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Pacific NW Geologic Mapping Project

Geologic maps of the North Cascades

Tcao-2. Bedded volcanic breccia and tuff of the Ohanepecosh Formation (Ohanepecosh episode, Tcao), northeast of Howard Hanson Resevoir [SPnw]. Note prominent intraformational unconformity, a common feature in volcanic areas where rapid erosion and deposition are often accompanied by ongoing deformation. Beds beneath this unconformity were deformed (tilted) and beveled by erosion prior to renewed deposition.
Other photos that show unit Tcao:

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Photo Indices: Captions (Additional photos home) | Map | Young rocks and deposits | Older rocks west | Older rocks east