( 2 ) there is stage of soil formation from the evolution of pedogenic environment in the weihe valley during holocene . soil formation shows the law of evolving from warm and wet strong soil formation period to cold and dry dust deposition period ( weak soil formation period ) and to warm and wet strong soil formation period again . the loess - soil sequence is a compound soil sectional system of different kinds of soil evolution under different bio - environment and pedogenic processes （ 2 ）通过对全新世渭河流域成壤环境演变问题的讨论，揭示了全新世渭河流域土壤的发育具有阶段性，表现为由温湿的强成壤期向冷干的沉积期（弱成壤期）演变、再向温湿的强成壤期演变的规律；黄土一古土壤序列是不同生物气候环境下、不同成壤过程发育的不同土壤类型演替而形成的复合型土壤剖面体系；而且由于冬夏季风环流及其环境效应在空间上的差异，使得复合型土壤剖面体系也存在着南北差异。
