Reports and updates for the project. Jump to: 2006 Update

Progress in 2007
We have made excellent progress with the survey this year. Magnetic geophysics has been completed on four fields followed by resistivity surveys of localised areas. Fieldwalking to collect surface artefacts has also continued and we conducted some experiments with 'dowsing'.

Many thanks first, to the owners and farmers of the land who have allowed us access to their fields and who continue to show great interest in our discoveries. Thanks to all NAG members and to our local volunteers for turning out to assist. We also thank Gridnine Geophysics in Grantham and Preconstruct Archaeology in Lincoln for their professional support and equipment used for the geophysics surveys.

Geophysics
Much of our geophysics has been conducted using a Fluxgate Magnetometer of the typical form shown here with one of the survey crew from GridNine geophysics.

A fluxgate can be balanced against the background of the earth's magnetic field to allow a sensitive measurement of the magnetic variation across a site. It was developed during WWII for use by aircraft in detecting submarines. The field area is first marked out in 30 by 30 metre squares to form a grid. As the operator walks the grid the equipment records the magnetic imbalance at predetermined intervals.

Several thousand readings will be accumulated for a typical survey and a computer program then plots them against the grid layout to form a pixelated image as shown below. The method is particularly useful to locate areas where material has been heated since burning or kiln firing substantially alters the magnetic alignment of any residues from the process. It is also able to detect underground building structure where blocks of stone or brick or a filled ditch show a different magnetic orientation from that of the surrounding soil.

We have also used resistivity surveying this year as shown in the above photograph. This technique measures the electrical resistance between a fixed probe in the grid and the probes inserted into the soil by the operator as he or she walks the field. Although the direct measurement is one of resistance between the probes, the value recorded is made up of a complex sum of the resistivity of each kind of material within the field. Damp soil will have a lower resistivity than a block of stone, for example. A computer program is used to compare the resistance readings across the grid and hence localise areas of high and low resistivity which can again be plotted as a grayscale image. This method is particularly useful to locate building material especially when the surrounding soil is wet from rain.

Pit formations
The magnetic and resistive geophysics surveys have yet to be fully evaluated but are showing clear evidence of both building structure and pits which may indicate kilns or hearth locations.

In several cases the images show 3 pits in a triangular formation as seen here. We don't know the significance of this formation but the duplication may indicate similar work activities taking place.

Scan images
The image to the left shows evidence of sub-surface linear, rectangular and circular formations with another 3-pit location.

The geology of the heathland has a broken limestone formation which clearly shows on the scans as a crackling effect.

Dowsing experiments
An interesting addition to our methods this year has been a few experiments with 'Dowsing'. Whether you are a convert or a skeptic, using the rods to dowse a field provides interesting participation for our volunteers while the professional crew is surveying with a magnetometer. We have recorded GPS positions of 'dowsing' finds and will compare these with the scientific data to see if there is any correlation.

New Finds
In all the fields surveyed to date, we have found significant quantities of Roman grayware sherds which was the most common, and the lowest cost, form of pottery in use. We also find smaller quantities of the more expensive Samian pottery which is often hand decorated. Medieval pottery is also present and some few pieces of flint.

Metal finds are quite rare during our fieldwalks - probably because, over many years, these fields have been scanned many times by metal detector enthusiasts. Coin finds are especially important in determining dates for occupation of a site but unfortunately, these metal finds are often not reported or logged for position. In many cases the landowner's permission is not obtained. We have seen the impact of this practice this year with a local landowner finding a group of metal detectors on his field without his permission.

The copper coin on the left is one missed by the metal detectors and was picked off the surface during a fieldwalk. A preliminary study indicates it may be 3rd or 4th century Roman with a reverse of a Standard Bearer holding a shield to the ground in the left hand. This form is recorded for coins of a military issue in the time of Gratian (367-383) or Valentinian (375-392). In that period, with the empire in turmoil, currency was sometimes in short supply and coins were minted locally and perhaps illegally. Further research may locate the mint which might be the one known to operate in Lindum Colonia (present day Lincoln).

Possible signs of glassworking
This image shows shards of glass found in a field where the geophysics also recorded a pit formation indicating a possible kiln or hearth. Some of the very thin glass has a coloured surface sheen and has been identified as Roman.

