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[21] [22] Thrust faults typically form ramps, flats and fault-bend (hanging wall and footwall) folds. A section of a hanging wall or foot wall where a thrust fault formed along a relatively weak bedding plane is known as a flat and a section where the thrust fault cut upward through the stratigraphic sequence is known as a ramp. [23]
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.
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.
The hanging wall, composed of extended, thinned and brittle crustal material, can be cut by numerous normal faults. These either merge into the detachment fault at depth or simply terminate at the detachment fault surface without shallowing. [5] The unloading of the footwall can lead to isostatic uplift and doming of the more ductile material ...
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 ...
Extensional faults form parallel to the axis of the rift. An extensional fault may be seen as a crack in the crust that extends down at an angle to the vertical. As the two sides pull apart, the hanging wall ("hanging over" the sloping fault) will move downward relative to the footwall. A rift basin is created as the crust thins and sinks.
Rollover anticlines are anticlines related to extensional normal faults. They must be differentiated from fault-propagation folds, which are associated with reverse faults. A rollover anticline is a syn-depositional structure developed within the downthrown block (hanging wall) of large listric normal faults. Such faults are typically regional ...
The Rocky Mountain Foreland is located east of the Teton fault and is a region of thicker crust. This section of crust is heavier and adds to the vertical downward force on the hanging wall of fault. The Yellowstone volcanic plateau is a region of uplift and expansion that influences both vertical and horizontal forces on the Teton fault.