The oldest visible impact crater on earth is the 70-kilometer-wide Yarrabubba crater in western Australia. A meteorite struck there 2.2 billion years ago, possibly causing a climate change that changed the whole appearance of the earth. Geologists write that in the scientific journal Nature Communications .
Scientists were already pretty sure that the Yarrabubba in western Australia is the oldest surviving impact crater, but by researching minerals in the soil, geologists could now actually determine an age.
At 2.2 billion years old, the crater is 200 million years older than the second-last. Second place goes to the 300-kilometer Vredefort crater in South Africa.
Presumably the impact of Yarrabubba contributed to a major change in the appearance of the earth. During the precambrium, an era from 4560 million to 542 million years ago, the earth was probably almost completely covered with ice several times. This is also called the 'snowball earth'.
Water vapor from meteorite impact possibly caused climate change
When Yarrabubba drilled himself into this ice crust, it possibly sent a large amount of water vapor into the air. This involves around 87 trillion to 5,000 million kilograms of water vapor.
Water vapor is an important greenhouse gas and the sudden presence of the gas would have caused a strong warming of the global climate.
The research was conducted by scientists from Curtin's School of Earth and Planetary Sciences in Western Australia, as well as researchers from the Johnson Space Center of the American space agency NASA.