The thickness of the lunar regolith has been previously estimated using
seismic, radar, and crater morphology data to be on the order of tens of
meters. In this study, we use rock abundance measurements from the
Diviner radiometer aboard the Lunar Reconnaissance Orbiter (LRO) to
provide new estimates of rock-free regolith thickness in recently-formed
impact craters. Diviner cold spots have been shown to last no longer
than a few 100 kyr, and thereby point to fresh craters on the moon.
Trends in Diviner data also show that deeper cold spot craters have
rockier ejecta. We employ statistical analyses to show that cold spot
craters in the lunar mare have rockier ejecta at smaller excavation
depths when compared to those in the highlands. We estimate that the
average rock-free regolith is 12.6 m thick in the mare and 18.5 m thick
in the highlands, which is consistent with previous estimates. We expect
these values will be highly variable due to differences in regolith
development and overturn across the moon.