here is
nothing borne on the surface. The moraine, therefore, consists
wholly of nether-formed and nether-borne severely triturated
materials (_moraine profunde_). The bowlders are, of
course, all rounded. This is one extreme. In the case of the
thin moving ice-fields, the _glacierets_ which still
linger among the highest peaks and shadiest hollows of the
Sierra, on the other hand, the moraines are composed _wholly
of angular blocks_. This is the character of the terminal
moraine of Mount Lyell glacier. These glacierets are too thin
and feeble and torpid to break off fragments--they can
only _bear_ away what falls on them. This is the
other extreme. But in the case of ordinary
glaciers--ice-streams--the bowlders of the terminal deposit
are mixed; the angular or upper-formed predominating in the
small existing glaciers of temperate climates, but the rounded
or nether-formed greatly predominating in the grand old
glaciers of which we have been
speaking. In the terminal deposits of these, especially in the
materials pushed into the Lake, it is somewhat difficult
to find a bowlder which has not been subjected to severe
attrition.

CHAPTER IX

THE LESSER LAKES OF THE TAHOE REGION AND HOW THEY WERE FORMED

This is not to be a description of the scores of Glacial Lakes found
in the Tahoe region, but an answer to the questions so often
asked about practically all of these lakes, as to their origin and
continuance.

Rich as our Sierras are in treasures none are more precious than
these. They give one pleasing surprises, often when least expected.
For while the tree-clusters, the mountain-peaks, and the glowing
snow-banks throw themselves into our view by their elevated positions,
the retiring lakes, secluded, modest, hide their beauty from us until
we happen to climb up to, or above, them.

From the higher summits how wonderfully they appear. Let the eye
follow a fruitful branch of an apple, pear or peach. How the leaves,
the stem, the fruit occur, in sure but irregular order. It is just
so with the glacial lakes of the Sierras. They are the fruit of the
streams that flow from the glacial fountains. They lie on rude and
unexpected granite shelves,--as Le Conte Lake; under the shadow of
towering peaks,--as Gilmore Lake; on bald glacier-gouged and polished
tables,--as those of Desolation Valley; embosomed in deep woods,--as
Fallen