Of various parameters of depths related to ore resources,the basicity mightreflect the differences in components or average chemical composition of theearth's crust. Amethod for calculating apparent basicity of the crust by usinggravity data is proposed in this paper with a discussion on some relativelydecisive parameters. Atechnique for dividing the crust and calculating thedepths of interfaces within the crust is also presented on the basis of apparentbasicity together with a description of its application in southeastern Hubei.