21 Replies to “Langland Pebbles 2”

  1. Wow. I’d be collecting so many I might need a truck to take them home. I especially like the veined ones. I also love the triangle of pebbles photo as an image. And that line of pebbles marching along the crack in the larger stone. What a lot you’ve captured here, both as info and as art compositions.

  2. how do you believe these polymictic pebbles, which are variously from the ORS, CARB LMST, MG and CMS, arrived on Langland?

  3. What a great collection of colours and patterns. I noticed that the pebbles on Oxwich beach were all steely blue – there are some like that in your photos.

  4. I love these shots, especially ones where pebbles are like rivers flowing out from clefts in the rock.

  5. An interesting question, Rob. I referred to it in earlier posts about Langland. The east side of Langland Bay coincides with the limit of a Late Devensian ice sheet that accumulated on the Brecon Beacons and mountains in central Wales and then flowed southwards through the South Wales Coalfield valleys to eventually join up in Swansea Bay. The terminal edge of the ice sheet crossed Gower from Langland Bay westward to Rhossili Bay. It seems that the great assortment of pebble types found on the shore at Langland Bay are at least in part made up from stones originating in the glaciofluvial sheet deposits that were dumped as the ice melted and retreated; that are now exposed by coastal erosion. The pebbles are the water-worn fragments (erratics) of Old Red Sandstone, Coal Measures and Millstone Grit, brought by the ice – together with local Carboniferous limestones.
    References:
    Barclay, W. J., 2011, Quaternary Deposits, in Geology of the Swansea district, a brief explanation of the geological map Sheet 247 Swansea, Keyworth, Nottingham, British Geological Survey, 21-25
    Bowen, D. Q., 1971, The Quaternary succession of South Gower, in Geological Excursions in South Wales & The Forest of Dean edited by D. A. Bassett and M. G. Basset, Cardiff, Geologists’ Association South Wales Group, 135-137
    Bridges, E. M. 1997, Mumbles and Langland Bay, in Classic Forms of the Gower Coast, Series Editors R. Castledean and C. Green, Sheffield, The Geographical Association, 16-17

  6. Hi Emma. The great variety of pebble types occurring at Langland Bay is probably the result of the erosion of a cliff deposit of glaciofluvial material brought from far away by the grinding action of thick icesheets as long as 14,000 years BP. They are mixed in with pebbles of local Carboniferous limestones (of which there are quite a few types or sub-divisions). At Oxwich I think the steely blue pebbles to which you refer are more likely just to be local limestone – but I am not sure of that. Oxwich is a place I must re-investigate. I have visited it in recent years but infrequently. In the late sixties I was there regularly with Swansea University Biology Society to survey the recovery of the intertidal organisms after the catastrophic effect of a particularly cold winter that destroyed almost everything living on British shores.

  7. I know how you feel, Claudia. I have had to curtail my pebble collecting these days. Just no room to store or display them any more. Taking large quantities might be a problem anyway, as so many places round the world are now protected and conserved, with pebble collection actually prohibited. I am still able to enjoy the images though.

  8. Thank you, Hamish. That is an interesting perspective on the images. I was seeing such shots the other way round, as the pebbles moving up-shore like a fluid to fill in all the grooves and furrows in the bedrock.

  9. Thank you, Evelyn. There is something about pebbles that is eternally appealing. Pocket-sized pieces of geological history and naturally artistic design.

  10. Yes, I thought of that too, that many time collecting is prohibited. Your photo also reminded me of another clay project I want to try: I had a a friend who used to make “pebbles” of clay, glazing them and so on, so that they looked like pebbles but you knew they weren’t. I put that on my list, also, for upcoming ideas to work on, Thank you!

  11. That’s very interesting. My parents have a pond in their garden and said that after the rest cold (it snowed three times where they live in Stroud) that everything had died in the pond, the frogs and newts and the water had gone black.

  12. I am sorry to hear that all the pond life died with the cold weather. It must have been very cold indeed. Do you think maybe the black water was due to all the decomposition products?

  13. Thanks for reply, about the origin of the pebbles at Langland.
    Assuming that most of the pebbles are derived from the glacial sediments what would be the nature of the beach sediments without a glacial source? Even the sand is dominatly comprised of quartz grains presumably derived from the glacial sediments.

  14. I guess, without a glacial source, the beach could be a rocky shore or platform with just some locally sourced limestone pebbles – perhaps something like Mewslade Beach in recent years when all the sand was temporarily washed away; or maybe a bit like the landward shore of the Worms Head Causeway on the eastern part (where the limestone is water-worn and smooth) before you get to Tears Point. Is that a plausible answer? What do you think?

    https://natureinfocus.blog/2014/02/17/storm-damage-at-mewslade-bay/
    https://natureinfocus.blog/2016/08/14/water-worn-limestone-1/
    https://natureinfocus.blog/2016/08/17/water-worn-limestone-2/
    https://natureinfocus.blog/2016/08/28/water-worn-limestone-3/

  15. Thanks for your reply.

    Your idea maybe correct, but perhaps it is also about ‘ survival of the fittest.’

    The dominance of quartz rich pebbles and quartz dominated sand at Langland may because they out compete other rocks and grains, especially limestone, which are softer and less able to withstand abrasion from the ‘harder ‘ quartz rich sandstones and conglomerates.

    By inference, where there are no quartz rich pebbles then we should expect to see that limestone pebbles are more common and are dominant…..as in the Patella Raised Beach and, as I remember, storm beaches in the Vale of Glamorgan.

  16. i am now concerned that there are going to be no pebbles left when I return……….after reading Claudia’s comments….

  17. I wouldn’t worry too much, Rob. Claudia would have a very long way to travel to Lagland, and the cost of excess baggage to take any pebbles home would be prohibitive!

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