Water-worn Limestone 3

Natural sculpturing of limestone on the Worms Head Causeway in Gower, South Wales.

You would think that all the limestone strata on the Worms Head Causeway in Gower would be worn down equally to a smooth, flat, even surface – but not so. Upstanding at various points on what I suppose is really a wave-cut platform (albeit eroded by acid rain and seashore creatures as well), isolated areas remain standing. They look like giant teeth embedded in the worn surface strata. I do not know why these areas are more resistant, however, I have read that some parts of the limestone become harder by dolomitisation, a process in which the calcium carbonate is converted to magnesium carbonate by the intrusion of seawater (I think before the original sediments harden and compact). Maybe that is the explanation.

Velella velella (By-the-wind Sailor) at Rhossili

By-the-wind sailor (Velella velella Linnaeus) on the beach at Rhossili, Gower, South Wales.

By-the-wind Sailors (Velella velella Linnaeus) have been washing ashore at Rhossili Beach over the past week. The sandy strandline has been dotted with dozens of the dark blue jellyfish-like creatures with their characteristic translucent sails. They are not actually jellyfish but pelagic (free-floating) colonial hydroids. [See also the earlier posts about this marine invertebrate in Sailing by Rhossili Bay and Bright Blue Blobs on the Beach.]

Water pattern & texture in Weymouth waves 2

The further you walk along Weymouth pier the deeper and bluer the water – turquoise tinted. In the shallows, the sand on the sea bed makes the water appear more yellow. On this calm day, the water surface was riffled by the wind to produce patterned textures where the transient ridges were delineated by the light they caught.

Flowering fields at Charlton Down

Yellow flowering oilseed rape crop in spring

The weather was very changeable but it was still a lovely spring afternoon for a walk up the hill to the barn. It is a good viewpoint up on Charlton Down, looking over the gentle rolling hills of arable farmland. I haven’t been along that path for some time and it was amazing to see the difference in the surrounding fields.  The young oil-seed rape plants that I had seen as raindrop-covered seedlings last December were now hip-high and covered in clusters of faintly scented yellow flowers. The grey skies broke with the brisk breeze and clouds scudded across the blue sky, making fast-moving shadows over the rural scene. The agricultural machinery parked by the barn remain a constant while everything around changes by the moment, with the weather, and through the seasons.

Water pattern & texture in Weymouth waves 1

Water pattern and texture on rippled shallow waves

These images are a study of patterns and surface texture on the shallow water over the sandy seabed at Weymouth, viewed from the promenade leading to the pier. I like the way that the waves look as if they are drawn with fine lines onto the sea with a white pencil. The clear water reveals the yellow of the sand below the waves. (If you wish, you can click on the photographs to enlarge them and see the details).

Belemnites at Seatown

Belemnite fossil in situ in Belemnite Marl at Seatown, Dorset, England.

The most common fossils at Seatown on the Dorset coast are belemnites. These are bullet-shaped internal hard parts of a type of extinct cephalopod (think cuttlefish, squid and octopus). For a great deal of the length of the beach, the rock strata are hidden by debris falling down from layers above. There are lots of minor mudslides and landslips. However, as you get nearer to the western extremity of the beach, approaching Golden Cap, a continuous kerb-like, harder, and more calcareous stone layer makes an appearance. This is the Belemnite Stone that has been raised to view by a small anticlinal flexure. Below it are many layers of Belemnite Marl that can be seen in cross-section in the vertical face at the base of the cliff; and also extending out horizontally beneath the gravelly beach and exposed at low tide. They alternate light and dark layers. Fossils are abundant with belemnites predominating but ammonites are also common. The huge numbers of belemnites are thought to have resulted from mass die-offs following mating frenzies.