The Northern Range consists mainly of Upper Jurassic and Cretaceous metamorphic rocks. The Northern Lowlands (the East–West Corridor and Caroni Plain) 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 Plain and the Nariva Swamp form the southern shoulder of this uplift.