The shore beneath the new sea wall in Lyme Regis looks very different now the old breakwaters or groynes have been removed. You can still see the linear concrete footings of the old wood and iron structures but most of the pebbles and cobbles that used to accumulate between the walls are now absent (at least for the moment). A bare rock pavement is revealed, comprising a series of steps representing the strata and colonised by seaweeds. Rippled sand sometimes deposits in the valleys between the rock ledges.
I discovered an interesting stretch of shoreline when I visited Lyme Regis yesterday. The cliff location is known as The Spittles and it is situated immediately east of the new sea wall. The tide was going out but not as far as in March 2010. Enough to disclose an array of boulders with scattered fossils, broken coloured glass, and rusting metal. The man-made junk resulted from a major landslide in 2008 when the contents of an old town rubbish tip (which had been in existence from 1920 to 1973) cascaded shore-wards with the rocks and mud. The junk continues to wear out of the cliff face to the present time.
There are some interesting items to be found. The rusting metal components, often with remnants of paint, provide intriguing contrasts with the natural environment in which they are lodged. There is a striking similarity between the metal colours and textures and those of the dead and dying autumnal colours of seaweed. As the water receded, it left intricate patterns in the sand around the rocks and even in fine sediments of smoother rock surfaces.
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.
On the beach at Fermoyle on the Dingle Peninsula in Ireland, the sea sifts and sorts the sand grains into different weights and colours to arrange in sinuous ripple patterns across the shore. The red particles from nearby outcrops of Devonian rock make contrasting curved lines along the receding water’s edge. At low tide level, the wet sand has been punctured hundreds of thousands of times by the beaks of shore birds both large and small. I have never noticed that before. There must be something about the texture of the sediment there that preserves the shape of the bills when they are withdrawn from the spot during feeding activities. It is plain that this particular place must have a very rich in-fauna of small seashore creatures like crustaceans, worms, and maybe molluscs.
A late winter afternoon on Knoll Beach at Studland in Dorset. The weather was cold but fine and everyone was out for a stroll across the long sandy shore. Children wrapped up warm and wearing Wellington boots ran and splashed on the water’s edge while gentle waves broke with white surf on the wet and gleaming sand ripples. A beautiful place as always.
These pictures were previously shown on the blog in early 2014. Click on any picture to enlarge.