The fault cliff refers to a steep cliff which formed along fault surface.The Ercengya Cliff was originally a contact zone of the mainfold  fault of metamorphic core complex and its overburden.The plane of original mainfold fault dips towards Wulaofeng peaks with gental angle. A high-angle normal fault which dips outside the mountain occurred in the section of Ercengya made the mountain body of Wulaofeng uplift quickly to form a high mountain,the mountain ahead decrease relatively, thus the Ercengya becomes a huge fault ledge.