The north depression in the southern Yellow Sea basin is one of the Cenozoic rift basins in the east margin of the Eurasian continent.The northeast sag in the north depression was formed by fault-bend folding of the hanging wall of the north dipping listric Weihai normal fault caused by the northward movement of the hanging wall.In the process of extensional fault-bend folding

the sediments deposited simultaneously and the growth strata were formed in the north sag and recorded the growing process of the northeast sag.Analysis of geometry of the growth strata shows that the northeast sag totally extends 10012 m with an average extension rate of 0.225 mm/a

quite similar to those of single sags in the Paleogene rift basins in east margin of Eurasia

such as the Bohai bay basin

the Subei basin

and the East China Sea basin.