På norsk
GeologyNorth America

The Columbia River Basalts

16.7 million yrs ago – 5.50 million yrs ago

Enough lava to bury a state

See it on the timeline

In depth

A flood basalt province forms when enormous volumes of runny lava pour from long fissures rather than from a single volcano. Individual flows in the Columbia River Basalts are among the largest known lava flows on Earth; some reached the sea, over three hundred kilometres away. The province is the youngest great flood basalt province and therefore the best preserved, which has made it the key to understanding older and far larger provinces such as the Deccan and Siberia, which are tied to mass extinctions. Weathered basalt also yields the deep, fertile soil in which the Palouse wheat is grown.

For children

Lava poured from long fissures in the ground and spread out like a flood, again and again over millions of years. In the end it covered more than two hundred thousand square kilometres, in places several kilometres thick. That is why much of Washington and Oregon consists of flat plateaus.

Sources

This event has no source references yet. Do you know where it is well attested — a book, an article, a reference work? We would very much like to hear from you.

Help us with sources

Connects to

Report a correction

Found something that does not hold? Tell us — sources help, but are not required.

Report a correction

Part of Terra Saga — the story of Earth on a timeline. terrasaga.org · Last changed 2026-08-16