LAKES OF THE LAFONTAN BASIN. 



63 



The resemblance of" Pyramid Lake to an arm of the sea is enhanced 

 by the presence of numerous sea-birds. About The Needles especially one 

 sees large numbers of gulls, terns, cormorants, pelicans, together with 

 geese, ducks, swans, herons, bitterns, etc. Many of these find convenient 

 nesting places in the hollows of the calcareous tufa. During our visit to 

 Anaho Island in August, 1882, there were two large pelican "rookeries," 

 in each of which there were GOO or 800 young birds. 



WINNEMUCCA LAKE. 



This, like its sister lake, occupies a long, narrow valley, formed by 

 orographic displacement, and is a fair illustration of a lake occupying a 

 fault basin. It is 26 miles long, with an average breadth of about 3^ miles, 

 the longer axis being due north and south. As in the case of Pyramid 

 Lake, its waters are alkaline and brackish. The following analysis by Prof 

 F. W. Clarke is of a sample collected in August, 1882, near the center of 

 the lake (at c, Plate IX) and 1 foot below the surface: 



Constitaents. 



One liter of 

 ■water con- 

 tains in 

 grammes- 



Silica (SiOs) .■ 



Magnesium (Mg) . . . - 



Calcium (Ca) 



Sodium (Na) 



Potassium (K) 



Chlorine (Cll 



Sulpburic acid (SO4) . 



0. 0275 



0. om 



0. 0196 



1. 2970 



0. 0686 



1. 6934 

 .1333 



Per cent, in 

 total solids. 



0.76 

 0.48 

 0.54 



36.00 

 1.90 



47.01 

 3.70 



Carbonic acid (CO3) by difference . 

 Total 



3.2567 I 

 . 3458 ! 



90.39 

 9.61 



Constitnents. 



Silica (SiOj) ..- 



Magnesium carbonate (MgCOa) - 



Calcium carbonate (CaCOsl 



Potassium chloride {KCl) 



Sodium chloride (NaCl) 



Sodium sulphate (NaaSOj) 



Sodium carbonate (NaaCOs) 



Probable com. 

 bination (in 

 grammes per 

 liter). 



_ 



0. 0275 

 0. 0494 

 0.0254 

 0. 1310 

 2. 6877 

 0. 1972 

 0. 4005 



Total (98.44 per ct. acconnted for) . 



3. 5247 



Nearly all of the water that supplies the lake enters at its southern 

 end, and consequently causes this portion to be fresher than the northern 

 part. As stated while describing the Truckee River, the water supplying 

 this lake is a branch of the main stream. The only published account 

 known to us of the bifurcation of the Truckee River, so as to supply two 

 lakes, is given by Mr. King,-'* who states that — 



At the time of our lirst vi,>iit ti> tliis region, in Ititi?, the river bifureated; oue half flowed iuto Pyra- 

 mid Lake, and the other through a river four or five miles long into Winnemucca Lake. At that time 



-"U. S. Geological Exploration of the Fortieth Parallel, Vol. I., pp. 50.")-6. 



