Scientists at Montreal's McGill University have added to the common theory about how the Earth's crust was created.

Don Baker and Kassandra Sofonio looked into a theory that not all of the Earth's crust was formed from the inside out, but that some of the crust fell to Earth from the atmosphere, Baker told CBC News in an interview.

He described it as "raining marbles," or silicate rain, formed by the high temperatures on the Earth's surface.

"These dissolved minerals rose to the upper atmosphere and cooled off, and then these silicate materials that were dissolved at the surface would start to separate out and fall back to Earth," Baker said.

This process helped create some of the earliest rock specimens known today.

Baker and Sofonio tested their theory in a lab using a mixture of silicate earth materials and water, put under extreme temperatures and high pressure, the results are published in the journal Earth and Planetary Science Letters.

A depiction of the process researchers believe helped form the Earth's crust. (Don Baker and Kassandra Sofonio/Earth and Planetary Science Letters)

The discovery could help other researchers trying to find signs of life on other planets, Baker said, explaining silicate rain is believed to have been observed on some exoplanets.

"Because the Earth was made this way, and we're looking for Earth-like planets, we may want to look for other planets that have evidence of this sort of mechanism occurring," he said. "It's another bit of evidence to look for."