Lunar pyroclastic deposits reflect an explosive stage of the basaltic volcanism that filled impact basins across the nearside. These fine-grained mantling layers are of interest for their association with early mare volcanic processes, and as possible sources of volatiles and other species for lunar outposts. We present Earth-based radar images, at 12.6 and 70 cm wavelengths, of the pyroclastic deposit that blankets the Aristarchus Plateau. The 70 cm data reveal the outlines of a lava-flow complex that covers a significant portion of the plateau and appears to have formed by spillover of magma from the large sinuous rille Vallis Schröteri. The pyroclastics mantling these flows are heavily contaminated with rocks 10 cm and larger in diameter. The 12.6 cm data confirm that other areas are mantled by 20 m or less of material, and that there are numerous patches of 2 cm and larger rocks associated with ejecta from Aristarchus crater. Some of the radar-detected rocky debris is within the mantling material and is not evident in visible-wavelength images. The radar data identify thick, rock-poor areas of the pyroclastic deposit best suited for resource exploitation.