DEXTRAL - 2 reference results
- This article is about the geologic usage, for human physiology usage see the articles laterality.
- The terms sinistral and dextral (or left-handed and right-handed) are also used to describe the direction of coiling in gastropod shells.
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.
Naming origin
Sinistral gains its origins from the Latin "sinister" for left-handed. The opposite sense of movement dextral gains its name from the Latin "dexter" 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 dikes
- Folding of strata proximal to a fault caused by frictional drag
- Shear sense indicators in sheared rocks such as
- Mica fish
- Extensional veins
- Shear deflections and stair-stepping of shear folia
Examples
See also
References
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Last updated on Wednesday September 03, 2008 at 14:30:58 PDT (GMT -0700)
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This article is licensed under the GNU Free Documentation License.
Last updated on Wednesday September 03, 2008 at 14:30:58 PDT (GMT -0700)
View this article at Wikipedia.org - Edit this article at Wikipedia.org - Donate to the Wikimedia Foundation
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