In the south of the strait, water depths rarely exceed 120 feet (37 metres) and are usually about 90 feet (27 metres). Toward the northwest, the bottom gradually deepens until it reaches to about 650 feet (200 metres) as the strait merges with the Andaman Basin. Numerous islets, some fringed by reefs and sand ridges, hinder passage at the southern entrance to the strait. The sand ridges are identified as accumulations of material that have been brought down by rivers from Sumatra. Geologically, the strait belongs to the Sunda Shelf, which was an extensive, low-relief land surface at the beginning of Quaternary time (about 2.6 million years ago), and appears to have remained undisturbed by crustal movements for about the past 7 million years. The strait attained its present configuration after having been inundated by the postglacial rise of the sea level resulting from the melting of land ice in higher latitudes.
Posted on: Mon, 09 Sep 2013 16:00:29 +0000
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