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A graben is a section of crust that has lowered relative to the blocks on either side, which is a result of its bounding faults dipping towards each other. [2] The plural of graben can be either graben or grabens. Graben form low-lying features such as basins and rift valleys. [1] [2] They can be very long relative to their width.
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, while that of the footwall is upward. The faults typically dip toward the center of the graben from both sides.
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.
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.
A downthrown block between two normal faults dipping towards each other is a graben. A block stranded between two grabens, and therefore two normal faults dipping away from each other, is a horst. A sequence of grabens and horsts on the surface of the Earth produces a characteristic basin and range topography.
Although sediments arrive primarily from the unfaulted side of the half-graben, some erosion takes place on the fault escarpment of the main border fault, and this produces characteristic alluvial fans where confined channels emerge from the escarpment. [9] Lake Baikal is an unusually large and deep example of half-graben evolution. The lake is ...
A larger graben is found in the subsurface below the Skagerrak, this north–south structure is called the Bamble-Oslo Graben. [7] The Viking Graben is separated from the Faeroe Shetland Basin below the Atlantic by the Shetland Platform, the two structures join in the area north-east of the Shetland Islands. [8] [9]
Parry Channel is a waterway in the Arctic Archipelago formed by the Parry Submarine Rift Valley. [26] [46] It consists of four waterbodies: Lancaster Sound, M'Clure Strait, Viscount Melville Sound and Barrow Strait. With a length of over 1,100 km (680 mi), Parry Channel connects Baffin Bay in the east with Beaufort Sea in the west. The north ...