The present paper sets out a new approach applicable to multiphase rock art panels where the images were produced by scratching the rock surface.  As a test case, two small fragments of stone from Piancogno (BS), Italy, were chosen: fragments showing complex compositions of both figurative and abstract scratching, often overlapping one another. Preparatory analysis involved the following steps: preliminary investigation with a digital microscope to quantify morphometric differences and points of intersection/overlap of the scratched lines; digital photo-mosaic of the engraved surfaces to obtain a very high-resolution image; digital vector tracing of the figures; comparison and checking against the traditional hand-made tracing.  The topology of the series of intersections between the incised lines was then analysed through a stratigraphic diagram modeled on the Harris Matrix. The result is a clear understanding of a complex sequence of overlapping and intersecting images – an understanding that would be hard to reach without such a topological/stratigraphic approach. Future applications will focus on understanding certain very complex panels at Piancogno with the aim of establishing a solid relative chronology for these little-studied images.