The rock coast of the British Isles: Shore platforms

Rock shore platforms, present on at least half of the 20 500 km-long coastline of the British Isles, are usually backed by cliffs of varying heights. They form in a range of material types from soft cohesive sediment to sedimentary and metamorphic rocks of varying strengths to very resistant igneous rocks. Lithology influences platform erosion rates: glacial till > London Clay > chalk > schist > limestone > basalt and granite. Chalk platform erosion rates adjacent to engineering structures are significantly higher than elsewhere on the platform. There are no published reports of erosion rates on British platforms developed in igneous rocks such as basalt and granite because they have proved too resistant to record values using a micro-erosion meter. The most intensively studied shore platforms in the British Isles are on Blue Lias limestone in south Wales and Cretaceous chalk in SE England and there is a need for more detailed studies on additional rock types, particularly for understanding key controls on platform morphology and rates of erosion. The issue of whether the shore platforms exposed at present day mean sea-level are inherited from earlier periods remains. The role of platform erosion in helping to drive cliff retreat is understudied and evidence that engineering structures may enhance platform erosion rates comes from only one rock type. Predicted climate change and sea-level rise scenarios combined with more intensive management of coastal systems mean that it is important to improve understanding of platform systems and their link to cliffs. There is much scope, using established and new methods of investigation, to address the issues raised by existing studies of shore platforms of the British Isles.