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

Summer vacation researching lakes
The Journal Gazette (8/25)
Steve Park, a seventh-grade science teacher from Riverview Middle School in Huntington, Ind. spent a portion of his summer on an Environmental Protection Agency research vessel.

Senators announce funding for University of Michigan project
WKZO - Washington, D.C. (8/25)
Senators Debbie Stabenow and Carl Levin say that a grant for the University of Michigan will help develop models to protect Lake Erie from the effects of algal blooms.

Residents get hands-on lesson about Maumee River conditions
WTVG 13 ABC - Toledo, OH (8/25)
More than two dozen people took a two-hour look at the Maumee River and nearby facilities that impact its condition. The tour, hosted by the Lake Erie Waterkeeper, was especially important this year because of the growing algae bloom in Lake Erie.

Save the River looks to boost its education program
TWC News - Syracuse, NY (8/20)
A volunteer for a non-profit dedicated to protecting the St. Lawrence River has published a book to benefit the cause.

Great Lakes Bay Regional Alliance aims to raise awareness of Bay City's schooner Appledore, other STEM teaching tools
MLive (8/20)
Great Lakes Bay Regional Alliance ambassadors and board members, joined Bay City, Mich. area educators and members of the media for a STEM excursion aboard the schooner Appledore IV.

Local teachers travel to study lakes
The Journal Gazette (8/4)
An Indiana high school teacher and his brother were among the group of educators who took part in a weeklong summer program at Michigan Technological University in Houghton, Mich., as part of the Great Lakes Teacher Institute.

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
References


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

1 | 2 | 3 | 4 | 5 | 6   next page