SUBMARINE GEOLOGY OF THE TONGUE OF THE OCEAN, BAHAMAS
NAVAL OCEANOGRAPHIC OFFICE NSTL STATION MS
Pagination or Media Count:
Seventy-three sediment cores, 6 grab samples, and 4 stereographic camera tracks were taken on the bottom and flanks of the Tongue of the Ocean, Bahamas. Laboratory analyses show the bottom sediment to be predominantly silt-sized skeletal and nonskeletal carbonate particles of both deep and shallow water origin. Organic carbon content of the sediment is low, averaging between 1.0 and 2.0 percent. Water content, void ratio, and porosity decrease with depth in the sediment, while conversely, density and cohesion increase. Sediment accumulation in the channel can be attributed to slow, continuous particle-by particle deposition from the overlying water column and turbidity current type deposition originating on the upper walls and bank edges of the channel. The latter type accumulation accounts for over 50 percent of the sediment column sampled. Rate of sediment accumulation is extremely high along the flanks and central reachs of the southern portion in the channel. Stereographic photographs of the channel bottom show a paucity of benthic animal or plant life, and, in general, an almost featureless unconsoli dated ooze is pictured. In the central, northern portion of the channel at 1,000-fathoms depth, a limestone outcrop is present containing cavities or basins suggestive of subaerial erosion at some earlier geologic time.
- Physical and Dynamic Oceanography