_Geology._--The greater part of Jamaica is covered by Tertiary deposits, but in the Blue Mountain and some of the other ranges the older rocks rise to the surface. The foundation of the island is formed by a series of stratified shales and conglomerates, with tuffs and other volcanic rocks and occasional bands of marine limestone. The limestones contain Upper Cretaceous fossils, and the whole series has been strongly folded. Upon this foundation rests unconformably a series of marls and limestones of Eocene and early Oligocene age. Some of the limestones are made of Foraminifera, together with Radiolaria, and indicate a subsidence to abyssal depths. Nevertheless, the higher peaks of the island still remained above the sea. Towards the middle of the Oligocene period, mountain folding took place on an extensive scale, and the island was raised far above its present level and was probably connected with the rest of the Greater Antilles and perhaps with the mainland also. At the same time plutonic rocks of various kinds were intruded into the deposits already formed, and in some cases produced considerable metamorphism. During the Miocene and Pliocene periods the island again sank, but never to the depths which it reached in the Eocene period. The deposits formed were shallow-water conglomerates, marls and limestones, with mollusca, brachiopoda, corals, &c. Finally, a series of successive elevations of small amount, less than 500 ft. in the aggregate, raised the island to its present level. The terraces which mark the successive stages in this elevation are well shown in Montego Bay and elsewhere. The remarkable depressions of the Cockpit country and the closed basin of the Hector river are similar in origin to swallow-holes, and were formed by the solution of a limestone layer resting upon insoluble rocks. The island produces a great variety of marbles, porphyrites, granite and ochres. Traces of gold have been found associated with some of the oxidized copper ores (blue and green carbonates) in the Clarendon mines. Copper ores are widely diffused but are very expensive to work; as are the lead and cobalt which are also found. Manganese iron ores and a form of arsenic occur.