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National Geologic Map Database

General Information

  • Title: Twin River Group (upper Eocene to lower Miocene); defined to include the Hoko River, Makah, and Pysht Formations, Clallam County, Washington
  • Author(s): Snavely, P.D., Jr., Niem, A.R., and Pearl, J.E.
  • Publishing Organization: U.S. Geological Survey
  • Series and Number: Bulletin 1457-A [p. A111-A120]
  • Larger Work: Sohl, N.F., and Wright, W.B., Changes in stratigraphic nomenclature by the U.S. Geological Survey, 1977
  • Publication Date: 1978
  • Map Scale: 1:807,591
  • Cross Section: None
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* Names and boundaries are not necessarily authoritative, and are provided here solely for general orientation.