Torresan, M.E., and Gardner, J.V.,2000, Acoustic Mapping of the Regional Seafloor Geology in and Around Hawaiian Ocean Dredged-Material Disposal Sites, U.S. Geological Survey Open-file Report 00-124.

Note the contrasting morphological styles of each coast reflecting major growth and mass-wasting processes characteristic of the Hawaiian Islands. The morphology of the region between Port Allen and Makahu�ena Point on the southwest flank of Kaua�i is the upper portion of a gigantic submarine debris avalanche. The insular shelf and slope collapsed catastrophically and was transported downslope. Note the large blocks and associated debris that forms a cone-shaped deposit in the central part of the image.

The seafloor morphology of the upper southeast margin of Kaua�i between Makahu�ena Point and Nawiliwili is composed of a relatively broad, gentle, southeasterly sloping terrace. The terrace is 10-13 km wide and trends northeasterly about 45 km. This terrace was constructed by lavas during a sea level low stand. Note the abrupt change of slope at the seaward edge of the terrace, which marks the position of the shoreline when the terrace was created. The steep change in slope at the outer terrace reflects the increased slope angle that occurs when lava passes from land to sea. The terrace was subsequently submerged as sea level rose concomitantly with island subsidence.

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Top of page Beginning of OFR 00-124 URL: http://geopubs.wr.usgs.gov/open-file/of00-124/fig2.html Maintainer: Susan A. Cochran Last modified: 12 Dec 2000 U.S. Department of the Interior, U.S. Geological Survey, Western Region Coastal and Marine Geology