Pebbles 1-5 TDPIR The pebbles on the beach at Trabeg on the Dingle Peninsula in Ireland are unusual in that they come from the conglomerate in the cliffs. Unlike most beach pebbles, these stones were smoothed and rounded millions of years ago on river beds before being deposited in layers of finer material that consolidated after major flood events.

5 Replies to “Pebbles 1-5 TDPIR”

  1. Hi Jessica,
    Several recent posts have arrived looking like the one below with tiny inaccessible images.
    Never happened before.
    Is it just me or is there a glitch?
    With best wishes,
    Hamish
    +44 7977 269778

    Liked by 1 person

  2. Hello, Hamish. Thank you for highlighting a potential problem with the blog pictures. Unfortunately I cannot see any attached image in your message, but I have checked the appearance of the blog both in the administrative panel and by externally accessing the versions on a PC, tablet, and smartphone. The images look alright to me. I thought maybe the problem lay with the new processing system that has been forced on WordPress users from last week – so checked everything. Seems to be OK there. I have changed the display option on this latest post from gallery mosaic to single column for you. That may work better. Otherwise it looks like there might be a problem with your phone. Thanks for telling me. Always wise to check things out. Best wishes, Jessica

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  3. appreciate your comment, but the pebbles in your photos are mostly red and green sandstone, which are presumably of Devonian age, and have been rounded more recently?????

    Liked by 1 person

  4. You are the expert Rob – but I am not sure that I am entirely wrong. I think that you may be right about some of the pebbles having been smoothed more recently from pieces of rock broken from strata interbedded with the conglomerate although locally those layers of rock were red rather than green. Other pebbles will surely have originated in the conglomerate and been rounded to start with, and this smoothness and wear enhanced by beach action. The conglomerate in the cliffs adjacent to the pebbles on the beach at Trabeg contained both rough and smooth stones in a fairly soft matrix, and the empty sockets where stones have become dislodged are visible (see the earlier post Rocks 1-5 TDPIR Image 2). The Geological Society of Ireland’s Geological Guide to the Dingle Peninsula describes the Dingle Group as containing ‘purple-red and grey-green conglomerates, sandstones and mudstones’. And regarding the Trabeg Conglomerate Formation itself, it says that they are composed of ‘quite well-rounded pebbles of red sandstones and siltstones, white vein quartz and chert, together with a very few pebbles of probable volcanic rock and a few of grey limestone’. So there is the potential for these types of pebbles derived from the exposed cliff conglomerate to be on the shore. I would think the situation as having some similarity to that found at Budleigh Salterton in Devon where the entire beach is comprised of pebbles that have eroded from the cliffs. That was my reasoning – but I am only an amateur and it is easy to be mistaken.

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  5. I see what you mean now!
    At first I only saw the loose pebbles on the beach, but now I have come across photos of the conglomerate in place, which contains rounded red pebbles, It appears that you are correct and at least some of the loose rounded pebbles on the beach are derived from the conglomerate..
    You will note that I am also a fan of pebbles!
    Thanks….

    Liked by 1 person

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