Fig. 5.

Exposure age versus distance projected along the long profile (Fig. 2C) of Pointed Canyon. Three samples (open symbols) yielded ages consistent with reworking by the Bonneville Flood and are not included in the fit (note one of the three falls nearly on the trend line). Error bars represent analytical uncertainty (Table S2), which is often smaller than the symbol size. The most upstream age of zero (filled circle) is assumed based on the observed location of active knickzone retreat (Fig. 3E and Fig. S2). Data suggest Pointed Canyon was 1.05 km long (blue star in Fig. 2B) when formation of the other canyons ceased (∼46 ka). The Bonneville Flood age range shown extends a few thousand years older than is typically reported based on revised chronology of paleoshorelines (27) and canyon exposure ages (28).