954 D. Submarine Geology and Geophysics OLR (1987)34 (11)

Results obtained using a standard NBS shipboard narrow-beam echo sounder and receiving antenna with an equally-spaced rectangular array for acous- tic imaging, are presented. The use of the multi- element antenna technique to study the structure of acoustic field backscatter from the sea bottom makes it possible to quickly obtain images of bottom sediments which can be used to identify high- backscatter areas. In many cases the identification of such areas may be of use in studies of the mor- phology of bottom sediments. Shirshov Inst. of Oceanol., Acad. of Sci., Moscow, USSR.

D40. Area studies, surveys, bathymetry

87:6268 Gujar, A.R., G.V. gajamanickam and M.V.

Ramana, 1986. Geophysical investigations off Vi|aydarg Bay, Maharashtra, west coast of India. Indian J. mar. Sci., 15(4):241-245. Natl. Inst. of Oceanogr., Dona Paula, Goa 403 004, India.

87:6269 Max, M.D., 1986: The three-phase development of

the Porcupine Seabight. Basin formation and the structurally-dependent sedimentary pattern. J. Petrol. Geol., 10(1):59-72. Naval Res. Lab., Code 5110, Washington, DC 20375-5000, USA.

87:6270 Whitworth, R. and J.B. Willcox (principal inves-

tigators) et al., 1985. Rig Seismic research cruise 1: Lord Howe Rise, southwest Pacific Ocean. BMR J. Aust. Geol., Geophys., 266:27pp.

Preliminary interpretation of 1250 km of high- quality multichannel seismic and magnetic data has indicated that an extensive basin containing at least 3000 m of sediment may be present on the western flank of the Lord Howe Rise. Deep-seated fault blocks in the basin, previously thought to be basement, appear to be sediments, which could be prospective. Sedimentary facies are interpreted as ranging from graben-fill to shelf, slope, and bathyal, resulting from progressive subsidence of the south- ern Lord Howe Rise from Maastrichtian time onwards. The origin of the basin has yet to be determined.

D70. Coasts, beaches, marshes

87:6271 De Vriend, H.J., 1987. 2DH mathematical modelling

of morphological evolutions in shallow water. Coast. Engng, Amst., 11(1):1-27.

A class of compound mathematical models is discussed, based on horizontally 2-D formulations of water and sediment motion in the coastal zone. The specific adequacy of the constituent models, the balance of the total model and the possibility of spurious interactions are considered. Lacunae in the knowledge, and the tools needed to judge a proposed model at these points, are indicated. Spurious interactions are described in further detail, and techniques to trace and avoid them given. These examples, concerning evolutions without the influ- ence of waves, show that advective acceleration terms in the flow model play an essential part in bottom evolution and its interaction with the current, and that incorporation of bottom slope effects on sediment transport is indispensable in models with a local transport formulation. Delft Hydraulics Lab., P.O. Box 152, 8300 AD Emme- loord, Netherlands.

87:6272 Douglass, S.L., 1987. Coastal response to jetties at

Murrells Inlet, South Carolina. Shore Beach, 55(2):21-32. Civil Engng Dept., Drexel Univ., Philadelphia, PA, USA.

87:6273 Griggs, G.B., 1987. Littoral cells and harbor dredging

along the California coast. Environ. Geol. Wat. Sci., 10(1):7-20. Board of Earth Sci., Univ. of Calif., Santa Cruz, CA 95064, USA.

87:6274 Hashima, Masahiro, 1986. Formation of a tombolo

between the upheaving two conical islands. Mer, Tokyo, 24(4):193-197. (In Japanese, English abstract.)

On the upwave side of the island, sand is transported toward the island lee by longshore currents. If the island is small, a single tombolo is formed at the center of the shadow. However, for the larger island, two sand spits appear on the sides of the shadow axis. These phenomena are used to explain the presence of a single tombolo observed at the volcanic island Iwo-Jima. The longshore circulations caused by breaking waves around a circular island are calculated numerically. Dept. of Phys., Natl. Defence Med. Coll., Namiki 3-2, Tokorozawa, 359 Japan.

87:6275 Hine, A.C., M.W. Evans, R.A. Davis Jr. and D.F.

Belknap, 1987. Depositional response to seagrass mortality along a low-energy, barrier-island coast: west-central Florida. J. sedim. Petrology, 57(3):