it Indians of the
ragged western coast of British Columbia and southern Alaska spread
their villages on the narrow tide-swept hem of the land, and subsist
chiefly by the generosity of the deep. They are poor landsmen, but
excellent boat-makers and seamen, venturing sometimes twenty-five miles
out to sea to gather birds' eggs from the outermost fringe of rocks.

[Sidenote: Contrasted coastal belts.]

As areas of elevation or subsidence are, as a rule, extensive, it
follows that coasts usually present long stretches of smooth simple
shoreline, or a long succession of alternating inlet and headland.
Therefore different littoral belts show marked contrasts in their degree
of accessibility to the sea, and their harbors appear in extensive
groups of one type--fiords, river estuaries, sand or coral reef lagoons,
and embayed mountain roots. A sudden change in relief or in geologic
history sees one of these types immediately succeeded by a long-drawn
group of a different type. Such a contrast is found between the Baltic
and North Sea ports of Denmark and Germany, the eastern and southern
seaboards of England, the eastern and western sides of Scotland, and the
Pacific littoral of North America north and south of Juan de Fuca
Strait, attended by a contrasted history.

A common morphological history, marked by mountain uplift, glaciation,
and subsidence, has given an historical development similar in not a few
respects to the fiord coasts of New England, Norway, Iceland, Greenland,
the Alaskan "panhandle," and southern Chile. Large subsidence areas on
the Mediterranean coasts from the Strait of Gibraltar to the Bosporus
have in essential features duplicated each other's histories, just as
the low infertile shores of the Baltic from Finland to the Skager Rack
have had much in common in their past development.

Where, however, a purely local subsidence, as in Kamerun Bay and Old
Calabar on the elsewhere low monotonous stretch of the Upper Guinea
coast,[454] or a single great river estuary, as in the La Plata and the
Columbia, affords a protected anchorage on an otherwise portless shore,
such inlets assume increased importance. In the long unbroken reach of
our Pacific seaboard, San Francisco Bay and the Columbia estuary are of
inestimable value; while, by the treaty of 1848 with Mexico, the
international boundary line was made to bend slightly south of west from
the mouth of the Gila River to the coast, in order to include in the