This section of the website is intended to explain why we use fieldwalking, how we conduct fieldwalking, and what we find when we do.  I also intend it to serve as a brief introduction to the technique for anyone who thinks that they may want to organise some basic archaeological survey work of this type, or to those who are planning to participate in fieldwalking but have no active experience of it.

As a technique of non-invasive archaeological survey, fieldwalking has been conducted at SHARP since the earliest stages of the project in 1996 and is still used consistently within the project.  When I use the term ‘non-invasive’, this indicates that the process it refers to does not penetrate the ground or disturb the archaeological record below the ground surface level at the time of the survey.  It does, however, alter the archaeological record as it exists within the plough-soil over time, although this will be discussed later.  

SHARP’s use of fieldwalking has resulted in some very useful data being collected, as well as some spectacular finds (see the What Has Been Found? Section, below).   

What is fieldwalking and why is it used?

Fieldwalking is the recording and usually the collection of archaeologically relevant material from the ground surface; hence another term used for fieldwalking is Surface Collection.  There is more than one way to go about fieldwalking, but only the method used by SHARP is covered in detail here as it is a tried-and-tested approach, which has consistently yielded results over time.  It can be used either in its own right as a stand-alone technique, or in advance of further archaeological work such as geophysics or excavation, or as part of a sequential prospection strategy involving a series of techniques arranged to provide the maximum data to inform the methodology of the subsequent technique.   

The primary purpose of fieldwalking is the collection of statistically useful data.  This can then be used to create accurate plots of finds, which can be analysed statistically or merely observed to detect obvious distribution patterns.  From this an idea of the types of subsurface archaeological finds and features can be gained.  If a particular artefact type is found during a survey it is a ‘safe bet’ that there was activity relating to that artefact present within the vicinity of the find spot.  Here lies its usefulness as a pre-excavation tool, aiding the targeting of geophysics or excavation.  What fieldwalking cannot tell us, unlike more invasive methods of archaeological activity such as excavation, is what is not present (although even when excavating, assumptions such as this are entirely at the mercy of the sensitivities of the excavators themselves).

How is fieldwalking carried out?

There are a number of methods than can be used once a suitable field or area has been located and permission granted for a survey to be conducted (always an important task, and one that should always be carried out unless fieldwalking on common land, which is unlikely as it is rarely going to be in a suitable condition).

All methodologies require participants to observe the ground (usually resulting in an aching back at the end of the day).  The difference is in the statistical sampling involved.  At SHARP we employ a method that allows us to sample 10% of the entire area being surveyed.  This creates a compromise between the collection of a statistically safe sample and an efficient collection process.  Other methods such as 100% collection across a total area tend to ignore this compromise and favour either speed at the expense of statistical safety, or statistical safety at the expense of time (more aching backs!).  At the end of the day it is the requirements of the survey, i.e. what you require the results for, which will generally prevail.

The fieldwalking surveys that are conducted by SHARP are done so in a very specific and consistent way.  This allows results from different areas to be compared, something which is useful given the basis for SHARP’s research within the parish of Sedgeford.  Once a field has been identified and permission granted, a baseline is created along the longest side of the survey area.  The area to be fieldwalked is then divided into 20m² grid-squares using pea-canes or ranging poles at the axis of the squares.  The fact that each grid-square is 20m² allows geophysics and metal-detecting teams to work in tandem or follow behind the fieldwalkers, a practise that has proved useful and efficient.  In situations where it is appropriate an Electronic Distance Measurer (EDM) can be used to layout the baseline and grid.  This is quicker and more accurate, however it is also significantly more expensive if hiring the EDM.  At SHARP a Pythagorean triangle equation is used to accurately layout the grid (if the two sides are 20m then the hypotenuse will be 28.28m, derived from Pythagoras’ a²+b²=c²).

Once the ‘gridding-out’ has been completed the transect lines can be attributed codes to aid in the post-survey recording and analysis of finds.  These usually start with the row being given a letter and the grid-square being given a number.  So the first square would be A1, followed by A2 etc, until the end of that row, with the next row beginning B1. If the area is large enough to require more than twenty-six rows then double letters are used (e.g. AA1, JJ19 etc).

