s. Such marine inlets create islands and peninsulas;
which are characterized by proximity to the sea on all or many sides;
and in the interior of the continents they produce every degree of
nearness, shading off into inaccessible remoteness from the watery
highway of the deep.

The success with which such indentations open up the interior of the
continents depends upon the length of the inlets and the size of the
land-mass in question. Africa's huge area and unbroken contour combine
to hold the sea at arm's length, Europe's deep-running inlets open that
small continent so effectively that Kazan, Russia's most eastern city of
considerable size, is only 750 miles (1,200 kilometers) distant from the
nearest White Sea, Baltic, and Azof ports. Asia, the largest of all the
continents, despite a succession of big indentations that invade its
periphery from Sinai peninsula to East Cape, has a vast inland area
hopelessly far from the surrounding oceans.

[Sidenote: Ratio of shoreline to area.]

In order to determine the coast articulation of any country or
continent, Carl Ritter and his followers divided area by shoreline, the
latter a purely mathematical line representing the total contour length.
By this method Europe's ratio is one linear mile of coast to 174 square
miles of area, Australia's 1:224, Asia's 1:490, and Africa's 1:700. This
means that Europe's proportion of coast is three times that of Asia and
four times that of Africa; that a country like Norway, with a shoreline
of 12,000 miles traced in and out along the fiords and around the larger
islands,[440] has only 10 square miles of area for every mile of
seaboard, while Germany, with every detail of its littoral included in
the measurement, has only 1,515 miles of shoreline and a ratio of one
mile of coast to every 159 square miles of area.

The criticism has been made against this method that it compares two
unlike measures, square and linear, which moreover increase or decrease
in markedly different degrees, according as larger or smaller units are
used. But for the purposes of anthropo-geography the method is valid,
inasmuch as it shows the amount of area dependent for its marine outline
upon each mile of littoral. A coast, like every other boundary, performs
the important function of intermediary in the intercourse of a land with
its neighbors; hence the length of this sea boundary materially affects
this function. Area and coastline are not dead mathematical