Abstract: The stiff clays beneath the Holocene strata at the Yangtze Delta are considered to be paleosols by their subaerial pedogenesis characteristics, such as cutans, cracks and microcracks, plant roots and debris, etc. The paleosol sections, which are more than 2.0 meter thick, contain several clay accumulation layers, however, the sections are lack of caliche. Foraminifera occurs in paleosols of more than half of the study cores. Magnetic susceptibilities of the paleosol sections are low and lack of distinct fluctuations, and the magnetic fabric parameters alternate within a wide scope. The above characteristics of the paleosol sections suggest that the parent materials of the paleosols are of flood plain deposits, and the paleosols are the results of successive deposition and continuing pedogenesis on flood plain.