1872.] 45 [Kneeland. 
these areas. Floods now arise from rains and melting snows in all 
probability as great as ever occurred from the melting of the glaciers, 
and yet their action upon the walls of the cafions and the contour of 
the valley is not perceptible. Such a flood occurred in the latter 
part of December of last year, 1871, as witnessed by Mr. Muir, and 
described in a letter from him, in which he writes that more than one 
hundred cataracts were then pouring into the valley, and forty in 
sight at one time, each one with more water than flows over the Ne- 
vada or Vernal fall in midsummer. We can not believe, therefore, 
that any causes now in action there, have had much to do with the 
formation of the cafions and the valley. 
Has ice, then, made this valley ? 
After Mr. Muir’s observations, there can be no doubt that ice once 
filled this valley, and overwhelmed it at least one thousand feet deep, 
making a total thickness, supposing the valley to have antedated the 
glacial period, of more than three thousand feet of ice. From the 
sketch as given by him, it will be seen that, while the upper layers of 
the ice stream moved with irresistible force and considerable velocity, 
as shown by the polishings and the inclination of the surfaces, the 
comparatively insignificant portion of the glacier in the valley, from 
the narrowness of the cafion of exit on the west, could not have moved 
much, but must have slowly wasted away, remaining long after the 
main glacier had disappeared, leaving a lake of gradually decreasing 
depth, and at last a wide valley, with the narrow and shallow Merced 
river in it, fed by the snows of the upper ridges. 
Was the valley formed by icer The Hetch-Hetchy valley, an 
-almost exact counterpart of the Yosemite, but smaller, and about 
sixteen miles farther north, through which flows the Tuolumne river, 
as the Merced flows through the Yosemite, throws light on this ques- 
tion. The Tuolumne glacier, the largest in this region, flowed across 
this valley and across a cafion three thousand feet deep, on its way 
to join the great glacier of the Merced basin below Yosemite; the 
course of the former across the latter is shown by the grooving of 
the rocks, and yet the Hetch-Hetchy valley and its cafion above 
show groovings in their own axis, about east to west, the great gla- 
cier moving more nearly south-west. The united Tuolumne and 
Merced glaciers, below Yosemite, moved very nearly west, across the 
numerous angles of the crooked cajion of the Merced. These two 
valleys and their cafions, though half a mile deep, and each with their 
local glaciers, were so smallin comparison to the great ice sheet, that 
