A graben is a down-dropped block between two parallel steep normal faults that dip towards each other and formed from extensional movement. Medium-large grabens are not bounded by a single normal fault but by several normal faults with similar bed attitudes in the form of step faults. The two sides of a graben may not develop in the same manner. Grabens are structural geologic features. Fault basins and rift landforms are usually composed of young medium-large grabens. Examples are the Rhine Graben in Europe and the Fenwei Graben in China, which are in the form of long narrow valleys or elongated basins or lakes.