ice along the shore line; it may also favour the
protection of the coast life against the severe cold of the winter
season.

The waves which successively come against the shore in any given time,
particularly if a violent wind is blowing on to the coast, are usually
of about the same size. When, however, in times of calm an old sea, as
it is called, is rolling in, the surges may occasionally undergo very
great variations in magnitude. Not infrequently these occasional waves
are great enough to overwhelm persons who are upon the rocks next the
shore. These greater surges are probably to be accounted for by the
fact that in the open sea waves produced by winds blowing in different
directions may run on with their diverse courses and varied intervals
until they come near the shore. Running in together, it very well
happens that two of the surges belonging to different sets may combine
their forces, thus doubling the swell. The danger which these
conjoined waves bring is obviously greatest on cliff shores, where, on
account of the depth of water, the waves do not break until they
strike the steep.

* * * * *

Having considered in a general way the action of waves as they roll in
to the shore, bearing with them the solar energy which was contributed
to them by the winds, we shall now take up in some detail the work
which goes on along the coast line--work which is mainly accomplished
by wave action.

On most coast lines the observer readily notes that the shore is
divided into two different kinds of faces--those where the inner
margin of the wave-swept belt comes against rocky steeps, and those
bordered by a strand altogether composed of materials which the surges
have thrown up. These may be termed for convenience cliff shores and
wall-beach shores. We shall begin our inquiry with cliff shores, for
in those sections of the coast line the sea is doing its most
characteristic and important work of assaulting the land. If the
student has an opportunity to approach a set of cliffs of hard rock in
time of heavy storm, when the waves have somewhere their maximum
height, he should seek some headland which may offer him safe foothold
whence he can behold the movements which are taking place. If he is so
fortunate as to have in view, as well may be the case, cliffs which
extend down into deep water, and others which are bordered by rude
and generally steeply sloping beaches covered wit