Chagos isles in the Indian Ocean are coral formations of a horse-shoe shape opening to the north-west, while the prevailing wind blows regularly from the south-east. The rapidity of the growth of the coral is a point upon which nothing certain can be stated, owing to the want of ancient observations with which to compare those of the present day. The Dolphin reef off Point Venus in Otaheite, when first examined by Captain Wallis in 1769, had twelve feet of water upon it. Captain Beechey found it in much the same state in 1826 after an interval of fifty six-years. But this reef being within the influence of rivers cannot be taken as a criterion of the increase of coral limestone, owing to the aversion of the zoophytes to fresh water. In the year 1792 the Matilda, a whaler, was wrecked in the night time upon a reef of coral rocks, in latitude 22° S., and longitude 138° 34'. Upon an island answering to this situation Beechey found unequivocal signs of a shipwreck; part of a vessel's keel and fore-foot, broken casks, a number of staves, hoops, lances, and harpoons, two anchors, and a leaden pump with the date of 1790 upon it. The date, the nature, and the situation of these remains, left no doubt that they belonged to the unfortunate Matilda; but whether they had been washed up to their present site by some extraordinary high tide and sea, or whether the reef had since grown upwards, and raised them above the reach of the waves, could not be determined. Beechey thought the former the most probable, but it is evident, as he remarks, that a considerable alteration has taken place since the wreck, as the crew described themselves to have been lost on a reef of rocks, whereas the island is fourteen miles in length, with a deep central lagoon, and has a well-defined aspect, one of its sides being covered nearly the whole way with high trees, which are very conspicuous, and could not fail to be seen by persons in the situation of the crew, had the same appearance been presented there. While the anchors were found not at all overgrown with coral, which may have arisen from the oxide formed being prejudicial to the animalcules, a species of large shell-fish, the Chama gigas, while the animal was yet living, was observed so completely covered, that a space of only two inches was left for the extremity of the shell to open and shut. It is supposed by conchologists that the chima may require upwards of thirty years to attain its full size, but from an isolated fact like this no judgment can be formed respecting the rate of advance of the coral formations in general. The augmentation may be slow, but it is steady and constant, for it is perfectly accordant with the instincts of animals to continue working without intermission until their labours are consummated, or their lives extinct; and it is obvious that until the dissolution of our planet shall arrive, the zoöphytes will perpetuate their races, and the ocean keep up its supply of lime. Comparing the state of the coral formations now in progress after the lapse of a century, only a slight alteration may be perceptible, so extensive is their area; but there can be no question that if we could study them after the lapse of several centuries, vast changes would be observable; the filling up of channels with reefs, and the conversion of reefs into islands. CHAPTER XI. ALTERATIONS OF COAST LINE. STRUGGLE for the mastery is perpetually going on between the sea and the dry land, in the course of which extensive changes are effected in the disposition of the coast, though mutual losses in the struggle are compensated by corresponding gains, so as to leave each of the contending agents in possession of about the same amount of territory. In some places the ocean obtains the superiority by very gradual advances, which only become sensible after long intervals of time, but occasionally, under the action of extraordinary storms, it bounds over the embankments of a low shore, sweeps them away entirely, overflows interior levels, and retains a permanent hold of its conquest. In other places its waters retire before the slow advance of the land, large tracts of which are formed by the constant accumulation of sand or the alluvium of rivers, and the coast invades the dominion of the deep, so that where its waves have gently played or wildly raged, a new theatre is created for human industry and the purposes of vegetation. The instances in which the sea encroaches in a sudden and violent manner are of rare occurrence; but taking a view of physical operations through several centuries, we find no inconsiderable number of examples of these hasty and terrible inroads. It has frequently happened in earthquakes, that the sea has rushed upon the shores in tremendous waves, dashed away whole masses of coast, and accomplished a lodgement for its floods where fields were verdant, and man had long enjoyed a quiet habitation. During the great earthquake at Lisbon, the water retired from the harbour and left the bar dry, but it suddenly rolled in again in an immense volume, which rose in some places to the height of sixty feet, inundating the western shores of Portugal, and a sea-port called St. Eubal's, about twenty miles south of the Tagus, was engulfed, and totally disappeared. The earthquake which