USGS home Scientific Investigations Map 2940 

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.
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