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Pomona Member of the Columbia River Basalt Group: an intracanyon flow in the Columbia River Gorge, Oregon.

January 1, 1980

The Pomona Member of the Saddle Mountains Basalt (Columbia River Basalt Group) occurs as an intracanyon flow greater than 75m (250ft) thick along the S side of the Columbia River Gorge between Mitchell Point and Shellrock Mountain, Oregon. Best exposures are at Mitchell Point, where this flow caps more than 70m (230ft) of cobble conglomerate that partially fills a canyon cut into flows of the underlying Frenchman Springs Member. These exposures provide a necessary link between outcrops of the Pomona Member in the Columbia Plateau and western Washington. Post-Frenchman Springs, pre-Pomona canyon cutting implies deformation in the ancestral Cascade Range between about 14.5 and 12Ma ago.-Author

Publication Year 1980
Title Pomona Member of the Columbia River Basalt Group: an intracanyon flow in the Columbia River Gorge, Oregon.
Authors J. L. Anderson
Publication Type Article
Publication Subtype Journal Article
Series Title Oregon Geology
Index ID 70012285
Record Source USGS Publications Warehouse