The future impacts of climate change – accelerated by human activity – are now widely reported, discussed and largely acknowledged. All the evidence indicates there will be an increase in the intensity of the earth’s weather systems leading to enhanced storminess, more droughts and flooding, enhanced melting of glaciers and icecaps, and an increase in global sea-levels. Yet somehow the implications for us personally can often seem remote and difficult to visualise. However, the Welsh coastline offers us the opportunity to look into the past to see that rising sea-levels are not a new phenomenon. Dotted around the Welsh and Irish coastlines, are the remains of pine and oak woodlands and fragmented blocks of peat that point to past and forgotten habitats to the waves that now beat against the shoreline.
The CHERISH Project has been working in this intertidal zone to record wrecks and relict archaeological landscapes, which also speak of loss and coastal change. However, another aspect of our work has been to determine the age of some of the relict landscapes of the Llŷn Peninsular in relation to our work on past sea-level change.
Whilst monitoring a wreck on Warren Beach at Abersoch in Gwynedd in 2018, the CHERISH team discovered a sizeable tract of fallen tree trunks and blocks of peat. The winter storms had removed vast quantities of sand exposing the peat. Some of the peat had been block-cut, presumably for fuel, but where it was undisturbed it was peppered with animal hoof prints, probably a mixture of deer and aurochs.
During the last glacial episode vast amounts of sea water was locked up in the huge ice sheets covering swathes of the norther hemisphere. It is estimated that sea-levels may have been over 75 metres lower than they are today. However, figure 3 shows that much of Cardigan Bay lies less than 50 metres below its current level. This area alone equates to 4400 square kilometres – 1/5th of total area of Wales.
Our research indicates that Warren Beach was a wooded habitat around 7,700 years ago, but also that the environment was changing. Ground water levels appear to have risen, probably drowning the trees, and initiating the formation of peat. We can speculate that as sea levels rose the beach barriers blocked the drainage of rivers like the Afon Soch as they advanced inland. We have also discovered that the sea reached Llyn Maelog near Rhosneigr on Anglesey around 7000 years ago, changing it from a fresh-water lake to marine inlet.
Radiocarbon dating has revealed that trees grew once again on the foreshore at Abersoch around 4,300 years ago, while at Borth and Ynyslas they flourished between 6,200 and 4,300years ago. At both site peat formation replaced the woodland habitat as the sea continued its inexorable rise which finally submerged the wetland and formed the current shoreline.
It intriguing to imagine the habitats that would have supported wild boar, Eurasian aurochs, bear, lynx and wolf that would have been hunted by the Mesolithic inhabitants. It seems plausible that they would have witnessed the encroaching sea and loss of landscape, passing on stories of changing environments to subsequent generations. How they made sense of the changes they experienced is anybody’s guess, but clearly they were unaware of the causes and helpless to influence them.
It is perhaps little comfort that our prehistoric ancestors had to contend with the same threats that we are facing today. The trajectory for future sea-levels means that further loss and environmental change are inevitable. However, unlike our ancestors, we should be aware that we are in-part responsible for the changes that will affect our children and grand-children, and more importantly we are not powerless to do something about it.