English: Wave-cut platform below Allt Wen So far, waves have worked their way into the folded strata up to this point. The rest of the rock on the right will be eroded away over the next few million years - or perhaps sooner if seawater levels rise as predicted. The ripple pattern in the wave-cut section shows that the light-grey strata are a less brittle than the darker ones, which tend to erode deeper. All of the rock is in fact grey - the reddish tinge is due to the setting sun. Allt Wen, the northern end of the coastal cliff south of Aberystwyth, is a remarkable geological site. A number of micro-folds only a few metres across with nearly parallel vertical limbs have been exposed on a wave-cut platform at the base of the cliff. The exact sequence of events that have taken place here is still debated, but it is thought that during the Caledonian orogeny 400Ma ago, freshly deposited layers of sediment became pressurised and folded before they were fully lithified and thus more deformable. There are also quartz veins parallel with the bedding in some places. It is thought that they were pressed into the fresh sediment before the folding took place. For more details, see the Geological Conservation Review's site report http://www.thegcr.org.uk/Sites/GCR_v03_C04_Site2318.htm . Turbidites of early Silurian age.