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] Horst and graben are formed when normal faults of opposite dip occur in pairs with parallel strike, and are always formed together. Each feature can range in size from a few centimeters up to tens of kilometers, and the vertical displacement can be up to several thousand meters. The movement on either side of each block is typically equal, resulting in little tilting.[2]
See main article: Horst (geology). A horst is a section of crust that has been lifted relative to the blocks on either side, which is a result of its bounding faults dipping away from each other. Horsts can form features such as plateaus, mountain ranges or ridges on either side of the valleys.
See main article: Graben. 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. The plural of graben can be either graben or grabens. Graben form low-lying features such as basins and rift valleys. They can be very long relative to their width.