Colour aerial photograph showing green patterns on a background yellow field in crop — Cropmarks of a late prehistoric settlement near Keysoe, Bedfordshire (NMR 27060/09) © Historic England: Photo by Damian Grady

Cropmarks of a late prehistoric settlement near Keysoe, Bedfordshire (NMR 27060/09) © Historic England: Photo by Damian Grady

Aerial Reconnaissance and Archaeology

Aerial reconnaissance is a very effective method of discovering and recording archaeological sites and involves archaeologists flying in a light aircraft, searching for, and photographing archaeological sites and landscapes.

While looking for archaeological sites in the form of cropmarks, soilmarks and earthworks, known sites are recorded to monitor their condition as are buildings and historic landscapes.

All the aerial photographs taken by or funded by Historic England are stored in our archive.

Colour photograph showing a high-wing, single engined Cessna 172 in flight

Archaeological aerial reconnaissance is best done using a high-winged aircraft (NMR 24511/02) © Historic England: Photo by Pete Horne

Discovery

Aerial reconnaissance involves an archaeologist flying in a light aircraft searching for and recording historic sites and landscapes. The geographical scope of observer-led reconnaissance is national, but is targeted to meet specific priorities and allow the flexibility to respond to seasonal weather conditions.

New sites are discovered in the form of cropmarks, soilmarks and occasionally earthworks.

Colour aerial photograph showing three fields in crop. The right-hand one has patterns of green lines on a yellow background

This photograph, taken in the hot summer of 2011, shows cropmarks of enclosures possibly dating from the Bronze Age through to the Roman period in the parish of Pidley cum Fenton, Cambridgeshire (NMR 27112/042) © Historic England: Photo by Damian Grady

The archaeologist carries a digital camera and a map with plots of known archaeological sites, including scheduled monuments, registered parks and garden, plus project specific targets.

Once a decision is made to take a photograph, the archaeologist directs the pilot to position the aircraft to get the best view of the site. The ideal angle will depend on what the photograph will be used for, including mapping, monitoring or illustration.

Colour image showing a map base with patterns of red lines indicating features and green dots representing recent photographs

Flight map extract from a tablet PC used by Historic England reconnaissance staff. Known archaeological features mapped from aerial photographs are in red, scheduled monuments (purple), recent photographs (dots) and soil map (yellow and brown). In the summer areas between the known archaeology will be targeted. © Historic England

Observer-led reconnaissance is a very effective way of discovering new sites and is a major contributor to Historic England’s aim of discovering England’s hidden heritage.

We do this by coordinating a national program of aerial reconnaissance with a mix of our own staff and local fliers funded via Heritage Protection Commissions (HPC).

Monitoring protected sites

An important aspect of the reconnaissance programme is the recording of scheduled monuments to assist colleagues in Historic England’s regional teams with monitoring the condition of protected monuments.

Aerial photographs taken at different periods can demonstrate how a site's condition can change over time. Common issues affecting scheduled monuments include animal burrowing, scrub growth, plough damage and vehicle damage.

Colour aerial photograph showing a sub-rectangular enclosure as green marks on a paler background in a fields under crop

These cropmarks are of the scheduled cursus monument at Warborough, Oxfordshire. Many scheduled monuments that are under arable cultivation like this are recorded on the Heritage At Risk register (NMR 27803/04) © Historic England: Photo by Damian Grady

Historic landscapes

Aerial photographs are also used to record and illustrate aspects of the historic environment showing how past human activity has shaped the landscape that we live in today.

Working with other experts in Historic England the reconnaissance teams contribute to a variety of projects from recording 20th century tower blocks to prehistoric field systems. The images are used in a variety of publications that inform and give guidance on how to protect the past.

Colour aerial photograph showing a shallow river valley with lots of small irregular fields, largely under pasture

This aerial photograph was taken to show the relationship between the farmsteads, tracks and irregular shaped fields along the river Yarty in the Blackdown Hills, Devon. Images like this are used in guidance documents for planners to provide a better understanding of how historic features form part of the character of this landscape (NMR 27891/06). © Historic England: Photo by Damian Grady