GLIN Daily News About GLIN
AboutEnvironmentHistory/CultureGeographyPollutionCareers/BusinessTeachers' Corner
water photo
What's New?

MSU conference explores need for greater international cooperation to protect vital global watersheds
MLive (11/25)
A recent Michigan State University workshop focused on water rights and improving cross-border policies for the protection of the great waters of the world.

VU students testing area waters
The Northwest Indiana Times (11/21)
Students of Valparaiso University, Ind., were at Lake Michigan to work on water quality measurements for an Environmental Protection Agency education project.

Forest Hills students put surf boards to the test in Lake Michigan
MLive (11/20)
Surf’s up! Well at least it was for some lucky students from Forest Hills Public Schools on Thursday, Nov. 19. Twenty students from each of the district’s three high schools had an opportunity to surf 10- to 12-foot waves at Grand Haven State Park, Mich.

City says yes to dock sale
Traverse City Record-Eagle (11/3)
In Traverse City, Mich., commissioners agreed to sell the coal dock marina to a group of nonprofit organizations focused on Great Lakes history, education and environmental protection to expand use for nonprofits and construct new, modern facilities.

TVDSB high school students learn about importance of Great Lakes
St. Thomas Times-Journal (10/31)
Participants at the Lake Erie Student Conference spent the day in Port Stanley, Ont., taking demonstrations on water quality testing, commercial fishing, birds of prey and the threat of invasive species.

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 ]

1 | 2 | 3 next page