Longitudinal triangular ripples in the Blake-Bahama Basin

Longitudinal triangular ripples developed in cohesive sediments were studied in the Blake-Bahama Basin (depth 4988 m, western North Atlantic) with a deeply-towed instrument package and the bathyscaphe "Trieste II". The 15 cm high by 75 cm wide by 2-10 m long ripples with triangular cross-section vary in orientation over several kilometers. These longitudinal bed forms are constructed of coarse sandy muds (20% sand) and are created by bottom current flow. Near the extremities of the field they appear to be buried, suggesting that the ripple field is not active at the present time. These ripples may be formed by short-lived, high-velocity bottom currents, and they may be commonly developed in the sediments of submarine canyons, deep-sea channels, and deep-sea areas episodically swept by strong currents.