The earth’s isostasy

of which the final outcome will be the earth itselfbecoming an ideal spheroid with concentric sphere structure and uniform den-sity in each sphere or layer

is a unified movement of the earth as a wholeand its interior spherical layers.The asthenosphere is the outermost sphereof the earth

in which the material can flow.Therefore

isostasy in the up-per part of the earth mainly occurs between the lithosphere and the astheno-sphere.This means that the top surface of the asthenos phere can be consi-dered as a surface of isostatic adjustment.Apart from isostasy

there arestill other movements which may disturb and destroy the isostasy

such asmantle diapirs and compression or tension of the lithosphere.Sedimentary ba-sins form and develop through new isostatic adjustment under the conditionthat the isostatic state somewhere in the upper part of the earth has beendestroyed.According to the initial cause of inducing subsidence of the basin and towhat extend the isostasy has occurred in the course of basin development

the author divides basins into three categories:the first

caused by sedi-ment-loading

is named sediment-induced basin;the second

by structure

is named structure-induced basin;and the third

not only caused but alsocontrolled its development by structure

is named stucture-controlled basin.Under the last has case

the isostasy is insignificant.Moreover

the writerhas discussed the mechanisms of their formation respectively.Finally

on the basis of the features of the basin development

the authorproposes and discusses the problem of the maturity of basins.