Dark-green stiff clay of Late Pleistocene in the Yangzi River Delta is a buried Paleosol Bed.It possesses the basic property of soil:1.contains root holes

fragments and dark network humus of plants;2.underwent clayization;3.eluviaton and illuviation could be found;4.lacking of lamination.The distinct defferences between the paleosol and ordinary soil are:1.The upper part of the paleosol is light

stiff

and the ratio of hyperconsolidation is 2.1～2.2

but the lower part is less consolidated.This is contrary to ordinary soil; 2.The paleosol is green and yellow-green;3.The paleosol contains various types of nodules.They are mainly pyrite→siderite→dialogite→limonite and pyrolusite from top to bottom

reflecting a transition process of reducing-oxidizing environment.Oxygen-rich sea-water resolved the organic matter in the paleosol through the action of bacteria.With the consumption ot free oxygen and the reduction of oxidized ions

HS

-

Fe

+2

Mn

+2

thus formed.This resultes in distinct changes of the colour

the hardness

the nodules and the clay minerals of the paleosol

thus changing the whole of the soil's property.