Page:EB1911 - Volume 28.djvu/564

Rh but during the succeeding Eocene period and the early part of the Oligocene. a profound subsidence led to the deposition of the Globiferina chalks and white Radiolarian earths of Jamaica, Cuba and laiti. 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 present day. Another important difference is that except in Trinidad and Barbados, which do not properly belong to the Caribbean 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. Cold, 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 80° 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 arc 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, 80° 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 are numerous and wide-spreading, produce the most valuable woods and delicious fruits. Palms are in great variety, and there are several species of gum-producing trees. Some locust trees have been estimated to have attained an age of 4000 years, and are of immense height and bulk. Piptadenia, on account of its almost imperishable character when in the ground, is used as a material for housebuilding. Xanthoxylon, the admired and valuable satin-wood of commerce, is common, Sapindus finds a ready market on account of its toughness; crab-wood yields a useful oil and affords reliable timber; and tree ferns of various species are common. Pimento is peculiar to Jamaica. But it is to the agricultural resources of the islands that the greatest importance attaches. For centuries almost the whole care of the planters was bestowed upon the cultivation of the sugar-cane and tobacco plant, but in modern times, as will be seen later, attention has been turned to the production of other and more varying crops. Crops of tobacco, beans, peas, maize, and Guinea corn are popular, and a species of rice, which requires no flooding for its successful propagation, is largely produced. Hymenachne striatum covers many of the plains, and affords food for cattle.

Fauna.—The fauna of the region is Neotropical, belonging to that region which includes South and part of Central America, although great numbers of birds from the North-American portion of the llolarctic realm migrate to the islands. The resident birds, however, eighteen genera of which are certainly Neotropical, show beyond doubt to which faunal region the islands properly belong. Mammals arc, as in most island groups, rare. The agouti abounds, and wild pigs and dogs are sufficiently numerous to afford good sport to the hunter, as well as smaller game, in the shape of armadillos, opossums, musk-rats and raccoons. The non-migrating birds include trogons, sugar-birds, chatterers, and many parrots and humming birds. Waterfowl and various kinds of pigeons are in abundance. Reptiles are numerous: snakes—both the boa and adder—are innumerable, while lizards, scorpions, tarantulas and centipedes are everywhere. Insects are in great numbers, and are often annoying. Among domestic animals mules are largely reared, and where the country affords suitable pasture and forage cattle-breeding is practised. Goats abound, and large flocks of sheep are kept for the sake of their flesh alone, as the climate is not adapted for wool-growing.

Area and Population.—The following list of the West Indian islands gives their area and population. Notwithstanding the