The Okefenokee is huge, covering hundreds of miles, but it is shallow — only two feet deep in many places — and it isn’t fed by any waterways. Rain is the swamp’s only source of replenishment.

A remarkable coincidence occurred 56,000 years ago, when the impact that created Meteor Crater triggered both a landslide-dammed lake and a paleolake formation in the Grand Canyon. Earth’s ancient ...

New research links the impact at Meteor Crater to a Grand Canyon landslide that may have created an ancient lake 56,000 years ...