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- Created on: 16-05-18 13:43
The adjacent North York Moors rise up to 400 m above sea level and comprise mainly sandstones, shales and limestones formed during the Jurassic period as well as some carboniferous rocks. South Flamborough Head is a large chalk headland. Its spectacular cliffs are topped with till, a superficial deposit left behind by glaciers during the Devensian glacial period. Differences in rock resistance are responsible for the high cliffs and the bay and headland sequence.
The dominant waves affecting this coastline are from north/northwest, with a fetch of over 1500 km. The most exposed parts of the coast are facing North , such as the area nearest to Saltburn. Rates of erosion vary, partly due to these differences in wave energy inputs, but also due to variations in the resistance of the different geologies. Weak shale and clay experience erosion rates of 0.8 m per year on average, while resistant sandstones and limestones erode at less than 0.1 m per year.
Monitoring of wave height using floating buoys in Whitby Bay during 2010–11 revealed that wave height often exceeded 4 m, even during summer months.
The high-energy inputs are also responsible for significant longshore drift from north to south along the coastline. In places, this sediment movement is interrupted by headlands, and sand and shingle then accumulate to form beaches in the bays, such as in Filey Bay.
The coastline between Saltburn and Flamborough is sub-cell 1d of the major sediment cell 1, which extends south from St Abbs in southern Scotland to Flamborough. Some of the sediment in sub-cell 1d has come from the nearshore area, driven onshore as sea levels rose at the end of the last glacial period. Sediment is also supplied by cliff erosion, including sandstone and chalk from the resistant rock outcrops and the boulder clay deposits which yield significant amounts of gravel. The only large river, the Esk, enters the North Sea at Whitby. This supplies limited amounts of sediment due to the construction of weirs and reinforced banks along its course (Figure 1.33).
Beach surveys have found that there had been a net increase in beach sediment of 9245 m3 between 2008 and 2011 at Saltburn. Zones of both beach erosion and accretion were observed within Filey Bay, which reflect the influence of winter storm systems with erosion at the back of the beach being particularly significant in the winter of 2010–11.
The sedimentary rocks of this…