The Quaternary strata in Laohushan area are mainly the torrenthial diluvium and river ter-race deposits,the ages of nearly 40 samples determined by¹⁴C,TL and diffusion equation meth-ods indicate that:the first terrace formed in Holocene, its age is about 4086±100a-4578±60a;the second terrace formed in late period of Late-Pleistocene,its age is about 23ka;the third terrace formed in early period of Late-Pleistocene,its age is about 72ka;the forth and fifth terraces formed in Middle-Pleistocene,their ages are about 217±35ka and 378±60ka,re-spectively. The deposits of Early-Pleistocene distribute only in some areas.perhaps formed in the early period of Early-Pleistocene.
By comparison with the loess profile at Jiuzhoutai of Lanzhou, the ages of I-V terraces are compatible with the ages of So,S_m^a,S_m^c,S₂,S₄ paleosoils in the standard profiles. The re-search results indicate that the formation of stratified landforms of rivers is associated with the tectonic movement,meanwhile,has a very closely inner relation to the global cold-warm alter-nation climate environment.