Long Island, Apostle Islands, Wisconsin Lake Erie Case Studies


Walkways over the marshes of Point Pelee, Ontario, Canada. (Photo by Sue Ann Campbell)

The Great Lakes region is full of diverse histories, environments and landforms, and each Great Lake has its own story to tell. To truly know the lacustrine barrier systems that are found in the Great Lakes, one must understand each system singularly before any generalizations can be made. Some systems will develop similar to oceanic barrier systems. Others will grow from circumstances completely foreign to marine environments. This site will examine two locations to emphasize in greater detail the similarities and discrepancies that can exist between oceanic and lacustrine barrier systems.

The first site we will investigate is Long Island, part of the Apostle Islands in Wisconsin, located on the southern shore of Lake Superior. Long Island is a recurved barrier island on the northwest tip of the Chequamegon Point barrier spit. It undergoes periods of attachment and detachment due to storm washover and the rise and fall of lake levels. The main source of sediment is input from the Kakagon and Bad Rivers to the east, and a dominant northwest drift continues to feed Long Island and Chequamegon Point.

Next, we examine two sites on the northern shore of Lake Erie: Point Pelee and Long Point, Ontario. Both of these sites are barrier spits, which owe their existence to glacial moraines. Point Pelee is a cuspate foreland built by two conjoined barrier bars with a central marsh. Current sources of sediment include the bluffs on the northeast side of the Point and the erosion of nearshore glacial sediments along the eastern shoreline. Since then, it has been retreating on the eastern side and accreting on the western. Long Point is an eastward-trending barrier spit fed by bluff erosion to its west. Its distal end is prograding into the lake, while its central and proximal regions are being eroded by winds and overwash.

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A COMPARISON OF OCEANIC BARRIER SYSTEMS AND GREAT LAKES BARRIER SYSTEMS
Copyright 2004, Jennifer Bruce