A lava plateau is a large, flat area of land created by lava filling in all the valleys and other depressions. Lava plateaus are created by low-viscosity basaltic magma, which spreads very quickly before it cools, allowing it to cover a large area.
Located in the northwestern United States, the Columbia Plateau is one of the world's largest lava plateaus. The lava flows creating this landform originated between 17 and 6 million years ago. Over 170,000 cubic kilometers of lava cover this region, and over 300 major lava flows contributed to its formation with vents measuring over 150 kilometers long.