Summit in Cook County, Illinois — The American Midwest (Great Lakes)
Glaciers and Prairie
Photographed by Sean P. Flynn, January 9, 2025
1. Glaciers and Prairie Marker
Glaciers:
The continental glaciers of the Great Ice Age scoured and scraped the land surface, pushing up chunks of bedrock and grinding them against each other and along the ground surface as the rock-laden ice sheets pushed southward.
Uncovered during construction of the nearby Spark Recreation Center, the rock in front of you is called a glacial erratic. It was carried and shaped in the glacial ice flowing south from northern Wisconsin or Michigan and deposited here at the end of the last ice age about 15,000 years ago.
Gouged grooves, parallel striations (scratch marks) and polished surfaces were formed when this boulder ground against other rock formations and sand grains in the moving glacial ice.
Prairies:
By the early 1800s, a tall grass prairie environment covered much of the area. Glacial deposits formed the parent soils, which were enriched over thousands of years by thick prairie vegetation. The fertile prairie sales are ideal for farming, and today the prairie in Illinois has largely been converted to farmland. Native prairie plants are growing around the glacial boulder in front of you.
Big Blue Stem grass sometimes grew tall enough to hide a person on horseback.
Erected by
this page online
Topics. This historical marker is listed in these topic lists: Agriculture • Environment • Horticulture & Forestry • Science & Medicine.
Location. 41° 47.234′ N, 87° 48.761′ W. Marker has been reported unreadable. Marker is in Summit, Illinois, in Cook County. It is on Archer Road (Illinois Route 171) south of 57th Street, on the right when traveling south. The boulder and its historical marker are just south of the recreation center building, located in Summit Park. Touch for map. Marker is at or near this postal address: 5700 South Archer Road, Summit Argo IL 60501, United States of America. Touch for directions.
Regionally, this marker is in Greater Chicago. It is also in the American Midwest and on the Great Lakes. Globally, it is in North America, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once the Viceroyalty of New France, the territory of the Mississippian Culture, and the Northwest Territory.
Other nearby markers. At least 8 other markers are within walking distance of this location: Veterans Memorial (a few steps from this marker); Father Marquette Landed Here (about 600 feet away, measured in a direct line); The Freedom Run (about 600 feet away); 9/11 Memorial (approx. 0.4 miles away); a different marker also named The Freedom Run (approx. 0.4 miles away); 3 Anti-Tank Gun M5 (approx. 0.6 miles away); Argo-Summit American Legion Post 735 (approx. 0.7 miles away); Mamie Till-Mobley (approx. 0.8 miles away). Touch for a list and map of all markers in Summit.
More about this marker. The marker has eroded over time and is barely readable; the text on this page may be slightly erroneous as a result.
Photographed by Sean P. Flynn, January 9, 2025
2. Glaciers and Prairie Marker
The glacial stone described on this marker is immediately behind it; Archer Road (IL-171) is the road on the rise in the distance.
Incidentally, another historical marker in this park, about 600 feet southeast of here and dedicated to Fr. Jacques Marquette and his encampment in the Summit area in 1675, is also composed of ancient glacial boulders that had been deposited in the area.
Also see . . .
1. National Park Service: Glacial Erratics. (Submitted on January 9, 2025, by Sean P. Flynn of Oak Park, Illinois.)
2. Summit Park District official site. (Submitted on January 9, 2025, by Sean P. Flynn of Oak Park, Illinois.)
Photographed by Sean P. Flynn, January 9, 2025
3. Summit Park
The rec center is on the left, the glacial stone and marker are center background, and a veterans memorial (partially obscured by the tree) is in the right side, in front of the picnic shelter.
Credits. This page was last revised on January 9, 2025. It was originally submitted on January 9, 2025, by Sean P. Flynn of Oak Park, Illinois. This page has been viewed 270 times since then and 50 times this year. Photos: 1, 2, 3. submitted on January 9, 2025, by Sean P. Flynn of Oak Park, Illinois.
