MEANS TAKEN TO ARREST THE DEPREDATIONS OF THE GERMAN OCEAN BY PUBLIC AND
PRIVATE INDIVIDUALS.—THE ERECTION OF JETTIES, PIERS, AND GROINS
CONSIDERED.—THE BENEFICIAL EFFECTS ARISING FROM THE TWO FORMER AT
YARMOUTH AND CROMER—THE PARTIAL FAILURE OF THE LATTER AT TRIMINGHAM, AND
THEIR INJURIOUS EFFECTS ON OTHER COASTS DEMONSTRATED.
IT appears, from the observations of Mr. Palmer and others, that if a
pier or groin be erected anywhere on our southern or south-eastern coast,
to stop the progress of the beach, a heap of shingle soon collects on the
western side of such artificial barriers, {42a} while on our eastern
coast, sand, stones, &c., accumulate to the northward.
The plans hitherto pursued by public and private individuals have been to
place abrupt perpendicular bodies, not to the southward of the property
they have been most anxious to save, but have erected them directly
opposite. Thus Mr. Wheatley, of Mundsley, {42b} had the hulls of old
vessels placed upon the shore at the base of the cliffs adjoining his
property; they were filled with large stones, secured with piles driven
into the beach on either side, fore and aft, also by a strong chain
cable, &c.; but a few years since they were entirely removed by the sea
during a heavy gale of wind from the north-west upon a spring tide.
The town of Cromer, {43a} on the same occasion, met with considerable
loss. The jetty erected at the north end of the town caused a large
mound of sand to accumulate to the eastward of it, presenting an inclined
surface towards the sea, and during the intervention of north-westerly
gales, indigenous grasses sprung up, and covered the surface nearest the
banks; this time, however, the jetty gave way, and the greater portion of
the mound of sand was removed; but still there was sufficient left to
convince the inhabitants, had the jetty been erected at the west end of
the town, their property would have been saved.
In the erection of a groin at Trimingham, {43b} a few years since, large
square piles, about ten or twelve inches in diameter, were driven into
the beach, at a right angle, to the base of the tall cliffs, and extended
to or beyond low water mark; they were left projecting a considerable
height above the then surface of the beach, and strong planks, fastened
with iron bolts, were continuously attached to the tops of the projecting
piles. The shallow existing must have been considerable in length,
breadth, and depth; for subsequently a heavy sea, produced from a
northerly gale, removed several of the piles entirely, and others were
forced from a perpendicular to a horizontal position.
This circumstance, however, is readily accounted for, the strata into
which the piles were inserted at a particular part, passed through blue
clay into blue sand of a loose texture, and the piles were not driven to
a depth necessary to reach or enter the solid strata beneath; now if we
take into consideration the length and depth of the shallow, and breadth
of surface presented by pile and plank, subjected to the full sweep of
the tidal current from north to south, or rather at this point from east
to west, aided and assisted by an increased flow of water from the
Atlantic, we cannot be surprised at the result above mentioned. It was
found necessary to support those left with additional piles placed
horizontally on the west side. The effect produced by this costly groin
was an accumulation of sea-beach materials to the northward, extending
about thirty yards from the base of the cliff towards the sea, reaching
to the top of the pile and plank; from thence an abrupt declination
ensued, and terminated at the part from whence the piles, &c., alluded to
had been removed.
Immediately to the southward of this barrier scarcely any accumulation of
sea-beach materials had taken place, and the sea was committing greater
ravages upon the cliffs adjoining than before. {44}
The plan of driving piles into the beach, for the purpose of retaining
it, and encouraging materials to lodge on its surface, and consequently
to break the force of the waves, has long been adopted on different
coasts in England; and where a continuation of them has been practised,
in certain localities, seem to have been attended with success; in others
they have exhibited only a partial protection, from their temporary
duration, and considerable inconvenience has been felt on coasts where
shingle predominates, from pebbles pouring over in great numbers during
heavy gales.
The immense quantity of sand displayed on this portion of the coast
affords not only a different feature, but more gratifying results may be
anticipated. In Yarmouth, the sea has not advanced upon the sands in the
slightest degree since the reign of Elizabeth, and where the town is
built became firm and habitable ground about the year 1008, from which
time a line of dunes has gradually increased in height and breadth,
stretching across the whole entrance of the ancient estuary, and
obstructing the ingress of the tides so completely, that they are only
admitted by a narrow passage, which the river keeps open, and which has
gradually shifted several miles to the south. {45a}
By the exclusion of the sea, thousands of acres in the interior have
become cultivated lands; and exclusive of small pools, upwards of sixty
fresh water lakes have been formed, varying in depth from fifteen to
thirty feet, and in extent from one to twelve hundred acres. {45b}
The benefit derived from the erection of piers at the Haven’s mouth, has,
in conjunction with the jetty, afforded great protection to the town of
Yarmouth. The tidal wave and current has been checked, the shore has
been elevated, retained, and rendered wider to the northward, as far as
Winterton; {45c} a shoal of sand has formed, and extends a considerable
distance into the sea, at right angles to the shore, beyond the
termination of the north pier, so that it has been found necessary to
place a buoy at its extremity, as a guide for the mariner to steer due
east from the Haven’s Mouth to Yarmouth Roads. The jetty, extending into
the sea upwards of four hundred and fifty feet, is now about to be added
to, in consequence of the shallowness of the water.
The question now arises, would the jetty and piers have been so
beneficial, had they not been continued into the sea to the extent
alluded to? Certainly not. The shoals of sand, which formerly existed
in the offing, have been removed, or rather have been converted into a
solid mass; the current has been diverted from a southerly to a
north-easterly direction, and the bed of the ocean nearest the shore has
been elevated, and no doubt terminates into the sea upon an inclined
plane.
The failure of groins, erected with pile and plank, appear to arise from
their being placed in a wrong situation, from their not extending far
enough into the sea, from the piles not being driven sufficiently into
the beach, and from their sudden elevation, present an abrupt surface for
the tidal wave to play upon, which during heavy gales of wind upon spring
tides, cannot withstand its powerful effect, should the materials lying
adjacent to or between them be removed. Therefore they can only be
available where the interstices are completely filled with sea beach
materials, and their durability must depend upon the latter cause.