TRINIDAD, the most southerly and, next to Jamaica, the largest of the British West Indian islands. Pop. (1931) including Tobago, 412,783. It is situated 6m. E. of the coast of Venezuela, between o° 3' and o° 50' N. and 60° 39' and 62° W. Aver age length, 48m. ; breadth, 35m.; area 1,754 sq. miles. In shape it is almost square, with promontories westward from its north and south corners, enclosing the Gulf of Paria. To the west of the northern spur lie several islands, of which Chacachacare, Huevos Monos and Monos Gaspar Grande are the most impor tant. The surface is undulating or level, except in the north and south, where there are ranges of hills running east and west, prolongations of the Venezuelan coast ranges. Of these the north ern is the more elevated, its highest point being Tucuche Peak (3,Iooft.). The southern hills attain Goof t. A small ridge runs east to west by south, through the centre of the island, from Manzanilla Point to San Fernando, with the isolated Mt. Tamana (1,028). The hills of the northern and southern ranges, fur rowed by innumerable ravines, are densely wooded.
In its geology, as well as in its flora and fauna, Trinidad differs little from the mainland, with which it was doubtless at one time connected. There are four mineral springs and several mud vol canoes, but the two most striking natural features are the Mara cas falls, and the Pitch lake. The Maracas falls, 312ft. high, are situated at the head of a valley of the same name, to the north east of Port of Spain. The Pitch lake lies some 38m. S.E. of the capital, by water, in the ward of La Brea. It is circular in form, about 3m. in circumference, and 1o4ac. in extent. The asphalt wells up in low bulging masses, separated from one another by narrow channels, in which the rain forms pools. Near the centre of the lake the pitch is always liquid and can be observed bub bling up. When the sun is hot the lightest footfall leaves an im pression, and the pitch emits a strong odour. The soil of the surrounding district is charged with asphalt, but is very fertile, while the road to the neighbouring port of La Brea, running over a bed of asphalt, moves slowly towards the sea like a glacier.
The lake is worked by a company which exports the asphalt to the United States, paying royalty to the local Government.
The mountain range which runs along the north coast is formed of clay-slates, micaceous and talcose schists, and crystalline and compact limestones, constituting the group of unknown age called the Caribbean series. The rest of the island is composed of Cretaceous, Tertiary and Quaternary strata. The Cretaceous beds rise to the surface in the centre and are flanked to north and south by later deposits. The relations of the various divisions of the Tertiary formation are still somewhat obscure; but they are grouped by J. B. Harrison into (I) Nariva and San Fernando beds = Eocene and Oligocene ; (2) Naparima marls = Miocene and (3) Moruga series= Pliocene and Pleistocene. The Naparima marls consist of a lower division containing Globigerina and an upper division with Radiolaria and diatoms and are clearly of deep-sea origin. The bitumen of the Pliocene and Pleistocene deposits appears to have been formed by the decomposition of vegetable matter. Salses or mud volcanoes occur upon the island.
The presence of oil under Trinidad had been suspected for many years, and early in the loth century the Government under took a geological survey. This survey revealed the presence of a series of anticlines at payable depths in the southern division of the island, and experimental borings by three companies, at La Brea and Point Fortin in the south-west, and Guayaguayare in the south-east, proved the presence of oil in large quantities. A considerable oil field has been located which has only in parts as yet been tapped, but a flourishing industry has already been established, the exports in 1928 being 5,200,000 barrels of oil and benzol, much of it refined locally.