One of planet’s largest volcanic eruptions

Researchers have determined that the Pacific Northwest was home to one of the Earth’s largest known volcanic eruptions, a millennia-long spewing of sulfuric gas that blocked out the sun and cooled the planet. Only two other eruptions — the basalt floods of the Siberian Traps and the Deccan Traps — were larger, and they led to two of the Earth’s great extinctions.
Geology News — ScienceDaily