The Origins of the Great Lakes Background InformationInteresting

The Origins of the Great Lakes

Background Information/Interesting Facts: - The Lakes: Eerie, Ontario, Superior, Michigan, Huron, 1/5 of the world’s fresh water Area: 94, 650 sq. miles 246, 000 sq. km The greatest depth of Lake Superior is 1, 333 ft; of Lake Michigan, 925 ft; of Lake Huron, 725 ft; and of Lake Erie, 212 ft. - The Great Lakes constitute the largest concentration of unfrozen fresh surface water in the western hemisphere. - The Great Lakes Aquatic ecosystem is obviously made up of the lakes themselves, but also the complex network of tributaries and groundwater on which the lake depends on

How the Great Lakes Were Formed • The present-day lake basins of Lakes Superior, Michigan, Huron, and Erie were formed when large masses of ice gouged out preglacial river valleys. The varying depths of the lakes are in part attributed to the differences in the thickness of the ice at the time of glaciation.

TIMELINE *Precambrian 3 Billion- 600 million years ago (30 feet) *Mesozoic 230 -135 million years ago (2. 3 feet) I I I *Paleozoic 600 -280 million years ago (6 feet) *Recent History Last 10, 000 years (. 001 inch) *Cenozoic 70 million years - present time (2. 5 inches) I I *Great Lakes Formed 10 -15, 000 years ago (. 25 inch) I I I

Minerals/Rocks Found in the Great Lakes Region • The primary rock exposed along the shore of Lake Ontario on both the US and Canadian shores in that area is an Ordovician age limestone about 400 million years old. • Locally, it may contain some fairly large orthocone cephalopod fossils • Further to the northeast in the Thousand Islands region lies an extension of the Canadian Shield known as the Frontenac Axis. This rock is mostly granitic gneiss and is about 1 billion years old • The principal minerals found throughout the Great Lakes region include: coal, natural gas, oil, uranium, salt, copper, zinc, gold, silver, iron ore, nickel, lead **Many of these minerals are useful for the creation of energy (like uranium for nuclear power or the fossil fuels natural gas, oil, and coal) while others are more useful for other industries such as heavy construction. It is important to mine for these minerals safely and efficiently so that we can protect the environment of Great Lakes Region and still benefit from its many gifts.

An Ariel View of the Great Lakes Region

Current Issues and Concerns • The water levels of the lakes fluctuate from melting snow, hot summers, rain, etc. Even though recently the levels have increased the level is still below the averages of prior years. • For example, Lake Michigan is 7 inches higher than it was this time last year, but it’s still 17 inches below the historic averages for March. • The worst oil spill in Great Lakes history happened in April 2002 and spread an estimated 255, 000 -gallon mixture of lube oil and diesel fuel in the Rouge River. From there, it floated downstream into the Detroit River and Lake Erie. • Wisconsin Energy Corporation wants to use Lake Michigan’s resources (83% more than they already do). Environmentalists are concerned that this could greatly impact the ecology of Lake Michigan.

Conclusion • The Great Lakes area covers Minnesota, Wisconsin, Illinois, Indiana, Ohio, Michigan, New York, Pennsylvania and the Canadian providences Ontario and Quebec. • It’s resources have been and will continue to be extremely helpful for many aspects of survival.