CLARK, JOSEPH C., IUP, Indiana, PA; WILLIAM R. DUPRE, University of Houston, TX; and LEWIS I. ROSENBERG, Consulting Geologist, Templeton, CA

Abstract: Geologic Map of the Monterey and Seaside 7.5-minute Quadrangles, Monterey County, California: A Digital Database

USGS Open-File Report 97-30 is a digital geologic map database that updates previously published mapping with substantial new mapping by the authors. The geologic map (sheet 1) covers the onshore and offshore greater Monterey Peninsula area and extends inland along Carmel Valley to the southeast and includes Laguna Seca to the northeast. A second sheet contains a plot of the explanation of units, and a map of subsurface structure of the Seaside area, together with a listing of 25 Quaternary deformation localities shown on sheet 1. An accompanying text file provides current information on the stratigraphy, structure, and Quaternary deformation of the area.

This area is situated within the complexly deformed Salinian block between the active San Andreas fault to the northeast and the San Gregorio fault zone to the southwest. Resting nonconformably upon the Salinian basement is an incomplete stratigraphic section ranging in age from "Paleocene" (more recently dated as early Eocene) to Holocene and locally includes Oligocene basaltic andesite flows.

The San Gregorio and Monterey Bay fault zones, both of which are seismically active, trend southeastward into the area, where they are represented by the offshore Carmel Canyon fault and onshore by high-angle faults that displace the Monterey Formation and locally offset Quaternary deposits. Faulted, folded, and tilted Pleistocene terrace deposits; faulted Holocene colluvium; and earthquake epicenters that align with mapped fault traces indicate ongoing tectonic deformation of this area.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California