Abstract

Dimensional grain orientation, imbrication, and sole features are studied in the Altamira Member of the Monterey Formation at Point Fermin, Los Angeles County, Calif. Statistically significant preferred grain orientation is shown by 35 samples. Throughout the 80-ft section there is angular divergence of 40 degrees -60 degrees (average 47 degrees )between the NW-SE grain orientation of the individual sandstone beds and the east-west linear sole features (groove casts and flute casts), owing to differences in direction or erosional and depositional currents. Three-dimensional orientation analysis shows the grains are oriented parallel with the depositing current. Up-current imbrication is shown by consistent southeast inclination of elongate grains; flute casts, cross-bedding, and paleogeography indicate a southeastward sediment source.

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