A combination of optical dating of aeolian sand, and radiocarbon datin
g of palaeosols and interdune sediments, has allowed some refinements
to the chronostratigraphy of the Nebraska Sand Hills. Our results dire
ctly confirm previous inferences that multiple phases of aeolian depos
ition, including megabarchan dune reactivation, occurred within the Sa
nd Hills during the middle and late Holocene. Optical dates on stratif
ied aeolian (barchan dune) sediments from two localities provide ages
ranging from c. 6 ka to <300 years ago. Weakly developed palaeosols in
tercalated within the dune sediments and other forms of post-depositio
nal modification indicate periods of relative stability and reduced du
ne mobilization. Optical dates on the upper 12-15 m of two dune exposu
res indicate repeated, possibly regionally correlative, reactivations
which occurred between c. 400-500 and 200-300 years ago. Comparison of
late-Holocene aeolian activity with local and regional palaeoclimatic
proxy records suggests that dune reactivation may have occurred frequ
ently, possibly in response to periods of extended (>20 yr) drought.