| This view is looking north from the visitor information kiosk/picnic
area at the Painted Hills Unit of John Day Fossil Beds National Monument. The hill (about 500 feet high) is called
Carroll Rim and was the source of many fossils early in the exploration
of the John Day region. The Picture Gorge Ignimbrite (a massive volcanic
tuff deposit) caps the hill (or cuesta; a cuesta is a hill typically capped by an erosionally resistant layer of the gently dipping strata). This massive
volcanic deposit overlies sedimentary beds of the middle Turtle Cove Member
of the John Day Formation (Fremd and others, 1994). The Clarno Formation consists of a thick section (up to 6,000
feet (1800 meters) of non-marine volcanic and volcaniclastic units that range in age from Middle
to Late Eocene (about 48 to 34 million years) and crops out throughout north-central Oregon (Bestland and others, 2002). |
