varying azimuths on an anisotropic surface. Figures 4-7-10 Illustrated 

 the ef£ect of linear features on two bathymetrlc profiles collected at 

 near right angles. To test the validity of the theoretical model to 

 actual bathjrmetry, It Is necessary to sample regularly around the com- 

 pass at a single location on the sea floor. This is only possible for 

 areas which have complete areal bathymetrlc coverage of high spatial 

 resolution. 



The most practical Instruments available for obtaining such data 

 are the multibeam sonar systems. These systems, which provide a "swath" 

 of discrete soundings on a line perpendicular to the ship's track, allow 

 complete coverage of an area. By conducting surveys in which the paral- 

 lel survey tracks are spaced so that the outer beams of adjacent tracks 

 overlap or are nearly juxtaposed, a complete two-dimensional survey can 

 be performed. Very few of such data sets are currently available. How- 

 ever, two data sets from contrasting geologic environments were made 

 available for this study (see Chapter 5, Section B). Both surveys were 

 conducted by the O.S. Naval Oceanographic Office using the SASS multi- 

 beam sonar system (Glenn, 1970). The recent acquisition of the academic 

 SEABEAM systems should provide more full-coverage surveys in the future. 

 New techniques for processing side-scan sonar data from the SEAMARC-1 

 system allow similar two-dimensional analyses to be performed at smaller 

 scales. 



Figure 6-4 presents the contoured bathymetry from the Gorda Rise 

 area of the northeast Pacific Ocean. Contours were created automati- 

 cally and only appear where supported by multibeam soundings. The 

 coverage is generally complete with the exception of a small area on the 

 western margin of the chart and small gaps between swaths. This chart 



88 



