1. Education
The Kankakee Torrent

Guest Column by GeoT
January 5, 2000

"All along the southbound Odyssey, the train pulls out at Kankakee" -- so wrote Steve Goodman in his song "City of New Orleans." Kankakee was a major station along the Illinois Central Railroad, it had to be for a prestigious train like "The City of New Orleans" to make a stop there. But, there are other interesting aspects to Kankakee as well.

Kankakee is a city in eastern Illinois south of Chicago. The site was first visited by the LaSalle Expedition in 1679. Potawatomies called the place Tiyaracke, it was also known as Theakiki and Quin-que-que by the French, which became the English name Kankakee. Kankakee began to grow when the Illinois Central located a depot there in 1855 - there were better business opportunities for them there than in older and more established Bourbonnais nearby.

But, Kankakee is also the name of a river. A river that begins in Indiana and flows westward into Illinois, it joins the Des Plaines River to form the Illinois River. The modern Illinois River follows the ancient valley of the Mississippi for a long stretch of its flow. We’ll see why.

15,500 years ago found glaciers to the north and east of the Kankakee area melting ­- melting very rapidly! Lobes of ice were in areas now occupied by Lake Michigan, the State of Michigan, and eastern Indiana. Meltwaters were pooled by moraines to the south, and huge lakes formed, but not for long. The moraines were breached, and the result was among the greatest floods of the Pleistocene Epoch. This flood had impact not only in the Kankakee area, but in areas far away as well, southern Illinois in fact! The flood is known as the Kankakee Torrent. There were subsequent episodes of flooding, but none so great at this.

Click here for a topographic map of the area

This area is along the southern bank of the Kankakee River. Look at the long narrow ridges trending to the northwest. Those are gravel bars deposited by the Kankakee Torrent. In places, the force of this flow was great enough to secure some of the dolomite bedrock! Examples can be seen in the gravel bars and as individual boulders on down the valley, in addition to huge glacial erratics released from the tills. The faster flow in the central flood area created a channel followed by the Kankakee River today. Floodwaters were directed westward by a moraine to the south and eventually those floodwaters ‘discovered’ the ancestral Mississippi valley (which had been abandoned) and continued their route to the south via this path. The modern intersection with the old valley of the Mississippi is known as the Big Bend of the Illinois River.

Fly the Illinois River

Click here for a topographic map of the area

Look how the tributary valleys are being deepened to the level of the Kankakee River. Once the flood subsided, the Kankakee outpaced them in downcutting. The tributaries are in the process of adjusting. Follow the steep contours along them to see how far this adjustment has progressed. There are small waterfalls along them, what geomorphologists would call a nickpoint. The place that marks the farthest point of gradient adjustment.

Many miles to the southwest, the Kankakee Torrent had an effect too. This was in the Havana Lowland. This is a shallow basin-like area between Pekin and Beardstown. Today it is a part of the Illinois River valley (relief map). It was in this area southeast of Peoria that the ancestral Mississippi met the Mahomet-Teays River from West Virginia. This lowland had been modified by Illinoian Age glaciers prior to the Kankakee Torrent. The tributary valleys had been filled with glacial drift, but the Mississippi and Mahomet-Teays Rivers remained. When a Wisconsinan Age glacier deposited its terminal moraine to the northwest, the Mississippi was diverted to the western route it follows today. The Havana Lowland and the abandoned Mississippi/Teays valley would await the Kankakee Torrent.

With the overtopping of the moraines to the northeast, the Kankakee Torrent flowed through the Havana Lowland and exited southward down the former valley of the Mississippi/Mahomet-Teays. Again, here, the torrential floodwaters moved immense amounts of sediment and eroded chunks of bedrock along its path. It also formed terraces over much of the surface. But it also created another curious thing here. Armored till balls. These are spheres of sticky clay till that were rolled along with the floodwaters, and collected a coating of pebbles. All the different types of pebbles are quite a rock collection! A very unique geologic specimen!

Click here for a topographic map of the area

This map shows the break in topography between the Wisconsinan age Shelbyville moraine and the surface of the Havana Lowland. The Shelbyville is the terminal moraine of the Wisconsinan stage in this part of Illinois. Look east of the town of Emden to see the Shelbyville moraine front. See the closely spaced contours crossing US Route 136? That’s it! The town of Delavan lays very near the meeting place of the ancestral Mississippi and Mahomet-Teays Rivers. The Havana Lowland is to the west (pan the map to get a better view). South of San Jose is a hummocky area of Illinoian age till. The Illinoian Ridged Plain. Look at Buxtom Hill, a prominent feature here.

In southern Illinois, sediment-laden floodwaters of the Kankakee Torrent and subsequent floods filled valleys with outwash incredibly quickly. Possibly, this filling blocked part of the Mississippi Valley near Cape Girardeau, Missouri and forced the river eastward to its present location from Thebes southward.

The mouth of the ancestral Ohio River was clogged as well which resulted in the Ohio pooling and eventually breaking through a low divide well to the east. Here, the Ohio took over the valley of the ancestral Tennessee River and used this route to join the Mississippi. The Ohio has maintained this more southerly route ever since. Its former valley is now occupied by Bay Creek in the eastern part, and the Cache River in the western. Geologists call these ‘underfit’ streams since they occupy valleys far too large for them to have eroded by their own power. The former Ohio Valley is clearly visible on remote sensed images as well as topographic maps.

Click here for a topographic map of the area

Here is where the Ohio was diverted. Look at the lowland between the hillier areas to see the former Ohio Valley. Look where the Ohio River’s width narrows considerably. This is where the divide was breached. Pan the map westward and then southwestward to see the place the Ohio and Mississippi used to meet before the glacial floodwaters and outwash re-arranged things!

So, melting glaciers many miles to the north not only had an effect locally but also in areas far removed from the Ice Age altogether. And, perhaps, most important of all, is the Illinois River, now known as the Illinois Waterway, that played a key role in the growth of tiny Fort Dearborn into the city of Chicago. And, many years later, the luxurious "City of New Orleans" would run 100 mph through east-central Illinois, except, of course, for that stop at Kankakee!

 

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GeoT is a long-time high school geography teacher from Illinois. In addition to geography, he enjoys railroads and model railroads, old Oldsmobiles, and gardening.

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