A system, method and memory medium for injecting positional information into a geological data set for improved modeling of surfaces in a geological formation. The method involves: (1) displaying a cross section of the formation through a selected subset of wells, where the displayed cross section includes well picks for the selected wells; (2) opening a gap in an unconformity of the displayed cross section, where the gap is opened at one or more wells that intersect the unconformity, where the gap represents non-deposition and/or material that is missing from the formation due to erosion; (3) receiving user input specifying positions of tops within the gap; and (4) closing the gap, where closing the gap includes calculating positions of restored tops based on the positions of the tops specified within the gap, where the positions of the restored tops are usable to model one or more surfaces in the formation.