Dry crack

Typical pattern of dry cracks in dried out mud in the semi-desert of Nevada, USA

A dry crack is caused by the relatively rapid loss of liquid from originally moist material, which consequently loses volume. Dry cracks therefore belong to the shrinkage cracks . The phenomenon occurs, for example, when sludge dries out (in natural waters such as in various man-made sedimentation tanks ) and when wood or concrete dries too quickly . The term “ shrinkage crack” is used in building science .

Fossil dry crack fillings (net strips) on the underside of a sandstone slab (Tambacher Sandstein, Ober rotliegend , Bromacker )

Drought cracks can be handed down in fossil form in continental sedimentary rocks . At undersides of sandstone slabs or benches they come as a negative casts in the form of so-called power bars before, sometimes with fillings of kick seals extinct terrestrial vertebrates (prime example: Chirotherium barthii in its type locality in Hildburghausen).

In experiments on industrially processed, montmorillonite- rich clay, it was found under laboratory conditions that the geometry of the drying cracks depends on how often the substrate has dried out. While drying out once resulted in a rectangular dry crack pattern, in the course of several cycles of drying out and subsequent rewetting a hexagonal geometry with cracks that are oriented at about 120 ° to each other developed.

Dry cracks several meters deep have been observed in dried-up sludge at the bottom of sedimentation basins for tailings from uranium mining.

See also

• Shrinkage (soil) , drying out of soils (shrinkage)
• Shrinkage (concrete)
• Dry cracks (wood)

Web links

Commons : Drought Cracks  - Collection of Images, Videos and Audio Files

• Cracks in wood caused by drying (accessed July 2, 2020)
• Not all cracks are the same (accessed July 2, 2020)
• Annual reports of the Natural History Society Nuremberg eV (accessed on July 2, 2020)
• Nitrate retention capacity of the soil (accessed on July 2, 2020)
• Recommendations for dike protection after the February storm surge in 1962 (accessed on July 2, 2020)

Individual evidence

1. ↑ Lucas Goehring, Rebecca Conroy, Asad Akhter, William J. Clegg, Alexander F. Routh: Evolution of mud-crack patterns during repeated drying cycles. Soft matter. Vol. 6, No. 15, 2010, pp. 3562-3567, doi: 10.1039 / B922206E (alternative full text access : ResearchGate ).
2. ↑ M. Schläger, Kh. Murtazaev, B. Rakhmatuloev, P. Zoriy, B. Heuel-Fabianek: Radon Exhalation of the Uranium Tailings Dump Digmai, Tajikistan. Radiation & Applications. Vol. 1, No. 3, 2016, pp. 222–228, doi: 10.21175 / RadJ.2016.03.041 (Open Access).