Figure 11. Curves showing sea level change, fauna discontinuities, and sequence boundaries for the world (columns 1, 2, 3) (Haq et al., 1988), the U.S.A. margins of the Gulf of Mexico (columns 4, 5, 6), and the Columbus Basin, Trinidad. Some sequence boundaries in the Columbus Basin appear correlative with time-equivalent sea level falls and associated sequence boundaries identified in other areas of the world. These sequence boundaries in the Columbus Basin are most likely a function of eustatic base-level change (E); others appear to have a more local tectonic origin (T). The tectonic nature of these boundaries is supported by the presence in some wells of Cretaceous, Eocene, and Oligocene fauna and flora identified as reworked in association with these boundaries (Pocknall et al., 1999). Sources for the curves are (1) Beard et al. (1982); (2) Lamb et al. (1987); (3) Haq et al. (1988); (4) Wornhardt and Vail (1990); (5) Pacht et al. (1990); and (6) Armentrout and Clement (1990).