Abstract:
By field investigation in the sandy area of Dali county in the lower reaches of Weihe River, a typical Holocene XYC drift sand deposit profiles was found and a soil layer was sandwiched in it. Through analyzing the sedimentary characteristics of grain- size, magnetic susceptibility, CaCO3 content and OSL dating, the results showed that, there existed drift sand layer and formed a sand landscape in the stage of early Holocene because of the dry climate and strong eolian process. In the middle stage of Holocene, the climate became warmer and wetter, the vegetation developed well, and the sand dunes were fixed, the cinnamon soil (S0) was formed because of the strong biological and weathering pedogensis in sandy area. In the late stage of Holocene, the eolian process renewed since 3 000 a B.P. because of the dryer climate and human activities, the quick sand activities became a natural landscape undulating sand dunes since the historical period, so the sandy area was famous and became a strictly special landscape in the relatively humid areas of the lower reaches of Weihe River. After the foundation of the People′s Republic of China, the ecological environment was improved gradually in sandy area through the government′s right guidance and local people′s rational reform. This result provided a new idea to further understand the environment change and formation of sandy area in the view of sedimentology and the long time scale.
