Columbia River Basalt Group
The Columbia River Basalt Group (CRBG) is the youngest, smallest and one of the best-preserved continental flood basalt provinces on Earth, covering over 210,000 km2 (81,000 sq mi) mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. The basalt group includes the Steens and Picture Gorge basalt formations.
The Columbia River Basalt Group (including the Steen and Picture Gorge basalts) extends over portions of four states.
Restoration of Miocene animals at the Picture Gorge Basalts
In the Palouse River Canyon just downstream of Palouse Falls, the Sentinel Bluffs flows of the Grand Ronde Formation can be seen on the bottom, covered by the Ginkgo Flow of the Wanapum Basalt.
CRB-Yellowstone mantle plume model
A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive and extrusive, arising when magma travels through the crust towards the surface. The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics. The formation of some of the LIPs in the past 500 million years coincide in time with mass extinctions and rapid climatic changes, which has led to numerous hypotheses about causal relationships. LIPs are fundamentally different from any other currently active volcanoes or volcanic systems.
Three Devils Grade in Moses Coulee, Washington is part of the Columbia River Basalt Group LIP.
Illustration showing a vertical dike and a horizontal sill.
