Ancient environment

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Ancient environment

This is a transcript of a QuickTime movie (2.7 MB) recorded in the Pilbara in 2005. Martin Van Kranendonk, of the Geolological Survey of Western Australia, discusses the evidence for an ancient environment at the Dresser formation.


At the famous site where we have taken a lot of people to come and look at the fossil stromatolites, there are a few geological features, which are very compelling for us, as geologists, that help us recognise the ancient environment in which the stromatolites grew. And one of the features that we see is immediately beneath the wrinkled stromatolite layers and the big domes, is a unit of rock that has these textures, these lines of textures, which cut across one another. And they’re the direct result of currents, water currents moving loose sediment on the sea floor back and forth. And the really compelling argument in favour of life growing in that environment of 3.5 billion years ago, is that the fossil stromatolites, which a lot of people have argued about; are they wrinkles, are they mineral growths, are they crusts, what are they? But they are growing directly on these ripples. So we have life on ripples, which is just what we see in so many places today, at beach lines, at Shark Bay where we’ve got stromatolites growing at shore line, it’s just a dread ringer.




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