Oak Park in Cook County, Illinois — The American Midwest (Great Lakes)

Volcanoes

Photographed by Sean P. Flynn, March 27, 2025

1. Volcanoes Marker

Inscription.
1.5 Billion Years Ago

Illinois is dominated by volcanoes

Topics. This historical marker is listed in these topic lists: Parks & Recreational Areas • Science & Medicine.

Location. 41° 53.076′ N, 87° 48.104′ W. Marker is in Oak Park, Illinois, in Cook County. It is on South Marion Street 0.1 miles south of Pleasant Street, on the right when traveling north. The stone is a part of the labyrinth located on the western edge of Mills Park. Touch for map. Marker is at or near this postal address: 217 Home Avenue, Oak Park IL 60302, 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 25 other markers are within walking distance of this marker: Solar System (here, next to this marker);

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Cambrian Sea (here, next to this marker); Ancient Illinois Climate (here, next to this marker); Amphibians (a few steps from this marker); Illinois Tulley Monster (a few steps from this marker); The Age of Mammals (a few steps from this marker); Sabre Tooth Tigers (a few steps from this marker); Beginning of the Wisconsin Ice Age (a few steps from this marker); Oak Park Sand Spit (within shouting distance of this marker); End of the Wisconsin Ice Age (within shouting distance of this marker); Hunter Gatherers (within shouting distance of this marker); Oak Savanna (within shouting distance of this marker); Potowatamie (within shouting distance of this marker); First European Settlers in Illinois (within shouting distance of this marker); Mills Park Labyrinth (within shouting distance of this marker); The Kettlestrings (within shouting distance of this marker); Pleasant Home Foundation (within shouting distance of this marker); Mills Park and Pleasant Home (within shouting distance of this marker); Mills Estate Purchase (within shouting distance of this marker); Herbert S. Mills (within shouting distance of this marker); Village of Oak Park

Mills Park Labyrinth image. Click for full size.

Photographed by Sean P. Flynn, March 27, 2025

2. Mills Park Labyrinth

(within shouting distance of this marker); Pleasant Home (within shouting distance of this marker); a different marker also named Mills Park and Pleasant Home (about 300 feet away, measured in a direct line); a different marker also named Mills Park and Pleasant Home (about 400 feet away); a different marker also named Mills Park and Pleasant Home (about 400 feet away). Touch for a list and map of all markers in Oak Park.

More about this marker. The stone is one of about 20 pavers in Mills Park that show the history of Oak Park from the dawn of the solar system through 2012. The pavers are part of a labyrinth embedded into the ground near the western entrance into Mills Park.

This particular stone is quite weathered and the words are hard to make out.

Related marker. Click here for another marker that is related to this marker. The Mills Park Labyrinth marker page includes a list of all 21 stones in the labyrinth in chronological order

Also see . . . Megafloods, megaquakes, and more unusual Illinois geology facts. This 2022 article from the Illinois State Geological Survey includes a description of Illinois'

Photographed by Sean P. Flynn, March 27, 2025

3. Mills Park labyrinth

only current "volcano," in the southeastern part of the state.

Excerpt: “[Illinois'] 'volcano is called Hicks Dome. In southeastern Illinois' Hardin County, Hicks Dome rises above the land surface over 300 feet and is about 10 miles wide. Its rocks are uplifted about 4,000 feet, with older rocks (Devonian) in the center, concentric rings of younger rocks (Pennsylvanian being the youngest), and many faults within. It has been interpreted as resulting from explosions beneath the surface and therefore is referred to as a 'cryptoexplosive' or 'cryptovolcanic' feature. It formed during the Permian, about 270 million years ago. The region of Hicks Dome is rich in fluorite and other minerals.”

(Submitted on March 29, 2025, by Sean P. Flynn of Oak Park, Illinois.)

Photographed by Sean P. Flynn, March 27, 2025

4. Mills Park labyrinth

A nearby historical marker says that the labyrinth's artistic style was inspired by the architect George W. Maher, who designed the Pleasant Home, located in this park.

Credits. This page was last revised on March 31, 2025. It was originally submitted on March 29, 2025, by Sean P. Flynn of Oak Park, Illinois. This page has been viewed 113 times since then and 11 times this year. Photos: 1, 2. submitted on March 29, 2025, by Sean P. Flynn of Oak Park, Illinois. 3, 4. submitted on March 27, 2025, by Sean P. Flynn of Oak Park, Illinois.