Faults are geologic features that can be present in any type of rock or rock structure. A fault is a plane (approximately) along which rocks have moved. This plane may be hard to see, unless the movement has displaced clearly visible structures, such as sedimentary beds. The photo shows a small block of sandstone in which color bands are evident. Faulting on a very small scale is spectacularly obvious in the multiple offsets of the layers. Identical features may be present in structures the size of mountain ranges.