Abstract

This paper is a sequel to Submarine mountains in the Gulf of Alaska (Murray, 1941) and concludes presentation of the U. S. Coast and Geodetic Survey's sounding data across the Gulf of Alaska and the eastern half of the Aleutian Trench.

The writer presents 6200 statute miles of profiles constructed from 45 sounding lines across the trench and from several lines paralleling the continental slope. The locations of all soundings used in the construction of the profiles (about 7000) are indicated. Accompanying contour maps are based on all available data.

The Aleutian Trench is about 2200 statute miles long, 50 to 100 miles wide, and has a maximum depth of slightly over 25,000 feet. The north side of the trench slopes 3°–4° and the south side l°–4°. Locally, however, the slopes exceed 30°. Submarine valleys indent the north slope and extend out to depths of 9000 to 12,000 feet. The maximum difference between the floor of the trench and the adjacent land features is about 32,000 feet. The locus of maximum relief is located midway along the arc of the trench.

The salient features of the submarine topography which must be considered in any investigation of the evolution of this region are:(1) The trench and the Aleutian Islands conform to the arc of a circle for 1400 miles. (2) The deeper part of the trench is in the western half. (3) In the Gulf of Alaska, numerous submarine mountains stand as high as 12,000 feet above the ocean floor. They occur singly or in groups, have truncated or rounded tops, and trend northwestward. This direction is transverse to that of the trench and suggests at least two episodes in the evolution of relief in the Gulf region alone. (4) The floors of the Gulf of Alaska and Bering Sea slope southwestward. (5) A curving submarine range, 12,000 feet high and 600 miles long, projects from the Aleutian arc into the Bering Sea.

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