6 
There is little lateral variation in the type of sediment in 
this area, for the range in median diameters of all samples was 
0.029 mm to 0.081 mm, the average being 0.051 mm. Grains of silt 
size are the most abundant, representing 50% of each sample. 
Sand size material constitutes 40% and clay size fragments 10% of 
the bottom material. The sediment is well sorted having an average 
Trask sorting coefficient of 2.21. The abundant quartz and feldspar 
grains in the sand fraction are angular. The range in the calcium 
carbonate content, derived from shells and shell fragments, is low 
with an average of 11%. 
From the data and an examination of the bottom sediments it 
is believed that this is an area of reasonably rapid deposition 
of detrital material, probably derived mainly from the adjacent 
sea cliffs. The inclusion of sludge in the deposits results in 
a dark color, a deficiency of oxygen in some of the sediments, and 
a likely overall reduction in the average grain size due to the 
fine nature of the particulate sludge debris. 
Orange County 
The sea floor in the vicinity of the Orange County ocean 
outfall is an area where sand accumulates nearshore and grades 
to silty sand offshore. The color of the sediment ranges from 
a light gray to almost black, and nearly all samples contain small 
blobs or streaks of sludge. The darker sediments, indicating a 
high sludge content, are generally farther from shore, although 
the bottom material south of the outfall also has fairly high 
quantities of this organic debris. Even though material of 
sewage origin is obvious in the sediments, no samples gave more 
