Geology Reference
In-Depth Information
Major geographic and structural features of the Deschutes-Columbia Plateau (after Smith, Bjornstad,
and Fecht, 1989)
Grande Ronde basalts being erupted, the crust at the
center of the plateau at Pasco, Washington, began to
fail and collapse downward to create a basin over three
miles deep.
Concurrently, the deformation of the plateau
caused minor folding over the Columbia basin and pro-
appeared further north, and the entire plateau was
tilted to the northwest by uplift along the Idaho
batholith. This tilting allowed the later Grande Ronde
flows to extend northward into central Washington and
enabled them to reach the Pacific Ocean by way of the
Columbia gorge. With as much as 36,000 cubic miles of
