Would you believe that there is a place right here in Central Illinois where one could stand upon the peaks of the Appalachian Mountains? In this same place, you can also look down into the remains of an ancient swamp that had insects with 6 foot wingspans. Sounds like a tall tale to tell around a campfire doesn’t it? But actually, it does exist. And if you have a little imagination and a rudimentary understanding of geology, it’s not a far-fetched thing at all. It’s actually all found within a natural area along the Kickapoo Creek known as Rocky Glen. It is a geological time capsule that offers us a glimpse into the bones of the earth.
On a recent hike lead by Ed Stermer, geology professor and board member of the Friends of Rocky Glen, I was given an insight into the story of Rocky Glen. It goes back some 300 million years, but in this unique natural area, it lies in plain sight. When you first enter the property along a creek, you will see the remains of an old coal mining operation. Piles of Turner Mine Shale, lie all along the creek. A waste product of a mine operation in the late 19th and early 20th century that extracted over 1.8 million tons of Springfield Coal from the earth. It is this coal that has its origins in the swamps of decaying vegetation some 300 million years ago.
Our planet has undergone many changes since then. As the swamps that would become beds of coal were in their prime, the Earth was a much different place. What would become Rocky Glen was close to the equator and at the edge of a shallow sea. To the east, the Appalachian Mountains rose like the Himalayas. Rivers from those tall peaks ran to the shallow sea. Vast amounts of silt, mud, and sand flowed through these rivers and entered the sea, much like the Mississippi River enters the Gulf of Mexico today. Those silts and sands would become deposited and form into sedimentary rocks that grace Rocky Glen today.
The grandest geologic feature in Rocky Glen is the deep sandstone box canyon upstream from the old mine. Here, erosion has opened the earth and exposed a large deposit of sandstone. If you look closely at the sandstone in the sunlight, you will see sparkles of light reflected off of the minerals within. These minerals contain mica, which was found within the Appalachian Mountains to the east. As the mountains were worn down, the mica was carried by water running westward. Rocky Glen is the ghost of the once towering peaks worn away by the eons.
More recently, great sheets of ice repeatedly moved through Illinois, burying the landscape in a hodgepodge of debris. The last time this occurred here was some 18,000 years ago. A long pile of debris formed an earthen dam that blocked the flow of the Kickapoo Creek. This formed a long lake that extended north-west towards where Jubilee College State Park is located today. As ice melted and the lake waters rose, the dam gave way and a torrent of water began scouring the landscape. In a geologic instant, vast amounts of soil were washed from the area, leaving behind only the hard bedrock. Exposing secrets that elsewhere have been hidden by glacial activity. Few places offer this glimpse into the distant past.
Luckily, Rocky Glen has a bright future. The Connaughton family, who had privately owned the land for generations, has patiently worked with both public and private partners to make sure Rocky Glen will be preserved. In a process that involved both IDNR and the City of Peoria, Rocky Glen was recently acquired as public land. The property is now owned by the Peoria Park District and they are working with the Friends of Rocky Glen to develop public access. The rugged terrain created by the unique geological history has created a bit of an access challenge. With no parking or trails available yet, the best way of visiting is to attend one of the monthly guided hikes lead by the Friends of Rocky Glen. To find out more about the hike schedule, visit the FORG website at: http://friendsofrockyglen.org or email friendsofrockyglen@gmail.com. Or you can call me at (309)681-2858.