Impact on Antarctica

19 Aug 2010

At August 17th ... there is a post on the impact crater discovered beneath the ice of Antarctica. At 500km across it is the biggest yet known. It dwarfs the Chicxulub crater in the Yucatan (demise of the dinosaurs) so it must equally have been associated with geological and biological changes - so the reasoning goes. However, dating something under the ice is difficult but scientists have looked around for a suitable 'big' event and noted one at 250 million years ago, at the Permian-Triassic boundary. At this time it is thought almost all animal life on earth died out. The dating is not a guess however as there is a specific geological feature that is probably associated with the crater - a huge rift in the crust between what is now Antarctica and Australia (both once part of Gondwanaland). However, it was not until approximately 100 million years ago that Australia actually split apart - and question marks have even been raised against this date (see earlier posts). The rift, it seems, was something similar to the modern Rift Valley and therefore could have been in existence for a considerable length of time before being divided by the sea (it is now beneath the Indian Ocean).