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TXV24

First time collecting micro-fossils

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TXV24

Hi, 

 

I collected some fossiliferous matrix yesterday from the Bembridge Marls Mbr. and Lower Hamstead Mbr. of the Bouldnor Fm. and was wondering if anyone could advise me on the best method to separate the clay from the micro-fossils. I've been interested in collecting micro vertebrate remains alongside the larger material for a while now and received a digital microscope for my birthday last week. I had a go at extracting some from some smaller pieces of matrix I collected last weekend (by simply washing the clay around in a bowl and then repeatedly decanting it) and produced a rodent incisor and various fish bones. I'm worried that just washing the clay around may destroy some of the fossils so I was wondering if there was a safer way to extract them that effectively separates the matrix from the fossils. The matrix itself is from estuarine facies, and is essentially clay that is heavily packed with gastropods, bivalve fragments, and vertebrate material (predominantly fish and crocodilians).  

 

Any help would be really appreciated, 

 

Theo 

 

 

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TXV24

@MarcoSr Thanks so much for your help. I've dried most of it already so have put the dry bits in the water to leave them over night as you suggested, and I'll try sieving them in the morning. Picking over the surface of some of the blocks I've already seen some fish teeth, jaws, and tonnes of vertebrae so if all goes well it should be very productive matrix!

 

Thanks again, 

 

Theo 

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TXV24

@jpc Thank you for the advice I'll make sure to give it a try!

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Yvie

Look forward to seeing your pictures.

 Yvie

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Brittle Star

I have processed a load of clay, as previously stated it has to dry out first, but if you are starting with wet clay break it up so when it dries it is in small pieces. I personally use old casserole dishes to spread the pieces out on then drizzle washing up liquid all over and then pour boiling water over it all to completely cover it. Leave to soak for 24 hours then I get my sieve, 300um catches the smallest visible under a microscope fossils, I have tried a smaller aperture sieve and compared what went through the 300 into it,  came to the conclusion that not worth the man hours as practically nothing got through. Anyway I get an old washing up bowl in the sink, first take off your U bend and put a bucket under it, saves blocking your pipes. Put hand hot water in the bowl then start putting the soaked clay into the sieve and using your hands just swish around and get the clay through the sieve, I have found forcing any remaining lumps through does not damage the fossils, when completely rinsed wash the residue out of the sieve into a shallow dish and leave to dry, personally I do not have the patience and Britain certainly does not have the sun so I dry in the oven, wacking up the heat for 15mins with no harm done as far as I can tell, then I use an old fashioned shaving brush to brush out the residue into a dish then I have a petrie dish lid under my microscope ( I have drawn lines on it with a fine permanent marker to make it easier to look at everything) then I put a pinch of residue into it and then work my way around the dish and tweezer out any fossils I find, being careful of the way you grip them otherwise they will ping off. Do not put so much in that the grains are on top of one another or you will miss fossils.

 

Nearly forgot, it helps to put a larger aperture sieve on top to catch the bigger pieces first and makes life a bit easier

 

I am sure there are more scientific methods, the washing up liquid apparently breaks down the clay, other household things do the same but are more caustic and expensive. It works for me and I have processed pounds of Oxford clay, matrix from the IOW is a doddle after that stuff.

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Coco

Hi,

 

To collect the small fossils of the clay, I well let dry the sediment, and after several operations of soaking in water and sieving, when there is not a lot of clay I soak sediment in some hydrogen peroxide, then there is no more clay at the end of operation.

 

Coco

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Acryzona

 I’ll add my two cents to this discussion  from my experience with Arkona shale. Soaking it overnight in water with some washing detergent seems to break up the clay and clean the smaller fossils. I would recommend getting a set of sieves with different mesh sizes say ranging from 15 mesh down to 80 mesh. Often times you can find these on eBay.  It’s much easier to search washed residue that are all roughly the same size and you’re less likely to miss smaller fossils that are hiding underneath or in the shadow of larger pieces of residue.

But getting back to the washing, you keep washing until the liquid that you decant off is clear and then you’re left with fine grain sand in your screens or bowl. Then you can dry this and use a small triple paintbrush to pick out your finds. With tweezers I’m always concerned about crushing a microfossil.

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