Recently completed hydrographic surveys by the Coast and Geodetic Survey cover an area of about 7000 square nautical miles south of the outer Florida Keys. Details of the topography of the continental slope that do not appear on published nautical charts are given. The principal features are (1) a swarm of valleys incising the slope south of Dry Tortugas, (2) an elongate terrace terminating to the west in an area of undulating bottom, and (3) two prominent escarpments and several minor slope breaks.

The valleys are believed to be related to two separate periods of valley formation. Straight downslope trends and leveed sides suggest turbidity-current action in at least some of the valleys. The escarpments are interpreted as having a fault origin, and the area of undulating bottom is believed to be a set of step faults related to the larger Pourtales Escarpment.

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