Tasmania was once wedged between Antarctica and North America, according to new research by geologists looking at the island state's former distance from mainland Australia.

The discovery by Tasmanian geologists came about by comparing rocks from Tasmania with sediment in places now vastly disconnected from the island.

PhD student at University of Tasmania Jacob Mulder had been researching rocks in Tasmania's north-west in a follow up to study by Dr Jacqueline Halpin from the ARC Centre of Excellence in Ore Deposits.

The pair found sedimentary rocks in the Rocky Cape Group had similarities to rocks from western areas of North America, when that continent was the Nuna supercontinent more than 1.4 billion years ago.

"It looks like a large size of this rock package was from North America, but there are also some signatures of Antarctic geology there in the Tasmanian rock," Mr Mulder told 936 ABC Hobart.

"They're transitional, between Antarctica and North America, which allows us to suggest that Tasmania sat somewhere between those continents."

Mr Mulder and Dr Halpin focused on single grains from the sedimentary rocks, called zircon which is robust and does not break down.

"Our earth is dynamic and it moves and it continues to move," Dr Halpin said.

"These are now rocks, they're no longer sand," she said.

Dr Halpin said the different grains within the rocks allowed age to be verified by isotope.

Drifting island caught in the sand

Dr Jacqueline Halpin and PhD student Jacob Mulder have found that the state was once far from mainland Australia. ( 936 ABC Hobart: Damien Peck )

Compiling data from other continents meant Mr Mulder was able to compare samples taken from the Rocky Cape Group and ascertain that Tasmania has been drifting further from mainland Australia than once thought.

"Jacquie's work showed that these rocks were very similar in age to a package of rocks that are now exposed throughout western North America," Mr Mulder said.

"It turns out they were far older than we thought... half a billion years older than we thought they were."

The rocks studied by the pair carried further messages about their origins.

"We looked at those kind of imprints in the rocks and we were able to look at which direction the sand was coming from at the time," Dr Halpin said.

"That sand was mainly coming from North America and east-Antarctica."

Mr Mulder said he had hit the jackpot with his PhD research and was pretty happy with the results.

"It's not bad looking at some pretty interesting rocks in your own backyard," he said.

