Cambering is a phenomenon typically seen at a valley crest or plateau margin whereby blocks of competent strata such as

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

stretch, tilt or rotate with respect to underlying incompetent rock layers such as

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

or mudstone. It results from the weaker underlying strata deforming under the weight of the strata above it. Cambering is associated with valley bulging and the development of gulls on the upper slopes. Valley bulging is the development of an anticlinal structure in the underlying weaker strata, the long axis of which is broadly coincident with the orientation of the valley. Valley bulging was first described in

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

within the upper Derwent catchment in

Derbyshire Derbyshire ( ) is a ceremonial county in the East Midlands of England. It borders Greater Manchester, West Yorkshire, and South Yorkshire to the north, Nottinghamshire to the east, Leicestershire to the south-east, Staffordshire to the south a ...

and is also encountered within the

Cotswolds The Cotswolds ( ) is a region of central South West England, along a range of rolling hills that rise from the meadows of the upper River Thames to an escarpment above the Severn Valley and the Vale of Evesham. The area is defined by the bedroc ...

. Gulls are fractures in competent strata that typically form parallel to a valley side in association with cambering. They occur on a range of scales with widths from millimetres to tens of metres. The gulls may be voids open to the sky or they may be partially or wholly filled with unconsolidated material such as earth or brecciated rock. Multiple gulls and areas of cambering occur in the Cotswolds where for example the

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s of the Inferior Oolite overlie relatively weak Liassic mudstones. The development of one or more of this suite of features has been linked to the rapid incision of a valley through competent strata into less competent strata below particularly in periglacial conditions. Recognition of these features is important for engineering geologists advising developers of physical infrastructure such as roads, bridges and dams in such areas.

References

{{reflist Geological hazards Geomorphology