Post by: chris on 12/10/2020 10:00:31
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Post by: chris on 12/10/2020 11:49:14
Post by: Colin2B on 12/10/2020 15:06:13
...... it doesn't explain the mechanism of its appearance, which I am eager to know...This is a guess, but it looks as though the soft clay has been lying on a bed of pebbles.
Post by: chris on 12/10/2020 17:18:49
This is a guess, but it looks as though the soft clay has been lying on a bed of pebbles.
A good thought. Thanks.
Post by: pensador on 12/10/2020 19:07:08
I was walking in the fields here in Cambridgeshire the other day and picked up this interesting piece. I'm wondering if anyone can explain to me how this pattern forms?
CHRIS-STONE.jpgIt might be caused by trace fossils of something like worms. The cambridgeshire area I think is formed from sediments both from marine and river deposits. The marks might be caused by something like prehistoric lugworms :) unless of course its soft clay thats been laying on a bed of pebbles and not a fossilized piece of rock.
Post by: chris on 12/10/2020 20:20:47
unless of course its soft clay thats been laying on a bed of pebbles and not a fossilized piece of rock.
No, it's a hard chunk of stone!
Post by: chris on 12/10/2020 20:45:47
Post by: chris on 12/10/2020 21:51:40
Post by: Bass on 12/10/2020 22:03:04
Post by: chris on 13/10/2020 09:35:18
Post by: chris on 13/10/2020 09:36:03
Post by: chris on 13/10/2020 09:38:22
(https://assets3.fossilera.com/sp/156035/coral-fossils/708x500%3E/actinocyathus-sp.jpg)
Looks VERY similar, so I think you've hit the nail on the head @Bass
Post by: Petrochemicals on 13/10/2020 23:02:08
Post by: Colin2B on 14/10/2020 09:04:18
PS - I think @Bass you trump the @Colin2B gravel in clay hypothesis!Trump? Trump?
How dare you use that foul word sir? I fear this means rocks at 50 paces.
Not clear from your photo, but do you have any of the central raised pips? There might be one or two lower left, but upper left the hollows look smooth and rounded. Odd that the hollows appear to be of different sizes, does that happen with coral fossils? Is there anywhere the rock is split perpendicular to the surface so you could see whether the pattern goes through?
Would be useful to know age of rock, I was looking for details of local geology and local societies, might be a clue there.
It looks like hexagons to me, straight lines, most efficient construction method I believeYes, but it also occurs incidentally whenever items are packed together eg honeycomb.
Post by: Petrochemicals on 14/10/2020 15:15:36
It could be made by the same process that produce d the giants causeway, maybe even by the same giant.It looks like hexagons to me, straight lines, most efficient construction method I believeYes, but it also occurs incidentally whenever items are packed together eg honeycomb.
Post by: Colin2B on 14/10/2020 17:48:23
It could be made by the same process that produce d the giants causeway, maybe even by the same giant.More likely his next door neighbour, the gnome
Unless @chris is a lot bigger than we assume 8)
Post by: Bored chemist on 14/10/2020 17:50:46
Trump? Trump?There are much ruder words for a fart.
How dare you use that foul word sir?
Post by: pensador on 14/10/2020 17:51:59
It could be made by the same process that produce d the giants causeway, maybe even by the same giant.It looks like hexagons to me, straight lines, most efficient construction method I believeYes, but it also occurs incidentally whenever items are packed together eg honeycomb.
Unlikely, the giants cause way is due to cooling volcanic rock. This is most definately organic in nature, I had been thinking along the lines of pipe rock, but with hindsight it is a piece of coral, as mentioned above.
If global warming raises the sea levels maybe cambridgeshire will go under the sea again, and corals will grow there again. But then again since the acidification of the oceans is increasingly killing of the corals, maybe corals will eventually become extinct.
Post by: pensador on 14/10/2020 17:55:55
A Trump might be a fart in England, but a Johnson is something you pee with in America. :)Trump? Trump?There are much ruder words for a fart.
How dare you use that foul word sir?
Post by: Bored chemist on 14/10/2020 18:57:55
And I'm not sure which is funnier.A Trump might be a fart in England, but a Johnson is something you pee with in America. :)Trump? Trump?There are much ruder words for a fart.
How dare you use that foul word sir?
Post by: chris on 15/10/2020 08:24:57
Not clear from your photo, but do you have any of the central raised pips?
Yes, I think, with the eye of faith, at least one is vaguely discernible: look at the facet above 3 on the ruler in my image - there are markings there that correspond to the central regions in the Moroccan specimen.
Post by: Colin2B on 15/10/2020 14:12:17
Yes, I think, with the eye of faith, at least one is vaguely discernible: look at the facet above 3 on the ruler in my image - there are markings there that correspond to the central regions in the Moroccan specimen.Yes, that’s what I was looking at. Are there any in the other indentations?
In the Moroccan specimen the light coloured lines are visible running down the broken side, indicating the structure goes right through the rock. Any sign of that on your specimen? Perhaps @Bass can help us understand what we are looking at, it appears to be a cluster of anemone corals where the silt has filled in the gaps, just not sure why the lines are there.
You might be interested in this, ammonite eggs in Kimmeridge clay. Although named after the bay, the clays are found in Cambridgeshire and contain a lot of sea creatures. If you look on the rhs of the photo you can see the other half of the impression and how silt fills the gaps.
I had been thinking along the lines of pipe rock, but with hindsight it is a piece of coral, as mentioned above.I agree, in pipe rock the burrows tend to be well spaced like ragworm on the beach.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.southampton.ac.uk%2F%7Eimw%2Fjpg-Weymouth-Relief-Road%2F9WRR-Ammonite-Eggs.jpg&hash=f95a6e1c343ae530640f913cc7dac37c)
Post by: Bass on 15/10/2020 23:47:12
Hard rock suggests limestone- I still vote for coral!
Post by: Colin2B on 16/10/2020 04:22:02
We shall overcomb!;D ;D
Hard rock suggests limestone- I still vote for coral!Yes, I was wondering if you know what we are looking at in the Moroccan coral. Are these originally hexagonal creatures or is this an artefact of the fossilisation process? I’m intrigued by the white boundaries.
@chris look at this pic
The central pips in some of your hollows (lower half) look very much like these structures, but I can’t see clearly from your photo. This is Jurassic coral.
https://www.therockgallery.co.uk/jurassic-coral-unpolished---tisbury-wiltshire-5465-p.asp
Post by: Bored chemist on 16/10/2020 08:43:58
Trumped? We shall overcomb!What's your view on a drop of vinegar?
Hard rock suggests limestone- I still vote for coral!
The acid test?
Post by: chris on 16/10/2020 08:59:23
indicating the structure goes right through the rock. Any sign of that on your specimen?
No, it doesn't go right through, it's a veneer on the surface. The underside is dense brown ?chert.