Orbital-science investigation: Part G: lineaments that are artifacts of lighting

Many Apollo 15 orbital photographs, particularly those taken at low Sun-elevation angles, reveal grid patterns of lineaments. In some circumstances, the grid pattern is present in areas where structural control seems unlikely. For example, in an oblique view (fig. 25-52), the ejecta blankets of two fresh impact craters seem to have two intersecting sets of lineaments. Because previous studies of impact craters indicate that concentric and radial trends are commonly present, that this pattern is unexpected. A crater-saturated surface on which a faint grid of linear markings can be discerned is shown in figure 25-53. Again, this pattern is unexpected for a surface that has been exposed to random impacts. In both situations, the azimuths of the main lineaments are approximately symmetrical to the direction of the Sun.