The entire county of Jennings was once covered by glaciers. The southern limit of the Illinoian ice sheet stopped around Bloomington, yet curved south to extend into Kentucky, covering all of Jennings. The Wisconsinan ice sheet stopped just north of Jennings County. Most of the county is covered by Illinois age drift, with a small band being Wisconsin in age. The glaciers are responsible for our mainly hard and compact clay soils and the rolling hills and meandering river.

The geologic ages of the formations near the surface are from the Quaternary, Devonian, and Silurian time periods. Most of the bedrock in the county is Devonian age limestone and shale. Much of the limestone, shale, and dolomite have been quarried for various purposes. All of these bedrocks were formed millions (350 approximately) of years ago as sediments accumulated on the ocean’s floor. Most of the county is under-laid with limestone. Certain bands of the exposed limestone is considered moderately fossiliferous. Exposed stone at the Vinegar Mill will show hundreds of thousands of different species preserved in the limestone. 

       Fossils at the Vinegar Mill                 Fossils at the Vinegar Mill          

Due to the limestone bedrock, Jennings County has numerous caves. Although most of the caves are not very large, the area attracts and supports many cavers. The caves are particularly suited for beginners and youth groups, such as scouting groups. Individuals from the Indiana Grotto Association are often in the county and can be contacted for more information.

Muscatatuck Falls (actually a limestone spring)

There are also many springs in Jennings. The Muscatatuck Park has a natural spring that opens up in a hill side and is often mistaken for only a falls. It does drain the natural hill side water, yet is connected to a underground system of water holding limestone caverns. Water will often come out during very dry periods and seems out of place. 

Rock Rest Falls in Cali State Nature Preserve

Due to the large amounts of rainfall and the limestone bedrock under most of Jennings, the county has numerous water falls. The Muscatatuck Park has many medium to small sized falls. The shale falls are often bowl shaped, where as the limestone falls are more blocky in nature. Shale falls are also found above and a bit away from lower limestone falls. These falls do not run at all times, but can be quite picturesque when flowing with either ice or water.

The highest point in the county is located in the Northeast corner and is slightly more than 890 feet above sea level. The lowest point in the county is 540 feet above sea level.

For information concerning caving opportunities in the county, please contact:

IDNR, Crosley S.F.W.    (812)-346-5596

Indiana Grotto Association    (317)-

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