The Variety We Find, Both As To The Contours And The Collocation Of
The Islands, Is Due Chiefly To Differences In The Structure And
Composition Of Their Rocks, And The Unequal Glacial Denudation
Different Portions Of The Coast Were Subjected To.
This influence
must have been especially heavy toward the end of the glacial period,
when the main ice-sheet
Began to break up into separate glaciers.
Moreover, the mountains of the larger islands nourished local
glaciers, some of them of considerable size, which sculptured their
summits and sides, forming in some cases wide cirques with canyons or
valleys leading down from them into the channels and sounds. These
causes have produced much of the bewildering variety of which nature
is so fond, but none the less will the studious observer see the
underlying harmony - the general trend of the islands in the direction
of the flow of the main ice-mantle from the mountains of the Coast
Range, more or less varied by subordinate foothill ridges and
mountains. Furthermore, all the islands, great and small, as well as
the headlands and promontories of the mainland, are seen to have a
rounded, over-rubbed appearance produced by the over-sweeping
ice-flood during the period of greatest glacial abundance.
The canals, channels, straits, passages, sounds, etc., are
subordinate to the same glacial conditions in their forms, trends,
and extent as those which determined the forms, trends, and
distribution of the land-masses, their basins being the parts of the
pre-glacial margin of the continent, eroded to varying depths below
sea-level, and into which, of course, the ocean waters flowed as the
ice was melted out of them.
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