Land management

DART sidetracked


Day Of Tweed

Day Of Tweed

Inevitably you get sidetracked…..

DART is burying temperature and soil moisture sensors at our test sites that take readings every hour or so. The data from these sensors will feed into soil and other models so we can get a better understanding of thermal emmisivity characteristics, soil-water percolation etc. and how this impacts on contrast identification and therefore the detection of archaeology. Most of these probes are bespoke units developed by the University of Birmingham. In order to test the veracity of these systems against an ‘off-the-shelf’ system we are collaborating with Van Walt Ltd to install their ‘off the shelf’ temperature and moisture arrays.

On Monday we will be installing the Van Walt sensors at our site in Cambridgeshire. Consequently I need to ensure that the last-minute logistics are sorted out and the programme of works is understood by all. Dr. Keith Wilkinson, our geoarchaeologist, set out the trench and borehole locations earlier today.

In addition we will be installing the Birmingham sensors in the same area in the week commencing 22nd August 2011. I have just booked the machine which will excavate and backfill the trench.

I also note that other people have put picture of themselves up. So….. here’s one of me. Today is a Tweed Friday and some stereotypes are worth maintaining! Unfortunately I have evolved in a way which precludes the growing of fancy facial furniture. I am therefore beard-free.

Predictive Modelling for Archaeological Heritage Management

Marlies Janssens (Vestigia BV, The Netherlands) is analysing Dutch soils today.

Vestigia BV, a Dutch company, operates in the field of commercial archaeology primarily as a consultant to policy makers, project developers, spatial planners on the role of cultural heritage, archaeology and history, in corporate, social and sustainable development. Colleague Marlies Janssens is conducting fieldwork today, with the aim to test the predictive model that was constructed based on desktop survey.

“Six in the morning: no office outfit for today. I’d better wear an old pair of jeans and firmly tied shoes. Because in my job at an archaeological consultancy company I’m not only working at the office. Several days a month I’m out in the field all through The Netherlands.  Today is one of those days. Together with one of my colleagues, in a car filled with geological and archaeological equipment like hand corers, sieves and sample bags, we’re heading for the cover sand region in the province of Brabant, The Netherlands. The local authorities here have asked us to develop an indicative map of archaeological values that can serve as a starting point for their local policy on archaeological heritage management. To develop this map we’ve already been analyzing existing maps (like soil maps, historical maps, geological maps), known archaeological sites and archaeological databases. However, analyzing a landscape from maps and databases will always leave us with questions which cannot be answered by desktop survey only.  “What do the soil layers look like?”, “Can we see former landscape surfaces which might have been inhabited during the past? And if so, are these surfaces and soils still intact? Or have they been disturbed by recent human activities?” To answer these questions we’ll have to conduct fieldwork.

And that’s what is scheduled for today. We’ll visit several sites as part of a larger project where several colleagues, each with his or her own expertise, will aim to answer these questions. Today we will mainly focus on the landscape an soil characteristics, since me and my colleague are both physical geographers and approach archeology from the landscape point of view.

The first stop is at a site which is indicated on the soil map as an ‘enkeerd’ or plaggen soil. This man-made type of soil is often associated with late-medieval farming, when people added a mixture of heath sods and cattle manure to fertilize their arable land. By doing this year after year, they created a thick humic agricultural topsoil. These soils have a high archaeological potential; archaeological remains can be found within this plaggen cover (for the late medieval period), or underneath the cover (for older the period prior to that). After we’ve asked the owner for permission to enter his field, we start coring and find a thick humic sand layer. First, we think that this might indeed be the enkeerd soil as described on the soil-map, but while getting deeper, we start doubting whether this is really the medieval soil we were expecting to find. The humic layer looks very homogeneous, and the transition from the black topsoil to the yellowish cover sand  underneath it looks very sharp. Imagine this farmer ploughing his land, blending the black topsoils with the yellowish cover sand year after year. That probably won’t result in a sharp  boundary between the two layers. Furthermore, an older soil, which is often found underneath these man-made soils, is completely missing.  Looking at the landscape and noticing that this field is extremely flat and somewhat lower than the surrounding areas, we have to conclude that this soil has probably been disturbed recently and is leveled with black sand. Former surfaces or soils are missing, so the archaeological potential might be lower than we would have thought before.

