Late-Holocene paleofloods in the Upper Little Tennessee River valley, Southern Blue Ridge Mountains, USA.

We derive a paleoflood chronology for the past 2000 years from three stratigraphic sections of overbank sediments with dates from radiocarbon, luminescence, 137Cs techniques, and historical records. Particle sizes were measured in 6–15 year intervals in post-1870 sediments and in 45–170 year intervals in pre-1870 sediments using an automatic laser analyzer. The sedimentological characteristics of ad 1948–2009 deposits were compared with gaging records, demonstrating that fine sand content and sorting discern time intervals of large floods, but flood magnitudes are not well resolved. This modern analog was applied to pre-1870 sediments and revealed two periods in the last 2000 years with large floods during ad 650–850 and ad 1100–1350, which are times when the regional tree-ring record showed extreme wetness and no severe or extreme droughts. Our findings indicate flood-prone phases of transitional climate at the beginning and end of the ‘Medieval Warm Period’ (MWP), and relatively subdued flooding during the ‘Little Ice Age’ (LIA), possibly correlated with rearrangement of macro-scale atmospheric circulation patterns between the MWP and the LIA. [ABSTRACT FROM AUTHOR]