Also found in: Dictionary, Thesaurus, Medical, Legal, Wikipedia.
Related to graben: rift valley
graben(grah -ben) An elongated depression of land between two faults. Lunar graben are usually 1–2 km wide and may be hundreds of kilometers in length.
a portion of the earth’s crust that is sunken relative to surrounding areas along steep, often vertical fractures, usually faults. The largest system of graben in the world is found in East Africa (Great Rift Valley). In Western Europe the largest graben is the valley of the Rhine River. Grabens on a planetary scale are called rifts. Grabens with additional fractures at their edges, which form a series of steps, are called complex grabens.