Columbia River Basalt Stratigraphy in the Pacific Northwest

In Cooperation with the Oregon Water Resources Department

Columnar basalt, Roza Member, Wanapum Basalt of the Columbia River Basalt Group, near Vantage, Washington (photograph by Terrence Conlon)

The Columbia River Basalt Group (CRBG) consists of a thick sequence of Miocene flood basalt that covered northern Oregon, eastern Washington, and western Idaho between 17 and 6 million years ago (Location Map). It is an important regional aquifer system, and, in its folded and faulted flows, it records the late Cenozoic structural evolution of much of the Pacific Northwest.

This Website contains stratigraphic information on the CRBG that is useful in many types of studies, including hydrogeologic, basin evolution, and geologic hazard investigations. A long-term goal is to compile geochemical and paleomagnetic data, and stratigraphic interpretations of the CRBG over its extent in three States.