Stromatolites at Dresser

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Stromatolites at Dresser

This is a transcript of a QuickTime movie (12.4 MB) recorded in the Pilbara in 2005. Martin Van Kranendonk, of the Geolological Survey of Western Australia, describes stromatolites at the Dresser formation.


This outcrop is nice in some ways, talking about diversity, we've got two quite prominent forms that for those of you who aren't familiar with them, particulary yet, but there is this thick black layer through here and when you look at it in detail it's got a lot of irregular texture. And the laminations are fine, crinkly laminations and that’s one aspect that is quite characteristic of modern stromatolites. In the geological context you often get changes in orientation of sedimentary layers, but these are usually quite regular, whereas something which is a microbialite, a stromatolite is one type of microbialite, for those who are not familiar. But they characteristically have a very fine wrinkly lamination because it's made up of variable thickness of a number of microbes. So we've got this one “mat horizon”, the stratiform variety and there is another one and there are several of different layers and in fact there are thin ones all the way through. This is one of the thickest that I've ever seen. But there are other localities with the same kind of thickness. And then you see that there are quite broad amplitude domical structures in the background there and through here, composed in cases of the same wrinkly laminated fine material and in other cases now also silicified. And then over the top you get a plainer sequence of grey and white cherts.




Early Life



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