Unconformity

As unconformity (after Latin: discordans, noncompliant) is referred to in the geology, the angular or irregular succession of rock strata lying. Discordant storage is the antonym of concordant.

The reason for the occurrence of unconformities different processes can be:

• An angular unconformity or tectonic unconformity, usually formed in sedimentary rocks that are tilted by tectonic movements, such as stretching, compressing, folding, lifting and lowering, or by singular volcanic events. The prominent rocks are then eroded, for example, a decline in sea level ( regression). Later sediments that can be deposited among other with renewed sea-level rise ( transgression ) are, again horizontally and consequently form an angle with the older rock layers. Between the two rock packages ( the hanging wall "up" and the footwall " below " ) is now a so-called hiatus. The accurate reconstruction of the ratios of deposits and unconformities to each other is of great importance for the understanding of the temporal evolution of a mountain ( orogeny ).
• If the gap ( hiatus ) was not created by tectonic movements, but only by erosion or Sedimentationsunterbrechung, for example, when a river cuts into the ground, and filled the valley with sediments self-generated, then one speaks of erosional.
• The so- called cross- stratification, or cross-bedding that arises, for example, in the sedimentation in running water, is sometimes referred to as Scheindiskordanz.
• A Dislokationsdiskordanz caused by shear ( dislocation ) of rock packages along faults. In the nappe also referred to as an oblique cutting.
• Magmengänge and salt domes penetrate the host rocks often also with an angle or with irregular contact surfaces.