THE SEA SHORE
27
The waves are the greatest inuenceat work mouldin g the
shore, breaking with fury against the land, washing away
loose material or, with the aid of pebbles and stones which
they dash against it, gradually eating into a hard, rocky
coast, forminga flat “.abrasion platform ”» at the baSe often
of toweng _cliffs.
Here we nd a typicalrocky shore, '
In other regions, on the other hand, the action of powerful
cross currents deposits great banks of sand, formed by the
breaking down of rocks.
At the mouths of rivers or in
sheltered'crecks and gulleys there are mud ats where the
sediment brought from land is deposited.
The action of
ice and of weàthering in general also assists in the wearing
away of the land and theformation of the shore, while the.
inuence of plants and animals is not to be neglected.
The former often help to bind together sand and mud»and
convert them into rm, dry land; encrusting animals, such
as bamacles and nimssels, may help to protect rocks, but
usually the action of animals is destructive, notably that
'
of the various rock borers.
.
'
A;feature of the greatest importance is the variability oi
conditions on the shore.
Not only does the sea cover and
uncover.it twice daily, but the ranges of temperature are
far greater, both yeay and often daily, than in any other
part of the sea.
An animal in moderately cool water at
high tide may be left stranded at low tide in_ a small rock
pool where the temperature rises to great heights under the
-
inuence of a hot summer: sun.
The “sh—allow water near the
shore is both warmer in summer and coolerin winter (when
ice may form on the shore) than the deeper water further
_
_
out; - The constitution of the sea is also apt to be variable,
especially near the mouths of rivers'_ where much fresh—
Water is mixed with it ; also in the height of Summer When,
in enclosed areas, evaporationmay make the sea more than
_.
usually salty. The inuence of light is very great, greater
27
The waves are the greatest inuenceat work mouldin g the
shore, breaking with fury against the land, washing away
loose material or, with the aid of pebbles and stones which
they dash against it, gradually eating into a hard, rocky
coast, forminga flat “.abrasion platform ”» at the baSe often
of toweng _cliffs.
Here we nd a typicalrocky shore, '
In other regions, on the other hand, the action of powerful
cross currents deposits great banks of sand, formed by the
breaking down of rocks.
At the mouths of rivers or in
sheltered'crecks and gulleys there are mud ats where the
sediment brought from land is deposited.
The action of
ice and of weàthering in general also assists in the wearing
away of the land and theformation of the shore, while the.
inuence of plants and animals is not to be neglected.
The former often help to bind together sand and mud»and
convert them into rm, dry land; encrusting animals, such
as bamacles and nimssels, may help to protect rocks, but
usually the action of animals is destructive, notably that
'
of the various rock borers.
.
'
A;feature of the greatest importance is the variability oi
conditions on the shore.
Not only does the sea cover and
uncover.it twice daily, but the ranges of temperature are
far greater, both yeay and often daily, than in any other
part of the sea.
An animal in moderately cool water at
high tide may be left stranded at low tide in_ a small rock
pool where the temperature rises to great heights under the
-
inuence of a hot summer: sun.
The “sh—allow water near the
shore is both warmer in summer and coolerin winter (when
ice may form on the shore) than the deeper water further
_
_
out; - The constitution of the sea is also apt to be variable,
especially near the mouths of rivers'_ where much fresh—
Water is mixed with it ; also in the height of Summer When,
in enclosed areas, evaporationmay make the sea more than
_.
usually salty. The inuence of light is very great, greater