The Columbia Plateau exposes dark rock that spans the states of Washington, Oregon, and Idaho. What made this vast plateau?

Question

layers of continuous basaltic lava flow that cooled and hardened
layers of batholith that eroded and became exposed
layers of metamorphic rock that eroded and extruded from deep in the earth's crust
layers of sedimentary rock that deposited, like the Grand Canyon

Answer 1

The Columbia Plateau was formed primarily from layers of continuous basaltic lava flow that cooled and hardened. This volcanic activity occurred during the Miocene epoch, resulting in extensive basalt formations across the region. The flows created thick layers of basalt rock, giving the plateau its characteristic dark appearance.