One of the great natural spectacles of the modern age has been the awakening of Kilauea, on the Big Island of Hawaii, which has continuously spewed lava since 1983. Yet, from the perspective of geologic history, this flow is but a momentary trickle. Consider, for example, the Siberian Traps.
In the late Permian, some 250 million years ago, vents opened in the crust of what is now north-central Russia and, over the next million years, a basaltic flood covered an area the size of our lower 48 States to a depth of 2 km; most geologists believe that the flow was triggered by a mantle plume which melted the overlying crust. The largest event of its kind in the history of our planet, the basalt and its associated volcanic debris extends from the Ural Mountains to the Lena River Valley. Today, this igneous province is named for the step-like terrain that erosion has left behind.
Having more than a spectacular effect on the landscape, this prolonged volcanic episode changed the climate of Earth, producing greenhouse warming, a toxic atmosphere and relatively shallow, acidic and anoxic ocean waters. Ninety percent of all species perished (including 95% of all marine life), resulting in the greatest mass extinction in the history of our planet; it would take almost 30 million years for Earth's ecosystems to recover, a period (Triassic) during which the first mammals and earliest dinosaurs appeared.
