1 Overview
Survey is the first stage in establishing what is known and what gaps in knowledge exist about a site, a landscape or a building.
Usually the first step is to search the documentary records – books, written papers, maps, diaries – to find out what’s been recorded in the past. The aim of the next phase is to enhance or clarify the written record and to fill knowledge gaps.
Field survey should try to establish the nature and extent of the visible remains. The outcome of research and survey is an enhanced suite of interpretations. This in turn raises questions for further documentary research, further field survey or intrusive fieldwork.
Every one of our surveys aims to enhance Canmore, the national database of Scotland’s places.
Our survey work records archaeological sites and monuments that range in date from the late upper Palaeolithic period (circa 13,000 BC to 10,000 BC) right up to the present day.
Find out about all of our records by visiting the online catalogue of Scotland’s historic environment. Search Canmore now.
2 Landscape surveys
Field archaeology projects involve searching for, mapping and noting previously unrecorded monuments in selected areas of Scotland. Known sites may be reassessed.
Methods of landscape survey vary depending on the:
- scale of the target landscape
- desired level of accuracy
Some surveys aim to give a ‘snapshot’ of vast areas of landscape under specific conditions. Accurate surveys call for instruments that can map and locate features precisely to the Ordnance Survey National Grid.
Archaeologists now regularly use:
- electronic, satellite-linked survey equipment
- aerial photography
- computer-based instant mapping technology
Developing techniques include:
- airborne remote sensing technologies
- side scan sonar (for underwater archaeology)
- 3D laser scanning
We carry out many of our surveys in partnership with other organisations such as the National Trust for Scotland, universities and community groups.
3 Site surveys
We will carry out a detailed survey of an individual monument either as a special survey or as part of a larger project.
Special surveys may be undertaken if:
- a specific threat to a site has been identified
- an external request has been received
- the Canmore database will be enhanced by surveying a site
In the context of a larger project, detailed site surveys are conducted to:
- illustrate reports and publications
- provide training opportunities for staff and others
- develop survey methodologies and standards
- enhance the Canmore database
Site surveys are more detailed than landscape surveys and aren’t restricted to the land surface. A site survey can also be used to survey maritime archaeology, cave archaeology and urban archaeology.
Whether focused on an archaeological site or a building, the range of survey techniques generally aim to record the:
- extent of the features that make up a site
- subtleties of form and relationship between observed features
The techniques are generally the same as those used for landscape survey, but they operate at a larger scale. Thus the density of measurement is greater and so the volume of data increases.
Interpretation must remain evidence-based and testable whether the survey employs the traditional techniques of optical instrument survey (e.g. theodolite or electronic distance measurement) or new digital survey techniques (e.g. laser scanning or 3D photogrammetry).
4 Geophysical surveys
Geophysical survey techniques can be used to observe features that survive beneath the present ground surface, even when the site’s entire nature and extent is masked by later soil accumulation.
Geophysical results must always be checked. This is done by ‘ground truthing’ – digging or boring holes into the site, to relate readings to reality.
Below are some commonly used geophysical survey techniques.
Resistivity measurement
Electricity passes more easily through damp soil than dry soil. Measuring resistance can help to detect features like:
- filled-in ditches – often relatively wet
- walls – where the soil covering may be thinner and drier
Magnetometry measurement
Metal objects or burnt material can cause changes in magnetic fields. A metal detector is just one of the many kinds of equipment that can show these changes.
Ground-penetrating radar (GPR)
A 3D picture is built up using special frequency signals that ‘bounce’ off buried remains and the points where different kinds of layers meet.