VML Dating of Precarious Boulders in the Mojave Desert, Western USA


Figure Caption:   Optical microstratigraphies in rock varnish from precariously balanced rocks (PBRs) in the Mojave Desert near Lake Mirage (about 35 km northeast of the San Andreas Fault Zone) in southern California. VML dating indicates that these PRBs have been exposed with little change in geometry for at least 12.5 ka, suggesting no earthquakes with ground accelerations greater than 0.2–0.3 g have happened in the region since the end of the last glacial period (cf. Bell et al., 1998; Brune et al., 2007). Varnish sampling spots on the pedal stones of the PRBs are marked with red dots.