Friday, June 21, 2024

Aerial images reveal 6,000 years of history in the South Downs

On a quiet day, you can walk on paths in the South Downs where it feels like you are in a landscape that is ethereally beautiful but remote and empty. With few visible ruins, you might have no idea that there is evidence all around you of millennia of human life and remarkable continuities.

Now, Historic England has analysed thousands of aerial images to map archaeological sites dating from the Neolithic to the Second World War across 74 square miles (192sq km) of the South Downs and the Weald to the north. The idea: to reveal and preserve the rich hidden archaeology of this corner of England for locals and visitors from around the world.

For the Downs From Above project, the heritage charity’s aerial investigation team analysed over 9,500 aerial photographs as well as aerial laser scans to locate, identify and record features from across thousands of years of intensive human activity. In addition to gaining a better understanding of previously known remains, the team discovered scores of sites unknown till now, including Bronze Age burials at the Devil’s Dyke beauty spot and several probable Iron Age or Roman settlements.

Matthew Oakey, Aerial Survey Principal at Historic England, said: “We have mapped 6,000 years’ worth of history. We’re moving from understanding the landscape through knowledge of discrete monuments gradually recorded over time, to seeing that landscape mapped out and understanding chronological and spatial relationships in far more detail. It’s about putting all the pieces of the jigsaw together.

A view along the northern scarp of the chalk downs, looking east from Ditchling Beacon. Photo: © Historic England Archive

“The project is also about understanding landscape change, because there has been a huge reduction in the amount of traditionally managed grassland. This started in the Second World War, when the Downs were requisitioned by the Army for food production. The ploughing up wasn’t quite as intense as it was in some areas, but, of course, food shortages continued into the late 1940s and early 1950s. So we can see that gradual erosion of the grassland in the Downs through historic photography.

He added: “It is a false distinction to talk about nature and heritage as separate, because they’re so closely intertwined. The only reason the Downs look like they are today is because of 6,000-7,000 years of human intervention that began when people cleared the woodland in the Neolithic period. Man’s intervention in the Downs has been absolutely instrumental in shaping them.”

The aerial photographs that the team used date from the 1920s to 2018 and include RAF image from the 1940s and 1950s that clearly show archaeological features that have been reduced or lost through subsequent ploughing. The lidar (light detection and ranging) images are from recent surveys by the Environment Agency that use aircraft-mounted lasers to build computer models of terrain, including very low-lying earthworks near-invisible in photographs and on the ground.

A static overview of the new interactive map, showing the density of archeological features in the landscape. © Historic England

The results, detailed in a report published today, reveal dense, complex networks of features, dating from the Neolithic onwards. An accompanying interactive map encourages people to discover and connect with this landscape and its history. Significantly, users can add data to the map to report the current appearance or condition of earthworks and share personal histories or connections to a site.

Oakey said: “So, you can go for your dog walk on the Downs and see on your mobile phone these thousands of years of history that you’re actually walking over. Something we and the National Trust are very keen on is its interactive nature. You can enhance the record with personal memories and even how you feel about a place. I think that’s something that is very, very interesting. A link between heritage and wellbeing is very much recognised in the UK now.”

The project area extends north from Brighton, Hove and Shoreham-by-Sea on the coast and includes a large part of the South Downs, mainly covered in large arable fields and free-draining open grassland. It also covers part of the Low Weald further north, with smaller pastoral and arable fields interspersed with areas of woodland, parkland and small watercourses.

In spite of the increase in ploughing in the South Downs from the mid-20th century, lower historic levels compared to other regions have preserved an abundance of archaeological earthworks. Some, mostly from the medieval period and later, are clearly visible on the ground, but many are buried remains that can only be seen from the air as crop-marks in arable or grass, or through lidar.

Features highlighted by the new survey and map include:

Prehistoric and Anglo-Saxon burials

Bronze Age and early medieval barrow cemeteries on Western Brow. Photo: © Historic England Archive.

Ancient burial sites from the Neolithic (about 4000 to 2200 BC) onwards were marked by the creation of mounds called barrows. These are dotted across the Downs, although most are located along the northern ridge. Cemeteries of multiple barrows developed over many centuries, and in some cases acted as a focus for burials as late as the early medieval, or Anglo-Saxon, period. The team said an exciting discovery from the project was the identification of barrows belonging to a Bronze Age cemetery south of the Iron Age hillfort at Devil’s Dyke.

In the report, they note: “Geophysical survey could be employed to try and ascertain the full extent of the site, as well as detailed terrain modelling using drone-mounted lidar or Structure from Motion [another mapping technique]. This site would provide a superb example for volunteer training, engaging the use of multiple forms of archaeological practice. This research could help inform future management of the site.”

At Western Brow, south of Westmeston village, there is a collection of barrows that can be seen from above to be of different size and shapes. Bronze Age (2600-700 BC) barrows tend to be larger and clustered in groups while early medieval barrows are generally smaller. The mounds on the east of the group at Western Brow are smaller and probably Anglo-Saxon.

