Geologists Find 2.2 Billion Year Old Crater In Australian Outback

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  via Science News

  Way out in Yarrabubba, Western Australia, where there's more red dirt than anything else, there is a 44 mile-wide impact crater. Earth is covered in craters and blemishes from meteorites that have hit our planet over the course of its 4.5 billion years of existence. That's very normal for a planet; just look at how many craters our Moon has. The thing with Earth is, since it's full of life, the surface of the planet is changing quite rapidly, obscuring craters that would have otherwise been noticed.

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  via Science Alert

  Until now, geologists thought the Yarrabubba crater was just another ancient crater. It's been known for about 20 years, but when geologists decided to date it with modern dating equipment, it turned out to be 200 million years older than the oldest impact crater known on Earth. The Yarrabubba crater is 2.229 billion years old - half as old as Earth. 

  Around the time the crater was made, Earth was experiencing an ice age. This period is referred to as the early Snowball Earth, a time when the Earth's atmosphere and oceans were still evolving, and becoming more oxygenated. 

  Computer generations posit that when the meteorite hit the Earth, it's likely that it collided with a continental ice sheet, sending huge amounts of rock, dust and ash into the air, like a huge volcanic eruption. This could have spread between 87 trillion and 5,000 trillion kilograms of water vapor into the atmosphere. As water vapor is a greenhouse gas, this event could have helped to modify the planet's climate and thaw it out. 

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  via Science Alert

  The geologists involved in the research were able to figure all of this out by examining the tiny zircon and monazite crystals in the rocks that were affected by the high-pressure shock wave that the meteorite created, damaging atoms and minerals on a minute level. Zircon and monzanite crystals have small amounts of uranium inside them, which decays into lead at a steady rate as it ages. Geologists were able to study this decay and tell how much time had passed, like reading a tree's age through it's rings. 

  Although it is still debated whether this meteorite caused the end of an ice age, it is accepted that extremely old impact events like the Yarrabubba crater definitely affected the Earth's climate history on a big scale. With each new discovery we learn a little more about the evolution of our amazing planet Earth.

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