Abstract: Tongzilin and Ertan etc.,are located in the lower reach of the Yalong River,a sequence of less dense sediments in the bottom of the valley named Xigeda Formation (Early Pleistocene) with a thickness of 70m.14C dating indicates an age ranging from 23000-10000 yrs for the lacustrine deposit,suggesting a time spanning Late Pleistocene and Early Holocene for the Tongzilin Formation.Tectonic deformation of the succession leads to a east-dipping sequences,the development of extension-torsion fault and compression fault,and a set of X-shaped jointa,suggesting that this area showed a tendency to uplift rapidly