The principal characters in which the history of
the ancient glaciers is preserved are displayed here in marvelous
freshness and simplicity, furnishing the student with extraordinary
advantages for the acquisition of knowledge of this sort. The most
striking passages are polished and striated surfaces, which in many
places reflect the rays of the sun like smooth water. The dam of Red
Lake is an elegantly modeled rib of metamorphic slate, brought into
relief because of its superior strength, and because of the greater
intensity of the glacial erosion of the rock immediately above it,
caused by a steeply inclined tributary glacier, which entered the main
trunk with a heavy down-thrust at the head of the lake.
Moraine Lake furnishes an equally interesting example of a basin formed
wholly, or in part, by a terminal moraine dam curved across the path of
a stream between two lateral moraines.
At Moraine Lake the canon proper terminates, although apparently
continued by the two lateral moraines of the vanished glacier. These
moraines are about 300 feet high, and extend unbrokenly from the sides
of the canon into the plain, a distance of about five miles, curving and
tapering in beautiful lines.
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