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. Had the general glacial denudation been
much less, these ocean ways over which we are sailing would have been
valleys and canyons and lakes; and the islands rounded hills and
ridges, landscapes with undulating features like those found above
sea-level wherever the rocks and glacial conditions are similar. In
general, the island-bound channels are like rivers, not only in
separate reaches as seen from the deck of a vessel, but continuously
so for hundreds of miles in the case of the longest of them. The
tide-currents, the fresh driftwood, the inflowing streams, and the
luxuriant foliage of the out-leaning trees on the shores make this
resemblance all the more complete. The largest islands look like part
of the mainland in any view to be had of them from the ship, but far
the greater number are small, and appreciable as islands, scores of
them being less than a mile long. These the eye easily takes in and
revels in their beauty with ever fresh delight. In their relations
to each other the individual members of a group have evidently been
derived from the same general rock-mass, yet they never seem broken
or abridged in any way as to their contour lines, however abruptly
they may dip their sides. Viewed one by one, they seem detached
beauties, like extracts from a poem, while, from the completeness of
their lines and the way that their trees are arranged, each seems a
finished stanza in itself. Contemplating the arrangement of the trees