Scientists discover the oldest known crater on Earth
Though erosion has made it visibly unnoticeable now, scientists have discovered geological features 3.5 billion years old in northwestern Australia that suggest the location is the oldest impact crater known on Earth.
The crater was discovered by geologists at Curtin University and the Geological Survey of Western Australia in the Pilbara region of northwestern Australia. While it’s hard to see directly as a classic crater shape, due to its age, the team found it through other evidence – namely “shatter cones,” geological features that form only when exposed to extreme pressures, like meteorite impacts or underground nuclear explosions.
The newly discovered crater is estimated to be at least 100 km (62 miles) wide, which suggests the original object that crashed into Earth was traveling at more than 36,000 km/h (22,000 mph), and would have caused destruction on a global scale. The impact appears to have occurred 3.47 billion years ago. “Before our discovery, the oldest impact crater was 2.2 billion years old, so this is by far the oldest known crater ever found on Earth,” said Professor Tim Johnson, co-lead author of the study.
You can read the published paper here. There are many assumptions and uncertainty in this conclusion, but it is likely correct.
The impact likely occurred during a time period scientists call the Late Heavy Bombardment, when the planets in the solar system were beginning to accrete out of the thick disk of dust and rocks that surrounded the Sun. On Earth most of the evidence of this bombardment is gone, destroyed by erosion and plate technoics. We only know about it from the craters on the Moon, Mercury, and Mars, where erosion has left those impacts mostly untouched.
Though erosion has made it visibly unnoticeable now, scientists have discovered geological features 3.5 billion years old in northwestern Australia that suggest the location is the oldest impact crater known on Earth.
The crater was discovered by geologists at Curtin University and the Geological Survey of Western Australia in the Pilbara region of northwestern Australia. While it’s hard to see directly as a classic crater shape, due to its age, the team found it through other evidence – namely “shatter cones,” geological features that form only when exposed to extreme pressures, like meteorite impacts or underground nuclear explosions.
The newly discovered crater is estimated to be at least 100 km (62 miles) wide, which suggests the original object that crashed into Earth was traveling at more than 36,000 km/h (22,000 mph), and would have caused destruction on a global scale. The impact appears to have occurred 3.47 billion years ago. “Before our discovery, the oldest impact crater was 2.2 billion years old, so this is by far the oldest known crater ever found on Earth,” said Professor Tim Johnson, co-lead author of the study.
You can read the published paper here. There are many assumptions and uncertainty in this conclusion, but it is likely correct.
The impact likely occurred during a time period scientists call the Late Heavy Bombardment, when the planets in the solar system were beginning to accrete out of the thick disk of dust and rocks that surrounded the Sun. On Earth most of the evidence of this bombardment is gone, destroyed by erosion and plate technoics. We only know about it from the craters on the Moon, Mercury, and Mars, where erosion has left those impacts mostly untouched.