Asteroid Earth
The flow of material inside and outside a crater called Aelia on the surface of the giant asteroid Vesta is seen in this composite handout image from NASA's Dawn mission provided by NASA's Jet Propulsion Laboratory on December 16, 2013. Reuters/NASA

Ever imagined how crystals formed inside Earth’s crust? Until recently, it was thought that plate tectonics created earth’s crystals. However, a new study, published in the journal Geology, has revealed something very different about ancient and oldest crystals. Researchers are of the opinion that violent asteroids from space bombarded a very young earth. These massive impacts left craters on earth’s crust. The oldest crystals were formed inside these craters. Interestingly, all this happened not long after earth was formed, about 4 billion years ago.

Rocks that formed as our planet formed have been instrumental in revealing details of early signs of life, climate variations over time and also when water first appeared on our planet. The ancient rocks in question are known as zircon crystals. The researchers from Trinity College in Dublin examined a relatively new impact crater to find out whether the same rocks resided there. This led to a brilliant discovery suggesting that the crystals came from asteroid impacts.

Scientists picked up innumerable zircons from the Sudbury impact crater in Ontario, Canada. This crater is believed to be nearly 2 billion years old. The scientists were mesmerised to find, as opposed to popular belief, that the very ancient zircon crystals were indeed formed in impact craters. To verify their results, the scientists compared the 2-billion years old crystals to crystals that are much more ancient (more than 4 billion years old). The results were the same. The hypothesis proved right.

“There's a lot we still don't fully understand about these little guys but it looks like we may now be able to form a more coherent story of Earth's early years. One which fits with the idea that our planet suffered far more frequent bombardment from asteroids early on than it has in relatively recent times” said lead researcher of the study, Gavin Kenny, in a press release.

The plate tectonic theory, which has been there for the past 10 years or so, is not being accepted by many scientists who are of the opinion that tectonic movements did not happen during the early stages of earth’s life. Even if they did, they were not happening the same way as we know of today.