The Northern Range consists mainly of Upper Jurassic and Cretaceous metamorphic rocks. The Northern Lowlands (East-West Corridor and Caroni Plains) consist of younger shallow marine clastic sediments. South of this, the Central Range fold and thrust belt consists of Cretaceous and Eocene sedimentary rocks, with Miocene formations along the southern and eastern flanks. The Naparima Plains and the Nariva Swamp form the southern shoulder of this uplift.
The Southern Lowlands consist of Miocene and Pliocene sands, clays, and gravels. These overlie oil and natural gas deposits, especially north of the Los Bajos Fault. The Southern Range forms the third anticlinal uplift. It consists of several chains of hills, most famous being the Trinity Hills. The rocks consist of sandstones, shales and siltstones and clays formed in the Miocene and uplifted in the Pleistocene. Oil sands and mud volcanoes are especially common in this area.