7 
than a slight hint of hydrogen sulfide odor; thus, the sediments 
are not deficient in oxygen. 
The bottom sediments here are much better sorted and coarser 
grained than those near Whites Point (Table 2). The range in 
median diameters is from 0.072 mm to 0.187 mm, with the higher 
medians occurring in the material closer to shore. The sorting 
coefficient averages 1.26, indicating the sediment to be very 
well sorted, approaching that expected in sands of the nearby 
beaches. This is not unusual, of course, because the source of 
the offshore sands is the adjacent beach, with a minor amount of 
material being contributed by the Santa Ana River during storms. 
The sands are relatively clean, with silt and clay grains 
constituting only 25% of the average sample, Grains in the sand 
fraction are angular and are comprised almost solely of quartz 
and feldspar, with quartz making up more than 50% of each sample. 
The calcium carbonate content, derived from shells and shell 
fragments, is especially low, averaging only 3% of the sediment. 
Sedimentation of beach-derived material is fairly rapid in 
this area and overshadows the addition of other materials, 
including sludge, by a great percentage. The only noticeable 
effect of the sewage discharge is a discoloration of the bottom 
material in an offshore and southerly direction. 
Santa Monica Bay 
Although a general description of the bottom sediments in 
Santa Monica Bay was given in the First Quarterly Progress Report, 
it is well to review the sediment distribution to relate it with 
the discussion of coliform bacteria in the bottom sediments in 
this report. 
