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World War II pillbox on eroding boulder clay, Filey Bay, England Boulder clay cliffs in Gwynedd with Dinas Dinlle in the background. Boulder clay is an unsorted agglomeration of clastic sediment that is unstratified and structureless and contains gravel of various sizes, shapes, and compositions distributed at random in a fine-grained matrix.
Chalk is a soft, white, porous, sedimentary carbonate rock.It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor.
Clay soils also resist wind and water erosion better than silty and sandy soils, as the particles bond tightly to each other, [14] and that with a strong mitigation effect of organic matter. [ 15 ] Sand is the most stable of the mineral components of soil; it consists of rock fragments, primarily quartz particles, ranging in size from 2.0 to 0. ...
Physical weathering, also called mechanical weathering or disaggregation, is the class of processes that causes the disintegration of rocks without chemical change. Physical weathering involves the breakdown of rocks into smaller fragments through processes such as expansion and contraction, mainly due to temperature changes.
The products of chalk weathering are dissolved in rainwater and are transported in stream flow. Chalk streams transport little suspended material (unlike most rivers), but are considered "mineral-rich" due to the dissolved calcium and carbonate ions. The surface water of chalk streams is commonly described as "gin clear".
Sediments containing more clay tend to be more resistant to erosion than those with sand or silt, because the clay helps bind soil particles together. [45] Soil containing high levels of organic materials are often more resistant to erosion, because the organic materials coagulate soil colloids and create a stronger, more stable soil structure ...
The chalk outcrop at Flamborough Head in the north produces a headland relatively resistant to coastal erosion whilst the coastline south of this at such places as Mappleton and Hornsea with their soft glacial deposits are vulnerable.
Cliffs are usually composed of rock that is resistant to weathering and erosion. The sedimentary rocks that are most likely to form cliffs include sandstone, limestone, chalk, and dolomite. Igneous rocks such as granite and basalt also often form cliffs.