Geography of Trinidad and Tobago passage. Trinidad is traversed by three distinct mountain ranges that are a continuation of the Venezuelan coastal cordillera. The Northern Range, an outlier of the Andes Mountains of Venezuela, consists of rugged hills that parallel the coast. This range rises into two peaks. The highest, El Cerro del Aripo, is high; the other, El Tucuche, reaches . The Central Range extends diagonally across the island and is a low-lying range with swampy areas rising to rolling hills; its maximum elevation is . The Caroni Plain, composed of alluvial sediment, extends southward, separating the Northern Range and Central Range. The Southern
Ojos del Salado of the Nazca Plate beneath the South America Plate became increasingly shallower and this caused volcanism to shift from the Maricunga Belt to the Ojos del Salado region. The Paleozoic basement crops out only northwest of Nevado Tres Cruces. Other geologic units in the region are Oligocene sedimentary units and volcanic rocks ranging from Oligocene age to less than 1.5 million years old. The area is part of a tectonic boundary between a volcanically active region north of the boundary and a less volcanically active region south of the boundary, which is also characterized by geographical differences, e.g. the presence