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1201 Views 3 Replies Last post: Mar 16, 2014 8:56 PM by MikeHardman RSS
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Mar 15, 2014 9:50 PM

What have we found today?? With pics

While out today we found these while in a bit of woodland with a stream. There were around 6-10 of these rocks/fossil shapes about 80cm wide and 30 in depth on average. The texture could only be described as like crocodile/dinosaur skin.  They were quite a site and would love it if someone could help to tell me a little more about them. My children were really excited to think they had found dinosaur egg. I am looking forward to find out more. Many thanks.

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    Mar 16, 2014 12:31 PM (in response to Rock girl)
    Re: What have we found today?? With pics

    I am fairly sure they are concretions, but larger than usual, especially for such ones with such 'crocodile skins'.


    If you were to saw through one, you'd find it criss-crossed by a network of minerals veins (often calcite). Such concretions are often call septarian nodules (there are technical differences between concretion and nodule, but in practice they are often interchanged).

    This page on concretions gives a clue to the range of sizes and forms, including a very nice photo of a septarian nodule sawn-through and polished (a third of the way down, on the right)



    Note that septarian nodules may or may not have the crocodile skin appearance on the outside.

    Sometimes, people think the croc-skin ones are turtle fossils; I have even seen them labelled as such in a museum.


    Septarian nodules can be very attractive, and collectable if so. This Google image search includes many nice ones


    Also note: the term 'septarian' has nothing to do with seven ('sept' in French). It comes from the Latin septum, meaning a partition or dividing wall. With septarian nodules, it relates to the mineral 'walls' dividing the interior.



    Your particular concretions / septarian nodules:

    I would be interested in knowing where you found them. I may be able to dig up some references to them.




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      • Currently Being Moderated
        Mar 16, 2014 8:56 PM (in response to Rock girl)
        Re: What have we found today?? With pics

        I'd need a more accurate location to stand a chance of telling you more (postcode / grid ref / annotated Google Earth map / etc.)

        I think they are rather unsual and distinctive. I would like to think they have been seen and studied before.



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