Figure 3    Temporal correlation of the late Pleistocene varnish climate record in the drylands of western USA with the GISP2 Greenland ice core record. Radiometric age calibration (Liu et al., 2000; Liu, 2003) indicates that wet events represented by Mn- and Ba- rich dark layers (WP0-WP6) in the varnish record largely correlate with cold periods of the Younger Dryas (YD) and Heinrich events (H1-H6) represented by the oxygen isotopic troughs (marked with shorthand arrows) in the ice core record (Grootes et al., 1993; Bond et al., 1999). The GISP2 timescale is from Meese et al. (1994) and Bender et al. (1994). The chronology of the YD and H1 - H6 is from Bond et al. (1999). The color scheme represents relative concentrations of Mn and Ba in varnish microstratigraphy: black = Mn- and Ba-rich; orange = Mn- and Ba-intermediate; yellow = Mn- and Ba-poor. LU = layering unit, MIS = Marine Isotope Stage, WP = wet event in Pleistocene.