The remnants of an eroding ironpan or ferruginous hardpan, exposed on the shore at Broughton Bay, Gower, South Wales. This has probably been created by the decomposition of the overlying peat layer dating from the relatively recent Holocene period. It is in the peat that you can find the stumps of trees from a submerged forest.
See the related posts:
Submerged Forest at Broughton Bay
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Wild edible mussels (Mytilus edulis L.) thrive around the Gower coast in South Wales. Although the area is perhaps better known for cockles (Cerastoderma edule L.), mussels grow in great abundance and are the second most important shellfish exploited in this area.
Good spatfalls result in millions of tiny mussels seeming to settle on every available surface that is subject to inundation by the sea, if only fleetingly at high tide or even just spray from the incoming tide. Rocks and boulders are obvious surfaces but strands of algae and living limpets also provide suitable habitats. The upper rocky shores appear to glisten with a richly textured carpet of the new generations of this bivalved mollusc. From a distance the mussel shells look black but, up close, it’s possible to see just how colourful and patterned some of these shells can be.
Not all the young mussels survive. These small seashore creatures compete for space on the settlement substrates. Some specimens fail to make it to maturity. Those that outlive the others can grow to good size. I feel particularly sorry for the poor old limpets which are increasingly weighed down as the covering mussels grow larger and larger.
Storm event and natural mortality can result in huge numbers of empty mussel shells on the beaches. Mostly, the empty shells are found with the two halves of the shell (the valves) stuck together by the ligament, as in life. They can look like decorative dark blue butterflies settled en masse on the sand. The last time I visited the place where Broughton Bay and Whiteford Sands meet, the strand-line was thickly covered with very smelly mature dead mussels on which the local gulls were feasting.
It is the small seed mussels that are collected regularly at extreme low tides from the boulders and pools around the old rusty iron lighthouse at Whiteford Point. In the next posting I’ll talk about how this is done and what happens to the millions of baby mussels that are collected.
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There must be a lot of careless or unlucky people around – judging by the number of lost boots, shoes and sandals that turn up on strandlines. I pity those poor folks who ended up walking home with bare feet or hobbling with just one shoe. The photograph above shows a boot I found last summer on Broughton beach: it had obviously been on a long sea voyage.
Here follows a small selection of the footwear that I noticed when I walked along Rhossili beach and Whiteford Sands over two days in April 2009.
Looks like someone has spent a lot of time on the beach at Broughton Bay, Gower, and taken a great deal of effort to create this wonderful multi-coloured display of fishing paraphernalia with floats, buoys, ropes and even a boat ladder. All this flotsam, washed up on the sandy seashore, now makes a wonderful sight as it festoons a nearby tree.
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The pattern of white dots and stripes on the blue-grey boulder (in the foreground of the picture above) is fossilised coral which lived between 290 and 340 million years ago. This boulder is one of many with similar fossils that come from the Carboniferous Limestone strata which are a major geological component of the tip of the Gower Peninsula. The original calcareous components of the coral skeleton have been replaced by white crystals, probably calcite. The process has preserved in fine detail the internal structure of the coral with its many internal dividers or septa. The way the beach boulders have weathered and worn has exposed the coral colonies within the rocks showing the long axes or longitudinal sections of the coral (the stripes) and the circular end views or transverse sections (the dots).
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An empty Skate egg case, or Mermaid’s Purse, caught up in marram grass on frosted sand dunes at Broughton Bay, Gower, West Glamorgan, New Year’s Day 2010. Looking a bit like a fat beetle clinging to the vegetation, the egg case was frozen into position where the wind had blown it from the water’s edge. Minute ice crystals glistened on the dune in the early morning sun. The blades of marram grass and the lower ‘horns’ of the egg case seemed to have been arranged in ready-made holes where the sand grains had frozen together instead of drifting snuggly up to them.
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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.
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