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Sand Ridges and Dunes in the Calumet Region
Nature Bulletin No. 709   March 16, 1963
Forest Preserve District of Cook County
Seymour Simon, President
David H. Thompson, Senior Naturalist

SAND RIDGES AND DUNES IN THE CALUMET REGION
Geographers call the area between South Chicago and Michigan City, Indiana, the Calumet Region because it includes Lake Calumet and the drainage basins of the Little Calumet and Grand Calumet rivers.

Passengers on airplanes flying to and from Chicago over the southern end of Lake Michigan can get a better idea of that region and what it was originally than those who travel on the railroads and highways. From the air, in spite of tremendous developments since 1905 when the U. S. Steel corporation purchased 8000 acres of sand dunes and swamps for its mills and a new city, Gary, you can still see ridge after ridge paralleling the lake shore as if the country had been furrowed by a gigantic plow.

The last glacier of the Ice Age, and Lake Chicago -- ancestor of Lake Michigan -- shaped the main features of Chicagoland. As the ice melted away the lake's surface was 60 feet higher than at present and it discharged torrents of water through the DesPlaines river and Sag valleys. As the glacier found new outlets, two other prominent beach lines were formed in the Calumet region, each about 20 feet lower than the previous one.

The famous Indiana dunes were built by winds sweeping down the lake and creating waves which washed sand and gravel up onto the shore; and then, after that dried, carrying sand inland until it piled up in ridges and dunes. One dune, Mt. Tom, is over 200 feet high. As the shore was extended into the lake, new ridges were created. Just as a snow drift forms where some object breaks the force of the wind, certain pioneer plants which are able to gain a foothold and survive on sun-baked sand- -such as tufts of beach grass and cottonwood seedlings -- play leading roles in the growth of a dune. With passing years, more and more kinds of plants occupied each dune in orderly succession until the oldest are now damp woodlands. In some places there are dozens of those ridges separated by strips of marsh and swamp.

Because its far-flung prairies were too wet to farm, the Calumet region was not settled as early as other parts of Chicagoland but the high dry beach lines have been main routes for travel around the tip of Lake Michigan since prehistoric times. Most famous of these is the Great Sauk Trail from Rock Island, Illinois, across northern Indiana, to Detroit. Those Indian trails were followed by the pioneers' wagons, later improved for horse-and-buggy travel, and now are arteries of roaring traffic.

Industry began with gristmills and sawmills, run by water power, along the Little Calumet and its tributaries. They ground meal and flour, and sawed lumber, for homes in early Chicago. Now the steel mills, cement plants, refineries and a vast complex of factories, served by railroad, highway and sea-going transportation, have made the Calumet region one of the greatest industrial areas in the world.

It is a floral melting pot -- a meeting place for plants from many regions. Few places on this continent have so many species in so small an area as in the sand dunes of northeastern Indiana. Within a stone's throw of one spot you can find plants of rich woodlands, of prairies and swamps, of northern pine woods and tamarack bogs, and plants of the desert. Some of that has been preserved in the Indiana Dunes State Park, which serves as a natural botanical garden as well as a recreational area. A proposed Dunes National Park would preserve still more of this wonderland.

On a low dune in Shabbona Woods preserve, east of South Holland, is our Sand Ridge Nature center which will be reopened to the public on May 1st.


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