English: Wave-cut platform below Allt Wen Alternating hard and soft layers have been folded up vertically and eroded by the tides, resulting in a regular ripple pattern at the surface. 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 .