The Chuckanut Mountains were formed by the folding of the Chuckanut Formation (which is predominantly made up of layers of 55-million-year-old sandstone, conglomerate, shale, and bituminous and sub-bituminous coal) and the later Huntingdon Formation (predominantly shale and sandstone) on top, as well as an exposed section of pre-Jurassic-age phyllite

citation

Wikipedia contributors. (2023, June 11). Chuckanut Mountains. In Wikipedia, The Free Encyclopedia. Retrieved November 16, 2023, from https://en.wikipedia.org/w/index.php?title=Chuckanut_Mountains&oldid=1159687292

Chuckanut Mountains (Wikipedia) The Chuckanut Mountains (from “Chuckanut”, an indigenous word meaning “long beach far from a narrow entrance”), or Chuckanuts, are located on the northern Washington state coast of the Salish Sea, just south of Bellingham, Washington. Being a part of the Cascade Range, they are the only place where the Cascades come west down to meet the sea. The Chuckanuts are considered to be a part of the Puget Lowland Forest Ecoregion.