CHAPTER V.
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.