf'fied, the flash of Ijreaking waves would reach the eye, and 

 lono; lines of froth would streak its surface. At such times abroad frincre 

 of snowy foam, produced by the churning of the alkaline waters, encircles 

 the shores and renders their outlines unusually distinct. Apparently 

 floating on the surface of the lake, there are two conspicuous islands, the 

 forms of which show that they are of volcanic origin. That these craters 

 were built since the encircling waters fell below their level, is shown 

 by their unbroken contours and by the absence of terraces on their outer 

 slopes. 



Beyond the lake the brown and barren land seems low and featui-e- 

 less, because of the elevation of our point of view. We can see far be- 

 yond the limits of the drainage basin, in which we are now specially 

 interested, and distiuQuish manv of the desert ransres of Nevada risiuff 

 above the purple liaze enshrouding their bases and obscuring the lifeless 

 lands between. The highest of these distant summits, which appeal's like 

 a spectral mountain floating in the sky, is even higher than the i)eak 

 on which we stand, but its naked sides are scorched to a cinder-like 

 redness by the desert heat, and no silvery stream can be detected in 

 the wild gorges scoring its flanks. Its sunnnit is seldom cloud-capped, 

 and only in the depth of winter is its ruggedness concealed by a 

 mantle of snow. 



Tf) the right of the lake is a long range of craters built of fragments 

 of volcanic rock thrown out during many violent eruptions, and now 



