Saturday Science: Wanderers

No, I'm not talking about comets or dessert nomads or the like, this is about continents. We tend to think of continental drift, if we think of it at all, as a slow, stately dance that follows a regular pattern. What we tend to forget is that the driving force, the convenction currents in the earth's mantle, change strength and direction -- they're no more permanent than anything else in the universe. For example, we're used to thinking of the configuration of continents as it exists now as sort of the template for the way it always was. Except that the breakup of Pangaea happened about 175 million years ago, and this sort of thing -- the continents moving around, joining and splitting, has been going on for over 3 billion years.

So we really shouldn't be surprised when geologists discover something like this:

Curtin University researchers have discovered rocks in northern Queensland that bear striking similarities to those found in North America, suggesting that part of northern Australia was actually part of North America 1.7 billion years ago.

The research paper in GEOLOGY published by the Geological Society of America, concluded that the rocks found in Georgetown, 412 kilometres west of Cairns, have signatures that are unknown in Australia and instead have a surprising resemblance to rocks found in Canada today.

Curtin University PhD student Adam Nordsvan from the School of Earth and Planetary Sciences said the findings were significant as they unlock important information about the 1.6 billion year old supercontinent Nuna.

“Our research shows that about 1.7 billion years ago, Georgetown rocks were deposited into a shallow sea when the region was part of North America. Georgetown then broke away from North America and collided with the Mount Isa region of northern Australia around 100 million years later,” Mr Nordsvan said.

“This was a critical part of global continental reorganisation when almost all continents on Earth assembled to form the supercontinent called Nuna.

So Pangaea was not the first supercontinent, by a long shot.

The article at the link is fairly brief but also interesting, and has a link to the full paper (which you can purchase if you're really interested).