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supplied by any forces now in operation. The rivers which discharge their contents into these estuaries are comparatively small streams, and quite incapable of performing such a task; and there is no wasting away of the coast-line at all comparable to the formation of these sand-beds.
On the East Coast, the Wash covers an area of about 157,600 acres, of which about 84,000 acres consist of sand-beds, dry at low water, the average thickness of which may be taken at 20 feet. The author has, at various times and under various conditions, analyzed the water flowing down the rivers which empty into this estuary, and ascertained that the quantity of matter brought down in suspension has only been sufficient to provide material for the growth of the salt marshes, which have accreted along the coast during the 1700 years that have elapsed since the enclosure banks made by the Romans, and is satisfied that it is physically impossible for these sand-beds to have been produced by detritus brought down by the rivers under their present condition.
The enormous accumulation of shingle known as the Chesil Bank, extending 10% miles from Abbotsbury to Portland, must have been accomplished under conditions very different to those which now exist.
The drift along this part of the coast is eastward, and the cliffs to the west consist principally of lias, limestone, clay, sand, and shale, containing only a small quantity of stone. An examination of the shore to the westward shows that the pebbles on most of the beaches are different in character to those on the Chesil Bank, and very limited in quantity, and that there is no continuance of the drift for any great distance, its progress being stopped in the bays by the projecting headlands. So far as any records exist, there does not appear to have been any material alteration in the size or form of this bank.
The same remarks apply very much to the large accumulation at the entrance to the Solent, known as the Hurst Castle Shingle Bank.” This bank extends across the channel, having its top 5 feet above high water, and stretches across the Solent for 3 miles, forming a steep submarine cliff from 20 to 70 feet in height. On the end of this bank a castle was erected four centuries ago, and,
" " The History of the Fens of South Lincolnshire.” Second edition. Chap. xvii. Simpkin, Marshall & Co. London, 1896.
? A full description of these banks and their surrounding circumstances will be found in Chapter VII., “Sonth Coast.”
so far as the records show, the size and character of the bank has remained unchanged since then. There is no drift of shingle to the leeward of this bank. The cliffs to the windward consist of drift, containing a limited supply of gravel, the waste of which does no more at the present time than supply the wear and tear of the wave-action on the exterior surface of the bank.
From Selsea Bill to Brighton is a long stretch of nearly straight coast, the greater part of which is entirely devoid of cliffs, the remainder, being bordered by low mounds of sand and clay, devoid of anything that can afford a supply of beach material. West of Selsea Bill are some low cliffs containing a small quantity of gravel, but the stones that fall from these do not pass round the point. With the exception of a few flints, that may occasionally be drifted ashore from the chalk which crops up at low water in a few places, there is not, over this length of 30 miles, any source from which any recent supply of shingle can be derived. Yet at Pagham there is a large bank of this material, extending over 2 miles, the part above high water being 250 yards wide, and covering an area of about 160 acres; and the whole line of coast between here and Brighton is bordered by a bank of flint shingle, which tends to drift easterly. Where this drift has been arrested at Shoreham, the shingle has accumulated in a large bank nearly 4 miles long.
A large proportion of the pebbles of which the shingle is composed may be traced as having been derived from the chalk; they are most of them rounded, but scarcely any have the flat oval shape that is common to pebbles on most shingle banks. Many are quite angular, and are still coated with the white colour of the chalk from which they are derived. The only solution as to their existence in their present position that appears feasible is that they were deposited on the coast at the time when the chalk cliffs between England and France were disrupted, or when the sea broke through the neck of land which connected the Isle of Wight with the coast of Hampshire.?
The gravel beds, which form a thick cap on the east coast of Dorsetshire, gradually decline to the eastward along the coast of Hampshire, and there are traces which indicate that at one time a river ran along the coast, of which the rivers Avon, Lymington, Beaulieu, Test, and Itchen were tributaries, and discharged
1 A full description of these banks and their surrounding circumstances will be found in Chapter VII., “South Coast.”
near to the east of Chichester harbour. The drift of this gravel, and the wearing away of chalk cliffs from 500 to 600 feet in height when the sea broke through the Solent passage, would lead to the deposit of a large quantity of flint and gravels, of which the accumulations at Hurst Castle and Selsea may]probably be the remains.
It seems improbable that the extensive banks of shingle at Aldborough and Weybourne, each several miles in-length, can have accumulated from any waste of adjacent cliffs now going on. The present source of supply is derived almost entirely from the waste of the cliffs, and the falling on to the beach of gravel originally deposited on their surface at the breaking up of the glacial period.
That beach material is derived very largely (from inland sources is shown by the colour of the flint pebbles. The flints derived from the waste of chalk cliffs are invariably black with a white exterior, while the colours of the majority of the flint pebbles forming the large accumulations of shingle, such as those at Hurst, the Chesil Bank, Dungeness, and on the beaches bordering on the chalk cliffs of the South Coast, are the same as those found in inland gravel beds, and vary from different shades of brown, grey, white, and red, the former being most prevalent. The average of several samples, taken from the beaches between Brighton and Dover, and from the Chesil Bank, gives the proportion as about 55 per cent. brown colour, 22 per cent. black derived from the chalk, and 10 per cent. grey, the remainder being red or other colours.
