Posts: 0
Threads: 0
Joined: Jul 2005
Posted by BAJR Host: Quote:quote:do you think we (in the UK) are missing something by not looking closer at topsoil distribution
Possibly we are, although there were a number of quite large-scale experiments in the '80s that investigated plough-soil archaeology with results that did not really justify the cost (e.g. an EH/Wessex project in the environs of Stonehenge). People like Colin Haselgrove have also published on this topic.
Investigating artefact distribution throughout the plougsoil thickness is very time-consuming and expensive relative to the quantity/usefulness of the data retrieved, so under most UK circumstances it needs a special reason to justify it.
However, one good compromise that can be applied at times, in several variants depending on the nature and circumstances of the project, is to do intensive fieldwalking/metal detecting on the excavation area, with good 2-D positional recording; mechanically strip; then fieldwalk and metal detect again before hand-cleaning, planning and starting to excavate features.
1man1desk
to let, fully furnished
Posts: 0
Threads: 0
Joined: Dec 2005
Serious question... but why all the fuss about detectorists investigating the topsoil by some archaeologists when others think the quantity of data is not appropriate?
Website for responsible Metal Detecting
http://www.ukdfd.co.uk
Recording Our Heritage For Future Generations.
Posts: 0
Threads: 0
Joined: May 2004
its more about cost/data recovery... which is where 1 man s sensible solution/compromise makes sense (on several levels- cost, recovery, outreach, cooperation etc)
Quote:quote:intensive fieldwalking/metal detecting on the excavation area, with good 2-D positional recording; mechanically strip; then fieldwalk and metal detect again before hand-cleaning, planning and starting to excavate features.
Its not that the info is not appropriate, it is jsut the hard facts of financial constraints.
It is one area where both the detectrorist and/or local group can carry out fieldwalking first... (where appropriate - of course!)
"No job worth doing was ever done on time or under budget.."
Khufu
Posts: 0
Threads: 0
Joined: May 2005
On the topic of ploughing, the experiments at Thornborough are eye opening.
These are at:
Code: http://www.archaeologicalplanningconsultancy.co.uk/thornborough/search_deliver.php?Unique_ID=32&Page=1/1
Posts: 0
Threads: 0
Joined: Jul 2005
Posted by garybrun: Quote:quote:why all the fuss about detectorists investigating the topsoil by some archaeologists when others think the quantity of data is not appropriate?
Actually, I think that metal detecting is a vary useful and cost-effective technique for some projects, which is why I included it in my 'compromise' solution. Some curators also write it into their briefs, making it a PPG16 requirement.
When I said that investigation of plough-soil archaeology often didn't justify the cost, what I was referring to was investigating the distribution of all artefact types (not just metal) throughout the thickness of the ploughsoil.
What that requires is the excavation of the plough-soil, generally by hand, in a series of thin 'spits', in a way that maximises artefact recovery and enables reasonably accurate recording of the spatial distribution of each type of artefact. It can produce useful results, but the cost is usually disproportionate to the degree of usefulness (although there are exceptions).
Hence my proposed compromise, which would only pick up non-metallic artefacts on the surface or base of the ploughsoil and slightly more for metallic artefacts, with a lot of material being machined off.
1man1desk
to let, fully furnished
Posts: 0
Threads: 0
Joined: Jan 2008
1man, I think it depends upon the site itself as to whether cost is justified-a good example is Horncastle in Lincs. Over the southern half of the town sealed by the topsoil there is a layer of dark earth which has material truncated out of features that it is sealing,and going through the finds in postX with the pot person she explained that quite a bit of pot from the dark earth fitted pot still in the features,and when their location within the dark earth layer was plotted they were directly over the features.
Admittedly the cost of such analysis cannot be justified for every site but we should still make the effort to recover the material from the spoil heaps of open trenches as without it how do we give a fullest picture of the range of finds from that area?
A fantastic site I was on near west Deeping in Lincs produced hundreds of neo/BA flints from the spoil heap-twice as many as actually came from the site![8D]
Posts: 0
Threads: 0
Joined: May 2005
DDL wrote:
Quote:quote:Over the southern half of the town sealed by the topsoil there is a layer of dark earth which has material truncated out of features that it is sealing,and going through the finds in postX with the pot person she explained that quite a bit of pot from the dark earth fitted pot still in the features,and when their location within the dark earth layer was plotted they were directly over the features.