desolated Peru in 1746 was attended with a similar attack upon the land by the ocean. The Pacific broke with resistless fury upon the coast, destroying several sea-ports, carrying ships a considerable distance up the country, and converting a large tract of inhabited land in the neighbourhood of Callao into a permanent bay. A remarkable swell of the sea occurred at Jamaica in 1780, the effect of submarine disturbance, when a great wave assailed the western coast, and swept away the whole town of Savanna la Mar in an instant, so that not a vestige of man, beast, or habitation survived the irruption. But in 1692 the coast of the island suffered still more extensive ravages from the violence of an earthquake. At Port Royal, then the capital, three quarters of the buildings, and the ground they stood upon, sunk down with their inhabitants entirely under Whitby Abbey. water. Large storehouses, erected near the harbour, subsided till they were from twentyfour to forty-eight feet under the level of the sea. Many of the buildings appear to have sunk without falling; for the chimney-tops were afterwards seen projecting, in some instances, above the surface of the water, with the mast-heads of several ships wrecked in the harbour. A frigate the Swan - which was undergoing repairs at the wharf, was driven over the tops of many of the submerged houses, and at last rested upon the roof of one of them, through which it broke. During the first shock, a tract of land adjoining the town, to the extent of about a thousand acres, was depressed, and the sea immediately rolled in. Such events as these may commend to our attention the ancient accounts of similar catastrophes as substantially true, though invested with fictitious details by the Greek historians and poets-the Ogygian flood, the Samothracian deluge, with "That watery massacre, which quite destroyed These great disturbances, and the changes that transpire in a more gradual manner, led Aristotle to remark, that the "same tracts of the earth are not some always sea, and others always continents, but every thing changes in the course of time." Violent tempests, without any submarine convulsions, have frequently brought large portions of the coast under the dominion of the ocean. According to popular tradition, the Goodwin Sands, off the Kentish coast, once formed part of the estate of Goodwin, earl of Kent, which the sea overwhelmed in the year 1099. It is certain that such catastrophes have repeatedly occurred, and our early annalists mention extensive depredations committed by the ocean upon our shores at that time. Florence of Worcester says:- "On the third day of the nones of Nov. 1099, the sea came out upon the shore, and buried towns and men very many, and oxen and sheep innumerable." The Saxon Chronicle likewise for that "On St. Martin's-mass day, the 11th of Novembre, sprung up so much of year states: the sea-flood, and so myckle harm did, as no man minded that it ever afore did, and there was the ylk day a new moon." The Goodwin Sands are now separated from the coast of Kent by the well-known roadstead of the Downs, a channel which is from three to six miles wide. It has been a common impression that they possess an ingurgitating property, so that ships striking on them are very speedily swallowed up; but the sand, which rests on blue clay, is found to be of the same quality with that on the shore about Deal; and, all circumstances considered, there is nothing improbable in the idea, that in the Saxon age this large bank, which is completely covered at high water, was either a cultivated island, or an integral portion of the neighbouring county. An obscure tradition likewise floats about Cornwall, that the western extremity of that county once extended farther than at present, and that a tract of country, called, according to Camden, Lionnesse, which the sea has washed away, anciently connected the Scilly Islands with the mainland, and formed part of the territory of the renowned King Arthur and his valorous knights. Although there is no evidence for this story, it may yet be deemed not unlikely, when we consider the general violence of the sea in that region, and the changes which have transpired there within the period of authentic history, and are still in progress. The Scilly Islands, though consisting chiefly of granitic rock, are at present slowly yet surely wasting away, owing to the rude assaults of the billows of the Atlantic, while an insulated rock, called the Wolf, lies between them and the main, composed of limestone, which yields more readily to the action of the waves, and may be a surviving fragment of the destroyed Lionnesse. Some Cornish writers suppose the Bay of Pen zance, in which the striking insulated rock of St. Michael's Mount occurs, to have once been a part of the mainland of Cornwall, submerged by a violent inroad of the ocean. The surface of the rock is every where covered by long hoary moss, which gives it a venerable ruin-like appearance, and perhaps originated the name it is said to have borne in the time of the Druids - the "Hore Rock in the Wood." There is evidence, which deserves attention, that the wide expanse of sea surrounding the rock at high water was, in ancient times, the site of a wood; and the Mount itself is believed to have been