40 GEOLOGICAL HISTORY OF LAKE LAHONTAN. 



RIVEES. 



The rivers that enter the Lahontan basin are the Humboldt, from the 

 east, Quinn River, from the north, and the Truckee, Carson, and Walker, 

 from the west and southwest. All these streams flow through partially filled 

 canons which bear evidence of having been excavated by stream erosion 

 previous to the first rise of Lake Lahontan. These rivers, like most others 

 in the Great Basin, vary greatly in volume during the year. In winter and 

 spring they become broad, rapidly flowing floods of muddy water that over- 

 spread their banks, but during the dry season, from May to November, they 

 shrink greatly in volume, and sometimes become dry for a large part of 

 their course. 



THE HUMBOLDT RIVER. 



This river^® rises on the eastern border of Nevada and flows westward 

 for approximately 200 miles, and enters the Lahontan basin through a pass 

 in the Sonoma Mountains, in latitude 41'^. From this point it continues 

 its course through Lahontan lake-beds for nearly 100 miles to Humboldt 

 Lake. Throughout the dry season this is usually its terminus, but during 

 the winter months the lake frequently ovei'flows, and the river continues 

 to North Carson Lake ("Carson and Humboldt Sink"), where its waters 

 are evaporated. The Humboldt before entering the Lahontan basin receives 

 a number of tributaries, the largest being Reese River, which enters from' 

 the south. During the summer and fall many of these streams, including 

 Reese River, fail to reach the main channel, their waters being dissipated 

 by evaporation or absorbed by the thirst)^ soil. In its course through the 

 Lahontan lake-beds between Golconda and Humboldt Lake, the river has 

 carved a canon, in places 200 feet deep, since the recession of the former 

 lake. The material removed in cutting this channel has been deposited in 

 the northern part of Humboldt Lake, and has contributed largely to the 

 formation of a broad low-grade delta that is already partially converted into 

 rich meadow-lands. 



'^Named Humboldt by Fremont, but was previously kuown as Mary's, orOgden River. See Fre- 

 mont's OeograpUicnl Memoir upon TTppt-r Cnlil'ornia, Wasbington, 18J8, page 10. 



