h to overcome the
cohesion of ice, there would be no spreading. _A glacier
running down a steep narrow canyon and out into the deep
water, and forming icebergs at its point, would maintain its
slender, tongue-like form, and drop its debris on each side,
forming parallel ridges, and would not form a terminal moraine
because the materials not dropped previously would be carried
off by icebergs_. In the subsequent retreat of such a
glacier, imperfect terminal moraines might be formed higher
up, where the water is not deep enough to form icebergs. It
is probable, too, that since the melting of the great "mer de
glace" and the formation of the Lake, the level of the water
has gone down considerably, by the deepening of the Truckee
Canyon outlet by means of erosion. Thus not only did the
glaciers retreat from the Lake, but also the Lake from the
glaciers.

As already stated, similar parallel moraine ridges are formed
by the glaciers which ran down the steep eastern slope of the
Sierras, and out on the level plains of Mono. By far the most
remarkable are those formed by Bloody
most Canyon Glacier, described by me in a former paper. These
moraines are six or seven miles long, 300 to 400 feet high,
and the parallel crests not more than a mile asunder. There,
also, as at Lake Tahoe, we find them terminating abruptly in
the plain without any sign of terminal moraine. But higher up
there are small, imperfect, transverse moraines, made during
the subsequent retreat, behind which water has collected,
forming lakes and marshes. But observe: these moraines are
also _in the vicinity of a great lake_; and we have
abundant evidence, in very distinct terraces described by
Whitney[4] and observed by myself, that in glacial times the
_water stood at least six hundred feet above the present
level_. In fact, there can be no doubt that at that time
the waters of Mono Lake (or a much greater body of water
of which Mono is the remnant) washed against the bold rocky
points from which the debris ridges start. _The glaciers in
this vicinity, therefore, must have_ run out into the water
six or seven miles, and doubtless formed icebergs at their
point, and, therefore, formed there no terminal moraine.

[Footnote 4: _Geological Survey of California_, Vol. I, 451.]

That the glaciers described