PROGRESS REPORTS ON RESEARCH SPONSORED BY THE 
BEACH EROSION BOARD 
Abstracts from progress reports on several research contracts in force 
between universities or other institutions and the Beach Erosion Board, 
together with brief statements as to the status of research projects being 
prosecuted in the laboratory of the Beach Erosion Board, are presented as 
follows: 
Mo Scripps Institution of Oceanogra hy, Quarterly Progress Report 
No.13, July-September 1952. 
SEASONAL VARIATION IN BEACH AND NEARSHORE SEDIMENTS 
The study of the seasonal variation in texture and composition of beach 
and nearshore sediments in the La Jolla area is nearing completion. All of 
the laboratory work and drafting have bem completed. 
Among items of interest from this study are the extreme variations in 
the content of mineral components such as mica (see previous Prog. Report) 
and heavy minerals, and the effect these variations have on particle-size 
distribution when analyzed by sieve and by hydraulic methods. 
Comparison of Sieve and Settling Tube 
Results of the particle-size distributions obtained by sieve and Emery 
settling tube were compared for 137 samples having various amounts of heavy 
minerals, micaceous material, and shell fragments. In general the results 
could be divided into several groups, depending upon the size of the material 
and the percentage of heavy minerals, mica, and shell fragments. It was found 
that the concentration of these constituents must be 15 per cent or more of 
the total sample before having an appreciable effect on comparisons of sieve 
and settling tube data. However, when present in these concentrations, all 
of the constituents caused noticeable changes in the median diameter and in 
the measures of standard deviation and skewness. 
In general the measure of the standard deviation was numerically greater 
for cases where the sediment was analyzed by sieving than where analyzed by 
the Emery settling tube, particularly for samples with high concentration of 
heavy minerals and micaceous material. Since the standard deviation is a 
measure of spread or sorting, this indicates that the sediment distribution 
is more homogeneous when considered in terms of hydraulic size, as in the 
case of the settling tube rather than geometric size, as in sieving. 
Distribution of Heavy Minerals 
The total amount of heavy minerals varied from 1.7 to 26.7 per cent 
in the sediments from Scripps beach and intercanyon shelf, while the coarse 
sands from the Point La Jolla pocket beaches commonly contained less than 
1 per cant and one sample from the beach north of Scripps had more than 70 
per cent heavy minerals. 
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