Portland State University. Department of Geology
Robert O. Van Atta
Date of Award
Master of Science (M.S.) in Geology
1 online resource (183p.)
Cowlitz Formation (Or. and Wash.), Stratigraphic geology -- Eocene, Geology -- Oregon -- Columbia County, Geology -- Oregon -- Washington County
The Upper Eocene Cowlitz Formation is exposed in surface outcrops southwest of the town of Vernonia, in Columbia County, Oregon. The Cowlitz Formation also occurs in the subsurface of the Mist gas field where its Clark and Wilson (C and W) sandstone member (informal) acts as a natural gas reservoir, and its upper Cowlitz mudstone member (informal) acts as a cap rock. Surface exposures and continuous core were studied in order to determine Cowlitz Formation stratigraphy, and its depositional environment. Fresh core samples were also studied petrographically, and with a scanning electron microscope, in order to determine the effects of diagenesis in the gas producing C and W sandstone member.
Farr, Leonard Carl Jr., "Stratigraphy, diagenesis, and depositional environment of the Cowlitz Formation (Eocene), northwest Oregon" (1989). Dissertations and Theses. Paper 3905.