Submerged forest at Broughton Bay

Ancient buried forest at Broughton Bay (1) - Remains of trees from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales.

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. 

ncient buried forest at Broughton Bay (2) - Remains of a tree (in clay) from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales. The stump of the tree trunk and the radiating roots indicate that the tree is still in situ as it was growing around 10,000 years ago.

Ancient buried forest at Broughton Bay (3) - Remains of trees from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales.

Ancient buried forest at Broughton Bay (4) - Remains of a tree (in clay) from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales. The stump of the tree trunk and the radiating roots indicate that the tree is still in situ as it was growing around 10,000 years ago.

Ancient buried forest at Broughton Bay (5) - Remains of a tree (in clay) from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales. The stump of the tree trunk and the radiating roots indicate that the tree is still in situ as it was growing around 10,000 years ago.

Ancient buried forest at Broughton Bay (6) - Remains of a tree from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales. The stump of the tree trunk and the radiating roots indicate that the tree is still in situ as it was growing around 10,000 years ago.

Ancient buried forest at Broughton Bay (7) - Remains of a tree, still in situ, from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales.

Ancient buried forest at Broughton Bay (8) - Remains of a tree from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales.

Ancient buried forest at Broughton Bay (9) - Common winkles grazing on the remains of a tree from an ancient submerged forest eroding out of the beach at Broughton Bay, Gower, South Wales.  

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11 thoughts on “Submerged forest at Broughton Bay

  1. Hi Jessica. I stumbled across your fantastic blog while searching for info on the submerged forest, which we walked past yesterday on the way back to the caravan we have just bought at Broughton Bay. We are starting to explore this wonderful area and your superb photos really highlight the interesting and sometimes amusing things to be seen here. I love your photo of the boot with the barnacles on it!
    Coincidentally, though I visited The Gower many times in my youth, coming from nearby Cardiff, the first holiday I had here with my wife and our girls a few years ago was based in Llanmadoc, staying with Anne and David Main at Tallizmand, and they were equally as good hosts then as now.

  2. Hello, Clive. I’m so pleased to hear that you like my blog and that you are finding it useful. How wonderful it must be to have a caravan at Broughton so close to the beaches – just a few steps and you’re on the sand. Gower is an incredible place. I would love to be able to spend more time there myself. There is always something to admire or investigate on its beaches. We will be going there again soon and staying at Tallizmand. I’ll tell Anne and David what you have said about staying with them a few years back.
    I hope you continue to have many happy times with your family on Gower.

  3. Thanks, Ian. I am about to write an update on this post (first posted 2009). I re-visited Broughton Bay this year (2012) and looked at the vertical and horizontal exposures of sediments where the ancient wood is being exposed. They seem to be disappearing fast and it would be good to record everything before it goes. The extremes of weather we are experiencing create conditions that are eroding back the softer sediments in this area at a noticeable rate.

  4. Great blog Jesssica, facinating to see submerged ancient forests from the past. I have seen this type of forest at Amroth and wondered if it was all part of the same forest connected to the Gower?I find it particularly interesting as i am a volunteer ancient tree hunt verifier for the woodland trust.

  5. Thank you, Michael. I think you are right if the trees are found on the beach at Amroth – the remains of trees around Gower are part of a forest that apparently filled most of the Bristol Channel at one time. Sounds like you do interesting volunteer work with the Woodland Trust.

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  9. Hi Jessica, I stumbled across your blog looking for details on the Helvetia. Fantastic photos and loads of info – thanks. I was on Rhossili yesterday and saw the shipwreck for the first time – still can’t get it out of my mind – so haunting.

    Quite near to the wreck are some other stumps which baffled me. They stand upright, about 1ft revealed from the sand. There does not seem to be any pattern to their position. Any ideas what they could be?

    I enjoyed looking at your patterns in the sand photos. I took some pictures yesterday as the wind was sweeping across the sand and leaving it dried and settled on the wet sand – amazing.

    Just one more question: At Rest Bay I took some pictures of more amazing sand patterns where a black subtance was being drawn over the sand by the tide, leaving it in sweeping, flowing lines – quite stunning. Any idea what the black stuff might be? To be honest, it looked like sand, but why would it be black?

    Lynn Bateman

  10. Hello, Lynn.

    Thank you for your comments. I am afraid I can’t tell you what the other stumps near the Helvetia wreck on Rhossili might be. There have been many shipwrecks on Rhossili beach and most are buried in the sand for the majority of the time, or only seen at the lowest of tides. I am sure they must all be listed somewhere but I cannot find the location just now. I have seen four of them. Two are always on show to varying degrees, the other two more elusive. I have also seen a poster showing the position of all the wrecks, so the information is out there somewhere.

    The other problem is that the sand shifts around the beach, becoming deeper first in one place then in another. This is dependent on tides, currents and weather. At different times, different parts of the same wreck will be exposed. If you Google for images of the Helvetia, for example, and there are many, you can see how varied it can look depending on sand depth. I would hazard a guess that the isolated stumps near to the Helvetia were actually part of the same wreck – but it isn’t possible to rule out part of another one.

    I have never been to Rest Bay so, again, can only suggest what the black substance like sand grains might be. Sand can be different colours at different depths. Below a 5 to 15 cm boundary, the sediments change from yellow to black, maybe separated by a thin grey layer. The black sand is anoxic (has no free oxygen) but anaerobic bacteria can thrive. The hydrogen sulphide, ammonia, or methane they produce during their metabolic processes give off an unpleasant smell. The hydrogen sulphide reacts with iron in the sand to form black iron sulphides that attach to or stain the sand grains and any other objects (like shells) buried at that level. As these grains are carried to the surface they are oxidised to ferric oxide that makes the grains yellow. Black grains can be brought to the surface by burrowing animals, bait diggers, and by stormy seas churning up the sea bed. The black grains may have different physical properties, like weight, that separates them from the unaffected grains on the surface.

    Another possibility might be that the black grains you noticed grains are a different mineral composition (not silica based, or calcium carbonate from shells); or the black grains making the patterns at Rest Bay might even have been microscopic fragments of mussel shells or charcoal.

    Hope this helps to answer your questions.

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