STRATIGRAPHIC EVIDENCE OF EPISODIC GULLYING ON THE CHINESE LOESS PLATEAU

Buried gullies are exposed along the margin of a loess tableland in road excavations near Tongchuan on the Loess Plateau of central China. They lie with in a thick loess/paleosol succession that spans at least the last 780,000 years. Constraining ages for gully cutting and filling are provided by the ages of loess and soil units cut by and capping the paleogullies. Gully cutting is initiated during the onset of interglacial conditions and ceases as the gullies begin to fill with colluvium and airborne dust during the transition from interglacial to glacial conditions. The episodic cutting and filling of gullies implies a basic astronomical (orbital) control of gully evolution involving cyclic changes in dominant summer and winter monsoon climates, surface hydrology, and vegetation cover.