An eroded impact crater
on Earth of which about 150 are known. Among the largest are the 200-km-wide
Sudbury Crater in Ontario, Canada,
and the 180-km-wide Chicxulub Crater which
extends into the Gulf of Mexico. While some astroblemes are almost 2 billion
years old, about 60% were formed within the past 200 million years.
| Manicougan Crater, Quebec, Canada
AND PLANETARY SCIENCE