11 



Median Diameters • 63 



Definition and Significance 63 



Distribution of Median Diameters 64 



Median Diameters of Sediments on Slopes 



and Canyons ■ 72 



Relation of Median Diameters to Depth 73 



Sorting 76 



Definition and Significance 76 



Sorting of Sediments in Santa Monica Bay-- 79 



Relation of Sorting to Depth 82 



Calcium Carbonate 84 



Origin of Calcium Carbonate 84 



Distribution of Calcium Carbonate 84 



Organic Matter 88 



Source of Organic Matter 89 



Distribution of Organic Material in 



Santa Monica Bay 90 



Cores 98 



ROCK BOTTOM AREAS 100 



Rocks in Place 100 



Gravel 102 



Phosphorite 105 



Significance and Origin of Phosphorite 105 



Character and Origin of Nondepositional 



Surfaces ■ 109 



Effect of Waves 113 



Possible Effect of Tsunamis 114 



Effects of Tidal Currents 114 



Non-Tidal Currents 115 



Mtidflows and Submarine Landslides 116 



Relation of Bottom Character to 



Surface Currents ■ 117 



Conclusions • 117 



SOURCE, TRANSPORTATION, AND DEPOSITION OF 



SEDIMENTS IN SANTA MONICA BAY 118 



Source of Sediments ■ 118 



Drainage Tributary to Santa Monica Bay 122 



Rate of Sedimentation-- — • 122 



Deposition in the Past Two Decades 130 



Submarine Landslides and Slumping 133 



GEOLOGICAL STRUCTURE OF SANTA MONICA BAY 135 



Seismology 135 



Thickness of Overburden 139 



Structure 142 



SUMMARY 152 



The Geologic and Geographic Setting of 



Santa Monica Bay 152 



Submarine Topography 153 



Unconsolidated Bottom Materials 154 



Relation of Transportation and Deposition 



of Sediment to Discharge of Sludge into 



the Bay 159 



