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valleys west of the north end of Yakoun lake. That the whole
lake basin was excavated or even deepened by a glacier is shown
to be improbable or impossible by the steep, unglaciated char-
acter of the islets in the lake. This damming of the valley,
(in pre-Glacial time) occupied by the present Baddeck and
Yakoun rivers as one continuous large stream, with Etheline,
Delta, and other creeks as tributaries, caused the lake basin
to form, shaped the present eastward bend of the Yakoun river,
and separated the upper part of the stream, to form
the Baddeck river. The glacial filling reduced the grade of the
valley, causing the upper part (the Baddeck river) to slacken its
rate of cutting and to braid its channel, and the upper reaches
of the Yakoun to assume their present sluggish character.

The Yakoun river for the greater part of it slength occupies
a wide valley. It flows in a narrow trench that is in places
canyon-like, with rock walls rising 50 feet from the water, and
maintains a moderate, continuous grade, uninterrupted by
pronounced rapids. King creek and the lower parts of Hidden
creek and Ghost river also occupy rather wide valleys with
moderate, uniform grades.

The valleys tributary to the southwestern end of Yakoun
lake, which extends into the Queen Charlotte range, are markedly
V-shaped, and little, if at all, modified by glacial erosion. The
sides of the valleys are very steep, in some cases sloping at angles
as high as 45 degrees. The submerged valleys occupied by
Long Arm, and Slatechuck valley are also remarkably steep-
sided, narrow, depressions, and seem to have been altered very
little by glacial action.

The northern part of the central depression of Graham
island is occupied by Masset inlet which is virtually the estuary
of the Yakoun river. There is apparently no geologic break
along this inlet, which probably represents the submerged lower
portion of the Yakoun River valley.

Coast-lines.

The varying effects of subaérial and marine erosion acting
on rocks of different characters, are well illustrated on Graham
island, where several varieties of rock form the sea coast.