Submerged forest at Broughton Bay

The ragged tree stumps and roots, strewn over the seashore at Broughton Bay on the north coast of the Gower Peninsula, are the remains of a birch tundra woodland that once covered the ancient land surface. They lie in position, just as they were growing before they were inundated. Ten thousand years ago in the Pleistocene Period, a large river, fed by tributaries such as the Loughor, occupied what is now the Bristol Channel with its Atlantic waters. The last extension of the ice sheets in this area, during the late Devensian Period, had been about 8,500 years earlier. As the ice receded up into the valleys of South Wales, the climate had warmed up and allowed vegetation to flourish. The sea level at that time was about 22.5 metres lower than it is at the present.

By the beginning of the Neolithic Period 5,700 years ago, however, the sea level began to rise because of the increasing volume of global meltwater and  its accompanying land subsidence. The forests and peat bogs of the coastal margins were submerged and buried in sediment…..until the 1980s when the remains began to reappear on Gower shores as the surface sediments began to erode away. Now, large expanses of Broughton beach have been stripped of sand showing the strata and entrapped woodland beneath.

Wood from these ancient forests is visible on the seashores of  Swansea Bay and Port Eynon on the south Gower coast as well. Large blocks of peat dating from this time also wash up on the sand at Whiteford – the next bay to Broughton. The plant species already recorded include silver birch, hazel, alder, elder, deergrass, rushes, irises and spurges. As I understand it, no full investigation of this palaeo-environment has yet been conducted. I hope that full attention can soon be given to this valuable evidence before the rapid rate of erosion destroys all that is readily accessible between tides. 

 

COPYRIGHT JESSICA WINDER 2013

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