Shorelines evolve. Changes happen – sometimes slowly and sometimes quickly. The winter of 2013 to 2014 brought severe storms and winds that impacted on all our British coastlines. Whiteford Sands on the north shore of the Gower Peninsula in South Wales was no exception. By May 2014 a dramatic change in the long line of dunes bordering the sands was clear to see. The dunes have been fixed for a long time with the outer slopes stabilised with marram grass, and a turf covering further inland. Small changes had been occurring steadily for many years with a gradual wearing away of the dunes. High tides and extreme weather events had been nibbling at the seaward faces. The erosion process has not been continuous but interspersed with periods of accretion both by water-borne and wind-borne sand.
The sand was originally deposited by a melting ice sheet in Carmarthen Bay, including the Loughor estuary on which Whiteford Sands is situated, and at Pendine Sands and Rhossili Bay. The first direct evidence for glaciation on Wales dates to 480,000 years ago in the Anglian Stage of the Pleistocene in the Quaternary Period when ice sheets enveloped Wales and the adjacent sea. The last ice coverage in the region was the Late Devensian Era about 24,000 years ago. There seem to be only minimal additions to the sand deposits from local sources since then because the Carboniferous limestones of the area dissolve rather than disintegrate into particles or grains. The sand is a therefore a finite resource albeit one that is controversially exploited locally by dredgers on the Helwick Bank just off the tip of Gower.
The sand is basically mobile within the area on the shorter and longer timescales. A useful and interesting research report on this subject is that by V J May on Carmarthen Bay in the Geological Conservation Review in which the sediment transport around the region is discussed. Figure 11.12 presents a sketch map of the key geomorphological features and sediment transfers of Carmarthen Bay. Figure11.13 depicts variations in accretion and erosion since 1950 in Carmarthen Bay. Figure 1.17 illustrates geomorphological features of Rhossili bay and Whiteford Burrows. The report records how and in which directions the sand is being shifted by river/estuarine currents, onshore and longshore drift; and where attrition and accumulation of sand is most marked. It is an intriguing read and gives much to elucidate the field observations I have been making in the area over the last decade.
2 Replies to “Sand Dune Erosion at Whiteford”
Interesting. I used to go on holiday with my parents to Pendine Sands (i.e. a long time ago!). What causes the stratification in the sand?
The stratification of the sand shows how the dune has slowly been built up, layer on layer, by wind bearing sand grains. The layers are rarely uniformly thick or horizontal and the shape of the layers or strata can reveal the direction in which the wind was blowing at the time. The layers get mixed up and disturbed sometimes by animal activity or by root growth of vegetation. Sometimes objects become incorporated into the deposit and are revealed when the dunes are eroded; these can include animal skeletons or old fishing nets.