A fault scarp characterized by lobes. They are common on the surface of Mercury, where they are relatively steep, with crest heights from 0.5 to 3 km, lengths from 20 to 500 km, with a broadly lobate outline on a scale of a few to tens of kilometres. They are probably due to reverse or thrust faulting resulting from compressive stress. They predate the close of the massive bombardment, and so are probably more than four billion years old. If so, they record an early period of planetary contraction.