Hadeon era not so hot
7 May 2005
by Richard
Conan-Davies
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The Hadeon Era (4-4.5 Billion years ago) in the geological timescale is called this from the Greek word for Hell or "Hades" and was presumed to be extremely hot, unpleasant and peppered with constant meteor strikes. But new research from the Australian National Univeristy (ANU) suggests that there was a lot more water present than previously thought and there was a bit more order to things. Geologist Professor Mark Harrison from the ANU, one of the authors of the new study, explained that "The chances are that if you showed up for an afternoon on the early Earth you would have seen blue oceans and sky, continents sticking out with roughly the same mass that we have today, and a fairly ordered environment. Meteorite impacts would have typically created rocks that melted at about 800- 1200°C. But according to a new analysis (measuring tiny amounts of radioactive decay products) of a mineral called zircon in ancient rocks from Jack Hills, Western Australia, suggests that the temperature of melting rocks was around only 690°C. To get such a low temperature there must have been a lot of water around. Having large amounts of water back in the Hadeon Era supports the hypothesis that Earth was an "Ocean World" much earlier than previously thought. This gives life the chance to develop some 700 million years earlier.
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  Artist impression of Hadeon Era according to new studies of zircon. It would have still probably be a fairly steamy place though. |
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Original News release from ANU
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