Discussion on the Distribution of Sea Floor Types at the Eastern Entrance to the Strait of Gibraltar, as Revealed by Grabs.

The sea floor of the eastern entrance of the Strait of Gibraltar is tentatively mapped - following a criterion of gradual change in bottom types typical of canyon estuaries - on the basis of samples from 27 bottom grabs. The tentative map differs from older ones in which patches of different bottom types were shown. The distribution of bottom types and the local bottom relief suggest that an important depositional process may be caused by occasional turbidity currents of shore origin. Mixed coarse material and debris in fact were found along the bottom and at the mouth of the narrow canyons that run from the Spanish and African coast and meet in the area surveyed. A gradual change in types of bottom, from coarse to fine grain, was found progressing to the east over a fan-shaped region of smooth bottom relief with an extension of about 4 x 9 miles.