Walking back from Spaniard Rocks now, I took a route closer to the dunes where the character of the shore is quite different from the wet sand and strandlines between high and low tide levels. Here there are pebbles. Rhossili’s pebbles intrigue me. I love scrambling over the banks of stones at the very top of the beach. The colours are lovely pastel shades with pinks and blues and overall reminding me of sugared almonds. A total delight. Many rock types are represented. Some have interesting patterns.
I like the way that the numbers of beach stones seem to increase or decrease depending on how they are pushed around the shore between one visit and the next, and how the sand changes its level and distribution throughout the year and the transition from season to season. This time the wooden ribs and keel of the shipwrecked ketch Anne were only just visible above the sand and pebbles. I like the way that pebbles are arranged partly buried in the damp sand that quickly dries to a different hue and texture. The pebbles underlie the tall sand dunes of the Llangennith Burrows. The dunes have been scooped out by stormy seas and footsteps in many places to demonstrate that even wind-blown sand is stratified; and marram grass roots exposed to air show how deep they penetrate the soft fine sediments to bind them together and stabilise the dunes.
Diles Lake is really a stream that drains the Llangennith marshes lying behind the dunes at Rhossili in Gower. The water is frequently dammed back to resemble a lake by banks of pebbles pushed upshore by strong tides – but the water always works its way through the pebbles and sand to flow across the beach, spreading out into myriads of shallow channels as it approaches the sea. Underwater, the many colours of the pebbles are clear to see, contrasting with the dry stones stacked to the side often showing a black coating caused by earlier burial at deeper anaerobic levels of the beach.
It can be quite tricky to cross the stream but on this occasion someone had conveniently made ‘stepping stones’ from an old pallet and driftwood. I noticed that the stream exiting the dunes had long trailing clumps of unpleasant-looking brown filamentous algae of a type resembling something more typical of polluted water – but I must have been mistaken because the water sampling point for Rhossili is nearby and it has only recently been declared of excellent bathing quality.
The heaped pebbles once over the stream had brightly coloured pieces of knotted rope from fishing activities and a scrunched up newspaper (perhaps it had held bait). My eye was also caught almost immediately by a much larger piece of vivid flotsam washed up and stranded at mid shore level. It was about 1 metre in diameter and hip high and made quite a sculptural addition to the beachscape. Faint embossed lettering provided the clue I needed to do an internet search and discover it was a wrecked rigid mooring buoy style MB350 made by the Norfloat company in Exeter.
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Playing with sand on an industrial scale at Weymouth Beach in Dorset this week, earth moving machinery has been restoring the shore to pristine condition by redistributing imported sand – ensuring plenty for sun-bathing and sand castle-making before the better weather and the influx of visitors arrive in this new season.
Some more images showing the subtle colour transitions and delicate branching patterns that characterise the low relief natural sculptures in the fine clean sand on the shore near Picquerel Point at Grand Havre in the Channel Island of Guernsey. The dendritic patterns have been created by sea water draining down the beach as the tide recedes; and this has led to a sorting out of particles by size, weight, and colour. The darker sediments that outline and emphasise the design may be organic remnants or different darker minerals. These patterns are the best of their type that I have seen – perhaps due to the very fine sand. The patterns are so delicate they could almost be drawings.
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Subtle colour transitions and delicate branching patterns characterise the low relief natural sculptures in the fine clean sand shown in this photograph. It was one of many taken on the shore near Picquerel Point at Grand Havre in the Channel island of Guernsey. The dendritic patterns have been created by sea water draining down the beach as the tide recedes; and this has led to a sorting out of particles by size, weight, and colour. The darker sediments that outline and emphasise the design may be organic remnants or different darker minerals. These patterns are the best of their type that I have seen – perhaps due to the very fine sand. They look like pencil sketches. I am definitely going to frame some of the images.
The sand on the Island of Herm, which is one of the Channel Islands, is mostly made of shells and shell fragments. A good place to examine the sand is Belvoir Bay where waves and currents wash shells ashore and break them up. The small cove lies at the foot of modest cliffs of Herm Granodiorite with xenoliths; and eroding rocky outcrops strew the shore at the base of the cliffs. Hollows and crevices in these rocks are filled with coarse shell sand containing many intact little shells of both bivalve and gastropod molluscs. Even minute sea urchin tests survive. I took a handful of the sand home to photograph against a scale, and compare them with some mature-size shells from the same beach and nearby Shell Beach. I have fond memories of visiting the island and collecting shells there forty years ago.
The shape of natural abstract sand sculptures, like these ripples on the seashore, result from complex interactions of water and substrate which are the subject of much research in the field of fluid mechanics. They are described as “small-scale three-dimensional bedforms due to interactions of an erodible bed with a sea wave that obliquely approaches the coast, being partially reflected at the beach” (Roos & Blondeaux 2001). Different combinations of three main perturbation agencies create different ripple designs.
Roos, P.C. and Blondeaux, P. (2001) Sand ripples under sea waves. Part 4. Tile ripple formation, J. Fluid Mech. vol. 447, pp. 227-246.