Abstract: There are many origins of the geomorphic scarp. One of them is the fault activity in the neotectonic time. So the geomorphic scarp could indicate the activity of the fault. However it still should make sure by the mutual verification with other data. Without doing it, the conclusion may be wrong. Based on the research on relationship between Mangshan scarp and Laoyachen fault, and according to interpretation of remote sensing images, middle-shallow layer seismic detecting and comparison of joint drillings, measurement of landforms etc., this paper propose that the Laoyachen fault is a NE-dipping pre-Quarternary normal fault. The geomorphic scarp was divided into three parts, general strike is NW—NWW. The elevation differences gradually decrease form north to south. The relationship between them shows geomorphic scrap was formed by erosional cutting of the Yellow River and its age should not be later Pleistocene.

Key words: Scarp, Active fault, Mangshan, Laoyachen fault