The outlets of this great "mer de glace" are yet imperfectly known.

A part of the ice certainly escaped by Truckee Canyon (the present outlet of the Lake); a part probably went over the northeastern margin of the basin.

My studies during the summer were confined to some of the larger tributaries of this great glacier.
[Footnote 1: This is the name given by Dr.LeConte to the Basin in which Lake Tahoe rests and including the meadow lands above Tallac.] [Illustration: Pyramid Peak and Lake of the Woods, near Lake Tahoe, Calif.] [Illustration: Snow Bank, Desolation Valley, near Lake Tahoe] [Illustration: Grass Lake, near Glen Alpine Springs] _Truckee Canyon and Donner Lake Glaciers_.

I have said that one of the outlets of the great "mer de glace" was by the Truckee River Canyon.

The stage road to Lake Tahoe runs in this canyon for fifteen miles.