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Central Michigan University opens interactive Great Lakes exhibit
WWTV-TV - Cadillac, MI (4/19)
The Great Lakes are the shining jewel of Michigan. And now there's a kid-friendly exhibit featuring the beautiful bodies of water.

60,000 trees and counting
Erie Times-News (4/17)
Sixty thousand and counting. That's how many trees and shrubs have been planted by Crawford County students in 16 years, in environmental projects sponsored by the Crawford County Conservation District and Pennsylvania state Bureau of Forestry.

Presque Isle an academic draw for Gannon students
Erie Times-News (4/10)
In Pennsylvania, Presque Isle State Park has long been a draw for tourists looking for the perfect place to swim and sunbathe. But the park, Presque Isle Bay and Lake Erie are also a draw for another group: science-minded students and their teachers.

TEACH Calendar of Events
What's going on in your neighborhood this month? Meet other people and learn together at recreational and educational events! Our new dynamic calendar is updated daily with current educational events.
How the Lakes Were Formed

table of contents
How the lakes were formed
Prehistoric glacial movements
Great Lakes system profile: Elevations and depths


How the lakes were formed

About a billion years ago, a fracture in the earth running from what is now Oklahoma to Lake Superior generated volcanic activity that almost split North America. Over a period of 20 million years, lava intermittently flowed from the fracture.

Lake Huron

This geomorphic age created mountains covering the regions now known as northern Wisconsin and Minnesota, and the Laurentian mountains were formed in eastern Canada. Over time these mountains eroded, while occasional volcanic activity continued. Molten magma below the highlands of what is now Lake Superior spewed out to its sides, causing the highlands to sink and form a mammoth rock basin that would one day hold Lake Superior. Eventually the fracture stabilized and, over time, the rock tilted down from north to south.

The region went from fire to ice with the arrival of the glaciers, which advanced and retreated several times over the last 5 million years. During the periods of glaciation, giant sheets of ice flowed across the land, leveling mountains and carving out massive valleys. Where they encountered more resistant bedrock in the north, only the overlying layers were removed. To the south, the softer sandstones and shales were more affected. As the glaciers melted and began receding, their leading edges left behind high ridges, some of which can be seen today in the cliffs of Door County, Wisconsin, and the Bruce Peninsula in Ontario. Huge lakes formed between these ridges from the retreating ice fronts, and continually changed over time as the ice sheet moved northward.

Watch the formation of the Great Lakes! [ Flash | HTML ]


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