TOPOGRAPHICAL. —THE SIERRA NEVADA. 1} 
and heading in the peaks to the south of Silver Mountain; then the Cala- 
veras, a small stream with only 389 miles of catchment area, rising near the 
grove of Big Trees of the same name; the Mokelumne, with 573 square 
miles of drainage, rising a little to the east of Silver Mountain; the Co- 
sumnes, with a catchment area just about equal to taat of the Mokelumne, 
but not heading on the main divide. North of this we have the extensive 
drainage system of the American River with its numerous branches, or forks, 
the most southern of which heads to the southwest of Carson Pass, on the 
north slopes of the ridges of which the southern sides feed the Mokelumne; 
the most northerly branch, on the other hand, heads near Donner Pass, 
about fifty miles farther north. The drainage area of the American River — 
a stream of great importance with reference to the subject of the present 
volume —is 1,889 square miles. “North of this again is Bear River, head- 
ing near Donner Pass, with 484 square miles of catchment area; then the 
Yuba, draining 1,329 square miles, also frequently to be mentioned in the 
course of this volume. Finally we have the Feather, with numerous branches, 
and a catchment area of 3,393 square miles, larger than that of any other of 
the streams flowing down the western slope of the Sierra. The head of the 
South Fork of the Feather is about four miles to the west of Pilot Peak, 
while the head of the North Fork is at Lassen’s Peak; the distance between 
these two peaks being about sixty miles. From Mount Stanford north, the 
water-shed of the Sierra presents a very irregular line, and the range is 
equally broken and irregular. Most of the area in question is drained by 
the North Fork of the Feather and its various branches, which run in nearly 
parallel depressions having the general trend of the Sierra and unite with 
the main stream which occupies a position tranverse to this, and in the lower 
portion of its course, for a distance of forty miles, runs in a deep caiion, re- 
ceiving no important tributaries. The main axis of the Sierra is prolonged 
from Mount Stanford through the Downieville or Sierra Buttes, Pilot Peak, 
Clermont, Spanish Peak, Ben Lomond, and Butt Mountain to Lassen’s Peak ; 
while nearly the whole drainage area of the North Fork of the Feather lies 
to the east of this between the parallel ranges previously spoken of, which 
are some five or six in number, the total width of the western slope in this 
portion of the range being aboyt eighty-five miles. The elevation of the 
dominant peaks in this region is not far from 9,000 feet; although Lassen’s 
Peak a little exceeds 10,500. The passes are all lower in proportion to the 
height of the crest than farther south; they range from 5,000 to 6,000 feet 
