The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth's Past Mass Extinctions

by Peter Brannen

the Finger Lakes of New York were carved by massive glaciers, while the Great Lakes are basically the world’s largest puddles, left when the ice sheets melted only a few thousand years ago. The most dramatic example might be in the epic Channeled Scablands of eastern Washington, which were carved by truly mind-blowing cyclical floods called jökulhlaups. During the last glacial cycle, as a massive ice sheet pushed into Idaho, the ice blocked the Clark Fork River and created an enormous dammed lake in Montana, six times the volume of Lake Erie. As the lake grew and grew, it eventually reached a depth of 600 feet, at which point the obstructing ice started to float. As water continued to gnaw at cracks at the base of the ice dam, the lake suddenly failed and the whole system collapsed in a catastrophic flood that—all at once—released ten times the flow of all the rivers in the world. Waves leaving ripple marks 450 feet long and carrying 30-foot boulders crashed through eastern Washington, tearing up the bedrock, sculpting canyons, and leaving the southeast corner of the state barren of soil and vegetation. When the glacial dam began to re-form, the lake began to fill once more, and eventually it burst again. And again. This catastrophe repeated itself perhaps as many as sixty times between 15,300 and 12,000 years ago. This was right about when the first Americans were wandering into the continent, and perhaps some unlucky few witnessed, and even perished, in these local apoca...