crystals in limestone rock, lichens on rock, limestone rock, moss on rock, rhos-on-sea, riprap breakwater, sea wall
On days when the wind blows in strongly from the north-east, blustering across the Irish Sea and whipping up the waves into foamy ‘sea-horses’, strolling along the promenade can be challenging and I have to admit, not that pleasant. On such a day I was heading towards Penrhyn Bay hoping to catch sight of Rock Pipits and to photograph Pied Wagtails, both of which I had seen recently on and around the sea wall there. The strength of the wind took me by surprise and if I had gone out with the sole purpose of taking an enjoyable walk I may well have reviewed my plans and set off elsewhere, but as I’d never seen Rock Pipits elsewhere, I was keen to see some.
Fortunately there is an alternative walk-way that was created when the original sea wall was constructed: a ledge, about 3′ (1m) wide was created on the wall’s seaward side placed about half-way up its height. In the 1980’s further protection from the wild winter seas was required and the breakwater, consisting of an immense pile of enormous rocks was piled in front of the wall. The rock pile rises higher than the walkway ledge, thus creating a sheltered passageway between the two structures. There is no view from there, the dark seawall encloses one side and the length of the summit of the rock pile the other, so other than for shelter from the wind I would not normally choose to walk this way.
The piling of large rocks, also known as riprap, at the base of vertical Edwardian and Victorian sea walls is frequently used as a secondary defence mechanism to prevent them being undermined. Riprap works by absorbing and deflecting the impact of waves before they reach the defended structure. The size and mass of the riprap material absorbs the impact energy of waves, while the gaps between the rocks trap and slow the flow of water, lessening its ability to erode soil or structures on the coast.
As I walked along, wondering where the vast amount of rock had been taken from, I began to see this confined, shaded and slightly claustrophobic space in a different way. I was drawn to individual rocks that had interesting surface patterns, crystals or layers of other types of rock or minerals and wished I knew what they were. I recognised too that a micro-climate exists here that is helping to create a habitat for an interesting number of plant species from vascular plants to mosses and lichens.
The rocks themselves are predominantly locally-occurring limestone and it is humbling to reflect on the fact that eons ago they would have been forming the sea-bed and now carry evidence to ancient life forms.
Plants have begun to colonise some of the spaces between the rocks and somehow manage to grow at the base of the rocks where they make contact with the sea wall.
As they frequently do, my walk turned out to be unexpectedly interesting and I did get to see my Rock Pipits, which will be featured in my next post that will be following very shortly.