Abstract: A method for formation structural interpretation while drilling a wellbore through subsurface rock formations includes interpreting rock formation strata with respect to measurements of a formation physical property made with respect to depth in an offset wellbore. A color is assigned to each of a plurality of selected value ranges of the measurements. The physical property of the formation is measured while drilling the wellbore through the subsurface rock formations. A color is assigned to the measurements made while drilling based on the assigned color to each of the selected value ranges. The assigned colors made while drilling are used to estimate a stratigraphic position of the wellbore during the drilling by comparing the assigned colors made while drilling to the colors assigned from the offset wellbore.