Illinois River Sandstone Bluffs, Starved Rock State Park - Utica, IL - Places of Geologic Significance on Waymarking.com

In Utica, on the south side of the Illinois River, is Starved Rock State Park, known for its great sandstone cliffs that overlook the mighty Illinois River. You might think that these cliffs were carved over thousands of years of gradual erosion by the river. However, these cliffs were scoured out in a matter of weeks by a cataclismic event called the Kankakee Torrent.

In fact, the entire upper Illinois River valley was carved out by this event. The bluffs are regularly high above the river and define a valley over a mile wide. Here, as well as nearby Buffalo Rock and Matthiesson State Parks, have features that particularly exhibit the forces involved in forming the upper Illinois River valley.

Most of the geological information came from the book, "Geology Underfoot in Illinois."

Entrance to the park is via IL Route 178 which runs north to Utica and is just north of the intersection with IL Route 71. The access road runs to a parking lot at the end. It is highly recommended that you go to the visitor center. There is a great 3-D map of the park showing the bluffs and canyons. There are also other natural science displays and a desk where staff can give you a map and point out specific features of the park. All of this is available at no charge. You can also download a trail map from the park web page.

The park is a great place to walk around. You don't have to be in top physical condition; however, there are a lot of stairs that cover elevation differences often over 100 ft. Check the web site or contact the state park for information concerning access questions.

There are several features in particular to see. Starved Rock is the first feature you encounter. It is a pillar of rock that once was where a fort was built by French explorers. Once you are up there, you have exceptional views of the Illinois River and the Starved Rock Lock and Dam that manages the water level and boat/barge traffic. There is also an island in the middle of the river that is known for spotting wintering bald eagles. Nearby is another outcrop that includes the viewing areas of Lover's Leap and Eagle Cliff. From there there are two paths: one that runs along the river shore at river-level and one that runs on the edge of the bluff at the top. There are connecting trails that traverse the bluff edge. From the base trail, several spurs run into the canyons where you can see the layered sandstone walls, mostly off-white to yellow in color. Canyon names include: French, Wildcat, Tonty, La Salle, Owl, Hidden, Hennepin, and Ottawa-Kaskaskia, and Illinois. If you can't make it to all of these canyons by foot (the last one are at least two miles straight from the visitor center) there are other parking spots available along Route 71.

The geological processes involved include ancient, slow changing processes (rock formations), and relatively modern fast changing processes (glacial erosion).

The rock formations were laid down over millions of years during the Ordovician and Pennsylvanian periods. The older and more conspicuous stone is the St. Peter sandstone, which is the off-white mineral. Then there are several narrow layers, including a layer of Colchester (No. 2) coal. Then, there is a thick top layer of gray shale that is topped by modern soil. There are other geological features involved including the La Salle anticlinorium, a feature where anti-clines or folds in the earth's crust can be located.

Illinois had two to three major glacier periods that at least partially covered the present day state. During the last great period, the Wisconsian, glaciers advanced to the northeastern part of Illinois, then retreated to modern Wisconsin and Michigan. Receding glaciers left moraines, some of which retained glacial meltwater. About 4,500 years ago, the moraines holding the meltwater gave way, and literally a wall of water over a 100 ft high and up to 180 ft high travelled west. These cliffs were carved in that initial torrent, then deepened by subsequent flows that came later. The torrents also went up the channels of ancient tributaries and widened the channels, forming the canyons today. Other erosion processes have further shaped the bluffs and canyons. Due to the different erosion levels of the sandstone, the water from today's brooks often cascade down several levels instead of one drop (no water was running at the time of visit due to it being late summer and the area being in a moderate drought).

Imagine being an early Native American in the area during that time. Suddenly, a tsunami-like wall of water comes through, possibly cutting you off from your family for weeks. In a few weeks, the landscape that you were familiar with is changed dramatically.

This park is definitely worth stopping to visit no matter how long you have. It is likely that several visits might be necessary to get the full experience.

Source:

Wiggers, Raymond. Geology Underfoot in Illinois. Mountain Press Publishing, Missoula, MT, 1997 (4th Printing 2009).

Waymark is confirmed to be publicly accessible: yes Access fee (In local currency): .00 Requires a high clearance vehicle to visit.: no Requires 4x4 vehicle to visit.: no Public Transport available: no Website reference: [Web Link] Parking Coordinates: Not Listed

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