| 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 |
  Location of the impact structure in Iowa, United States  Manson impact structure (Iowa) | |
The Manson impact structure is an impact structure near the site of Manson, Iowa where an asteroid or comet nucleus struck the Earth during the Cretaceous Period, approximately 74 Ma.[1] It was one of the largest known impact events to have happened in North America.[2] Previously it was thought to have led to the extinction of the dinosaurs until isotopic ages proved that it was too old.[3]
- ^ "Manson". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 2017-10-09.
- ^ "The Manson impact was the biggest thing that has ever occurred on the mainland United States. Of any type. Ever," Bill Bryson, A Short History of Nearly Everything 2003:238.
- ^ Pfeiffer, Eric. "Ancient meteorite standing between one Iowa town and its water supply". Yahoo! News. Retrieved 17 February 2012.