The Chuckanut Mountains (from "Chuckanut", an indigenous word meaning "long beach far from a narrow entrance"^[1]), or Chuckanuts, are located on the northern Washington state coast of the Salish Sea, just south of Bellingham, Washington, United States. 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.

The range contains Larrabee State Park, the first State Park to be designated in Washington (1923). Its mountains include:

• Anderson Mountain
• Blanchard Mountain
• Chuckanut Mountain (including North Chuckanut Mountain, South Chuckanut Mountain, and Chuckanut Ridge)
• Galbraith Mountain (also known as North Lookout Mountain)
• King Mountain
• Lookout Mountain
• Sehome Hill
• Squalicum Mountain
• Stewart Mountain
• Toad Mountain

Geology

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.^[2] The Chuckanuts are well known for their Tertiary Period leaf fossils.^[3]

In 1988, an outcrop of metamorphic phyllite, green chert, and milk quartz on Blanchard Mountain was exposed by a construction crew. The outcrop is unique for its unusually large chunks of stilpnomelane.^[4]