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126 Views 4 Replies Last post: Dec 6, 2017 8:53 AM by Dr T RSS
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Dec 5, 2017 2:45 PM

Possible echinoid and other fossil?

Hi, while patrolling Canford heath nature reserve in Poole I found this (fosa1-4 attached) rock in an old quarry pit at 50.755891,-1.950281

 

Also a week before a colleague of mine found the attached fossil only 20m away from the second find which appears to be an echinoid, can you confirm the finds and also would this area of Poole likely to once have been whithin a shallow sea or is it more likely imported rock as alot of the nearby tracks have been made-up from exported material over the last 100 years.

 

Though I am hopeful that this quarry pit which is currently 64m above sea level once was thriving with sea life.

 

Regards,

Jordon

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    Dec 5, 2017 5:57 PM (in response to Sharpy254)
    Re: Possible echinoid and other fossil?

    Hello and welcome to the forum. You are quite right - these are flint internal casts of parts of sea urchins which are made up from regular  'plates' to form a shell (or test).

     

    ech.jpg

     

    These are from thee Upper (Late) chalkbetween 70 & 85 million years old. There is also a great article on flint, but am unable to find it on my computer at the moment, but I'm sure Dr T will include it.

     

    Regards

    Colin

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    Dec 5, 2017 11:09 PM (in response to Sharpy254)
    Re: Possible echinoid and other fossil?

    Agree fragmented flint casts of echinoids.  Originally lived in the Chalk seabed some 80-85 million years ago but recycled into the younger strata and then again into river gravels during and since the last Ice Age.  I expect your pit is a gravel pit and not a chalk pit?

     

    Bedrock map

    Capture.JPG

    Superficial Deposits map

    Capture1.JPG

    To make this article legible, you need to Rt Clk to Open Link in New Tab, then +

    2014 Mortimore on Flint.jpg

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    Dec 6, 2017 8:53 AM (in response to Sharpy254)
    Re: Possible echinoid and other fossil?

    Flint (silica) is harder than steel and survives a lot of recycling - most of the English Channel coast and offshore seabed is composed of flint from the former extensive cover of >1000ft of flint-bearing Chalk (blue) across almost all the British Isles. 

    chalk-sea_web-schmal crop.jpg

    The lightest green on the Mesozoic map below is the present outcrop of the Chalk

    Compare with the map above and note how much has been eroded and the flint recycled...

     

    The white in the London area comprises rocks overlying the Chalk.  The other white is pre-Mesozoic.

    The top two greens are Cretaceous; the middle three are Jurassic; the bottom two are Triassic.

    UK Mesozoic.jpg

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