HOWARD R. GOULD’s scientific contributions

Numerous bottom samples collected from two segments of the continental shelf and the upper part of the continental slope provide a fairly complete picture of the distribution of sediments and environments of deposition in the northeastern Gulf of Mexico. Off the west coast of central Florida, the unconsolidated sediments are arranged in six zones roughly paralleling the coast. The innermost zone has an average width of about 20 miles, and its sediments are composed chiefly of detrital quartz derived in part from adjacent rivers and beaches and, in part, from older coastal plain sediments inundated by the sea as it rose from a previously lower level. The five outer zones, combined, have an average width of 100 miles, and their sediments consist almost exclusively of calcareous organic debris of marine origin. In general, the unconsolidated sediments are thin and discontinuous, leaving many exposures of underlying Pleistocene formations. Several lines of evidence attest to a long still-stand of the sea at a depth of about 30 fathoms during the Pleistocene Epoch. These included: (1) an abrupt break in slope at a depth of 35 fathoms denoting the outer edge of the continental shelf which is produced at a depth no greater than 5 fathoms below the sea surface, (2) the concentration of Pleistocene shallow-water Foraminifera, typical of a coastal environment, at a depth of 30 to 50 fathoms, and (3) the occurrence of Pleistocene reefs of coralline algae, reefs that are typical of a shallow-water, near-shore environment, at depths of 30 to 50 fathoms. Off northern Florida and Alabama, detrital quartz is the dominant constituent of the unconsolidated sediments for a distance of about 50 miles from the coast. Compared to the central Florida sediments, the greater seaward extent of the terrigenous materials in the northern Florida and Alabama area is attributed chiefly to a much greater supply of detritus from adjacent rivers during the low stand of the sea in the Pleistocene and since the rise in sea level from that stage. Seaward of this broad detrital zone, the sediments consist mainly of calcareous organic debris. Five distinct assemblages of Recent benthonic Foraminifera, each with a narrow depth range, are recognized in the unconsolidated sediments of the northeastern Gulf. These together with other features of the sediments serve to distinguish the present coastal environment. Several results of this investigation may have direct application to the problem of locating ancient shore lines, particularly in areas where the environments of deposition have been similar.