ed from rain by a covering of large
boulders. On the north half of the range the striated and polished
surfaces are less common, not only because this part of the chain is
lower, but because the surface rocks are chiefly porous lavas subject to
comparatively rapid waste. The ancient moraines also, though well
preserved on most of the south half of the range, are nearly obliterated
to the northward, but then material is found scattered and
disintegrated.

A similar blurred condition of the superficial records of glacial action
obtains throughout most of Oregon, Washington, British Columbia, and
Alaska, due in great part to the action of excessive moisture. Even in
southeastern Alaska, where the most extensive glaciers on the continent
are, the more evanescent of the traces of their former greater
extension, though comparatively recent, are more obscure than those of
the ancient California glaciers whore the climate is drier and the rocks
more resisting.

These general views of the glaciers of the Pacific Coast will enable my
readers to see something of the changes that have taken place in
California, and will throw light on the residual glaciers of the High
Sierra.

Prior to the autumn of 1871 the glaciers of the Sierra were unknown. In
October of that year I discovered the Black Mountain Glacier in a
shadowy amphitheater between Black and Rod Mountains, two of the peaks
of the Merced group. This group is the highest portion of a spur that
straggles out from the main axis of the range in the direction of
Yosemite Valley. At the time of this interesting discovery I was
exploring the _neve_ amphitheaters of the group, and tracing the
courses of the ancient glaciers that once poured from its ample
fountains through the Illilouette Basin and the Yosemite Valley, not
expecting to find any active glaciers so far south in the land of
sunshine.

Beginning on the northwestern extremity of the group, I explored the
chief tributary basins in succession, their moraines, roches moutonnees,
and splendid glacier pavements, taking them in regular succession
without any reference to the time consumed in their study. The monuments
of the tributary that poured its ice from between Red and Black
Mountains I found to be the most interesting of them all; and when I saw
its magnificent moraines extending in majestic curves from the spacious
amphitheater between the mountains, I was exhilarated with the work that
lay before me. It was one