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 sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

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. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

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 country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

within the upper Derwent catchment in

Derbyshire Derbyshire ( ) is a ceremonial county in the East Midlands, England. It includes much of the Peak District National Park, the southern end of the Pennine range of hills and part of the National Forest. It borders Greater Manchester to the nor ...

and is also encountered within the Cotswolds. 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 ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s of the

Inferior Oolite The Inferior Oolite is a sequence of Jurassic age sedimentary rocks in Europe. It was deposited during the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Pet ...

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