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Recent Marine Sediments of Bolinas Bay, California: Part B -- Mineralogical Data


This section of the study of Bolinas Bay deals with the heavy mineralogy of the 0.175 - 0.124; 0.124 - 0.088; and 0.088 - 0.061 mm size fractions of 49 sediment samples (Fig. 1) [see Isselhardt and others (1968) for grain size and sizing procedure] plus the 0.124 - 0.088 and 0.088 - 0.061 mm size fractions of one disaggregated cliff sample 2030. Offshore rock samples 1974, 1975, 1976, 1977, 1998 and 2000 and cliff and shore samples 2027, 2028, 2029, 2031, and 2032 were not dis aggregated for mineralogical analyses. These rock samples will be discussed in Part C. Sample 1988 was lost and 2007 was too small for analysis.

The treated size fractions were divided further by separation in the heavy liquid tetrabrom-ethane (Krumbein and Pettijohn, 1938, p. 325) with a density of 2.95 gms/cc. Particles with a density greater than 2.95 gms/cc were called heavy. Particles with a density equal or less than 2.95 gms/cc were designated light. Grain mounts were made of both the heavy and light particles of each size fraction on glass slides with Cadex mounting media (index of refraction = 1.55).

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