Name Oregonia applied to upper division of Arnheim bed, distinguished by occurrence at base of characteristic Richmond fossils LEPTAENA RICHMONDENSIS-PRECURSOR, RHYNCHOTREMA DENTATA-ARNHEIMENSIS, and DINORTHIS CARLEYI. Overlies Sunset division of Arnheim bed. Thickness 26 ft. Age is Late Ordovician.

Source: GNU records (USGS DDS-6; Reston GNULEX).

Name Oregonia, with its type locality in OH, is inappropriate for stratigraphic unit in south-central KY. Most of Oregonia of Foerste is herein referred to Reba Member of Ashlock Formation (both new).

Source: GNU records (USGS DDS-6; Reston GNULEX).

Named biofacies are recognized as true rock-stratigraphic units and here redefined by rules of the 1983 North American Stratigraphic Code. Oregonia, previously considered a member of Arnheim Formation, is here raised in rank to formation along with underlying Sunset Member. Arnheim is restricted from the study area. Composite and supplemental reference sections are designated. Contacts are redefined. Oregonia consists of interbedded fossiliferous shale and limestone. Laterally equivalent, in part, to Dillsboro Formation of IN and Bull Fork Formation of KY. Underlies Waynesville Formation. Age is Late Ordovician (Cincinnatian).

Source: GNU records (USGS DDS-6; Reston GNULEX).