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Discovering Our Hidden Heritage

The different perspective or ‘bird’s eye view’ reveals previously unrecognised archaeological sites. The plan and extent of buried archaeological remains are indicated by ‘cropmarks’ - patterns which can only really be appreciated from the air.  

Low light highlights the form and layout of archaeological earthworks or walls that may not have been noticed or appreciated on the ground.  We can use this information to target ground based techniques such as geophysical survey and analytical earthwork survey.

We have 3 levels of survey:

  • Identification through aerial reconnaissance
  • Interpretation and understanding through mapping and recording
  • Assessment of significance and targeted ground based follow up work

Cut-away diagram illustrating the effect of buried remains on crops growing above
Cropmarks are differences in the colour and / or height of a crop. The variation in growth is caused by what is present below the plough-soil. The patterns of buried remains are best viewed from the air © Historic England

Hidden heritage from the air

Aerial photography and other remote sensing techniques such as airborne laser scanning (lidar) help us to identify and record illusive archaeological features.  Aerial photographs and lidar data held in national and local archives are a huge resource for studying archaeological sites and landscapes.

Colour aerial photograph showing patterns of colour differences in crops
Buried remains of ditches revealed as cropmarks near Kimbolton, Cambs. The pattern of this extensive site can be seen from the air and indicate multiple phases of settlement and land division (NMR 27106/40) © Historic England

The best way to collate and understand the archaeological information on aerial images is to map it accurately and to provide interpretations of the sites and landscapes.  The National Mapping Programme (NMP) is a standard promoted by Historic England for use of aerial images for research and management.

The Historic England Archive is essential to our work, as a repository and disseminator of survey results, and as the main source of aerial photographs.

Historic England use National Mapping Programme standards and contracted NMP teams are funded by Heritage Protection Commissions and sometimes the Heritage Lottery Fund.

NMP project data is always supplied to the relevant Local Authority Historic Environment Record (HER) and project reports are available online.

Archaeological features mapped in red and green covering most of a greyscale Ordnance Survey map
Heritage Protection Commissions funded archaeological survey, by Cornwall Council, near Dorchester. Map compiled from aerial photographs and lidar to National Mapping Programme standards. Base map OS Licence 100024900. 2015. NMP data © Historic England

Bringing it all together – hidden heritage and landscapes

Large area mapping and assessment collates the information from numerous aerial sources and depicts the form and extent of archaeological information from different periods and with differing levels of visibility on the ground.

The composite map encourages a layered view of the landscape, where the aerial evidence, and information from other sources and survey techniques, provides glimpses of the changing use of an area over thousands of years.

This is an important viewpoint in terms of heritage protection which considers all known aspects of past land use in the context of managing future change.

Information from NMP projects can be used for research and further work using different techniques. When incorporated into historic environment records, the aerial photograph and lidar mapping provides essential information on the extent and nature of archaeological sites to inform management and the planning process.

A range of strategic large area projects identify, record and improve understanding of sites and landscapes across England. Historic England staff work closely with Local Authorities, and other partners to ensure projects are focused on key areas potentially under threat from agriculture, strategic development, or where there is simply a lack of knowledge.

Hidden heritage on the ground

Most archaeological investigation starts at the site level and works outwards to look at the environs. Historic England, and its predecessors, has a long tradition of looking at landscapes and using this as a way of focussing in on key components.

The landscape overview provided by aerial interpretation and mapping provides a highly effective framework for this kind of further assessment.

Archaeological features mapped in green covering most of a greyscale Ordnance Survey map
Part of the West Wiltshire mapping from aerial photographs showing multiple phases of field systems and an intriguing double ditched enclosure with a funnel entrance, all seen as cropmarks. Base map  OS Licence 100024900. 2015. NMP data © Historic England

We use different approaches and survey techniques  to explore sites discovered from aerial sources and to try to understand gaps in the aerial evidence. Recent projects are exploring best practice for recognising and identifying archaeological assets on a landscape scale, leading directly to heritage protection.

Each project covers a different type of landscape with a variety of heritage management issues and opportunities for archaeological survey

The first two projects were:

A third project, for South West Cambridgeshire, is in progress.

Photograph of a vehicle-towed caesium magnetometer array in action in a ploughed field
Geophysical survey to enhance understanding of enclosures and boundaries discovered on aerial photographs near Chalfield as part of the West Wiltshire NAIS project © Historic England: Photo J Last

The images used on this page are copyright Historic England unless specified otherwise. For further details of any photographs or other images and for copies of these, or the plans and reports related to the project please contact the Historic England Archive.

For further information on a project or any other aspect of the work of the Remote Sensing Team please contact us via email using the link below.

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Group of people standing on a stony mound
Historic Places Investigation

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