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Coastal Centre concerned about plastic pollution in Lake Huron
Owen Sound Sun Times (7/17)
Everyone has a role to play in turning the tide on the growing problem of plastic pollution in the Great Lakes. That's the message from Ontario's Lake Huron Centre for Coastal Conservation outreach specialist, who is working to educate people on simple ways to help combat the issue.

Elementary Adventure Day outing provides hands-on fun
The Ashland Daily Press (7/12)
Just over half-a-dozen youngsters gathered at the Northern Great Lakes Visitor Center, in Wisconsin, to participate in the first of this year’s three 4-H Elementary Adventure Day’s.

Summer interns help to research Lake Erie issues
The Toledo Blade (7/5)
Eleven college and university students from across the United States are studying freshwater lake issues this summer at the University of Toledo’s Lake Erie Center.

Anglers enlisted in water fight
Great Lakes Echo (6/29)
A recent study by researchers at Cornell University, in N.Y., revealed that anglers in the Great Lakes region are aware of and concerned about the threat of aquatic invasive species (AIS).

Lake State opens Sea Grant office
Sault Ste. Marie Evening News (6/29)
Lake Superior State University officially welcomed its new Michigan Sea Grant office to campus with a ribbon cutting ceremony Monday morning.

Stone Lab hosts series of experts to discuss lake
Port Clinton News Herald (6/28)
In Ohio, people looking to learn more about the issues facing Lake Erie will have several opportunities this summer to hear firsthand from the experts in the field who deal with those issues every day.

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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