Bronze Age and Roman field boundaries

Lidar showing part of the field system on Balmer Down. Image: Historic England, via Environment Agency

Traces of early settlements and farmland can be seen as cropmarks and earthworks across the Downs. The most prevalent features on the new map are field systems defined by lynchets, or raised banks that were formed as plough soil accumulated at the field edge. These date from the Bronze Age onwards — albeit later than the earliest barrows — and were developed and used through the Iron Age and Roman periods. Some lynchets such as those on Balmer Down survive up to three metres high but many have been levelled and are only visible in aerial images.

Oakey said: “You can you can see from the map just how intensively farmed the South Downs were — more intensively than today in some respects.”

The team identified several previously unknown settlements associated with these field systems and of probable Iron Age or Roman date. The field systems fell into disuse in the medieval period when former arable land was used as pasture for sheep farming, to supply wool and meat. Physical evidence of sheep farming exists across the South Downs in the form of dewponds and livestock enclosures. Dewponds are man-made drinking pools for animals, situated on ridges, hilltops and within combes — the latter name for valleys or hollows deriving from the same Brittonic source as the Welsh cwm.

Remnants of tracks and routeways

Lidar showing trackways on the north face of the down between Westmeston Bostall and Plumpton Bostall. © Historic England, via Environment Agency

Traces of numerous tracks, hollow ways and paths criss-cross the Weald and South Downs. These represent fragments of complex networks of routeways from many periods.

A striking feature are deeply incised tracks and paths known as “bostalls” — a Sussex name for incised routes, probably drove ways, which lead up the steep northern scarp of the South Downs from the Weald onto the open Downs. These were used not only to move livestock to pastures and markets, but also by smugglers carrying contraband from the coast. The name may be derived from the Old English words beorg, meaning hill, and stigel, meaning a rising path

Scars of industry

Wolstonbury Hill photographed in low sunlight highlighting the prehistoric enclosure and other features. Photo: © Historic England Archive

Sussex was known for its abundance of raw materials that fed many industries going back to prehistoric times. The aerial photos and lidar images reveal several areas of multiple small extractive pits, probably for flint, within and around the earthwork ramparts of a Bronze Age hilltop enclosure at Wolstonbury Hill. In an example of echoes and continuity through time, a flint mine on the hill supplied the gun flint market during the late 18th and early 19th centuries

Chalk extraction and lime burning have also left marks on the landscape, including in the form of a post-medieval chalk pit dug into the western flank of the same Wolstonbury Hill. The Roman historian Pliny noted that the Britons dug up chalk to spread onto their fields, improving growing conditions. According to Historic England, it is likely that some of the marl pits resulting from such extractions and mapped in the survey date from his era or earlier.

Landscapes of leisure

Coloured late 19th- or early 20th-century postcard of ladies enjoying Devil’s Dyke, near Brighton. Photo: Historic England Archive

Devil’s Dyke — a 20-minute bus ride from Brighton station — is now a popular spot to walk, cycle, fly kites and picnic while enjoying sweeping views of the South Downs. However, Historic England says it is quite different to the attraction that drew visitors in droves following the expansion of the railways in the mid-19th century.

In its Victorian heyday, the site not only offered the Dyke Hotel — built around 1831 — but also an adventure park with fairground attractions occupying much of the interior of the Iron Age hillfort. Thrillseekers could ride a rollercoaster or even traverse the Devil’s Dyke in a metal cage on an aerial ropeway suspended between pylons on either side of the valley. Some traces of these attractions can still be seen on the lidar images.

Wartime relics

The remains of the WW1 camp at Shoreham visible as earthworks in the 1940s. Photo: Historic England Archive (RAF Photography)

The remains of an important First World War training camp at Shoreham survived as earthworks into the 1940s and are recorded on Second World War RAF aerial photographs. Numerous practice trenches were constructed in and around the huts. Nevertheless, the bulk of training earthworks were dug to the north of the camp, where traces remain in the landscape. The most imposing of these were on the southern slope of Thundersbarrow Hill, where two opposing trench systems including front lines, support lines and communication trenches, were constructed over a length of almost 300m.

Many of the training earthworks at Shoreham were reinstated during the Second World War, for both training and defensive purposes. In 1940, Brighton and the adjacent coastline were considered a possible landing area for a German invasion, and defences were established at strategic strongpoints including the Devil’s Dyke hillfort. The area’s chalk upland eventually became a training ground and staging post for the D-Day invasions in 1944, after the tables had turned.

Bren gun carriers on patrol in the South Downs due to invasion fears in August 1940. Photo: Imperial War Museum, © IWM H 2965

Downs from Above is a project from the Changing Chalk partnership, which is led by the National Trust and supported by a National Lottery Heritage Fund grant and funding from People’s Postcode Lottery. The partnership aims to engage communities as active participants in the discovery, interpretation and celebration of the cultural heritage of the Downs.

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