Most life was wiped out, and the creatures that did survive huddled in small pockets of open water, where hot springs continued to bubble up. This was Snowball Earth â a deep freeze that began around 715 million years ago and held Earth in its icy grip for a good 120 million years. There are no other comparable glacial periods on Earth.
Lake Barkley Lake Levels. The lake's level is fluctuated from summer to winter for flood control purposes. Summer pool (359 ft. sea level) is normally reached by May 1. The water level begins dropping gradually on July 1, and winter pool (354 ft.) is reached by December 1.
The before images were taken when the lake level was 1,111 feet above sea level. Lake Mead hasnât been officially fullâ1,221 feet above sea levelâsince 1983. The massive intake towers on the Hoover Dam in Lake Mead straddle the Nevada/Arizona border, in this 2007/2014 before-and-after. Should the current drought continue, the Hoover Dam could lose the ability to generate electricity. Image: Ethan Miller/Getty Images. Thanks to an ongoing mega-drought, Lake Meadâs water level will continue to fall for the indefinite future.