Abstract:
(1) Field mapping and biostratigraphic data indicate that the Yamhill Formation overlies and is younger than the Tyee Formation; interfingering of the two formations is not indicated. (2) Stewart's correlation of the Yamhill Formation with the Sacchi Beach member of the Tyee was based on incomplete knowledge of the range in time of key species. Presently available information rules out age equivalence of the two units. (3) Available biostratigraphic data suggest that the sub-Yamhill "Siletz River" is younger than the sub-Tyee Siletz River and may even be post-Tyee in age.
Description:
Introduction -- Previous work -- Lithologic discrimination of the Tyee and Yamhill Formations -- Stratigraphic relationships of Tyee and Yamhill Formations -- Biostratigraphic relationships of the Tyee and Yamhill Formations -- Stratigraphic relationships of the Siletz River Volcanics and Yamhill Formation -- Conclusions -- Register of localities -- Acknowledgments -- References.
