Images from the Columbia River Flood Basalts in Washington

View from the east side of the Columbia River with I-90 in the fore ground. Each of the dark layers across the way is an individual basalt flow, one stacked on top of the other.

View from the west side of the Columbia River of stacked basaltic lava flows from top to the bottom of the cliff. In this area it is basaltic lava flows as far as the eye can see.

Some 75 miles away from the I90 bridge, this is Grand Coulee, and more basaltic lava flows of this Large Igneous Province for as far as the eye can see.

A distinctive characteristic of these lava flows is how they have been fractured into columns, often of a hexagonal shape as seen here. This is from the thermal contraction as the lava cools.

In some places these cooling fractures generate more complex radiating patterns reflecting a more complex pattern of heat flow out of the lava flow as it crystallized.

Map showing the extent of the Columbia River Flood Basalts from http://vulcan.wr.usgs.gov/Volcanoes/ColumbiaPlateau/Maps/map_columbia_river_flood_basalts.html .