An inquiry addressed to fishermen and others, often very intelligent men and having a good local knowledge of some particular shingle beach, as to where the shingle has come from, generally elicits one of two answers, either that “it grows like everything else,” or else “ that it comes from the sea.”
The opinion that shingle and sand are derived from the seabed is one that has a very general acceptance, and, so far as shingle is concerned, may, in a limited sense, be not altogether contrary to the fact.
On coasts where the sea has encroached, and the cliffs are wasting away, the floor of the sea for some distance out from the shore consists of the same rocks as the cliffs, and in some places remains uncovered by sand. During heavy seas rock fragments become disintegrated by the waves breaking in the shallow water and are cast on to the beach, and drifted above the line of ordinary high water. This drifting is frequently aided by the flotation afforded by seaweed attached to, and growing on, the stones.
: Mr. Kinahan, in his paper on “ Travelling Sea-Beaches” (Min. Proc. Inst. C.E., vol. lviii., 1878), records instances of this, which occurred within his experience on the flat sandy strand of the coast of Galway. During a heavy gale stones weighing from 2 to 3 cwt., with large masses of seaweed growing on them, were loosened from their bed at a depth of 15 fathoms, and thrown on to the beach,
Mr. Shaler, in his account of the sea-beaches of the Atlantic coast, states that boulders lying on the sea-bed at considerable depths, having seaweed attached to them, are borne by the heave of the sea on shore; and gives an example, Marble Head beach, where, during a violent storm, a quantity of boulders, estimated at 10 tons, were cast up on to the beach over the length of a quarter of a mile.
An example of the way in which shingle may be derived from the sea-bed may be found at Sheringham and Cromer, where chalk containing large flints is exposed for some distance from the shore, and where flints are cast up on the beach ; in a lesser degree this is also the case on the Sussex coast near Lancing, where the chalk with flints is exposed in the bed of the sea at low tides, and stones are occasionally washed ashore.
The same also occurs on the Lincolnshire coast, where the boulder clay containing rock fragments of all kinds is exposed on the beach at low water, and the stones, loosened during gales, are drifted shorewards.
Beach Material derived from the Land.—The instances above quoted are exceptional, and it may be accepted as a fact that beach material drifted along the shore is entirely derived from the cliffs.
The all-devouring sea yields practically nothing in the shape of beach material to the land.
There are only three agents capable of bringing material to the shore from the sea-wind, tidal currents, and breaking waves, and what these bring has been previously cast off from the land.
Materials of less specific gravity than the water, and floating on the surface, may be drifted on to the beach by the action of on-shore winds. In the case of sand-dunes the material is drifted by the wind from the sea-shore, but the supply was originally derived from the débris of the land. The currents due to the flood tide, and also to winds blowing continuously in one direction, may also transport floating substances, and drift material along the bottom; but the velocity of these currents is too weak to move or transport anything of larger bulk than grains of sand.
As to the assertion that sand is thrown on to the shore and into estuaries from the sea : taking into consideration the long periods during which such an operation must have been going on, it is obvious that, if such be the case, the coasts must have increased and extended seaward, and estuaries have become dry land, long ages ago; whereas the degradation of the coasts and the encroachment of the sea on the land is a well-known fact; and, so far as any historical records exist, estuaries, except when receiving the deposits from rivers which drain into them, or from the wearing away of adjacent coasts, have retained the same characteristics for hundreds of years. Along the coasts of England, bordered by rocks easily acted upon by the waves, are to be found, under the water, the remains of towns and villages which the sea bas swallowed up; and in other parts, where the rocks consist of harder materials, the gradual slope of the rocks and hills which formerly passed down into the sea now exhibits high cliffs and steep escarpments-standing witnesses to the encroachment of the sea.
If sand and shingle are being continually cast up from the bed of the sea, beaches would be steep, and not flat, as generally found. As a matter of fact, however, beaches become denuded during onshore gales, and grow during those which blow off shore.
In the rare cases where beds of shingle are found below low water, these permanently retain their position, and the stones of which these banks are composed are not washed on shore.
As an example of this, reference may be made to the large bed of shingle known as the “Skerries,” 3.1 miles long by half a mile wide, situated about a mile off the shore, near Start Point, on the coast of Devon, in 11 to 2 fathoms of water. Although occasionally this submarine bank of shingle alters its shape due to tidal action, or to wave-action during heavy gales, it retains its position, and there is no evidence of its diminution or of the drifting of the shingle shoreward.
The same is the case with the “Shambles," a large bank of shells and gravel about a mile off Portland Bill. The most ancient charts to which there is any reference show this bank as