In southeastern Washington state, the Palouse River dives 200 feet (60 meters) off cliffs created by lava flows that occurred over 16 million years ago. While this in itself is impressive, researchers recently discovered something even more astounding about these cliffs: They were created by the third-largest eruption in Earth's history.
The research by Washington State University, funded by the National Science Foundation, appears in the journal Geology and details a thousand-year span during which an explosion of sulfuric gas blocked out the sun and chilled the Earth.
"This would have been devastating regionally because of the acid-rain effect from the eruptions," John Wolff, a professor in the WSU School of the Environment said in a university statement. "It did have a global effect on temperatures, but not drastic enough to start killing things, or it did not kill enough of them to affect the fossil record."