Mackin's (1950) instructions to view a geologic map of cross-faulted strata down the dip of the bedding, to “see” the sense of dip separation directly, should be modified to view the map in the direction of plunge of the trace of displaced surfaces on the fault. However, even though the separation sense is then correctly interpreted, the sense of slip components and respective sense of separation may disagree, depending on the geometric relations of the pitch of the net slip and the pitch of the trace of the bed or vein on the fault.