Geologic map of the Cape Disappointment-Naselle River area, Pacific and Wahkiakum counties, Washington

The Cape Disappointment-Naselle River area is in southwestern Washington at the mouth of the Columbia River.  The area encompasses several major estuaries and their adjacent highlands, which reach elevations of about 2,000 feet.  Rainfall is abundant and produces heavy vegetation and deep weathering of the bedrock.  Natural bedrock exposures are restricted to stream courses along larger drainages, although a network of logging roads provides excellent access to most of the area and widespread, but somewhat ephemeral, exposures of bedrock.