Clay minerals
The Caribbean's floor is composed of sub-oceanic sediments of deep red clay in the deep basins and troughs. On continental slopes and ridges calcareous silts are found. Clay minerals likely having been deposited by the mainland river Orinoco and the Magdalena River. Deposits on the bottom of the Caribbean Sea and Gulf of Mexico have a thickness of about . Upper sedimentary layers relate to the period from the Mesozoic to the Cenozoic (250 million years ago to present) and the lower layers from the Paleozoic to the Mesozoic.