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Supercontinents Before Rodinia

Rodinia

Q: I have read that there is evidence for a supercontinent that preceded Rodinia, but I have not seen any evidence or any further explanation. I'd be very grateful if anyone can clarify this possibility.


From Mr Les Strong (October 2009)

Reply by Dr Ted Nield
Thank you for your inquiry about pre-Rodinian supercontinents. Of course the short and cheeky answer might be: “buy my book “Supercontinent"!…. But the more informative answer would be that the number and names of supercontinents before Rodinia rather depends on who you ask.

The Earth seems to run a very rough cycle from supercontinent to supercontinent lasting in the order of 500-600 million years. This makes it the longest cycle in the whole of nature, and three times longer than the time it takes for our Solar System to orbit the galaxy.

Establishing the existence of a supercontinent before Pangaea (the latest one to disperse) is extremely difficult as most of the obvious evidence has been destroyed - and the further back you go, the more has been lost. Pangaea broke up about 250 million years ago and Rodinia about 760 million years ago. In between these two, some authors place another, Pannotia, which they say broke up at 550 million. Personally I have no truck with Pannotia.

Rodinia is thought to have assembled at 1.1 billion years. Before that at 1.8 billion came the possible assembly of a supercontinent known as Nuna or Columbia, and at 2.5 billion the assembly of Kenorland. A very early continental mass may be represented by Ur at 3 billion years.

The book to consult for possible reconstructions of these highly speculative early supercontinents is “Continents and Supercontinents” by Rogers and Santosh (Oxford University Press). This is a graduate level textbook. I do not go so much into specifics in my book, but I do examine the methods whereby geologists can, using Samarium and Neodymium isotopes, work out details of former supercontinental masses for which all other evidence has long ago been effaced.