Figure 9    A debris flow fan (~ 0.04 km² in size) on the east side of Death Valley, California (upper panel) and optical microstratigraphies of rock varnish from the fan deposits (lower panel). Seven fan units (Df1-Df7) were identified on the basis of fan morphology and degree of varnish coverage (see Table 4). VML dating results (reported in cal YBP) indicate that emplacement of these fan units was more likely to have occurred during relatively wet periods of the Holocene. Note that while optically similar due to thin sections with slightly greater thickness, the Holocene dark layers in these images often contain less Ba than the pre-Holocene dark layers, as illustrated in (C) and (F). The brown burn marks in (C) were made by electron microprobe during line profiling.