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In geology, horst and graben (or range and valley) refers to topography consisting of alternating raised and lowered fault blocks known as horsts and grabens. The features are created by normal faulting and rifting caused by crustal extension . [ 1 ]
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 ]
Fault scarps are exposed on the horst block and expose the footwall of the normal fault. This is a type of block faulting known as grabens and horsts. This basin and range topography is symmetrical having equal slopes on both sides of the valleys and mountain ranges. Timelapse of tilted block faulting
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.
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.
Lifted type block mountains have two steep sides exposing both sides scarps, leading to the horst and graben terrain seen in various parts of Europe including the Upper Rhine valley, a graben between two horsts – the Vosges mountains (in France) and the Black Forest (in Germany), and also the Rila – Rhodope Massif in Bulgaria, Southeast ...
In Nevada's recent geologic past, tectonic changes have created normal faults and creating the basin and range horst and graben terrain. Thinning of the upper crust caused deeper, highly metamorphosed rock masses to rise to the surface, where it is overlain by younger faulted and domed rocks.
The range is a classic example of horst and graben (fault-block) topography with pluvial (ephemeral) lakes occupying the graben basins. The eastern escarpment of the range overlooks the Surprise Valley in California and Warner Valley in Oregon, enclosed basins that contain Upper Alkali Lake , Middle Alkali Lake , and Lower Alkali Lake along the ...