22 NORTH AMERICAN FAUNA. [No. 16. 
streams. They average about « thousand feet in depth, and their 
slopes are as steep as permitted by the unstable material through 
which they are cut—usually pumice, gravel, and fragments of lava. 
Owing to the fact that all of the great glaciers are on the north, east, 
or southeast sides of the mountain, the canyons made by their rivers 
are necessarily on these sides also. The only one of any size which 
does not come from a glacier is Diller Canyon, on the west side of 
Shastina. 
In most, if not all, cases the bottoms of the canyous in their upper 
courses are bridged for long distances by masses of ice and snow—the 
dumps of avalanches. Below these snow bridges are vast accumula- 
tions of loose stones, which in several instances, as in Brewer, Bolam, 
and Whitney canyons, are piled up in a curious manner. During 
periods of high water the rocks that fal! in are carried down by the 
torrent and deposited on each side in banks several feet high, so that 
the traveler on reaching the bottom has to climb up over a ridge of 
loose stones and down again before coming to the stream. These lat- 
eral ridges form miniature canyons in the bottoms of the big ones. 
Most of the canyons have falls several hundred feet high in their upper 
courses, and some have other falls farther down. Notable falls are 
found high up in the canyons of Mud Creek, Ash Creek, Bolam Creek, 
and Whitney Creek. While difficult of access, they are well worth the 
effort of a visit. 
Mud Creek Canyon (pl. 111), the only one likely to be seen by the 
ordinary visitor to Shasta, is not easy to cross except near the mouth 
of Clear Creek, which comes into it from the east. Its east bank is a 
precipitous single slope about 1,000 feet in height. Its west bank, 
except above timberline, is broken by a forest-covered terrace or bench, 
and both descents are likewise steep, though less difficult than the oppo- 
site side. The canyon of Ash Creek is better timbered and a little less 
precipitous than that of Mud Creek. The canyons of Bolam and Whit- 
ney creeks, like that of the upper part of Mud Creek, are terrific naked 
chasms, very deep and so steep that in most places the loose material 
of their sides will not sustain the weight of a man—much less that of a 
horse—and when disturbed dashes in avalanches to the bottom. 
Diller Canyon is peculiar (pl. 11). Itis a tremendous gash on the west 
side of the otherwise symmetrical cone of Shastina, which it cleaves 
from top to bottom before taking its practically straight westerly 
course down the rest of the mountain. It is the only canyon on Shas- 
tina, the only notable one on the west side of Shasta, and the only one 
anywhere on the mountain that does not emanate from a glacier. Its 
stream comes from enormous banks of perpetual snow. 
While the upper parts of the canyous are exceedingly steep and 
barren, and practically devoid of vegetation, the middle and lower 
parts are invaded by the trees of the adjacent slopes, and in marshy 
and springy spots contain patches of willows, alders, and a multitude 
