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| Hell Creek Formation Stratigraphic range: Upper Cretaceous 66.8–66 mya | |
|---|---|
 Exposure in the badlands near Fort Peck Reservoir | |
| Type | Geological formation |
| Underlies | Fort Union Formation |
| Overlies | Fox Hills Formation |
| Lithology | |
| Primary | Claystone, mudstone |
| Other | Sandstone |
| Location | |
| Region | Montana, North Dakota, South Dakota, Wyoming |
| Type section | |
| Named for | Hell Creek, Jordan, Montana |
The Hell Creek Formation is a series of rocks where fossil dinosaurs are found. The strata are mostly Upper Cretaceous and some lower Paleocene rocks in North America.
The name comes from Hell Creek, near Jordan, Montana. The formation includes portions of Montana, North Dakota, South Dakota, and Wyoming.
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