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Up to Discussions in Fossils and rocks
456 Views 14 Replies Last post: Aug 10, 2018 9:59 AM by garymunro RSS
garymunro Novice
garymunro
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Jul 19, 2018 12:49 PM

Is this a fossil or preserved oyster shell?

P1040338.JPGI found this many years ago whilst operating an excavator in Oxfordshire.

P1040336.JPG

 

Message was edited by: garymunro

  • Dr T Master
    Dr T
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    Jul 19, 2018 5:22 PM (in response to garymunro)
    Re: Is this a fossil or preserved oyster shell?

    This is a fossil oyster - maybe from the Upper Jurassic Oxford Clay - possibly Gryphaea dilatata

    If so, then about 160 million years old.

    If you can give the exact location I can post the relevant geology map.

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    • garymunro Novice
      garymunro
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      Aug 7, 2018 4:30 PM (in response to Dr T)
      Re: Is this a fossil or preserved oyster shell?

      Hello Dr T

      Sorry for delay the fossil was found just North of the M4 and just West of the A34 literally a couple or so miles past and to the left of where the two roads cross eachother.

      The area is covered in aggregate extraction points many of which are now freshwater fishing lakes.

      Apparently these mineral deposits were laid down during the last Ice age and the river Thames at that location, was eight miles wide. How true that is much your territory. Thank you for your time :)

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      • Dr T Master
        Dr T
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        Aug 7, 2018 6:37 PM (in response to garymunro)
        Re: Is this a fossil or preserved oyster shell?

        If you mean near Chieveley (from which I am sending this) then your fossil is not in place.  All the rocks in this area are Upper Cretaceous Chalk or superficial deposits derived from it.  There are no extraction points so I think you have the wrong location info.  Please try again and mark it on a snip of a Google map - thanks

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        • garymunro Novice
          garymunro
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          Aug 7, 2018 8:29 PM (in response to Dr T)
          Re: Is this a fossil or preserved oyster shell?

          Your right, thinking back, I came off at the Wantage road, think it was East Isley area fairly close to the A34

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          • Dr T Master
            Dr T
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            Aug 8, 2018 8:35 AM (in response to garymunro)
            Re: Is this a fossil or preserved oyster shell?

            If was was excavated in situ from bedrock then it must have come fom the Oxford Clay (OC on the map). Otherwise it had been dumped by man or transported by rivers during and after the Ice Ages..  Was it a deep excavation with dark grey sticky clay or was it gravel?

             

            Lft Clk to enlarge

             

            Bedrock Geology Map:-

            Capture.JPG

            Superficial Deposits:-

            Capture.JPG

             

            Most of the gravel extraction was in the Theale-Reading area and the Staines-Heathrow area further south and east

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            • garymunro Novice
              garymunro
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              Aug 8, 2018 3:04 PM (in response to Dr T)
              Re: Is this a fossil or preserved oyster shell?

              The area we were digging had been stripped of overburden there was a layer of graded gravel about 3m deep and then dark grey clay. There was a pump sump dug in 1corner of the cut and the fossil was in the spoil from the sump pit. There also seemed to be huge snail like shapes in the pile but they just fell apart and seemed to be made entirely of clay. Hope this is helpful. The excavated gravel went via a conveyor straight into a concrete batching plant on the site.

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  • Dr T Master
    Dr T
    Currently Being Moderated
    Jul 25, 2018 3:51 PM (in response to garymunro)
    Re: Is this a fossil or preserved oyster shell?

    Please mark this as Answered - thx

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