Sandyforth Opencast

[ammocarbsteve]

a small rhizodont jaw....

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[ammocarbsteve]

not a lot of fossils filling just one drawer for many many hours collecting and effort getting there every night but well worth the effort producing some nice material I had not previously come across...

[Joe Botting]

This really is excellent, Steve. It's clearly written as an informal summary rather than a scientific document, but all the information is there, and you've got good arguments too. You've even picked up on some of the most interesting bits of information, such as the rarity of the nodules above the Wigan 4', given their abundance and productivity at Crockhey. This, of course, is all to do with changes in the chemistry, sedimentology and ecology across the Carboniferous landscape. I don't honestly understand why you get so many more nodules at one site than another, and I haven't seen that addressed in papers, even though there has been a lot of work describing the detailed chemical formation process (e.g. eprints.whiterose.ac.uk/399/1/raiswellr5.pdf). The latter show that they formed as a result of methanogenesis - bacterial action in anoxic conditions - and therefore the very high sedimentation rate that you note was critical to the nodules growing prior to decay of the carcasses. All this is useful.

What strikes me is that this gives the impression of being an unusually-vertebrate oriented collection, with relatively few plants. Why, one wonders? Were there lots of poorly-preserved plant fragments as well, suggesting that the conditions allowed most to decay before burial? (I think that's what you're saying.) That would fit with the remains being dominated by fish hard tissues, which would last longer - so was this then mostly a site with lower sedimentation than normal? Perhaps it was away from the major channels, in a semi-permanent pool or lake area, so that even in floods the sediment supply would be lower than elsewhere. This could be tested by looking at the balance of different plants; if I remember rightly, the horsetails dominated at the edges of main channels, then it goes rapidly into lycopod-dominated floodplain, with the seed-ferns and other groups mainly growing further away. What you say about the plants that turned up might support your idea of a marginal levee area, which also fits well with the juvenile fish argument. Basically, it all seems to fit together.
If you have a healthy population of fish, then this must have been a pretty permanent (and therefore deep) feature. If it represented something like an old ox-bow, though, then there should be clear evidence in the sedimentology, in the form of sandbars somewhere in the muddy sequence. I'm guessing, of course - there isn't quite enough to go on, even though what you've written is a superb start. You can see what I mean, though, I hope, about all the different bits of information that become relevant when you're trying to piece it all together. I often use the phrase that you did - it's all part of a jigsaw.

As for the fossils themselves, the most exciting for me are the little syncarids. To find five in a small area in one day is very interesting indeed, and potentially allows a better characterisation of their preferred habitat (if we can work out what that was...). The question is, did you find other creatures along with them or was that little patch dominated by the syncarid? Likewise for each productive band - keep the data for each faunule separate, and they becomes much more informative. Those syncarids, though, are the only case I can see of the best sort of preservation. The black mudstone/siltstone with the rhizodont jaw is lovely, of course, but didn't need exceptional preservation. If one was targeting one place for future digs, then that one has the most potential (shame the site's closed, really...).

Finally for now, I completely agree with the importance of documenting each site that one works on in some form - they might not all produce wonders, but whatever they produce (even nothing) is useful and interesting information in the grand scheme of things. Can I suggest trying to formalise this a little bit more, just for your own benefit and any readers? Even some clearer organisation would make a difference - introduction to site (with a map), sedimentology with log, flora (and distribution), fauna (and distribution), comparison with Crockhey (and elsewhere), discussion. It's got a partial shape already, but just putting things in a rigorously thorough form can help to clarify one's thoughts a lot.

If you can put it together with good fossil illustrations, then turn it into a pdf, it's also easily put up on the web somewhere. Alternatively, it could be the beginning of an e-book documenting the faunas and floras from of the Lancashire/Staffordhire coal pits... etc. As I say, there would be an audience for a book like that - not a huge one, but definitely an audience. Even a little pamphlet-like book for a nominal 50p on amazon would at least make it accessible. So many options, so little time...

For the Builth Inlier, we have a grand plan for publishing the Big Book of Fossils one day, documenting all the sites, faunas, ecology and so on. It might be a few decades away yet, though. At the moment, we've got a database of all the occurrences in our l30-odd localities, but it's very hard to keep up...

[ammocarbsteve]

Hi Joe.... Thanks and glad you like it.... I suppose it is more of a summary of my experiences there fossil finds and a bit of history and I take on board what you say about more structure to the format... I can look at that sometime....

You are right about the plant material it was poorly preserved and fragmentary usually in a compact shale layer often unrecognisable in form other than 'plant'...apart from some calamites casts which seemed to come from one area although all this material is ex situ....There was also the usual non marine bivalve layer you tend to come across in these exposures....I think you could be right about a permanent lake of some type certainly whthe fine dark sediment was laid down...

Heres a 'double' syncarid.... Not as well preserved as the single and as you say strange to all occur from one area (a couple of truckloads in one area on the spoil heap)....

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[ammocarbsteve]

These were all we found together that day but as I said nodules were very uncommon which we found strange but experience collecting carb sites has taught me not to expect prolific numbers of fossils every time....We picked the area clean smashing the shale blocks up looking for nodules and it was all dug over and reburied down the main hole the day after...`

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[pleecan (Peter Lee)]

Excellent Post Steve!!!!!!!! Well done!

[Joe Botting]

Jan 17, 2014 15:39:29 GMT -5 ammocarbsteve said:

Hi Joe.... Thanks and glad you like it.... I suppose it is more of a summary of my experiences there fossil finds and a bit of history and I take on board what you say about more structure to the format... I can look at that sometime....

You are right about the plant material it was poorly preserved and fragmentary usually in a compact shale layer often unrecognisable in form other than 'plant'...apart from some calamites casts which seemed to come from one area although all this material is ex situ....There was also the usual non marine bivalve layer you tend to come across in these exposures....I think you could be right about a permanent lake of some type certainly whthe fine dark sediment was laid down...

Heres a 'double' syncarid.... Not as well preserved as the single and as you say strange to all occur from one area (a couple of truckloads in one area on the spoil heap)....

A double syncarid is quite a find - they're certainly scarce things most of the time. Presumably this says something about their ecology, if they can be abundant in this particular habitat (whether a permanent pool, or something else)... not sure what yet though.

The structure of this sort of write-up is basically just to make it as easy as possible for the reader to get the information that they want - although I find setting it out logically really does help with clarifying one's thoughts as well.