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Neolithic Houses find - Seedy Girl - 8th March 2013
Dinosaur Wrote:My last 'possible' Neo building the enviro people managed to select a 'short-lived' C14 sample too small to date... :face-crying:
...shame the big lumps of charcoal got ignored really...the 'specialists' don't get to do the sample-selecting any more, certainly not on my projects anyway }:face-approve:
:face-thinks: Hello :face-stir: I have, you've obviously forgotten, mind you, you have badgered me to be more decisive with the charcoal selection....but to go back on :face-topic:. I think the Neolithic houses are fab and am deeply envious :face-approve:
Neolithic Houses find - P Prentice - 9th March 2013
Dinosaur Wrote:Ask the specialists concerned - they've managed it several times!
Actually I've got several samples that are 'iffy' on the weight front at the moment, not sure whether to recommend, but in those cases it's the only material available - it's a different matter when there's 'less good' but lots-of-it charcoal but you still wind up with no date...nearest thousand years would have been fine...
i have got Neo dates from partial seeds - what lab are you using?
Neolithic Houses find - Dinosaur - 9th March 2013
So have I, but there are limits! No probs with the lab (SUERC), but they've got to be given enough to play with :face-approve:
Constant challenge, deciding whether to go for the 'good' date, with the possibility of failure, or the 'safe' but less precise date - of course with a decent budget this would be less of a problem, but that's down to fostering a culture where curators are more prepared (or able) to lean on the clients a bit harder
Neolithic Houses find - P Prentice - 9th March 2013
if you are trying to date something with less mass than a partial seed you must surely have to uncertain as to its provenance?
Neolithic Houses find - Dinosaur - 9th March 2013
Some of those 'indet cereals' turn out to be a bit of husk with nothing inside, but there's a limit to what the likes of Seedygirl can do poking about with a scalpel to check em in advance without ending up with some black powder - plus of course the C14 lab needs to clean the samples when they get them so what you send isn't what gets finally processed. From experience nice fat single cereal grains are the reliable minimum, anything below that seems to be pot luck whatever the quoted 'minimum sample' weights - will find out from the next batch of 'iffy' samples...
oh, and yes, I agree some of the samples selected by third parties in the past have been decidedly dubious (black fluff never inspires confidence), that'll be one reason I now ignore such advice and use my own judgement which frankly has proved rather more effective in providing the goods :face-approve:
Neolithic Houses find - BAJR - 10th March 2013
THis does lead me to consider a need for a simple field guide to what to actually take ( and how) for a sample.
Neolithic Houses find - Dinosaur - 10th March 2013
Some people do seem to have a frightening lack of knowledge of what constitutes a 'high quality' C14 sample - articulated bone and internal pot residues come top of my list, anything like seeds or charcoal are way down, but context is everything
Neolithic Houses find - pdurdin - 10th March 2013
Dinosaur Wrote:...what constitutes a 'high quality' C14 sample - articulated bone and internal pot residues come top of my list, anything like seeds or charcoal are way down, but context is everythingWould you (or someone else) care to expand upon that? Why is charcoal a poor sample, for instance?
Neolithic Houses find - P Prentice - 11th March 2013
pdurdin Wrote:Would you (or someone else) care to expand upon that? Why is charcoal a poor sample, for instance?wood for hearths/ovens/corn drying etc could lie around for yonks before someone burns it - oak for instance could already be 500 years old before it dies and another 100 before someone burns it. any fleck of charcoal could lie around in soil for 1000s years and still turn up in a sealed context - even stuck to a much later pot. even if you date a large sample the conventional way you still cant be sure how many episodes of burning you are measuring and intrusive charcoal will change the average you can measure etc. if you sample a burned down building you still cant know if the wood was reused from an earlier structure
i used to think hazel nutshells were more reliable but they aint.
Neolithic Houses find - Dinosaur - 11th March 2013
I've got a EBA pit soon to be published where they'd apparently been drying and burning waterlogged wood dragged out of an adjacent wetland - slight 3000yr discrepancy between C14 dates from the wood and the other stuff in the pit! Small bits of nutshell are highly suspect since it's really durable and floats about forever, unless there are, say, 500 nuts crammed into a small pit, Mr Prentice is right, they always have to be regarded as suspect - can do you an early Neo date from an Iron Age roundhouse... The worst are carbonised wheat grains which are round and exactly the right size for worm-burrows, so can now scientifically prove that the Neolithic in Wetherby continued up to only 900 yrs ago (cue all the Yorkshire jokes...), never touch cereals unless there's good evidence for them being contemporary to the context. In general avoid anything small enough for the worms unless there's reasons to think it belongs there.
Articulated bone can't be residual (or it wouldn't still be articulated) and nice sooty pot-residues are only likely to be still attached to the pot if it's in its primary point of deposition.
Having said all that, charcoal does have its uses, you can go too far disregarding it as C14-fodder, it's just rarely any use for tight dates - but am hoping Seedygirl's sample from the outer edge of her in situ charred post-base hits a nice steep bit on the calibration curve :face-approve: