Thetford Forest Archaeology Methods  

Exposed soils

Typical restocked compartment at Thetford

A linear method of field-walking was designed, suitable both for the pine forest environment, and the project aims. The method had to be suitable for being carried out by a single surveyor working alone. Transects, or lines are walked at regularly spaced intervals, along the recently cut planting furrows (shallow trenches cut through the forest turf by a plough mounted on the front of a tractor, that pulls a planter behind it) of restocked pine forestry compartments. These transects were each divided into 20 metre long stints, which were measured by a measuring wheel, pushed along during the survey. These planting trenches are quite, narrow, usually only a metre or so wide. They are also frequently blocked, where the plough fails to contact the turf. Where these trenches are blocked, the surveyor jumps across to the nearest clear trench, and continues the transect.

The transects are usually spaced apart to a default of 40 metres. However, if conditions permit, the transect frequency is occasionally increased to a spacing of 30, 20, or even 10 metres space apart. This, along with the viewing width directly affects the sample percentage - the survey area that is actually walked and searched. The viewing width is adjusted not only to reflect the soil exposure of a planting furrow, but is also used to reflect the survey conditions, such as the degree of weathering on the surfaces

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This page last updated

2006-01-14
(y-m-d)

Paul Brooker
Forestry stocking furrow - exposed soils

Collections

All recognised artefacts are collected, apart from burnt flints and modern tile or brick. Finds are washed, coded with a transect/stint number, and bagged. I catalogue the finds, along with eight figure grid references. A survey plan at a scale of 1:2500 is attached, and then the finds are despatched to the county records officer for second opinion, and for entering onto the sites & monuments record.

The following figures are calculated for each survey: survey area; sample percentage; sample area; grid reference; lithic density (the density of struck flints); burnt flint density. These figures are deduced by entering the number of stints, viewing width, and number of finds onto a spreadsheet.

In addition to the surface-collection survey, other methods are sometimes employed, including: earthwork survey, pathside reconnaissance; and metal detection. Surveying is suspended from late February, to mid September, to prevent the disturbance of breeding birds, particularly to the Woodlarks who nest on the ground in restocked compartments. Incidentally, I carry out the surveys single handily. I work light - tools include a measuring wheel; 50 metre tape measure; compass; notebook; and collection bags. With the relaunch of the project, I expect to add a handheld GPS, and a digital camera to that list!

survey plan

Public deposition of the finds: After the local government archaeologists have added the records to the SMR, I collect the finds. Eventually, I plan to deposit all of the finds from all of the projects together at one public storage point, so that they can form a reference collection for the Thetford Forest area.

The image to the right is an example copy of a forest-walk survey plan, that was supplied to the SMR officer along with all removed finds, and OS grid references etc. The transects divided up into 20 metre long stints can be seen.

Surveying by GPS

I have introduced a handheld GPS (Global Positioning System) receiver, since resuming surveys in 2006, following a six year break. GPS data is fed to the Gartrip program for recording, analysing, and digital mapping. I can draw out and check grid references, by downloading my tracks and waypoints onto a digital map. Survey map plans can also easily be created by drawing the transects on top of the displayed tracks and between waypoints. GPS accuracy is the deciding point. Handheld GPS may not be perfectly accurate, but for the purpose of my surveys, it is probably accurate enough. Examining the data on digital maps acts as a quality check. Trials so far suggest that the GPS is actually enhancing my accuracy rather than corrupting it. For example, furrows are not always perfectly parallel, and this shows up on the GPS digital maps.

I am now experimenting with using the GPS as a measuring tool - for spacing out transects. I am also considering experimenting with using the GPS for measuring out stints. This would mean that I would no longer have to drag the measuring wheel around everywhere, or stake out tapes. It would be surface-collection linear sampling by handheld GPS! I am looking at traces of my surveying activities to decide if that would be practical. I will only rely on GPS if conditions permit - satellite visibility.