evidence of the fact that Fallen Leaf Lake glacier was once a
tributary of a much greater glacier which filled Lake Tahoe.

The only other agency to which we could attribute this
transportation is that of shore ice and icebergs, which
probably did once exist on Lake Tahoe; but the limitation of
the pebbles to the western, and especially the northwestern
shores, is in exact accordance with the laws of glacial
transportation, but contrary to those of floating ice
transportation--for lake ice is carried only by winds, and
would, therefore, deposit equally on all shores.

Again: I think I find additional evidence of a Lake Tahoe
"mer de glace" in the contrasted character of the northern and
southern shores of this Lake.

All the little glacial lakes described above are deep at the
upper end and shallow at the lower end. Further, all of them
have a sand beach and a sand flat at the upper end, and great
bowlders thickly scattered in the shallow water, and along the
shore at the lower end. These facts are easily explained,
if we remember that while the glacial _scooping_ was
principally at the upper end, the glacial
_droppings_ were principally at the lower end. And
further: that while the _glacial_ deposit was principally
at the lower end, the _river_ deposit, since the glacial
epoch, has been wholly at the upper end.

Now the great Lake, also, has a similar structure. It also has
a beautiful sand and gravel beach all along its upper shore,
and a sand flat extending above it; while at its lower, or
northern end, thickly strewed in the shallow water, and along
the shore line, and some distance above the shore line, are
found in great abundance _bowlders of enormous size_.
May we not conclude that similar effects have been produced by
similar causes--that these huge bowlders were dropped by the
great glacier at its lower end? Similar bowlders are also
found along the northern portion of the eastern shore, because
the principal flow of the ice-current was from the southwest,
and in the fulness of glacial times the principal exit was
over the northeastern lip of the basin.

_b. Origin of Lake Tahoe_. That Lake Tahoe was once
wholly occupied by ice, I think, is certain; but that it
was scooped out by the Lake Valley glacier is perhaps more
doubtful. All other Sierra