As part of a continuing program, Texas A. and M. University has been making a surface‐ship gravity survey of the Gulf of Mexico. The 1963 free‐air anomaly map of the Gulf is the second in a series of maps resulting from these investigations; it includes not only a larger area than the first map, but also measurements having considerably higher accuracies. The present map indicates, as the first one suggested, that the Gulf of Mexico is essentially in isostatic equilibrium but contains local mass anomalies. Two cross sections of crustal layers were constructed which are consistent with the gravity observations and published seismic‐refraction results. One section extends from Galveston, Texas, to the Yucatan Peninsula, and the other from the Sigsbee Deep to Florida. Both sections consist of four to six layers, in which layer densities were assumed to be uniform laterally and the density below the Mohorovičić discontinuity constant. Densities of the layers were converted from seismic velocities using the Drake and Nafe curves. A free‐air anomaly profile across the Cayman Trench is included.
Free air anomaly map, Scotian Shelf - Sable Island