This scenario makes me wonder once again about something that I have long suspected about "dark earth" horizons. Namely that they are not homogenous deposits of re-worked plough-soil truncating all below them, but a mix of dumped organic deposits and cut features. The fitting pot from the "dark earth" may have been within a cut feature partly cutting the dark earth but extending into lighter deposits or subsoil below. Because it is notoriously difficult to see cuts in dark deposits the machining is usually done to the lighter material below.
Advances in the understanding of post-Roman urban deposits seem to depend on how well the excavator digs and interprets this problem "dark earth". I've long hoped for the invention of dark earth visibilty goggles  . Until then maybe a more North-American system should be applied rather than the use of the big yellow trowel.
Posts: 0
Threads: 0
Joined: Jun 2004
Hmm
We had a similar layer on a site recently. We stuck a few narrow slots through it, found features underneath, then excavated more of the layer in a grid of small squares around the points through which the features were hypothesised to have cut. The distribution of artefacts confirmed that the features did indeed cut through the layer, which was a very worthwhile result as it discounted various other interpretations for the layer (colluvium, flooding event, etc.). However, we still couldn't find the features' edges until physically below the layer (and nor could several emminent site visitors). I could have found the edges with a lot of soil micromorphology samples, but I don't think the client would have been keen. There's a steep curve of diminishing returns here, and we have sufficient unquestionably-stratified artefact assemblages from the lower parts of the features for reliable dating.
Essentially, we applied the first law of archaeological resource allocation: 'Yes, but what does it tell us?'
It's worth noting that this kind of stratigraphy defies the rigid lines inherent in British archaeological recording. For example, an horticultural soil may develop over many years while pits are continuously excavated. One might invent an arbitrary palaeo-land-surface for each identified cut, but that would still be a fudge as pedogenic processes will have destroyed those surfaces, even if they could be defined as events (which all British 'contexts' are). In the end, you have to find peace with cut lines on your sections that just disappear into nothingness without reaching the surface (as geologists are happy to do).
Posts: 0
Threads: 0
Joined: Jul 2005
Posted by Dirty Dave: Quote:quote:I think it depends upon the site itself as to whether cost is justified-a good example is Horncastle in Lincs. Over the southern half of the town sealed by the topsoil there is a layer of dark earth which has material truncated out of features that it is sealing
This certainly does sound like a circumstance in which investigation of the 'dark earth' layer would be appropriate, although you would have to work out a sensible methodology.
However, it doesn't sound like ploughsoil - we are talking about a distinct layer, separate from the topsoil, and we are in a town, not in arable land. We also know that it is there before we start.
I think in my previous posts I did acknowledge that there are circumstances in which investigation of the topsoil/ploughsoil is justified, in varying degrees of detail depending on the site. My main comments related more to the 'typical' British plough-truncated rural site, in which there may or may not be some useful information in the ploughsoil, but it is unlikely to be sufficiently useful to justify the time and resources required to recover it.
All archaeological excavations are, to some extent, sampling operations, and there is no such thing as 100% data recovery. This is just one example of the type of sampling decision that needs to be made. The important thing is to consider the method/approach afresh for each new site, not to adopt a simple 'blanket' approach for all rural sites.
1man1desk
to let, fully furnished
Posts: 0
Threads: 0
Joined: Sep 2007
Quote:quote:Originally posted by 1man1desk
Posted by Dirty Dave: [quote]I think in my previous posts I did acknowledge that there are circumstances in which investigation of the topsoil/ploughsoil is justified, in varying degrees of detail depending on the site.
As I believe I said in the top post of this thread, in the US we often have nothing except a plowed strata on top of subsoil. At least where I currently work we also tend to have pretty shallow deposits, 60 cm to 1 m below the surface, depending of course on previous land use etc. So we're limited to either disturbed contexts or very occasionally some features which extend into the undisturbed subsoil. If we ever did have sites with intact stratigraphy I suspect we would focus mainly on that, but honestly it's so rare here that documentation is handled on a case by case basis.
|
