GLACIERS OF -THE SIERRA COSTA MOUNTAINS 45 
was accomplished, depressions were left at the foot of the preci- 
pices which had been produced by the removal of the talus 
material and some of the solid rock. In several cases one may 
stand on a high peak and throw a stone so that it will drop into 
the clear water of a lakelet, 1000 feet below. These high preci- 
pices are another characteristic of the glaciated valleys, for they 
never occur elsewhere in these California mountains. 
The glaciers headed in valleys whose altitude is now between 
6500 and 7500 feet above the sea, and descended to 5000 or 
5500 feet (with two notable exceptions). Thus the declivity 
of the glaciated valleys is great; but the descent is effected by 
a series of terraces or steps, gentle slopes alternating with steep, 
almost precipitous, sections where the valley floor is rapidly let 
down 100, 200 or even as much as 500 feet vertically. These 
““steps’’ are only in small part due to moraines, being composed 
mainly of solid rock. Over them the glaciers cascaded, forming 
extensive crevasses, then coalescing into a solid mass and mov- 
ing along smoothly a mile or more to the next cascade. Toward 
the close of the ice period, when the main glaciers had shrunk 
to insignificant remnants, tiny glaciers continued to issue from 
under the local névés in the coves high up on the mountain sides, 
and cascaded over precipices as much as 500 feet in height. 
I have mentioned a sufficient number of the features of these 
valleys to place it beyond doubt that they have suffered glacia- 
tion in some past period, and to demonstrate that the glacial 
action was essentially identical in character with that at present 
obtaining in the high Alpine valleys of Switzerland. 
CHARACTERISTIC FEATURES OF INDIVIDUAL GLACIERS 
The Castle Creek glaciey.— At its maximum extension, this 
glacier had a length of about two miles, a width of one quarter 
to one half mile and a depth of 500 to 800 feet. It was situated 
at the northern foot of Tamarack peak, near the junction between 
Trinity, Shasta and Siskiyou counties. The present altitude is 
about 6500 feet. Within the limits of its site are six pretty lake- 
lets, one lying at the foot of a 1000-foot precipice. The glacier 
