proportion of flints in the chalk was calculated much higher than that given by Lamlardie, whose estimate further experience has satisfied the author is more in accordance with facts.

The accumulation at Dungeness, however, only represents a portion of the flints eroded from the cliffs, as there is the large accumulation at Pevensey, and the shingle-banks spread all along the coast to the east of Beachy Head. The time, therefore, during which the Dungeness shingle has been accumulating must largely exceed that given in the above calculation if it has all come from the cliffs.

The bulk of the pebbles consists of flints, and mixed with these are chert and other stones from the Wealden series and greensand formation. There are also some stones entirely foreign to the rocks of this part of the coast. These may have been derived from ballast contained in vessels wrecked in the locality. In the British Association Report of 1895 a list of these foreign pebbles is given, but this does not state what proportion they bear to the whole. Taking into consideration the source of supply, it seems remarkable that only 11 per cent. of the flint pebbles at Dungeness (taken from the surface) are of the same colour, black, as those derived from the chalk cliffs; about 25 per cent. being brown, and the remainder various colours, including red.

Dymchurch and Romney Marsh.-On the south-east coast of Kent Hampshire, and north-east of Dungeness, is a low flat tract of valuable grazing and arable land, covering 60,000 acres, of which Romney Marsh, containing 24,000 acres, forms part, which, in the whole or in part, comprises twenty-seven parishes.

For the protection of this land, the surface of which is from 8 to 11 feet below the level of high water of spring tides, a seawall extending from New Romney to Hythe, a distance of 4 miles, was constructed by the Romans during the occupation of this country. The top of this bank is 20 feet wide, and from 10 to 13 feet above high water. The method of protection which has of late years been adopted resembles more nearly the Dutch system than any other work in this country.

Previous to the beginning of the present century the bank had been protected by huge groynes, or "knocks," consisting of blocks of stone secured between timber piles placed at right angles to the coast. They were 100 feet in length, and started level with the top of the bank, sloping seaward at an inclination of 1 in 10, some of them being divided at the sea end into the

shape of the letter Y. Although they were not effectual in protecting the bank, these groynes were the means of accumulating a certain amount of shingle.

In 1803 Mr. Rennie was called in, and the first attempt was made to reduce the works of repair to a system, a sum of £56,000 being expended over the part west of Dymchurch. The slope of the bank was increased from 1 in 2 to 1 in 6, and protected with "arming," consisting of brushwood secured by hop poles fastened to piles driven into the bank. After this the shingle began to disappear from the beach, and the "arming was from time to time carried lower down. Twenty years later the brushwood was superseded by blocks of Kentish rag stone.

From this time till about twenty years ago groyning seems to have been almost abandoned.

About the year 1837 Mr. Elliott was appointed superintendent or "expenditor" of the bank, and under his direction, with the

concurrence of Mr. Walker, who had been consulted, the protective works assumed very much their present form. The whole face of the bank was pitched with stone, the lower part being reduced to an average slope of 1 in 8 or 9 up to high water, and above this 1 in 6, terminating with a curve of 7 feet radius. Timber piles were driven into the slope, connected by walings running parallel with the bank, placed about 50 feet apart, and between these were placed blocks of Kentish rag stone, varying in size from 12 inches in depth at the foot and top, and 15 inches in the centre; the inner slope being 1 to 1. As far as practicable the stones were bedded in concrete, but at the lower part the cement was washed away before it had time to set.

This pitching and piling has been gradually carried forward as the beach became denuded of shingle and sand, until the slope has attained a length of 150 feet at the east and 80 feet at the west end.

The seaward slope is finished at the top by a Kentish ragstone parapet. This pitching and parapet extend westward for 3 miles from the Grand Redoubt to High Knock. to Jeffreston the embankment is unprotected. portion was set back fifty years ago, the original line having been abandoned.

Beyond this
This latter

The area of the pitched slope exposed to the action of the sea covers 40 acres.

The sea breaks against this wall over its entire length, and great difficulty has always been experienced in maintaining it, due to the scouring away of the foreshore. The greatest damage is done by south-east gales, which blow dead on shore; with north-west or off-shore winds the beach grows up. The western end is protected to a great extent from south-west gales by the projection of Dungeness. Even at the time the works described above were completed the surf sometimes overtopped the new work, although 12 feet above ordinary high water spring tides, and it was found that the waves sucked out every particle of sand and shingle from between the stones. Between 1859-70 the paving was extended further down, and a number of faggot and oak groynes constructed. Several of these were swept away by a storm in 1869, and, the groyning being neglected, the beach gradually became lowered. Between 1870-90 low-water mark was advanced 300 feet nearer the bank. The depth of water being thus increased, the effect of the waves became so disastrous as not only to suck out the sand and shingle, but also the stone pitching. During gales in 1859, 18,000 square yards of the pitching was destroyed, and between 1870-90, £68,296 was expended in defence works. Between 1880-90 nineteen high groynes, varying in length from 120 to 200 feet, were placed between Dymchurch and High Knock.

