10 THE AURIFEROUS GRAVELS OF THE SIERRA NEVADA. 
an inspection of the map, much better than can be described in words. The 
height of the dominating peaks in this part of the Sierra is still considerable, 
it being from 12,000 to 13,000 feet, and the passes range from 9,000 to 
10,000 feet. The width of the chain is here quite large, it being fully 
eighty miles in a straight line from the edge of the foot-hills to the main 
divide at the head of the Tuolumne. 
The descent on the eastern slope of the Sierra in this portion of the range 
is very steep, —fully a thousand feet to the mile. As opposite the more 
southern portion of the mountains we have Owen’s River and Lake, without 
any outlet to the sea, forming a long and narrow closed basin, so here oppo- 
site the head of the Tuolumne, at the foot of the eastern crest of the Sierra, 
we have a large lake (Mono Lake) about fourteen miles Jong, and about 
6,500 feet lower than the highest adjacent points of the Sierra crest. This 
also forms a closed basin, and from here north the drainage eastward from 
the summit of the range is into a series of depressions without outlet, form- 
ing a part of the Great Basin system. Indeed, from Mono Lake north it is 
not easy to separate the Sierra proper, on the east slope, from the Great 
Basin ranges. From the head of the Mokelumne River, at the grand vol- 
eanic peak of Silver Mountain, there is a continuous chain of elevations, 
crossed by narrow passes, running north and abutting on Carson River, form- 
ing the chain so prominently seen in looking towards the east, from Genoa 
and Carson City. A few miles northwest of Silver Mountain, at the head of the 
South Fork of the American River, the Sierra seems to divide, a spur almost 
equal in elevation to the main range going off to the north, and forming 
a very distinct range as far as the Truckee River. Between this spur and 
the more easterly main divide lies Lake Tahoe, a noble body of water, a 
little over twenty miles long, and from eight to twelve miles wide. This 
lake, which has an elevation of a little over 6,000 feet, is connected by the 
Truckee River with Pyramid and Winnemucca lakes, which belong to the 
Great Basin system. The main crest of the range to the east, at the head 
of the forks of the American River, are a little over 9,000 feet in elevation, 
and the passes from one to two thousand feet lower than this. Mount Stan- 
ford, just north of Donner Pass, — the one by which the Central Pacific rail- 
road crosses the Sierra, — is 9,102 feet in elevation, or just about 2,100 feet 
higher than the pass which is four miles to the south. 
The principal rivers which flow down the western slope of the Sierra, 
from the Tuolumne north, are: the Stanislaus, draining 971 square miles, 
