LAKES OF THE LAHOKTAN BASIN. 69 



and depth with the alternation of seasons. In 1882 its area was about 40 

 square miles, with a depth of four feet throughout its central portion. Its 

 waters are alkaline, and contain 1.4725 grammes of solids in solution to the 

 liter; of which 0.2135 gramme is silica, as reported by Prof F. W. Clarke 

 from a partial analysis of a sample collected in October, 1863. 



The lake is supplied almost entirel}' by the Carson River and usually 

 overflows through a slough into North Carson Lake.^' 



The low muddy shores are strewed with the dead shells of Anodonta 

 Planorhis, Limncea, etc., but, so far as known, no mollusks are now living 

 in the lake. 



WALKER LAKE. 



The southern extremity of the Lahontan basin is occupied by Walker 

 Lake, which, next to Pyramid Lake, is the most picturesque and attractive 

 of the desert lakes in the Lahontan basin. 



A correct outline of the lake, as it existed in 1882, is given on Plate 

 XV. As may be gathered from the map, the lake is 25.6 miles in its longer, 

 or north and south axis, and has an average width of between 4.5 and 5 

 miles. Its area is 95 square miles As on the map of Pyramid Lake, the 

 actual soundings are given in figures, and the somewhat conjectural topog- 

 raphy of the bottom is represented by dotted contour lines. Over a large 

 area in the central and western portions it has a remarkably uniform depth 

 of 224 feet; but as a rule the depth increases as one approaches the west- 

 ern shore, which is overshadowed by ragged mountains. The bottom 

 throughout the central portions is composed of fine tenacious mud, which 

 in many places is black in color, and has the odor of hydrogen sulphide. 

 Coarser deposits, consisting of sand and gravel, mingled with the empty 

 shells of Pyrgula, Pompholi/x, etc., were found only in the immediate neigh- 

 borhood of the shore. No mollusks were found living in the lake; but the 

 conditions of environment being so similar to what has been observed in 

 Pyramid Lake, it is thought that a more careful search would show that 

 Walker Lake is also inhabited by a few species. Analyses of the water, 

 collected in September, 1882, one foot and 215 feet below the surface 



^' See ante, page 44. 



