Successful Bitterroot crossing with Nez Perce guides — Patrick Gass: June 27, 1806

we renewed our march, proceeding over some of the steepest
mountains I ever passed. The snow is so deep that we cannot
wind along the sides of these steeps, but must slide straight
down. The horses generally do not sink more than three
inches in the snow; but sometimes they break through to
their bellies. We kept on without halting to about 5 o’clock
LEWIS AND CLARK EXPEDITION — 251
in the evening, when we stopped at the side of a hill where the
snow was off, and where there was a little grass; and we here
encamped for the night. The day was pleasant throughout;
but it appeared to me somewhat extraordinary, to be travel-
ling over snow six or eight feet deep in the latter end of
June. The most of us, however, had saved our socks as we
expected to find snow on these mountains.