10 comments on “Driftwood 7

  1. Fantastic shape of this one ! Quite envious of the larger pieces of wood you find on your beaches 🙂

    • Actually, this one is not strictly speaking driftwood. It is the remains of a tree trunk which was drowned as sea levels rose about 10,000 years ago. It was buried in peat, the decomposition of which stained it with rust. In recent years the overlying sand, clays, and peat have been stripped away, leaving the wood exposed. The peat has lenses of crumbling mussel and cockle shells – as well as being inter-laced with all sorts of leaves, twigs, nutshells, and woody fragments.

      • Fascinating. So this is probably a victim of the end of the last ice age, I suppose.

      • Yes, I guess so. It was the melting of the ice sheets that basically caused the sea levels to rise and flood lower lying coastal areas. Prior to that, the Bristol Channel was woodland with rivers flowing through it. The channels of the rivers can still be detected on the seafloor of the Channel today – bathymetry and all that.

      • On the other hand, only the end of the ice age made it possible for trees to grow there. So it created a temporary opportunity, first giving and then taking.

      • The ice sheets advanced and retreated several times in this part of the world with so called glacial and interglacial periods, but as far as any specialists can work out, the ice did not ever extend as far South as the tip of the Gower Peninsula at Rhossili or the Bristol Channel. So although vegetation types may have been affected by the vissitudes of the prolonged cold period, it is likely that the trees persisted throughout the “ice age”.

      • I have to leave that to the experts (and you are far more of an expert in such matters than I am). However, I suppose that during the glacial periods there would have a zone of tundra south of the ice. Taiga or even temerate forrests would have been far further south. However, I don’t know where were the borders of the different vegetation types during the glacial periods.

      • I only know what I read up and it is often difficult to put everything into sequence and chronological order. However, in the book The Geology of South Wales by Gareth T. George, he says concerning the area in which the driftwood was photographed “a variety of recent deposits, including peat from the submerged forest and wind-blown sand, are exposed. Here the peat contains in situ stumps and fallen branches of alder, birch, hazel and oak, and in some areas it has been altered to a ferruginous hard pan. The broad-leaved forest that produced this peat began growing about 8000 years ago (I made a mistake about that date J.W.) as a result of an increase in temperature and rainfall after the last Devensian glaciation; growth continuing until the coastal plain was flooded during the later part of the Flandrian transgression”.

        The end of the Devensian glaciation was 11.8 thousand years ago. The Flandrian transgression happened between 10,000 and 5,000 years ago. So there was a short period after the ice retreated when it was warm enough for a deciduous woodland to develop before being swamped by the gradually melting ice.

      • hazel and oak sound like it was quite warm. Must have been a nice area before it was flooded. 🙂

      • People were around and surviving in the location at that time. Interesting human and animal bones have been recovered from caves very close to the submerged forests. It was obviously a good environment in which to live.

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