The Caribbean Plate occupies most of the region between continental North and South America. A large part of it was formerly part of one of the oceanic Pacific plates, isolated from the rest of the Pacific by the Middle America subduction zone (Mann et al., 2007a). The Caribbean Plate has probably moved much more slowly in a mantle reference frame (Müller et al., 1999; Levander et al., 2006) than the North and South America plates, which have moved westward past the Caribbean Plate as a result of sea-floor spreading on the Mid-Atlantic Ridge. Sea-floor spreading started at different times. North America began to move relatively westward past the oceanic Caribbean Plate 180 million years ago, whereas South America started its westward journey 55 million years later, at 125 Ma. Because of its late start, the west coast of South America is at about the same longitude as the east coast of North America (Levander et al., 2006).
Part of the Caribbean Plate is an ancient island arc (Great Arc of the Caribbean), and part is an oceanic plateau (Caribbean Large Igneous Province, or CLIP), so that Caribbean ocean floor is shallower than normal oceanic crust (Burke et al., 1978; Robertson and Burke, 1988; Mann et al., 1990).