Once this is complete fieldwalking can begin.  Obviously, it is not essential that all grids be marked out when fieldwalking begins, as it can be completed in stages based on resources.  As I have mentioned, SHARP employs a 10% collection strategy.  This is achieved by fieldwalkers complying with the following procedure.  Each row (the line between grid-squares along the alphabetical axis – A, B, C etc) acts as a transect.  Each row is broken down into individual 20m segments by the squares, and it is these that are walked.  One person is allocated to each 20m transect and is provided with an appropriately marked finds bag to put any finds they collect in.  Then each 20m transect (marked out by the pea-canes which show the grid-square axes) is walked for a period of 10 minutes.  This allows statistical comparability between the results from each grid.  The fieldwalker on each 20m transect will collect finds within an area 1m to either side of the imaginary transect line.  Thus, from each grid-square a 2m x 20m area is sampled, providing a 10% sample from that grid square.  This systematic approach has proved fruitful for SHARP, although different methodologies may be more appropriate under different conditions.

The maintenance of the time:distance procedure is important.  Because the technique is not 100% statistically reliable (for one thing it relies on a relative sample) any process that can stabilise this is useful. 

Other methods that are used elsewhere include the same process that is used by SHARP, but with a 100% sampling strategy.  Obviously this is much more labour intensive.  In conditions where time is an essential factor a systematic sampling strategy may be abandoned altogether and a ‘sweep’ of the area conducted by a number of fieldwalkers arranged in a line and walking at the same pace.  This can identify materials present within the fieldwalked area, but it cannot locate them to a specific spot or refined area.  SHARP, on the other hand, can locate fieldwalked finds to an area of +20m.  From this we can group finds and plot them in various forms onto a GIS program to produce plots based on material type or time period.  Statistical analysis can also be applied if considered appropriate or necessary.

N.B.

One factor that must be appropriate for the application of fieldwalking is the ground surface.  If there is ground cover then it is difficult or impossible to view artefacts exposed within the top layer of the plough-soil.  Similarly, a recently ploughed or turned over topsoil with some weathering is more appropriate than a well weathered and compacted one, as finds can become camouflaged and flush with the ground surface and so less visible to the passing eye.  Another factor to be taken into account is visibility, with an appropriate light level being advantageous.  Usually, a low sun or a moderate level of cloud cover can aid vision as there will be less glare and reflection off of the ground.       

Ethical Issues

One issue that arises from the process of fieldwalking is shared with the prospection technique of metal detecting.  This is the removal from the archaeological record of artefacts, an issue, which is less polarised and controversial than metal detecting among archaeologists, although, can be discussed here briefly.  The practise of fieldwalking where archaeologists remove artefacts from the ground-surface does not have an impact on subsurface archaeological features in a way that metal detecting can.  However, it does alter the state of the archaeological record by removing artefacts from the plough-soil.  This process is not as controversial as is made out, in my opinion.  If artefacts were not collected by fieldwalkers they would mostly be abraded and broken down over time by the effects of agricultural practises, and natural processes such as weathering, erosion.

Alternatives to removing artefacts from the ground surface do exist.  One involves the marking of find-spots with identification taking place in the field and the position of the find located by GPS or the use of an EDM.  This is costly and time consuming however, and relies on accurate identification of finds in the field, which is often very difficult.  For efficiency the method used by SHARP is the most appropriate to us.

A further ethical issue is the handling of finds.  Many people do not have a problem with handling all types of finds, but for those who do not wish to handle finds such as bone, be it animal or human, this can be difficult to avoid in the field.  Much bone, when weathered and abraded whilst in the ground can appear similar in appearance to pot or some types of rock.  It is only on closer inspection that it becomes apparent that it is bone, and this can provide an ethical dilemma for some.

What has been found?

Below is a selection of the types of materials that have been found during SHARP fieldwalking surveys between 1996 and 2004. 

Flints
Pottery
Selection of coins from different periods
The Sedgeford Torc Terminal
Modern agricultural machine parts

Acknowledgements

On behalf of SHARP I would like to thank all the landowners, farm managers, game-keepers and other staff who have allowed us to conduct fieldwalking surveys on their land, and who have provided cooperation, assistance and patience since 1996.

Dave Bonner.
March 2005.