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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.
TEACH Shoreline Geology

table of contents
Introduction: Glaciers and more glaciers
Let's go to the beach!
The sandy dunes
Marshes, bogs, and swamps
Isle Royale
Human impacts and the future

Great Lakes Shoreline Geology

Miners Castle. Click for larger image. From the wetlands along Lake Ontario's shore, to the sand dunes along Lake Michigan, to the rocky shore of Lake Superior, the Great Lakes shoreline abounds in diversity. Millions of years of glacial formation, wind, lava flows, and changing lake levels have sculpted a unique and ever changing shoreline. These shoreline systems absorb the brunt of wind and wave energy from the lakes, helping to protect the inland areas. Let's explore!

Glaciers and more glaciers

Six hundred million years ago, during the Paleozoic Era, central North America was covered by a shallow sea. This sea deposited a lot of sand, salts, and silts, which, after time, were compressed into limestone, sandstone, shale, halite, and gypsum.

Pleistocene glaciers. Click for larger image The sea retreated from the Great Lakes region before the end of the Paleozoic Era. Eventually, the earth cooled, and during the Pleistocene Epoch, about 1 million years ago, the ice ages began, and glaciers advanced and retreated many times over what is now the Great Lakes region. Being over one mile thick, these glaciers flattened and carved large holes in the land. Where they encountered more resistant bedrock, such as volcanic deposits, only the overlying layers were removed; but, the softer sandstone and shale allowed the glaciers to dig out the large basins that make up the Great Lakes today.

As the glaciers melted and began receding, their leading edges left behind high ridges and fascinating rock formations, some of which can be seen today in the cliffs of Door County, Wisconsin, and the "flowerpots" on Bruce Peninsula in Ontario. Flowerpot Island. Click for larger image.Huge lakes formed between these ridges from the retreating ice fronts. As many as 8-12 ice ages occurred, each lasting around 50,000 years; during the longer, warmer periods in between each ice age, plants and wildlife returned to the area.

The last glacier began retreating around 14,000 years ago, and the earth warmed considerably. As the glaciers melted, the resulting water, called meltwater, filled the huge holes left by the glaciers. During this time, the lakes were much larger than they are now, and they had different river outlets. But as the ice retreated, the St. Lawrence River Valley revealed itself as the outlet to the Atlantic Ocean, and the lake levels eventually dropped to current levels.

See the TEACH topic How the Lakes were Formed for a more detailed discussion on glacial formation.

Graphics: Miners Castle on Pictured Rocks National Lakeshore; glacial advance during the Pleistocene Epoch; and, a "flowerpot" on Flowerpot Island on Bruce Peninsula

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