海底砂州の分布パターンについての一試論

抄録

On some navigational charts, there are numerous large submarine sand ridges to be seen where strong tidal currents occur. Such ridges in northern and eastern Yellow Sea and Malacca Strait are described here, and the distribution pattern as well as some general features are discussed.
Evidently, sand ridges have been formed by the agency of tidal flow, by which process, sedimentary ridges and ridges of erosional remnant are formed. The ridges of straight type are distinguished, too, from the ones of snaky type by the distribution pattern. The straight ridges are generally very large and long, and are parallel each other with regular intervals.
The distribution of straight ridges is limited within 54 meters in depth and disappears in the region where ancient sediments crop out as relic or where tidal motion is weak. Regional difference in the depth of ridges reflects the forming age of ridges. Lower ridges are older ones constructed when sea level stood at 20 meters in depth about 7, 000 years ago. They have been modified and annexed to recent ridges, and evolved into present form during the following sea level rise.
Generally speaking, ridges of locally or regionally equal depth have equal interval in distribution, and in good correlation, the deeper the depth of ridges, the wider the interval. This connection is suggestively analogous to the relation between bottom height and depth of flood flow.