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Fault (geology) Satellite image of a fault in the Taklamakan Desert. The two colorful ridges (at bottom left and top right) used to form a single continuous line, but have been split apart by movement along the fault. In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant ...
Growth faults have two blocks. The upthrown block – the footwall – is landward of the fault plane and the downthrown block – the hanging wall – is basinward of the fault plane. Most deformations occur within the hanging wall side. The downthrown block slips downward and basinward relative to the upthrown block.
Types of faulting. Anderson's theory of faulting, devised by Ernest Masson Anderson in 1905, is a way of classifying geological faults by use of principal stress. [1] [2] A fault is a fracture in the surface of the Earth that occurs when rocks break under extreme stress. [3] Movement of rock along the fracture occurs in faults.
View of Doso Doyabi, Snake Range, Nevada, which was formed by detachment faulting. A detachment fault is a gently dipping normal fault associated with large-scale extensional tectonics. [ 1] Detachment faults often have very large displacements (tens of km) and juxtapose unmetamorphosed hanging walls against medium to high-grade metamorphic ...
Reverse faults. A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. [ 1][ 2] If the angle of the fault plane is lower (often less than 15 degrees from the horizontal [ 3]) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an overthrust or overthrust fault. [ 4]
Fault scarp. An eroded fault scarp from the Gobi Desert of Mongolia (left) and at Borah Peak in Idaho. The latter fault scarp (white line at the base of the tan hills) was formed in the 1983 Borah Peak earthquake. A fault scarp is a small step-like offset of the ground surface in which one side of a fault has shifted vertically in relation to ...
Basin and range topography is characterized by alternating parallel mountain ranges and valleys. It is a result of crustal extension due to mantle upwelling, gravitational collapse, crustal thickening, or relaxation of confining stresses. [1] [2] The extension results in the thinning and deformation of the upper crust, causing it to fracture ...
A graben is a valley with a distinct escarpment on each side caused by the displacement of a block of land downward. Graben often occur side by side with horsts. Horst and graben structures indicate tensional forces and crustal stretching. Graben are produced from parallel normal faults, where the displacement of the hanging wall is downward ...