Some Geologists Admit That The Uninterrupted Chain Of Islands From Trinidad To Florida Exhibits The Remains Of An Ancient Chain Of Mountains.

They connect this chain sometimes with the granite of French Guiana, sometimes with the calcareous mountains of Pari.

Others, struck with the difference of geological constitution between the primitive mountains of the Greater and the volcanic cones of the Lesser Antilles, consider the latter as having risen from the bottom of the sea.

If we recollect that volcanic upheavings, when they take place through elongated crevices, usually take a straight direction, we shall find it difficult to judge from the disposition of the craters alone, whether the volcanoes have belonged to the same chain, or have always been isolated. Supposing an irruption of the ocean to take place either into the eastern part of the island of Java* (* Raffles, History of Java, 1817, pages 23-28. The principal line of the volcanoes of Java, on a distance of 160 leagues, runs from west to east, through the mountains of Gagak, Gede, Tankuban-Prahu, Ungarang Merapi, Lawu, Wilis, Arjuna, Dasar, and Tashem.) or into the Cordilleras of Guatimala and Nicaragua, where so many burning mountains form but one chain, that chain would be divided into several islands, and would perfectly resemble the Caribbean Archipelago. The union of primitive formations and volcanic rocks in the same range of mountain is not extraordinary; it is very distinctly seen in my geological sections of the Cordillera of the Andes. The trachytes and basalts of Popayan are separated from the system of the volcanoes of Quito by the mica-slates of Almaguer; the volcanoes of Quito from the trachytes of Assuay by the gneiss of Condorasta and Guasunto. There does not exist a real chain of mountains running south-east and north-west from Oyapoc to the mouths of the Orinoco, and of which the smaller West India Islands might be a northern prolongation. The granites of Guiana, as well as the hornblende-slates, which I saw near Angostura, on the banks of the Lower Orinoco, belong to the mountains of Pacaraimo and of Parime, stretching from west to east, * (From the cataracts of Atures towards the Essequibo River. This chain of Pacaraimo divides the waters of the Carony from those of the Rio Parime, or Rio de Aguas Blancas.) in the interior of the continent, and not in a direction parallel with the coast, between the mouths of the river Amazon and the Orinoco. But though we find no chain of mountains at the north-east extremity of Terra Firma, having the same direction as the archipelago of the smaller West India Islands, it does not therefore follow that the volcanic mountains of the archipelago may not have belonged originally to the continent, and formed a part of the littoral chain of Caracas and Cumana.* (* Among many such examples which the structure of the globe displays, we shall mention only the inflexion at a right angle formed by the Higher Alps towards the maritime Alps, in Europe; and the Belour-Tagh, which joins transversely the Mouz-Tagh and the Himalaya, in Asia. Amid the prejudices which impede the progress of mineralogical geography, we may reckon, 1st, the supposition of a perfect uniformity of direction in the chains of mountains; 2nd, the hypothesis of the continuity of all chains; 3rd, the supposition that the highest summits determine the direction of a central chain; 4th, the idea that, in all places where great rivers take rise, we may suppose the existence of great tablelands, or very high mountains.)

In opposing the objections of some celebrated naturalists, I am far from maintaining the ancient contiguity of all the smaller West India Islands. I am rather inclined to consider them as islands heaved up by fire, and ranged in that regular line, of which we find striking examples in so many volcanic hills in Auvergne, in Mexico, and in Peru. The geological constitution of the Archipelago appears, from the little we know respecting it, to be very similar to that of the Azores and the Canary Islands. Primitive formations are nowhere seen above ground; we find only what belongs unquestionably to volcanoes: feldspar-lava, dolerite, basalt, conglomerated scoriae, tufa, and pumice-stone. Among the limestone formations we must distinguish those which are essentially subordinate to volcanic tufas* from those which appear to be the work of madrepores and other zoophytes. (* We have noticed some of the above, following Von Buch, at Lancerote, and at Fortaventura, in the system of the Canary Islands. Among the smaller islands of the West Indies, the following islets are entirely calcareous, according to M. Cortes: Mariegalante, La Desirade, the Grande Terre of Guadaloupe, and the Grenadillas. According to the observations of that naturalist, Curacoa and Buenos Ayres present only calcareous formations. M. Cortes divides the West India Islands into, 1st, those containing at once primitive, secondary, and volcanic formations, like the greater islands; 2nd, those entirely calcareous, (or at least so considered) as Mariegalante and Curacoa; 3rd, those at once volcanic and calcareous, as Antigua, St. Bartholomew, St. Martin, and St. Thomas; 4th, those which have volcanic rocks only, as St. Vincent, St. Lucia, and St. Eustache.) The latter, according to M. Moreau de Jonnes, seem to lie on shoals of a volcanic nature. Those mountains, which present traces of the action of fire more or less recent, and some of which reach nearly nine hundred toises of elevation, are all situated on the western skirt of the smaller West India Islands.* (* Journal des Mines, tome 3 page 59. In order to exhibit in one point of view the whole system of the volcanoes of the smaller West India Islands, I will here trace the direction of the islands from south to north. - Grenada, an ancient crater, filled with water; boiling springs; basalts between St. George and Goave. - St. Vincent, a burning volcano. - St. Lucia, a very active solfatara, named Oualibou, two or three hundred toises high; jets of hot water, by which small basins are periodically filled.

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