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'Once in a lifetime ' experience: Lighthouse keeper on Lake Superior
CBC News (5/19)
A group is hiring two students to serve as lighthouse keepers this summer on Porphyry Island, about 40 kilometers east of Thunder Bay, Ont.

Superior students set sail for hands-on learning about St. Louis River, Lake Superior
Wisconsin Public Radio (5/16)
Close to 1,500 students from northern Minnesota and Wisconsin set sail for a day on St. Louis River to learn about the Great Lakes, as part of the week-long St. Louis River Quest.

Tree group aims to ‘ReLeaf’ Michigan
WKAR - East Lansing, MI (5/10)
An Ann Arbor-based organization has been planting trees all over Michigan since 1988. ReLeaf Michigan helps property owners learn about trees and how to plant them, citing their numerous benefits.

Coldwater bacteria threatens Great Lakes salmon
Charlevoix Courier (5/3)
A new study shows a bacterial disease that sickens fish whether raised in captivity or in the wild is imperiling popular salmon species in the Great Lakes Basin.

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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