Abstract: Longfang-Guan depression is located in the north part of Jizhong Graben where the North China oil-field lies. It is a monofault and dustpan- shaped basin formed during the end of Mesozoic.In the steep side of the basin(i.e.Guan--Jiuzhou region),a trench face gravity flow deposition with the feature of a fan shape arises.From the observation of the core and mainsupport mechanism of sediments,gravity flows in this area can be classified into debris flow, grain flow and turbidity current.