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NATURAL BREAKWATERS. 151
When this is the case, it is the crumbling masses and the pebbles of the
strand which themselves serve as bulwarks of defense to protect the wall
of the cliffs from fresh damage. Supported in a slope on the lower part
of the rock, or else scattered in the waves and transformed into shelves,
tl*e fallen blocks break the force of the waves, and retard the progress
of erosion. It is thus that on the coasts of the Mediterranean, near
Vintimillia, the lower strata of the cliffs are composed of a sandy clay,
which the rain alone suffices to wash away, and this gives rise to a talus
of masses of solid conglomerate detached from the upper layers, which
thus protects the cliffs from the fury of the waves. In the same way, on
the sterile shores of Brittany, the blocks of granite, cracked in all directions, and converted into shingle which the sea carries away and returns
again, maintain intact during centuries the walls of rocks of which they
formerly made a part.
The cliffs of Normandy, composed of materials much less hard than
those of the promontories of Brittany, are also more easily worn away;
still, we must attribute their rapid erosion principally to the coastal current which carries away the shingle accumulated at the base of the rocks.
The talus of fallen blocks constitutes at first a perfectly sufficient* defense
against the fury of the waves; but little by little the chalky part of the
rock is dissolved and deposited here and there on the mud-banks, while
the masses of flint disengaged from the substance of the stone cease to
present a sufficient resistance to the waves, and are carried away into the
neighboring bays in immense processions parallel to the shore. On the
south coast of England the current of the coast is much less energetic,
and the talus can, in consequence, long resist the attacks of the sea. A
few years ago the waters undermined with a threatening rapidity the
base of the cliff which rises not far from Dover, on the western side, and
which the English have consecrated to Shakspeare, in remembrance of
the beautiful description which he has given of it in King Lear. To
preserve this historical promontory, the houses that it supports, and the
railroad which runs through it in a tunnel, they formed the plan of blowing down the upper part. In the presence of an immense crowd, assembled to see this new spectacle, they fired hundreds of pounds of powder
buried in a mine, and enormous masses of rock fell with a crash from the
top of the hill; and now the force of the waves is broken on their talus.
Mr. Beete Jukes thinks that during eighteen centuries this cliff "and the
neighboring rocks have been worn away by nearly one mile.*
In the North Sea there is an island which, by a singular misapprehension, was believed to have been consecrated to Freya, the goddess of Love
and Liberty, and whose ancient name of Halligland (land with the inun-
aated banks) has been transformed for foreigners into that of Heligoland
(Holy Land). The island, composed entirely of mottled stone, formerly
surrounded by cretaceous beds, presents to the sea all round a cliff about
200 feet high, worn away at the base by the waves. By employing the
* School Manual of Geology, p. 89.
| Title | The ocean, atmosphere, and life |
| Creator | Reclus, Elisée |
| Publisher | Harper |
| Place of Publication | New York |
| Date | 1873 |
| Language | eng |
| Type | Books/Pamphlets |
| Title | 00000168 |
| Type | Books/Pamphlets |
| Transcript | NATURAL BREAKWATERS. 151 When this is the case, it is the crumbling masses and the pebbles of the strand which themselves serve as bulwarks of defense to protect the wall of the cliffs from fresh damage. Supported in a slope on the lower part of the rock, or else scattered in the waves and transformed into shelves, tl*e fallen blocks break the force of the waves, and retard the progress of erosion. It is thus that on the coasts of the Mediterranean, near Vintimillia, the lower strata of the cliffs are composed of a sandy clay, which the rain alone suffices to wash away, and this gives rise to a talus of masses of solid conglomerate detached from the upper layers, which thus protects the cliffs from the fury of the waves. In the same way, on the sterile shores of Brittany, the blocks of granite, cracked in all directions, and converted into shingle which the sea carries away and returns again, maintain intact during centuries the walls of rocks of which they formerly made a part. The cliffs of Normandy, composed of materials much less hard than those of the promontories of Brittany, are also more easily worn away; still, we must attribute their rapid erosion principally to the coastal current which carries away the shingle accumulated at the base of the rocks. The talus of fallen blocks constitutes at first a perfectly sufficient* defense against the fury of the waves; but little by little the chalky part of the rock is dissolved and deposited here and there on the mud-banks, while the masses of flint disengaged from the substance of the stone cease to present a sufficient resistance to the waves, and are carried away into the neighboring bays in immense processions parallel to the shore. On the south coast of England the current of the coast is much less energetic, and the talus can, in consequence, long resist the attacks of the sea. A few years ago the waters undermined with a threatening rapidity the base of the cliff which rises not far from Dover, on the western side, and which the English have consecrated to Shakspeare, in remembrance of the beautiful description which he has given of it in King Lear. To preserve this historical promontory, the houses that it supports, and the railroad which runs through it in a tunnel, they formed the plan of blowing down the upper part. In the presence of an immense crowd, assembled to see this new spectacle, they fired hundreds of pounds of powder buried in a mine, and enormous masses of rock fell with a crash from the top of the hill; and now the force of the waves is broken on their talus. Mr. Beete Jukes thinks that during eighteen centuries this cliff "and the neighboring rocks have been worn away by nearly one mile.* In the North Sea there is an island which, by a singular misapprehension, was believed to have been consecrated to Freya, the goddess of Love and Liberty, and whose ancient name of Halligland (land with the inun- aated banks) has been transformed for foreigners into that of Heligoland (Holy Land). The island, composed entirely of mottled stone, formerly surrounded by cretaceous beds, presents to the sea all round a cliff about 200 feet high, worn away at the base by the waves. By employing the * School Manual of Geology, p. 89. |
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