133 



ALLUVIUM. 



ALLUVIUM. 



131 



up opposite to the delta of a great river, they accelerate its formation, 

 for the matter brought down, in place of being carried far out to sea, 

 is deposited in the intermediate space, and the sand-bank in time 

 becomes united to the delta. 



An extensive waste of the land is in constant progress along every line 

 of coast which presents an abrupt face to the sea. The amount and 

 rapidity of that waste depend upon a variety of circumstances : the 

 nature of the rocks of which the cliffs are composed, according as they 

 are capable of long resistance, or are easily acted upon by the weather 

 and the sea ; the force of the tides and currents ; the greater or less 

 frequency of storms ; all these accelerate or retard the destructive 

 force of the ocean. In this case also, as well as in the action of running 

 water on the land, the force is greatly augmented when the water is 

 charged with solid matter. The violent surge of a tempest dashing 

 against a cliff detaches large blocks, and sweeps them away ; but the 

 next returning wave hurls them back again against the cliff, and thus 

 a powerful artillery is supplied by the land for its own destruction. 

 When we look upon a map of the world, and see the irregular form 

 and indented line of coast of every continent and island, we have before 

 us the most irresistible proof of the powerful force of the waves, and 

 that the line of the shore must have been formed, in a great degree, 

 by the action of the sea. 



The east and south coasts of Great Britain, from the nature of the 

 rocks of which they are composed, and from the violent storms to 

 which they are exposed, are extremely subject to decay. The Shetland 

 and Orkney Islands are laid open to the whole violence of the waves of 

 the Atlantic, and the ocean-current runs in the Pentland Frith, in 

 ordinary spring-tides, at the rate of 10J miles an hour, and about 

 13 miles during storms. The steep cliffs on the shores of the 

 Shetland Islands are hollowed out into caves, so that the sea enters 

 in some places to the depth of 250 feet, lofty arches are worn in pro- 

 jecting rocks, and almost every promontory ends in a cluster of pillars, 

 obelisks, and towers, the last fragments of extensive continuous strata. 

 In stormy winters, vast blocks are moved from their seat, overturned, 

 dashed into the sea, or carried considerable distances up acclivities. 

 In this case, even rocks of the hardest composition have been unable 

 to withstand the force with which they have been assailed. Islands 

 have been wholly destroyed, and the remains of others rise like the 

 iiiins of a Palmyra in the desert of the ocean. Representations of 

 these have been given by Dr. Hibbert in his description of the Shet- 

 land Islands, and the following is a copy of one of the most striking. 







In the year 1795 a village on the coast of Kincardineshire was swept 

 away by a storm in one night, and the sea penetrated 150 yards inland, 

 where it him maintained its ground ever since. Almost the whole 

 coast of Yorkshire, from the Tees to the Humber, is in a state of 

 constant decay, especially between Flamborough Head and the Spurn 

 Point, the rate of encroachment at (Jwthorpe being at present about 

 four yards in a year. An inn at Sherringham, on the Norfolk coast, 

 built in 1H05, 70 yards from the sea, in 1829 was separated only by a 

 small garden from the edge of the cliff. There is now a depth of water 

 xiiflirient to float a frigate at one point in the harbour of that place, 

 where, only half a century ago, there stood a cliff 50 feet high, with 

 houses upon it. The whole site of ancient Crumer now forms a part of 

 the German Ocean. Dunwich, once a flourishing and populous town, 

 and the most considerable sea-port on the coast of Suffolk, has been 

 gradually swept away, so that there now only remain about twenty 

 houses. The church of Reculver, on the const of Kent, was nearly a 

 mile' inland in the reign of Henry VIII. ; it iB now little more than 60 

 from the water's edge. 



The whole coast of Sussex has been incessantly encroached upon by 

 the ea from time immemorial ; tracts of 400 acres have been carried 

 away at one time ; and the old town of Brighton, which stood between 

 the site of the present cliff and the sea in the reign of Elizabeth, has 

 been wholly destroyed. The projecting foreland of Beachy Head is 

 falling away rapidly : in the winter of 1852 many large portions gave 

 way and fell into the cea, among which were some of a picturesque 

 form, known as the Charleses, which were much visited by tourists. 

