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THE WEST INDIES

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Originally appearing in Volume V28, Page 545 of the 1911 Encyclopedia Britannica.
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THE WEST INDIES, sometimes called the Antilles (q.v.), an archipelago stretching in the shape of a rude arc or parabola from Florida in North America and Yucatan in Central America to Venezuela in South America, and enclosing the Caribbean Sea (615,000 sq. m.) and the Gulf of Mexico (750,000 sq. m. in area). The land area of all the islands is nearly 100,000 sq. m., with an estimated population of about 62 millions; that of the British islands about 12,000 sq. m. The islands differ widely one from another in area, population, geographical position, and physical characteristics. They are divided into the Bahamas, the Greater Antilles (Cuba, Jamaica, Haiti and Porto Rico), and the Lesser Antilles (comprising the remainder). The Lesser Antilles are again divided into the Windward Islands and Leeward Islands. Geographically, the Leeward Islands are those to the north of St Lucia, and the Windward, St Lucia and those to the south of it; but for administrative purposes the British islands in the Lesser Antilles are grouped as is shown in the table given later. Geology.—The West Indies are the summits of a submerged mountain chain, the continuation of which towards the west must be sought in the mountains of Honduras. In Haiti the chain divides, one branch passing through Jamaica and the other through Cuba, the Cayman Islands and the Misteriosa Bank. In Das Antlztz der Erde, E. Suess divides the Antilles into three zones: (I) The first or interior zone, which is confined to the Lesser Antilles, is entirely of volcanic origin and contains many recent volcanic cones. It forms the inner string of islands which extends from Saba and St Kitts to Grenada and the Grenadines. The western part of the deep-cleft island Guadeloupe belongs to this zone. (2) The second zone consists chiefly of Cretaceous and early Tertiary rocks. In the west it is broad, including the whole of the Greater Antilles, but in the east it is restricted to a narrow belt which comprises the Virgin Islands (except Anegada), Anguilla, St Bartholomew, Antigua, the eastern part of Guadeloupe and part of Barbados. (3) The third and outermost zone is formed of Miocene and later beds, and the islands which compose it are flat and low. Like the second zone it is broad in the west and narrow in the east. It includes the Bahamas, Anegada, Sombrero, Barbuda and part of Barbados. Geologically, Florida and the plain of Yucatan may be looked upon as belonging to this zone. Neither Trinidad nor the islands off the Venezuelan coast can be said to belong to any of these three zones. Geologically they are a part of the mainland itself. They consist of gneisses and schists, supposed to be Archaean, eruptive rocks, Cretaceous, Tertiary and Quaternary deposits; and the strike of the older rocks varies from about W.S.W. to S.W. Geologically, in fact, these islands are much more nearly allied to the Greater Antilles and to Central America than they are to the Lesser Antilles; and there is accordingly some reason to believe that the arc formed by the West Indian Islands is really composite in origin. Although the three zones recognized by Suess are fairly clearly defined, the geological history of the Greater Antilles, with which must be included the Virgin Islands, differs considerably from that of the Lesser. In Cuba and Haiti there are schists which are probably of pre-Cretaceous. age, and have, indeed, been referred to the Archaean; but the oldest rocks which have yet been certainly identified in the West Indies belong to the Cretaceous period. Throughout the Greater Antilles the geological succession begins as a rule with volcanic tuffs and conglomerates of hornblende-andesite, &c., in the midst of which are intercalated occasional beds of limestone with Rudistes and other Cretaceous fossils. These are overlaid by sediments of terrigenous origin, and the whole series was folded before the deposition of the next succeeding strata. The nature of these Cretaceous deposits clearly indicates the neighbourhood of an extensive area of land; but during the succeeding Eocene period and the early part of the Oligocene, a profound subsidence led to the deposition of the Globigerina chalks and white Radiolarian earths of Jamaica, Cuba and Haiti. The Greater Antilles must at this time have been almost completely submerged, and the similar deposits of Barbados and Trinidad point to a similar submergence beyond the Windward Islands. In the middle of the Oligocene period a mighty upheaval, accompanied by mountain folding and the intrusion of plutonic rocks, raised the Greater Antilles far above their present level, and united the islands with one another, and perhaps with Florida. A subsequent depression and a series of minor oscillations finally resulted in the production of the present