Figure 1. LROC image of a boulder-covered bench crater. The crater has formed in a basaltic regolith close to the Apollo 12 landing site. The impact has punched through the thin regolith cover and into the harder rock, excavating large blocks that have covered the surrounding surface. This example is 130m in diameter, so the regolith here must be less than about 13m deep. By determining the maximum size of craters in this area which have not excavated boulders the actual depth of the local regolith can be determined. (LROC image M114104917L/ASU/NASA).