Manson impact structure
| Manson impact structure | |
|---|---|
Manson impact location shown in red on bedrock map of Iowa | |
| Impact crater/structure | |
| Confidence | Confirmed |
| Diameter | 35 km (22 mi) |
| Age | 73.8 ± 0.3 Ma Late Cretaceous |
| Exposed | No |
| Drilled | Yes |
| Bolide type | Chondrite |
| Location | |
| Coordinates | 42°35′N 94°33′W / 42.583°N 94.550°W |
| Country | United States |
| State | Iowa |
| Municipality | Manson |
The Manson impact structure is an impact structure near the city of Manson, Iowa where an asteroid or comet nucleus struck the Earth during the Cretaceous Period, approximately 74 Ma. It was one of the largest known impact events to have happened in North America. Previously it was thought to have led to the extinction of the dinosaurs until isotopic ages proved that it was too old.