Geologic map of Quaternary deposits south of Grays Harbor and near Willapa Bay, southwestern Washington coast

Abstract

New 1:24,000 scale geologic mapping on the southwestern Washington coast, south of Grays Harbor and along Willapa Bay, indicates nine Quaternary units in what was previous mapped as a single unit. These units include estuarine and near shore sediments, tidal channel sands and gravels, and fluvial gravels and sands, as well as spatially limited river terrace deposits and a quartzite-cobble-bearing sediment that may be related to the Columbia river. Mapping also shows regions previously mapped as Quaternary deposits that are likely regional bedrock. Geologic map is accompanied by pamphlet describing the newly mapped units as well as stratigraphic and topographic sections from the mapped region. Also included are field notes and photographs and an appendix describing geomorphic analyses that aided geologic mapping.