洮河临洮段田家河阶地的形成时代及其地貌学意义

he river terrace is an important carrier of researching the development of the upland and the river valley and the evolvement of the regional landform, the research into whose morphology and chronology can provide abundant palaeoenvironmental information such as its tectonic movement and climate changes. Field survey shows that Tao River is developed in the Linyao Basin, with the river terraces of 6-8degrees reserved, among which the highest terrace gravel layer is exposed in the vicinity of the Tianjiahe. According to the Palaeomagnetism Test and Climatic Stratigraphy based on the terrace covered with loess, the bottom of the eolian loess is Ancient Soil S8, which shows the formation age of the vicinity of the Tianjia River was 0.87 Ma and indicates the formation of the contemporary valley industry in Linyao Basin. And now the restructuring of the water system in Longzhong Basin may result from the dramatic rise of the Qinghai-Tibetan Plateau. Also the stratigraphical studies show that terrace downcut of the Tianjia River happened during the transformation from the glacier to interglacial period, proving the climate change of the Orbital Scale is an important factor to influence the development of the landforms of the valley.