Geologic map of the Redwood Creek drainage basin, Humboldt County, California

A 1:62,500-scale geologic map with 14 rock stratigraphic units and an accompanying explanatory text are used to describe the geology of the Redwood Creek drainage basin of northwestern California. A large part of Redwood National Park is located in the downstream part of this actively eroding drainage basin. The bedrock consists primarily of Mesozoic sedimentary and metamorphic rocks. The structurally complex Franciscan assemblage of rocks underlies most of the basin, but rocks of the Klammath Mountain tectonic province occurs in a small eastern part of the basin. Most major boundaries between Mesozoic rock units are north-northwest trending faults parallel to the regional structural trend. Extensive areas of surficial coastal plain sediments, landslide deposits, stream terrace deposits and modern alluvium are also present; these areas help identify loci of vigorous recent erosion. (USGS)