Search results
Results from the WOW.Com Content Network
In physical geography and geology, a horst is a raised fault block bounded by normal faults. [1] Horsts are typically found together with grabens. While a horst is lifted or remains stationary, the grabens on either side subside. [2] This is often caused by extensional forces pulling apart the crust.
The features are created by normal faulting and rifting caused by crustal extension. [1] Horst and graben are formed when normal faults of opposite dip occur in pairs with parallel strike, and are always formed together. Each feature can range in size from a few centimeters up to tens of kilometers, and the vertical displacement can be up to ...
The asymmetry of a half-graben strongly affects syntectonic deposition. Comparatively little sediment enters the half-graben across the main bounding fault because of footwall uplift on the drainage systems. The exception is at any major offset in the bounding fault, where a relay ramp may provide an important sediment input point.
Fault name Length [km] Location Sense of movement Time of movement Associated earthquakes Sources Aedipsos-Kandili Fault: 60: North Euboean Gulf, Greece: Normal: Active
With crustal extension, a series of normal faults which occur in groups, form in close proximity and dipping in opposite directions. [4] As the crust extends it fractures in series of fault planes, some blocks sink down due to gravity, creating long linear valleys or basins also known as grabens, while the blocks remaining up or uplifted produce mountains or ranges, also known as horsts.
Normal faults can evolve into listric faults, with their plane dip being steeper near the surface, then shallower with increased depth, with the fault plane curving into the Earth. They can also form where the hanging wall is absent (such as on a cliff), where the footwall may slump in a manner that creates multiple listric faults.
Cross-cutting relationships can be used to determine the relative ages of rock strata and other structures. Explanations: A – folded rock strata cut by a thrust fault; B – large intrusion (cutting through A); C – erosional angular unconformity (cutting off A & B) on which rock strata were deposited; D – volcanic dike (cutting through A, B & C); E – even younger rock strata (overlying ...
Normal and reverse faulting are examples of dip-slip, where the displacement along the fault is in the direction of dip and where movement on them involves a vertical component. Many earthquakes are caused by movement on faults that have components of both dip-slip and strike-slip; this is known as oblique slip.