topography. The geology of the Lesser Antilles is somewhat different. In some of the islands there are old volcanic tuffs which may possibly be the equivalents of the Cretaceous beds of Jamaica, but volcanic activity here continued throughout the Tertiary period and even down to the ()resent day. Another important difference is that except in Trinidad and Barbados, which do not properly belong to the Carib-bean chain, no deep-sea deposits have yet been found in the Lesser Antilles and there is no evidence that the area ever sank to abysmal depths. In the foregoing account the chronology of R. T. Hill has been followed; but there is still considerable difference of opinion as to the ages and correlation of the various Tertiary deposits and consequently as to the dates of the great depression and elevation. J. W. Spencer, for example, places the greatest elevation of the Antilles in the Pliocene and Pleistocene periods. Moreover, chiefly on the evidence of submerged valleys, he concludes that practically the whole of the Caribbean Sea was land and that a complete connexion existed, by way of the West Indian bridge, between North and South America.' ' The mineral wealth of the islands is not remarkable. Gold, silver, iron, copper, tin, platinum, lead, coal of a poor quality, cobalt, mercury, arsenic, antimony, manganese, and rock salt either have been or are worked. Asphalt is worked to considerable advantage among the pitch lakes of Trinidad. Opal and chalcedony are the principal precious stones. Climate.-As in most tropical countries where considerable heights are met with-and here over 15,500 sq. m. lie at an elevation of more than 1500 ft. above sea-level-the climate of the West Indies (in so far at least as heat and cold are concerned) varies at different altitudes, and on the higher parts of many of the islands a marked degree of coolness may generally be found. With the exception of part of the Bahamas, all the islands lie between the isotherms of 77° and 82° F. The extreme heat, however, is greatly tempered by the sea breezes, and by long, cool, refreshing nights. Frost is occasionally formed in the cold season when hail falls, but snow is unknown. The seasons may be divided as follows. The short wet season, or spring, begins in April and lasts from two to six weeks, and is succeeded by the short dry season, when the thermometer remains almost stationary at about 8o° F. In July the heat increases to an extent well nigh unbearable. No change occurs till after a period varying from the end of July to the beginning of October, when the great rainfall of the year begins, accompanied by tremendous and destructive hurricanes. This season is locally known as the " hurricane months." The annual rainfall averages 63 in. These storms arise in the Atlantic and towards the east. For a day or two they follow a westerly course, inclining, at the same time, one or two points towards the north, the polar tendency becoming gradually more marked as the distance from the equator increases. When the hurricanes reach latitude 25° N., they curve to the north-east, and almost invariably wheel round on arriving at the northern portion of the Gulf of Mexico, after which they follow the coast line of North America. Their rate of speed varies considerably, but may be said to average 300 M. per day among the islands. The usual signs of the approach of the cyclones are an ugly and threatening appearance of the weather, sharp and frequent puffs of wind, increasing in force with each blast, accompanied with a long heavy swell and confused choppy sea, coming from the direction of the approaching storm. December marks the beginning of the long dry season, which, accompanied by fresh winds and occasional hail showers, lasts till April. The average temperature of the air at Barbados, which may be taken as a favourable average, is, throughout the year, 8o° F. in the forenoon, and about 82° in the afternoon. The maximum is 87°, and the minimum 75° Flora.-The flora of the islands is of great variety and richness, as plants have been introduced from most parts of the globe, and flourish either in a wild state or under cultivation; grain, vegetables, and fruits, generally common in cool climates, may be seen growing in luxuriance within a short distance of like plants which only attain perfection under the influence of extreme heat, nothing being here required for the successful propagation of both but a difference in the height of the lands upon which they grow. The forests, which 'See E. Suess, Das Antlitz der Erde (Wien, 18d5; Eng. trans., Oxford, 1904) ; J. W. Spencer, " Reconstruction of the Antillean Continent," Bull. Geol. Soc. Amer., vol. vi. (1895), p. 103 (Abstract in Geol. Mag., 1894, pp. 448-451): see also a series of papers by J. W. Spencer in Quart. Journ. Geol. Soc., vols. lxvii., lxviii. (1901, 1902); R. T. Hill, " The Geology and Physical Geography of Jamaica," Bull. Mus. Comp. Zool. Harvard, vol. xxxiv. (1899).
End of Article: THE WEST INDIES
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