distant five or six miles from the former shore. At low water, many large trees have been dug up from the surrounding sands, which the miners regard as monuments of the vegetation of the antediluvian world. But the druidical name indicates that these trees were flourishing here at a comparatively recent period: and the freshness and preservation of some of them support the conclusion; for, besides the roots and trunks of large forest-trees, there are many small bushes with leaves and nuts upon their branches, which appear to have been growing where they are found. It has been inferred, from the circumstance of ripe nuts and leaves remaining together, that a sudden irruption of the sea must have taken place in autumn, which submerged this woodland district, and has since buried the vegetation beneath a bed of sand from one to two feet in thickness. In the time of Edward the Confessor, the rock of St. Michael's Mount was the site of a monastery, described as being near the sea; and as the storm of 1099, mentioned in the Saxon Chronicles, occurred in the autumn, the submersion of the district has been referred to that inundation. A series of more authentic notices of extensive inroads of the sea when agitated by storms upon the coast of Sussex, occurs in Dr. Mantel's account of the geology of that county. Within a period of no more than eighty years, twenty of these invasions are mentioned, in which tracts of land of from twenty to four hundred acres in extent have been swept away at once, the value of the tithes being mentioned by Nicholas in his Taxatio Ecclesiastica. Brighton, when a mere fishing village, in the reign of Elizabeth, stood upon a site where the sea now rolls, and the chainpier stands. The more important of these sudden and terrible actions of the sea, since the eighth century, are mentioned in chronological series in the following table, taken from the work of M. Hoff, with some additions from other sources. Years. 800. The sea carries off a large quantity of the soil of Heligoland, islands in the German Ocean, off the mouth of the Elbe, previously of considerable extent, but subsequently much reduced. 800-900. Tempests change the coasts of Brittany valleys and villages are swallowed up. The Bretons have a tradition, which has descended from the fabulous ages, of the destruction of the south-western part of Brittany. 800-950. Violent storms agitate the lagunes of Venice. The isles of Ammiano and Costanziaco disappear. 1044-1309. Terrible irruptions of the Baltic on the coasts of Pomerania, which commit great ravages, and give rise to the popular rumour of the disappearance of the fabulous city of Vineta. 1106. Old Malamocca, a considerable town near Venice, engulfed by the sea. 1218. A great inundation formed, near the mouth of the Weser, the gulf of Jadhe, so named from the small river which watered the fertile country destroyed by this catastrophe. 1219, 1220. Terrible storms form the island of Wieringen. This lies to the south of Years. 1221, 1246. 1251. the Texel, and was part of the mainland of North Holland in the year 1205. It was detached from the continent by the high floods which occurred in the annexed years. 1277, 1278, Inundations engulph the fertile country of Reiderland, an alluvial plain 1280, 1287. at the mouth of the Ems in the time of the Romans, stretching between Groningen and East Friesland. Two small streams, the Tiam and the Eche, which watered this district, disappeared. The town of Torum, a considerable place, was destroyed, along with upwards of fifty markettowns, villages, and monasteries. A new gulf, called the Dollart, now occupies their site. 1282. Violent tempests break the isthmus which united Holland with Friesland, and form the Zuider Zee. 1240. An irruption considerably changes the western coast of Schleswig; many fertile territories are swallowed up, and the arm of the sea which separated the island of Nordstrand from the continent is greatly enlarged. 1300, 1500, Three fourths of Heligoland are swept away. 1649. 1300. Ciparum, in Istria, destroyed. 1303. A great part of Rugen engulfed, and many villages on the coast of Pomerania. 1337. An inundation carries off fourteen villages in the isle of Cadsand, in Zealand. 1421. An inundation covers a district named Bergseweld, in Holland, destroys twenty-two villages, and forms the Bies-bosch, a large sheet of water extending from Gertruidenberg to the isle of Dordrecht. 1475. Land near the mouth of the Humber swept away, and several villages destroyed. 1500. The parish of Bourgneuf, in Brittany, and several others in that neighbourhood, overflowed. 1510. The Baltic forms the mouth of the Frisch-haff. 1530–1532. The sea engulfs the town of Kortgene, in the island of North Beveland. In the latter year the eastern portion of South Beveland is carried away, with several villages, and the towns of Borselen and Remerswalde. 1570. A violent storm destroys half of the village of Scheveningen, north-west of the Hague. The church, once in the middle of the village, now stands on the shore. 1625. The sea detaches part of the peninsula of Dars, in Swedish Pomerania, 1634. An irruption submerges the whole island of Nordstrand, a large and 1719. Land torn away at Catwyck, which, though once far from the sea, is now upon the shore. |