| Big Hill Formation | |
| Type: | Formation |
| Age: | Late Ordovician |
| Period: | Late Ordovician |
| Prilithology: | limestone |
| Unitof: | Richmond Group (geology) |
| Underlies: | Manitoulin Dolomite |
| Overlies: | Stonington Formation |
The Big Hill Formation is a geologic formation in Michigan. It preserves fossils dating back to the Ordovician period. A fossiliferous site on the Stonington Peninsula (in Delta County) includes a dolomite bed of the Big Hill Formation which has abundant and well-preserved fossils. The most common fossils are soft-bodied medusae (jellyfish), followed by linguloid brachiopods, algae, and arthropods (namely chasmataspidids, leperditid ostracods, and eurypterids). This site is considered a Konservat-Lagerstätte, and is commonly referred to as the Big Hill Lagerstätte or Big Hill Biota.[1] [2]