Settlers in the Valley also saw the rock deposit as a source of building material, with basalt quarried from Cowiche Canyon ...

To the north, the batholith is overlain by altogether different and much younger rocks. These are part of the Columbia River flood basalts, one of the largest outpourings of lava flows on Earth.

A map of Columbia River Basalt Group highlighting the Steens Mountain and Picture Gorge sub-units and areas where Oregon sunstones have been found. OPB ...

Lava flows of the Columbia River Basalt Group are tens to hundreds of miles long and likely record the emergence of the Yellowstone hotspot after a period of relative dormancy.

Flows of the Columbia River Basalt Group crop out mostly in eastern Washington and the High Lava Plains of central Oregon, but also extend westward through the Cascade Range to the offshore ...

This is magmatic spatter—the remains of lava ejected high into the air, 15 million years ago from a vent that gave fiery birth to the Roza member of the Columbia River basalt flows.

After all, most of the country lacks the layered volcanic flows that spread to form the Columbia and Snake river plains. But basalt has one virtue that other geologic formations lack.

Even though the Columbia River Flood Basalt Province is the smallest and youngest flood basalt province in the world, it still covers nearly 210,000 square kilometers of the U.S. Pacific Northwest.

It was created when Columbia River basalt flows erupted in Idaho around 15 million years ago, poured down the Columbia River’s channel and then fanned out, to the ocean and down the Cascade ...

Runners, bicyclists and walkers in Columbia Park have probably noticed a couple 1,500-pound basalt slabs installed along the path in recent days. Those are part of one local teacher’s decades ...

Runners, bicyclists and walkers in Columbia Park have probably noticed a couple 1,500-pound basalt slabs installed along the path in recent days. Those are part of one local teacher’s decades ...