Photointerpretive map of landslides and surficial deposits of northernmost Napa County, California

This map shows various types of landslide deposits, scarps, and related topographic features, in addition to other types of surficial deposits, in northernmost Napa County, California.  It was prepared by viewing overlapping vertical aerial photographs with a stereoscope.  This method allows the geologist to see a three-dimensional model of the terrain to be analyzed and thereby permits him to map the distribution and infer the nature and origin of various landforms.  Interpretations were checked by low altitude air reconnaissance in January 1975, but the deposits and features shown on this map have not been checked on the ground.  They do, however, represent a consensus of judgment by both authors.