58 



and feldspar. The average heavy mineral content of these 

 sands is 6,2% with a range of from 2.6 to 21.37o. The most 

 abundant heavy minerals are rock fragments, magnetite, horn- 

 blende, and epidote. Proportions of quartz, plagioclase, and 

 orthoclase show fairly constant relationships with an average 

 value of 507o for quartz, 49% for plagioclase, and 1% for 

 orthoclase, Foraminifera and shell fragments are present in 

 these sands, but are not abundant. 



Rounding of the grains shows a wide range, with the larger 

 particles generally showing some degree of abrasion. This 

 characteristic is a distinguishing feature of these sands. 

 The range of rounding is from .10 to .60, and the sphericity 

 ranges from .70 to .80. 



Occurrence 



Rock - fragment sand occurs in linear patches nearshore 

 between the Hyperion Outfall and Santa Monica, and on the 

 north side of Redondo Canyon where it lies in a depression 

 trending north from the canyon. The largest occurrence in 

 areal extent is on the outer portion of the shelf at the 

 head of Santa Monica Canyon. This accumulation covers the 

 entire head of the canyon and extends south into an area 

 shoreward of the gravel and rock on the central shelf pro- 

 jection. Deposits of rock-fragment sand result in high median 

 diameters and in sediments which have 80% or greater sand 

 content. 



