Tuesday 18 August 2009

Limes Congress

The dig may be over, but there is no rest for the wicked. Although most of us are trying to grab a well-earned rest before commencing the post-excavation analysis of this season's fieldwork, there is still plenty to do. Today the site was visited en masse by all the delegates from the 21st Limes Congress which is currently taking place in Newcastle. This is the major international conference on Roman frontiers and has brought in scholars from across Europe and beyond; just looking at the programme I can see that there are people from Germany, Austria, France, Holland, Italy, Israel and many other places. These are the leading researchers in their fields; not surprisingly the prospect of their visit was a little intimidating! However, at the end of the day having given four site tours to a total of over 200 visitors I can say all went very well. They were interested and asked some searching questions. We also got plenty of positive feedback, which was very gratifying. There were also some extremely useful suggestions- two separate people noted that the site looked very like Barrack 13 from Housesteads- I'm looking forward to chasing this up further when the forthcoming publication of the Housesteads excavations arrives in the library.

It wasn't all just entertaining visitors today though. I had a useful chat with one of my colleagues in the Department of Archaeology today about the potential of scientific dating on the site. One of the challenges we are presented with is the difficulty of dating any activity between the end of the Roman period and the 12th/13th century. This is due to the general lack of diagnostic artefactual material in this period (apart from the limited quantities of Anglo-Saxon metalwork that is found north of the Tees). This is further complicated by the fact that any early or indeed late medieval activity on site will churn up earlier Roman layers incorporating Roman objects in later deposits. The practical upshot of this is that 5th century layers will only contain 4th century (and earlier)datable material in them. This means we have to cast around for alternative ways of dating the late activity. Obviously one potential is C14 dating - we have a number of probable 5th century features which contain enough bone for radiocarbon dating. However, we also have a number of areas of burning on some of the floor surfaces within the building which we'd like to date. However, these consist only of burning and scorching to the stones themselves; ploughing and worm action has removed any charcoal and ash from these features and they are not directly associated with other datable features. They could be sub-Roman or early medieval; equally they could be 15th century. So, how do we date them? Well one possible approach is thermoluminescence dating (TL). I won't explain the science as I don't understand myself in much detail. The key factor is that the sandstone slabs on which some of these hearths have been placed contain quartz crystals which can be used for TL dating. So, next week I'll be taking one of these slabs back to the Department for an initial assessment for its potential. If we get good results we'll look for funding to pay for a series of dates (it costs £500 a shot if any of our readers are feeling generous!). I'll report back on this further soon.

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