 By the undermining of the sea on the coast of Dorsetshire, in 



1792, a portion of land 600 yards from east to west, and a mile and 

 a quarter from north to south, sunk 50 feet in 24 hours. The island 

 of Heligoland, off the entrance of the river Elbe, has been reduced to 

 the fourth part of its size within the last 500 years, and since 1770 has 

 been divided into two parts, the channel between them being navigable 

 by large ships. Nowhere has the sea made greater inroads than on the 

 coast of Schleswig. The island of Nordstrand, in the earlier part of 

 the 13th century, was separated from the main-land by a narrow 

 stream, and was 50 miles long and 35 broad, populous and highly 

 cultivated. In the year 1240 a great part of it was destroyed, and at 

 the cud of the ICth century it was reduced to an .area of 20 miles in 

 circumference. The industrious inhabitants endeavoured -to save their 

 territory by the erection of lofty dikes ; but in October, 1C34, a great 

 storm devastated the whole island, destroyed 1340 people, and 50,000 

 head of cattle ; and three small islets, which have since considerably 

 diminished, were all that remained of the once fertile and populous 

 Nordstrand. 



It would be superfluous to give, in this place, farther instances of 

 the like nature : those we have already mentioned have all occurred 

 within the historical era ; others, however, still more remarkable in 

 extent, date from a much earlier period of the earth's history, and the 

 evidence of their occurrence is supplied by the identity in composition 

 of the opposite portions of the separated lands. There is every reason 

 to believe that England once formed a part of France : the cliffs on 

 the opposite sides of the channel are identical with those at the Straits 

 of Dover ; and between Folkestone and Boulogne a submarine chain 

 of hills is, in some places, only 14 feet below the surface at low water. 

 From the German Ocean to the Straits the water becomes gradually 

 more shallow, diminishing, in a distance of 200 leagues, from 120 to 

 18 fathoms ; and in the same manner, from the Straits to the mouth 

 of the English Channel, there is a gradual increase of the depth of the 

 water, so that at the Straita there is a ridge with a fall to the west and 

 to the east. In the wearing of the sides, and consequent widening of 

 the Straits, which is now going on, we see only an advanced stage of a 

 work of destruction which has been many thousand years in operation. 

 That Sicily was at one time united to Italy was a tradition in the time 

 of Virgil ('^Eueid,' iii. 414) : 



' Th' Italian shore 



And fair Sicilia'a coast were one before 



An earthquake caused the flaw : the roaring tides 



The passage broke that land from land divides ; 



And where the lands retired the rushing ocean rides." 



Drydeu's Trans. 



All modern observations on the structure of the opposite shores, 

 the bottom of the intervening sea, and the violence with which it is 

 often agitated, give every degree of credibility to the tradition. But 

 as Sicily is in that part so frequently convulsed by volcanic fires, it is 

 veiy probable that subterranean movements have greatly contributed 

 to the formation of the Straits of Messina. In like manner, there is 

 every reason to believe that the island of Ceylon was at one time united 

 to the continent of Hindustan. [ADAM'S BRIDGE, in GEOG. Div.] 

 Humboldt is of opinion that the Caribbean Sea was once mediterra- 

 nean, inclosed by a circuit of land, of which St. -Domingo, Jamaica, and 

 Cuba, are the principal remains ; and the whole form of the land from 

 the promontory of Yucatan, through the above-named islands to 

 Trinidad, and the coast of Cumana, with its deeply-indented shores, 

 the numerous islets and shoals, give countenance to the conjecture, 

 and justifies the belief that we see in the West India Islands the 

 monuments of the irresistible force of the waves of the Atlantic, 

 co-operating with subterranean agency, through an indefinite succes- 

 sion of ages. 



To what, it may be asked, does all this lead ? If such a constant 

 destruction of the land be a part of the system of Nature, it necessarily 

 follows, that, if her laws continue to endure, the whole of our present 

 continents must in time disappear under the surface of the sea. 

 Undoubtedly to that, and to no other conclusion must we arrive ; but 

 such a transference of the land which now rises above the surface of 

 the sea is in perfect accordance with what geology tells us has been 

 the economy of Nature in times past. All the stratified masses of 

 which the crust of the earth is composed, however high their position 

 may now be, must at one time have been at the bottom of the sea ; 

 and the materials of which they are composed must have constituted 

 the component parts of other rocks, which, in a former condition of 

 the earth's surface, must have been acted upon and abraded by similar 

 agents. In every great group of strata we find beds composed of 

 large water-worn fragments, materials supplied, most probably, by 

 rivers which had a rapid descent to the sea; but as such water- 

 courses form but a small proportion to those which traverse low and 

 level countries, and carry only the finer particles to the sea, so we 

 find that the beds of conglomerates bear only a small proportion to 

 those strata the materials of which are in a comminuted state an 

 additional fact in support of the doctrine, that the formation of strata 

 in past times took place under circumstances analogous to those which 

 are now in progress ; that in, that the laws of the material world 

 have continued unaltered. But renovation as well as decay is a part 

 of the economy of Nature ; and the same subterranean forces which 

 raised our present continents, may, in after ages, repeat the process, 



