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Ferricrete is a hard, erosion-resistant layer of sedimentary rock, usually conglomerate or breccia, that has been cemented into a duricrust by iron oxides. The iron oxide cements are derived from the oxidation of percolating solutions of iron salts. [1]
Examples of hard engineering include: Groynes – Low walls constructed at right angles to retain sediments that might otherwise be removed due to longshore drift.These structures absorb or reduce the energy of the waves and cause materials to be deposited on the updrift side of the groyne facing the longshore drift.
Erosion and changes in the form of river banks may be measured by inserting metal rods into the bank and marking the position of the bank surface along the rods at different times. [23] Thermal erosion is the result of melting and weakening permafrost due to moving water. [24] It can occur both along rivers and at the coast.
A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. [1] Concretions are often ovoid or spherical in shape, although irregular shapes also occur.
Skarn – Hard, coarse-grained, hydrothermally altered metamorphic rocks; Slate – Metamorphic rock - A low grade metamorphic rock formed from shale or silt; Suevite – Rock consisting partly of melted material formed during an impact event – A rock formed by partial melting during a meteorite impact
Over time the coast generally evens out. The softer areas fill up with sediment eroded from hard areas, and rock formations are eroded away. [4] Also erosion commonly happens in areas where there are strong winds, loose sand, and soft rocks. The blowing of millions of sharp sand grains creates a sandblasting effect. This effect helps to erode ...
Without the constant presence of water, stacks also form when a natural arch collapses under gravity, due to sub-aerial processes like wind erosion. Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast—the stack. Eventually, erosion will cause the stack to collapse, leaving a stump.
Panhole: a shallow depression or basin eroded into flat or gently sloping, cohesive rock. [2] Collapse-related: Sinkhole: a depression formed as a result of the collapse of rocks lying above a hollow. This is common in karst regions. Kettle: a shallow, sediment-filled body of water formed by melting glacial remnants in terminal moraines. [3]