Study on Tectonic Deformation of Yellow River Terrace in Erdos Hequ Section

This paper study the well exposed profiles of Yellow River terraces in Hequ county area.The result shows that the Yellow River three or four grade terraces in this section were formed in the Pleistocene period,second grade terraces were formed in early Late Pleistocene and first grade terraces were formed in Holocene.In this area,the Middle Pleistocene uplift rate is 0.14 mm/a,the late Pleistocene uplift rate is 0.18 mm/a,the Holocene uplift rate is 0.70 mm/a.The sudden increasing of uplift rate in late Pleistocene and Holocene may be related to through of Sanmen Lake in lower reaches of the Yellow River,regional base level of erosion decreasing and river erosion increasing.