In a report on the condition of the bank made in 1892, the late Mr. Case, A.M.I.C.E., who had been appointed the expenditor in 1890, stated that there were holes in the face of the bank below the pitching from 4 to 5 feet deep, which showed clearly the destructive effect the masonry pitching had on the foreshore; that there was abundant evidence to prove that the foreshore

had been wasting away ever since the bank had been paved, the depth of water increasing year by year; and that the pitched masonry slope had worked its own destruction by scour at the base. The previous expenditor had reported that the beach had become 6 feet lower at the foot of the bank than when he first took charge of it a few years previously.

In 1891 about 81 acres (40,000 square yards) of the pitching was destroyed.

In the winter of 1893, during a series of heavy gales, the bank was so damaged that it was estimated by Sir J. Wolfe Barry and Mr. Matthews, who were consulted by the Commissioners, that to thoroughly restore the injured portion of it, extending over three-quarters of a mile, and to provide fortythree heavy groynes in front of the wall, which they advised should be constructed, would cost £41,000.

On the advice of Mr. Case, previous to incurring the large expense involved in the heavy groynes recommended, a system was adopted of placing low groynes along the beach at right angles to the bank, extending from mean high-water level to low water.

Mr. Case, after a careful study of the conditions of the beach, found as the result of experience that the best effect could be obtained in accumulating material on the beach by means of low groynes, commencing with a rake of 1 in 12 at the upper end, and increasing to 1 in 40 lower down, and towards low water 1 in 70, this being the natural inclination of this sand beach.

Owing to the shingle being trapped at Dungeness, the supply along this part of the coast is very scanty, the material of which the beach is composed consisting principally of coarse sand mixed with some small shingle. The substratum of the beach consists of sand and mud to an unknown depth. Groynes on this principle were accordingly erected. The upper end of these commences at about the level of mean high water, and the lower end is carried as far below low water spring tide as possible.

The uprights of these groynes consist of two 7-inch by 21-inch red fir battens, spaced 7 feet 6 inches apart. Between these uprights are placed 7-inch by 24-inch planking in 7 feet 6 inch lengths, spiked to the uprights, placed horizontally, and stepped to follow the natural inclination of the beach. The height at the commencement did not exceed 2 feet 6 inches above the beach, the planking being raised as the sand and shingle

accumulated, and where required the height of the uprights was increased by bolting an additional length of battens. For fixing the battens, holes were sunk in the sand about 3 feet square and 4 feet deep, the uprights placed in them, the holes being filled with dry cement concrete, well trodden down, and covered over with part of the excavated material. Groynes 420 feet in length were constructed in this manner, at the rate of about one groyne a day.

The sand and shingle accumulated between these groynes at the rate of about 2 feet a year; and in the course of three years Mr. Case stated that the beach became raised in places 8 feet near the front of the embankment, and that low water was driven 300 feet back; and at the western end the waves, which formerly broke on the wall when it was protected by the twenty high groynes, do not now reach it.

The average depth of sand and shingle collected between the Grand Redoubt at the east end and Dymchurch was 4 feet 6 inches, the total quantity being estimated at 1,500,000 tons. The foreshore has been built up to the natural inclination of repose, and is now undisturbed by gales; the beach, also, has been changed from mud and sand, with pools of water, to a well-consolidated mixture of beach and sand.

Between 1894-99 a length of 10 miles of these low groynes was erected, which extend westward as far as Dymchurch. They are spaced 150 to 200 feet apart, and are from 700 to 1000 feet long. The cost of repairing the bank and constructing these groynes during this period was £19,000. The process of erecting further groynes and raising those already put down is being continued.1

Hythe. Between Dymchurch and Hythe the beach is becoming denuded of shingle and is being gradually lowered. The waves at high water reach up to the Martello Tower to the west of Hythe, and during a gale in 1899 the beach up to the foot of the tower was scoured away, and the tower was split in two and became in a ruinous condition.

At Hythe there were formerly some groynes along the shore, but they were neglected and allowed to get out of repair, and consequently the beach became much denuded.

1847.

66

Paper by Jas. Elliott on "Romney Marsh," Min. Proc. Inst. C.E., vol. vi.,

The Dymchurch Wall and Reclamation of Romney Marsh," by Edward Case. Paper read at British Association, Dover, 1899.