The key of automated reasoning and extraction of terrain features with contour maps is the mining and description of topologic relations among contour lines.This paper suggests the networks of topologic relations（NTR） to describe the topologic relations among geographical objects

and three kinds of NTRs named the binary subdivision tree（BST）

the incremental contour tree（ICT） and the networks of topologic relations of contour lines（NTRC） are presented to express the topologic relations among complicated contour groups having unclosed contour lines.These models have ultimately dealt with the lateral uncontinuity of contour lines and make the automated reasoning with contour maps more easily and exactly.