A new study has shown the impact of 12,000 years of sea level rises on Isles of Scilly.

The Lyonesse Project, published by Cornwall Council, was commissioned by Historic England following the discovery of a submerged forest in St Mary’s Road by local diver Todd Stevens. 


Popularly associated with the legendary lost land of Lyonesse, Scilly was one large island 9,000 years ago. Lyonesse, said to have extended westwards from Land’s End to the islands, was reported to had 'fair-sized towns and 140 churches' before being engulfed by the sea.


The 500-year period between 2500 and 2000 BC saw the Isles of Scilly lose the equivalent of 66% of its land area.


Charlie Johns, Archaeology Projects Officer for Cornwall Council's Cornwall Archaeological Unit, said: “After this, the rate of change slowed significantly so that by circa 1500 BC the pattern of islands was approaching that of today, but with the dramatic difference of a vast intertidal area of saltmarsh in what is now the islands’ inner lagoon.


“Much of this would have remained useful land, especially for grazing animal stock and would have been passable with ease almost all of the time.


“It was not until there was an open channel north of St Mary’s during most states of the tide that the saltmarsh began to erode rapidly: radiocarbon dates suggest this is likely to have occurred in the early medieval period, after 600-670 AD.”


Work on the project was carried out between 2009 and 2013 by the Cornwall Archaeological Unit, with experts from Aberystwyth, Cardiff, Exeter, Plymouth, Oxford and Glasgow Universities and Historic England’s Scientific Dating Team. Volunteers and local experts from the Cornwall and Isles of Scilly Maritime Archaeological Society and the Islands Maritime Archaeology Group were also involved. 


The aim of the project was to reconstruct the evolution of the physical environment of Scilly during the current geological epoch; investigate the progressive occupation of this changing coastal landscape by early peoples; explore past and present climate change and sea-level rise; and develop geophysical techniques for mapping submerged ancient landscapes.


Daniel Ratcliffe, Inspector of Ancient Monuments for Historic England in the South West, said: “This new cutting edge research will be instrumental in refining our knowledge of how Scilly’s populations have responded to the ever present challenges of living within an evolving coastline throughout history.”


More information is available on the Cornwall Archaeological Unit website.

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