A large sedimentary ridge extends east of Caicos Passage (Bahamas) toward the Silver Abyssal Plain. This asymmetrical ridge is steepest on the south side and lies parallel with the Bahama Banks. Small V-shape depressions observed on the crest and north slope may be submarine channels. Three 6-meter-long cores taken at approximately 2,850 fathoms consist of pelagic clays (illite and chlorite) with interbedded calcarenites. The calcarenites consist of foraminifera (benthonic and pelagic), pteropods from both noritic and littoral depths (indicating considerable displacement of fauna), and finer material. Primary structures such as graded bedding, cross-bedding, convolute bedding, and parallel bedding were observed in the turbidite beds. Considerable mechanical sorting of fau al species due to differential settling in a single sequence resulted in two distinct sediment facies; the lower consisting of foraminfera and pteropod tests and the upper consisting of clay, discoasters, and coccoliths. The pelagic sediments of the three cores show close correlation in their variation of carbonate content. These variations may reflect climatic changes.

A single stratigraphic sequence is seen in the three cores. Each has a similar carbonate curve, similar sequence of manganese-stained layers and a similar sequence of sediment colors. One correlative calcarenite thins from 24 cm. to 13 cm. and the mean grain size decreases from .04 mm. to .018 mm. as distance from the probable source increases by 50 miles.

End_of_Article - Last_Page 546------------