What’s so great about the Great Lakes? - Cheri Dobbs and Jennifer Gabrys

View full lesson: http://ed.ted.com/lessons/what-s-so-great-about-the-great-lakes-cheri-dobbs-and-jennifer-gabrys The North American Great Lakes — Huron, Ontario, Michigan, Erie, and Superior...

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What's so great about the Great Lakes?They're known as America's inland seas.The North American Great LakesHuron,Ontario,Michigan,Erie,and Superiorare so massive that they border eight statesand contain 23 quadrillion liters of water.That's enough to cover the land area of the contiguous United Statesthree meters deep.These vast bodies of water span forest,grassland,and wetland habitats,supporting a region that's home to over 3,500 species.But how did such a vast and unique geological feature come to be?The story begins near the end of the last ice age over 10,000 years ago,a time when the climate was warmingand the glaciers that cloaked the Earth's surface began their slow retreat.These immense ice sheets carved out a...