Figure 6. Isopach map of the Puerto Rico-Virgin Islands carbonate platform with 100 m contour interval, thickness in meters. The change from a highly stratified sequence to a chaotic sequence has been interpreted in all seismic reflection profiles shown in Figure 2 as the basement of the carbonate platform. From the interpretation of this basement, the thickness of the carbonate platform has been calculated using a general velocity of 2750 km/s. Boundaries of the carbonate platform are based on interpretation done in side scan and seismic reflection data. Major depocenters include the North Coast basin and the area west of the Mona rift.