n, in Fallen Leaf Lake Canyon (Glen Alpine Basin),
burst out the waters of Glen Alpine Springs, highly charged
with bicarbonates of iron and soda.

_d. Glacial Deltas_. I have stated that the moraines of
Cascade Lake and Emerald Bay glaciers run down to the margin
of Lake Tahoe. An examination of this portion of the Lake
shore shows that _they run far into the Lake_--that
the Lake has been filled in, two or three miles, by glacial
debris. On the eastern margin of Lake Tahoe, the water, close
along the shore, is comparatively shallow, the shore rocky,
and along the shore-line, above and below the water, are
scattered great bowlders, probably dropped by the main
glacier. But on the west margin of the Lake the shoreline is
composed wholly of moraine matter, the water very deep close
to shore, and the bottom composed of precisely similar moraine
matter. In rowing along the shore, I found that the exquisite
ultramarine blue of the deep water extends to within 100 to
150 feet of the shore-line. At this distance, the bottom could
barely be seen. Judging from the experiments of my brother,
Professor John Le Conte, according to which a white object
could be seen at a depth of 115 feet, I suppose the depth along
the line of junction of the ultramarine blue and the emerald
green water is at least 100 feet. The slope of the bottom is,
therefore, nearly, or quite, 45 degrees. It seems, in fact, a
direct continuation beneath the water of the moraine slope. The
materials, also, which may be examined with ease through the
wonderfully transparent water, are exactly the same as that
composing the moraine, viz: earth, pebbles, and bowlders
of all sizes, some of them of enormous dimensions. It seems
almost certain that _the margin of the great Lake Valley
glacier, and of the Lake itself when this glacier had melted
and the tributaries first began to run into the Lake, was the
series of rocky points at the head of the three little lakes,
about three or four miles back from the present margin of the
main Lake; and that all lakeward from these points has been
filled in and made land by the action of the three glaciers
described_. At that time Rubicon Point was a rocky
promontory, projecting far into the Lake, beyond which was
another wide bay, which has been similarly filled in by
debri