The origin of the tooth is unknown at this time but most probably animal!

Plans for 2008
The survey season for 2007 is almost at an end with the winter crops now seeded and access to fields again restricted. We still have work to do cleaning and classifying the new finds and gaining more insight from the geophysics scans.

There will be an opportunity for more fieldwork next spring but much of 2008 will be occupied with preparing and publishing our survey report. We have video footage of all the activities and will prepare a 30 minute DVD record of the project. Additional details will be posted here as work progresses.

Announcing the Project
We held our first Public Meeting in Navenby in January 2006 to announce the project and seek volunteers. Interest was very encouraging with 60 people signing up to help with work parties for field walking, pot washing, classification and geophysics surveys. Professional archaeological service teams and local heritage organizations have also been very supportive.

This is an aerial view of the first field chosen for our survey. The road at the bottom is High Dyke and follows the course of Ermine Street running north (left) to south. The road at the left is Green Man Lane. The choice of fields throughout the project is largely determined by the time of year and the cycle of the crops since all of the land is under cultivation. After this photograph was taken, the field was ploughed and harrowed so the surface was ideal although the weather was freezing!

Laying out the field grid
February 10th 2006
The first task was to make a full GPS survey of the field and lay out 52 grid squares each of 30 x 30 metres. This is done so that finds collected could be noted for position within the field. For this we hired the services of a local professional survey team. Volunteers helped with the positioning of flag markers at the corners of each square and learned a little about how satellite positioning systems operate. We placed a more permanent marker at one corner of the field so that grid locations could be reconstructed if necessary for a future survey.

Field walk
Saturday 11th February 2006
Now came the hard part. About 50 volunteers turned out on a cold and frosty morning to walk the grid squares with a numbered bag and collect interesting surface material. This was not a trivial matter since the Navenby heath is heavily scattered with pieces of limestone broken up over many years of ploughing. A group of experts brought along samples of the type of remains to look for - pottery sherds, building materials and tiles, early flint pieces with examples from medieval and later periods as well as Roman. We collected 52 bags of material to be cleaned and sorted. Unusual items (metal pieces for example) were photographed on the spot and recorded.

Sorting the material
Following a Pot Washing session on 13th May, volunteers gathered in the Village Hall on 29th July to sort and classify the finds. To help with this we had the excellent support of a local expert, Ann Downey. Volunteers learned to identify the various types of pottery firing methods and glazes used in different periods. Everyone enjoyed the event with many expressions of delight at handling a piece of broken pottery collected from a field where it had lain for perhaps 2000 years.

What did we find?
A full discussion of finds must await analysis of the results from all the fields at the end of the project. We identified a significant amount of Roman pottery remains, mainly grey ware, along with some medieval and later finds. A scatter diagram of finds shows no particular point of aggregation that might indicate a site of special interest within the field. This is a good result from our first field which lies at the northern edge of the village. Our volunteers gained the experience of surveying and field walking and learned to identify the various forms of significant material.

Mortarium
Part of a Roman mortarium which is the bowl section of a pestle and mortar used for grinding material in food preparation.

Samian Pottery
This is part of the rim from a piece of Roman Samian pottery which was a more expensive form than Grey Ware of which we found plenty of examples.

Concrete
This is perhaps our most exciting find, identified as a piece of Roman concrete. Concrete was expensive to make and thus only used for significant structures or for waterproof applications. This was found close to the southern edge of the field so we are eager to see what may be uncovered when we survey the adjacent area. (Note: Chemical analysis has confirmed this as of Roman origin)

What next?
The land we are surveying is under cultivation and, perhaps because of the unusually warm weather, we were not able to have access to our next field during 2006. We knew this would be a difficulty at certain times and hence scheduled the project over three years to survey six areas of land.

We shall complete at least two further fieldwalks during 2007 and also begin both resistivity and magnetic geophysics surveys. A 2007 report will be posted here.

At the end of the project a complete set of documents, images and video of project activities and results will be made available in public archives.

If you are in the local area and would like to join us as a volunteer please get in touch. The only requirement we have is that anyone under the age of 16 must be accompanied by a responsible adult.