The next coring, we had better luck. About a few hundred meters away from the previous site, we’ve found a podzol soil, which is still intact. These soils have been formed in cover sands since the start of the Holocene, about 10.000 years ago. This means that the surface we are standing on now,  is the same surface as the one people could have lived on  since the Stone Age.  Later in the afternoon we were also lucky enough the find a nice undisturbed enkeerdsoil, with remains of an older podzol soils underneath, meaning high archaeological potential for the complete range of historical and even prehistorical periods.

At the end of the day, after visiting some more sites in this cover sand region and several brook valleys, we’re heading back home again, feeling a bit tired from working in this very sunny afternoon, but also satisfied.  Actually seeing the landscape and the (sub)soils  in the field definitely gave us a better idea of the this area, which will help drawing up the archaeological document. Moreover, this was again one of those days that make me realize how lucky I am to have a job in archaeology that offers the opportunity to go outside and work in these lovely Dutch landscapes.”

Introduction: Medieval water management, some experimental archaeology

It is only the 20th of July as I write this introduction. I have recently signed up for the Council for British Archaeology ‘Day of Archaeology’ and I have not got long to organise things. The big question I had was ‘what to do’? As there are umpteen things on my list of things to do,  I could have chosen any one of them to promote on the day itself. Did I want to excavate? No, not really. The time and effort, not least the organising, involved in that would have been to much at such short notice. But, I do not like to have things to easy, achievable yes, easy no. So this is what I have started to organise for the day itself.

The Welsh Cistercian abbey of Llantarnam was  founded in or around 1179 and it lasted until the dissolution. It is thought that none of the original building survives and like so many other abbeys that share that distinction, it has not really been investigated with a keen eye, until now. Within its outer precinct (although that is a subject of debate) it possesses  the remains of some remarkable water management systems that the Cistercian monks are renowned for. The hydraulic systems extended far and wide beyond the outer precinct but, as they enter the grounds of the abbey, the management of water becomes almost microscopic. It is two of these features that I would like to investigate for The Day of Archaeology.

There are, of course, many leats feeding the whole system: Existing features include two dams with a drainage system attached to one of them, weirs that contain evidence for sluice gates, the remains of a medieval bridge that not only has evidence for sluice gates, one of them is till intact and working. There is a fishpond weir,  possible wharf, a culvert built over one of the mill tail races and a sluice gate built into the same. It is, quite literally, jam packed with archaeological features although it has to be noted that the largest construction project appears to be the canalisation of the Dowlais Brook.

Long, straight sections of rivers and brooks can indicate archaeological interference

The Dowlais Brook: Long, straight sections of rivers and brooks can indicate archaeological interference.

It is the possible wharf and drainage system attached to the dam that I am going to concentrate on though. And it has taken some arranging. Amazingly,the weather hasn’t seen the need to rain heavily for some time now in South East Wales and this presents me with a problem. If I want to trace a drainage system from a medieval dam to its outlet how do I attempt that without any water? I had two options, I could either ask the fire brigade to flood the system with water, or ask somebody who specialises in drains (that they would use to flush out blocked drains during their course of work)
and carries a supply of water with them to do the same. I asked both and recieved a positive reply from the latter.

The next problem I thought of, as I was probably going to be on my own for the day, was how to record the drain trace? As I study at the University of Wales Newport, Caerleon Campus I thought I would ask for a favour to be returned from some of their film students. Hopefully they will be there to record the experiment, if not I will have to record it with photographs. Either way it should not be a problem.

The dam nestles quite nicely next to the Magna Porta - The Great Gate

There are two leat systems feeding it.

 

 

 

 

 

 

 

 

 

 

 

The outlet is interesting. After heavy rain it appears to be  in good working order – or is it?

Showing the construction of the drain outlet

Showing the construction of the drain outlet

Buried deep in woodland, this drain outlet still carries water during heavy periods of rain

Buried deep in woodland, this drain outlet still carries water during heavy periods of rain

 

 

 

 

 

 

 

 

 

 

It should be interesting to see how all of this turns out. The drain outlet shown above is quite a way from the dam outlet and it feeds the Dowlais Brook.

The other feature I am hoping to investigate is a possible wharf. The canalisation the Dowlais makes navigation easier and if that is so whoever utilised it would have needed an area to berth their cargo.

A possible medieval wharf

It does not look much now but lets see if I can clean it up for some photographic recording

So people, here goes. Lets see if all of this turns out ok.

 

Good luck to all of you with whatever you do for The Day of Archaeology.

DS.