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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 23 (1939)

Issue: 12. (December)

First Page: 1878

Last Page: 1879

Title: Problems of Sediment Transportation off the Coast of California: ABSTRACT

Author(s): Roger Revelle

Article Type: Meeting abstract

Abstract:

Several kinds of evidence obtained in recent investigations suggest that water movements of sufficient strength to move sand grains over the bottom may exist at least occasionally at all depths in the open sea. Sediments are absent from topographic highs rising one or two hundred fathoms above the general level of the sea floor even at depths of two miles or more. Thin layers of well sorted fine sand intercalated with thicker layers of clayey muds are characteristic of inshore basins off Southern California at depths of over half a mile and at distance of thirty or more miles from land. Current velocities of nearly one-half knot were measured within two feet of the bottom at 1,100 fathoms in the Santa Cruz Basin south of Santa Cruz Island, 500 fathoms below the sill or th eshold of the basin. Other similar measurements show that the strongest bottom currents shift irregularly in both speed and direction. They may be regarded as representing lateral turbulence or eddy motion in which eddies have vertical axes and are perhaps a few miles in

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diameter. The presence of silts and muds on the bottom in certain areas of highest observed velocities indicates that these eddy currents are not competent to prevent all deposition. Since evenly distributed eddies cannot alone produce any net transport, other factors such as the gravitational component down slope and steady weak currents must cooperate in preventing deposition on certain areas of rocky bottom and in transporting debris to the regions of accumulation.

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