ANCIENT ALPINE (GLACIERS, OF SEEIE Sit RRA COSI 
MOUNTAINS IN CALIFORNIA 
INTRODUCTION 
NORTHWESTERN California is a vast complex of mountains, 
forming the Klamath system, whose geological features are 
similar to those of the Sierra Nevada range. Centrally situated 
within it is a series of high granitic and syenitic peaks, consti- 
tuting the range of the Sierra Costa Mountains. Beginning in 
Castle Crag, about fifteen miles southwest of the lofty volcanic 
peak of Mt. Shasta, they trend thence southwestward about fifty 
miles, with an average width of between fifteen and twenty 
miles. Within this territory of eight or nine hundred square 
miles there are a score or more of bare, ragged peaks rising to 
altitudes of 7200 to 9345 feet above the sea. Between them 
are deep, narrow valleys whose floors have altitudes between 
2500 and 6500 feet, averaging about 4000 feet. Some of the 
more elevated of these present distinct evidences of past glacia- 
tion. The glaciers were very localized in development, never 
coalescing to form a general glaciation of any part of the terri- 
tory, and hence the glacial phenomena displayed in these moun- 
tain valleys are characteristically different from those of the 
drift-covered regions of the Mississippi basin. 
GENERAL DESCRIPTION OF THE GLACIAL PHENOMENA 
There is a radical difference in topography between the 
glaciated and non-glaciated valleys. The latter are V-shaped 
gulches with steep straight slopes and a width at the bottom often 
but little greater than that of the stream flowing within them. 
In places they are very rocky, with jagged ledges projecting 
from their sides. All the stony material found on their slopes 
is of the rock species underlying the soil on each particular 
slope. The same valley, traced up to where it once possessed a 
glacier, will rather abruptly change its form to a broad and 
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