47 



exceptions, most of the samples outside the gravel area between 

 the two submarine canyons contain less than 50% gravel (Fig. 14), 

 Samples collected with the snapper sampler within the gravel 

 area generally contain less than 50% gravel, although those 

 near rock outcrops are composed of nearly 1007o gravel. This 

 fact, in conjunction with the abundance of gravel in cores 

 and biological hauls, suggests that elsewhere in the bay the 

 gravel is partly or completely covered or dispersed with 

 finer sediments as shown schematically in Figure 15. In this 

 diagram, a hypothetical east-west cross-section is shown 

 across the gravel area. The boundaries of the gravel area 

 indicated in the diagram were determined by dredging. Because 

 the gravel is covered in part by finer sediments which are 

 lost during dredging, the uniform distribution of the gravel 

 shown in Figures 13 and 14 probably does not actually exist. 



Sand , Silt , and Clay in the Sediments 



In addition to the other charts showing many of the 

 characteristics of bottom sediments in Santa Monica Bay, 

 contour charts showing the proportions of sand, silt, and 

 clay in the sediments are presented in Figures 16, 17? and 18.. 

 The distribution patterns of these components are not dis- 

 cussed because they repeat information contained in other 

 charts, such as bottom sediment types (Fig. 13), and only 

 tend to bear out and re-illustrate those conclusions. Their 

 main use is as a reference to better visualize the nature of 

 the sediment in each portion of the bay. In this respect, 

 as the charts show only the proportions of sand , silt , and 



