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Ingeology,horst and graben (orrange and valley) refers to topography consisting of alternating raised and loweredfault blocks known ashorsts andgrabens. The features are created bynormal faulting andrifting caused bycrustal extension.[1] Horst and graben are formed when normal faults of oppositedip occur in pairs withparallelstrike, and are always formed together. Eachfeature can range in size from a fewcentimeters up to tens ofkilometers, and thevertical displacement can be up to several thousand meters. The movement on either side of each block is typically equal, resulting in little tilting.[2]
A horst is a section ofcrust that has been lifted relative to the blocks on either side, which is a result of its bounding faultsdipping away from each other.[2] Horsts can form features such as plateaus, mountain ranges or ridges on either side of the valleys.[1]
A graben is a section of crust that has lowered relative to the blocks on either side, which is a result of its bounding faultsdipping 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.
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