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Mudcrack
Mudcracks (also known as desiccation cracks or mud cracks) are sedimentary structures formed as muddy sediment dries and contracts.〔Jackson, J.A., 1997, ''Glossary of Geology'' (4th ed.), American Geological Institute, Alexandria, VA, 769 p.〕〔Stow, D.A., 2005, ''Sedimentary Rocks in the Field'', Academic Press, London, 320 p.〕 Crack formation also occurs in clayey soils as a result of a reduction in water content. 〔("Factors Effecting Mud Crack Formation in Ankara Clay" )〕
== Formation ==
Naturally forming mudcracks start as wet, muddy sediment desiccates, causing contraction. A strain is developed because the top layer tries to shrink while the material below stays the same size. When this strain becomes large enough, channel cracks form in the desiccated surface material, relieving the strain. Individual cracks spread and join up forming a polygonal, interconnected network. These cracks may later be filled with sediment and form casts on the base of the overlying bed.
Syneresis cracks are broadly similar features that form from subaqueous shrinkage of muddy sediment caused by differences in salinity or chemical conditions,〔 rather than subaerial exposure and desiccation. Syneresis cracks can be distinguished from mudcracks because they tend to be discontinuous, sinuous, and trilete or spindle-shaped.〔Allen, J.R.L., 1982, ''Sedimentary Structures: Their Character and Physical Basis'' (v. 2): Elsevier, Oxford, 593 p.〕
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