| Eau Claire Formation | |
|---|---|
| Stratigraphic range: Cambrian | |
 Eau Claire Formation (Middle to Upper Cambrian; Warren County core, Ohio) | |
| Type | Formation |
| Unit of | Munising Group |
| Underlies | Davis Formation, Galesville Sandstone, Kerbel Formation, Knox Dolomite, and Potosi Dolomite |
| Overlies | Mount Simon Sandstone |
| Thickness | 400 to 1000 feet in Indiana [1] |
| Lithology | |
| Primary | Sandstone |
| Other | Siltstone, shale, dolomite |
| Location | |
| Region | Indiana, Illinois, Wisconsin, Michigan, Minnesota, western Ohio, and western Kentucky. Equivalent to the Bonneterre Formation in Missouri [1] |
| Country | United States |
| Type section | |
| Named for | Outcrops along the Eau Claire River, Eau Claire County, Wisconsin [1] |
| Named by | E. O. Ulrich |
The Eau Claire Formation is a geologic formation in the north central United States. It preserves trilobite fossils from the Cambrian Period. [1]
