Blue Lake Record

(a) Blue Lake varve thicknesses plotted as the standard deviation from the mean thickness (5-point moving average). Black vertical bars indicate inferred cool intervals in the Brooks Range. (b) Blue Lake temperature reconstruction shown as the difference from the last millennium average (51-point moving average) with the grey lines denoting the upper and lower 95% CI. (c) Glacier fluctuations in the Brooks Range (Ellis and Calkin 1984). (d) Greater Yukon aridity as represented by the Marcella Lake d18O record (Anderson et al. 2007). The grey area highlights the period during which precipitation, rather than summer temperature, is believed to have dominated varve formation in Blue Lake