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UNDER CONSTRUCTION as of October 26, 2008 |  |
Snoqualmie Batholith - late Oligocene to early Miocene (28 Ma[million years ago] to 22 Ma). Uplift and erosion of the Old Cascade Volcanic Arc exposed plutonic rock of the Snoqualmie Batholith near Snoqualmie Pass. Intrusive rock types found within the Snoqualmie Batholith range in composition from granite to gabbro. Granodiorite is the most prevalent exposed rock type. Other lithologies within the batholith include porphyritic dacite, andesite, aplite, and intrusive breccia (Livingston, 1971).
Source: Generalized Geologic Maps of the Skykomish River and Snoqualmie Pass 1:100,000 Quadrangles. Base Map from Microsoft Virtual Earth.
Livingston, Vaughn E., (1971) Geology and Mineral Resources of King County, Washington. Bulletin - Division of Mines and Geology (State of Washington) 63, Pages 200.
