An international team of researchers has found the strongest evidence yet that parts of North America and Antarctica were connected 1.1 billion years ago, long before the supercontinent Pangaea formed.

"I can go to the Franklin Mountains in West Texas and stand next to what was once part of Coats Land in Antarctica," said geochemist Staci Loewy, who led the work. "That's so amazing."

The researchers found that the composition of magnetic isotopes in rocks taken from Antarctica's Coats Land were "indistinguishable from rocks of the Keweenawan province" in Michigan. The U.S. rocks come from a rift that runs from the Great Lakes to Texas.

The two rock samples are reportedly the exact same age and have identical chemical properties.

"Together with paleomagnetic data, this suggests that the Coats Land block was a piece of Laurentia near west Texas 1.1 billion years ago," according to a press release about the research results.

The work strengthens support for the so-called SWEAT hypothesis, which posits that ancestral North America and East Antarctica were joined in an earlier supercontinent called Rodinia. 

Loewy works out of California State University, Bakersfield. The study's results are being published in the September issue of Geology.

On a related note, a recent article at io9 looks at how flaws within diamonds give clues to how the Earth was acting when they were created - and how it's changed.