When we talk about Earth, the first impression that comes to our minds is solid, with a crust made of moving tectonic plates. And nobody would have imagined that gases would provide vital information about this solid surface's evolution.

But noble or inert gases, such as helium, argon and neon, inside the earth's thickest layer, the mantle, have given clues about the planet's birth.

In a research published in Nature Geoscience, lead author Dr. Mark Kendrick from the University of Melbourne's School of Earth Sciences said inert gases trapped inside the Earth's interior provide important clues into the processes responsible for the birth of our planet and the subsequent evolution of its oceans and atmosphere.

The new study defies the earlier conclusion that neon and other noble gases arrived on the planet only with meteorites. It shows the mixing of atmospheric gases in the mantle during subduction -- the process in which one plate is pushed underneath another plate into the underlying mantle when plates collide.

This finding is important because it was previously believed that inert gases inside the Earth had primordial origins and were trapped during the formation of the solar system, Kendrick was quoted by eurekalert.org as saying.

To conclude their research, the researchers analyzed noble gases and halogens trapped inside serpentinite rocks collected from mountain belts in Italy and Spain. These rocks were formed on the sea floor and were partly subducted into the Earth's interior before being uplifted to their current positions by the collision of the European and African plates.

Our study suggests a more complex history in which gases were also dissolved into the Earth while it was still covered by a molten layer, during the birth of the solar system, Kendrick said.

The study was done in collaboration with researchers from the Australian National University, Canberra, and The University of Genoa, Italy.