All the islands
of the Alexander Archipelago, as well as the headlands and promontories
of the mainland, display telling traces of this great mantle that are
still fresh and unmistakable. They all have the forms of the greatest
strength with reference to the action of a vast rigid press of
oversweeping ice from the north and northwest, and their surfaces have a
smooth, rounded, overrubbed appearance, generally free from angles. The
intricate labyrinth of canals, channels, straits, passages, sounds,
narrows, etc. between the islands, and extending into the mainland, of
course manifest in their forms and trends and general characteristics
the same subordination to the grinding action of universal glaciation as
to their origin, and differ from the islands and banks of the fiords
only in being portions of the pre-glacial margin of the continent more
deeply eroded, and therefore covered by the ocean waters which flowed
into them as the ice was melted out of them. The formation and extension
of fiords in this manner is still going on, and may be witnessed in many
places in Glacier Bay, Yakutat Bay, and adjacent regions. That the
domain of the sea is being extended over the land by the wearing away of
its shores, is well known, but in these icy regions of Alaska, and even
as far south as Vancouver Island, the coast rocks have been so short a
time exposed to wave-action they are but little wasted as yet.
Pages:
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40