Studies of seismic reflections from thin layers on the ocean bottom in the western North Atlantic

Seismic reflection profiles were made of shallow sub-bottom reflectors in three different physiographic provinces of the North Atlantic. In the Hatteras abyssal plain at 32°42′N, 71°30′N, a layer 0.16 km thick with velocity of about 1.7 km/sec was observed. The reflections from the thin sediments in the Blake-Bahama basin were too irregular for interval velocity analysis. Two reflecting layers on the crest of the outer ridge at 29°42′N, 73°23′W, were observed at 0.06-km and 0.11-km sub-bottom depths. Interval velocities were measured to be 1.4 km/sec for the upper layer and 1.6 km/sec for the lower layer. Errors are estimated to be of the order of ±0.2 km/sec. From the character of the outer ridge reflection profiles the sediments appear to be uniform laterally over distances of several kilometers.