The Bottoms Of The
Main Valleys, Once Grooved And Planished Like The Glacier Pavements Of
The Sierra, Lie Buried Beneath
Sediments and detritus derived from the
adjacent mountains, and now form the arid sage plains; characteristic
U-shaped canyons have
Become V-shaped by the deepening of their
bottoms and straightening of their sides, and decaying glacier
headlands have been undermined and thrown down in loose taluses, while
most of the moraines and striae and scratches have been blurred or
weathered away. Nevertheless, enough remains of the more recent and
the more enduring phenomena to cast a good light well back upon the
conditions of the ancient ice sheet that covered this interesting
region, and upon the system of distinct glaciers that loaded the tops
of the mountains and filled the canyons long after the ice sheet had
been broken up.
The first glacial traces that I noticed in the basin are on the
Wassuck, Augusta, and Toyabe ranges, consisting of ridges and canyons,
whose trends, contours, and general sculpture are in great part
specifically glacial, though deeply blurred by subsequent denudation.
These discoveries were made during the summer of 1876-77. And again,
on the 17th of last August, while making the ascent of Mount
Jefferson, the dominating mountain of the Toquima range, I discovered
an exceedingly interesting group of moraines, canyons with V-shaped
cross sections, wide neve amphitheatres, moutoneed rocks, glacier
meadows, and one glacier lake, all as fresh and telling as if the
glaciers to which they belonged had scarcely vanished.
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