Foraminifera and calcareous nannofossils have been found in late Pliocene to Quaternary salt lake sediments in northwestern China．Evidence of transgression is suspicious。In the newly pub— lished table“The stratigraphic Correlation of the Tertiary in Petroliferous Areas of China” (1991)，great revisions have been made of the age values of strata．The authors conclude that the early Tertiary lake level change in the eastern part of the mainland of China does not corre— spond with the eustasy at that time．The conclusion of the transgression drawn ftom the view that the lake level change coincides with eustasy according to the oldage values of strata，lacks the reliable chronostratigraphical foundation．