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:''This article is about the geologic usage, for human physiology usage see the articles laterality.''
The terms 'sinistral' and 'dextral' refer to the horizontal movement of blocks on either side of a fault or the sense of movement within a shear.
;Sinistral or ''left lateral'' movement: Movement is sinistral (left handed) if the block on the other side of the fault moves to the left, or if straddling the fault the left side moves toward the observer.
;Dextral or ''right lateral'' movement: Movement is dextral (right handed) if the block on the other side of the fault moves to the right, or if straddling the fault the right side moves toward the observer.
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Contents

Naming origin

Identifying sense of throw

Examples

See also

References

Naming origin

Sinistral gains its origins from the Latin "" for left-handed. The opposite sense of movement dextral gains its name from the Latin "" for right-handed.

Identifying sense of throw

Identifying the sense of throw of a fault or the sense of shear can be achieved via several methods:

★ Mappable offset of rock units

★ Offset of visible bedding, cross cutting dykes

★ Folding of strata proximal to a fault caused by ''frictional drag''

★ Shear sense indicators in sheared rocks such as

★
★ Mica fish

★
★ Extensional veins

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★ Shear deflections and stair-stepping of shear folia

Examples

Banded gneiss with dike of granite orthogneiss with sinistral shear

Boudinaged jasperoid in sheared basalt, Fortnum Gold Mine, Australia. Example of dextral shear

Boudinaged quartz vein in dextral shear foliation, Starlight Pit, Fortnum Gold Mine, Western Australia

See also

★ Fault (geology)

★
★ Thrust fault

★ Shear (geology)

★ Transform boundary

References

★ Schlumberger Oilfield Glossary