Slipping Away: Coastal Erosion and Archaeology

Erosion of our shores is nothing new. Though the rate of erosion may be increasing due to climate change, England’s coastline has always been on the move.

Global sea levels have risen by some 110-130m since the melting of the vast ice sheets that covered the world’s continents 22,000 years ago (the high point of the last Ice Age). Until some 8500 years ago Britain wasn’t even an island, and people could walk between East Anglia and the Netherlands across so-called ‘Doggerland’ (now inundated by the North Sea).

Erosion is justifiably seen as a threat to people’s homes and livelihoods as well as to the nation’s historic fabric. But coastal erosion is also capable of uncovering buried archaeological gems before destroying them.

In celebration of the annual Festival of Archaeology (15 – 30 July), Marcus Jecock, Senior Investigator and Coastal Survey Lead at Historic England, takes us through 7 of the best archaeological discoveries recently revealed by, or presently at risk from coastal erosion:

1. Britain’s earliest inhabitants, Happisburgh, Norfolk

Happisburgh footprints by Simon Parfitt - Copy
The human footprints exposed on the beach at Happisburgh in Norfolk in 2013. They are thought to be between 800,000 and 1 million years old. © Simon Parfitt.

Getting on for 1 million years ago, the River Thames flowed further north than today and reached the North Sea near the modern village of Happisburgh (pronounced Hayesborough) on the Norfolk coast.

The old river channel is buried by thick glacial deposits, but the silts laid down within it are briefly exposed as the sea erodes the overlying sediments. These deposits have produced the earliest known evidence of humans in Britain. As well as flint tools and butchered animal bones, in 2013 a series of human footprints were found preserved in the mud. The footprints were rapidly recorded by a team led by the British Museum before they were washed away.

2. Bouldnor Cliff, Isle of Wight

Bouldnor Garry Momber with recovered flints courtesy of M Pitts - Copy
Garry Momber of the Maritime Archaeology Trust displaying a handful of Mesolithic worked flints retrieved from the seabed off Bouldnor, Isle of Wight © Mike Pitts

The erosive force of the sea is not confined to the shoreline; tides and storms also remove sediments laid down on the sea floor. Off the coast of Bouldnor on the Isle of Wight, excavations by the Maritime Archaeology Trust have been exploring a submerged landscape since 1999. It dates back 8000 years to the late Mesolithic period when sea-levels in this region were some 11-12m lower than today. The eroding archaeological deposits have produced flints and timber worked in ways that we used to think were unknown in this country before the Neolithic period (which didn’t start until 2000 years later).

The site has also produced the earliest known example of string, and last year evidence of bread wheat DNA was found. This raises the possibility that Mesolithic people were trading with continental neighbours for wheat 2000 years before the previously accepted date for the introduction of cereal agriculture to Britain.

3. ‘Seahenge’, Holme-next-the-Sea, Norfolk

Sea Henge
Sunrise over ‘Seahenge’ on 20 May 1999 prior to excavations later that year. © Historic England / Alun Bull

The site known popularly as ‘Seahenge’ comprised a circle of timber posts surrounding an upturned tree stump. It was first revealed eroding out of the beach at Holme-next-the-Sea, Norfolk, in 1998 and completely excavated the following year.

Dendrochronology (dating of wood by analysis of preserved tree rings) showed the monument to date to 2049 BC. Its function is less certain, but it was probably connected with rituals to mark the passage of human spirits between the worlds of the living and the dead.

4. Kilnsea Warren henge, barrows and timber circle, Spurn Point

Kilnsea Warren - Copy
The tips of an arc of timber posts briefly revealed on the beach at Kilnsea Warren, East Yorkshire. The posts have been radiocarbon-dated to between 2040 and 1880 BC. © Peter Balson

The Holderness coast in East Yorkshire is eroding rapidly – in places by up to two metres a year. If that rate of erosion has been constant throughout later history, it means that the coast of Holderness has retreated inland by some 4km since the arrival of the Romans in AD 43, and perhaps 8km (5 miles) since the Neolithic/Bronze Age transition 2000 years before that.

Archaeological sites that were several miles inland when they were created are now being revealed (and destroyed) by coastal erosion. At Easington and Kilnsea, which lie north of Spurn Point at the mouth of the Humber Estuary, sites identified on the beach in recent years have included a late Neolithic henge monument and a Bronze Age house and burial mounds. Recently an arc of timber posts was also briefly revealed. The posts were radiocarbon dated to between 2040 and 1880 BC, as part of palaeoenvironmental research commissioned by Historic England for its programme of Rapid Coastal Zone Assessment Surveys, before the sea once more covered them in shingle.

Nothing more is known about the form or function of the posts, but the site is a possible parallel to Seahenge.

5. First World War pillboxes, Holderness

Holderness pillbox BA10, view from s west
A sunken machine-gun post defending the shoreline against the threat of German invasion in 1917 at Auburn Sands, East Yorkshire © Roger Thomas

Also under threat from erosion on the Holderness Coast are a number of concrete guard posts, or ‘pillboxes’ – many recently identified as dating from the First as opposed to the Second World War.

Some are actively being eroded by the sea, but others survive a little way inland. We’ve just listed at Grade II a selection of the better preserved examples at Auburn together with others further down the coast in the parish of Skidbrooke with Saltfleet Haven in Lincolnshire. They are thought to have been built in early 1917. Many show evidence of adaptation and re-use in the Second World War.

6. Low Hauxley, Northumberland

Low Hauxley Cairn under excavation
The kerb of the Early Bronze Age cairn on the cliff edge at Low Hauxley, Northumberland, during excavation in 2013. © Peter Murphy.

Since 1983, a number of human burials dating to the Early Bronze Age have been exposed in sand dunes that fringe the beach at Low Hauxley, Druridge Bay, Northumberland.

As a result of a series of small-scale rescue excavations over the last 30 years, we knew that the burials lay beneath a stone cairn that was being progressively eroded by the sea. By 2010 it was apparent that the site would soon be completely lost, and in 2013 what remained of the cairn was excavated by a team of archaeologists led by Clive Waddington. The excavations revealed that the cairn had been constructed on a small hill rising up out of a coastal saltmarsh, and that the hill had previously been inhabited by Mesolithic peoples.

7. Mersea Island, Essex

West Mersea trackway
© CITiZAN/Oliver Hutchinson. The West Mersea trackway in situ on the beach, prior to lifting of the individual timbers.

On Mersea Island in Essex, part of what appears to be a prehistoric timber track was recently found eroding out of the Thames foreshore and recorded by the CITiZAN project. Most of the trackway had already been lost to erosion, but three planks survived. Each plank was originally held in place by timber pegs hammered through mortise holes in its ends. The trackway would have been laid down to facilitate passage across damp ground, probably saltmarsh. The planks are currently being conserved and dated by Historic England. One has been dated using dendrochronology, and shown to be from a tree felled sometime after 952 BC. The trackway therefore dates to the Late Bronze Age.

 

The annual Festival of Archaeology starts on July 15th, with hundreds of events hosted by museums, heritage organisations and community groups, giving you the chance to find out about the archaeology of where you are.

See what’s going on near you here.

 

Further Reading

 

Historic England Bookshop 

 

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