A combination of optical dating of aeolian sand, and radiocarbon dating of palaeosols and interdune sediments, has allowed some refinements to the chronostratigraphy of the Nebraska Sand Hills. Our results directly confirm previous inferences that multiple phases of aeolian deposition, including megabarchan dune reactivation, occurred within the Sand Hills during the middle and late Holocene. Optical dates on stratified aeolian (barchan dune) sediments from two localities provide ages ranging from c. 6 ka to <300 years ago. Weakly developed palaeosols intercalated within the dune sediments and other forms of post-depositional modification indicate periods of relative stability and reduced dune mobilization. Optical dates on the upper 12-15 m of two dune exposures 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 frequently, possibly in response to periods of extended (> 20 yr) drought.
Ahlbrandt, T.S. and Fryberger, S.G.1980: Gelogic and paleoecologic studies of the Nebraska Sand Hills: US Geological Survey Professional Paper 1120-A, 28.
2.
Ahlbrandt, T.S., Swinehart, J.B. and Maroney, D.G.1983: The dynamic Holocene dune fields of the Great Plains and Rocky Mountain basins, USA. In Brookfield, M.E. and Ahlbrandt, T.S., editors, Eolian Sediments and Processes, Amsterdam: Elsevier, 379-406.
Aitken, M.J. and Xie1992: Optical dating using infrared diodes; young samples. Quarternary Science Reviews11, 147-52.
5.
Antevs, E.1962: Late Quaternary climate in Arizona. American Antiquity128, 193-98.
6.
Brumby, S.1992: Regression analysis of ESR/TL dose-response data . Nuclear Tracks and Radiation Measurements20, 595-99.
7.
Dean, J.S.1988: Dendrochronology and paleoenvironmental reconstruction on the Colorado Plateaus. In Gummerman, J.G. , editor, The Anasazi in a changing environment, Cambridge: Cambridge University Press, 75-86.
8.
Dean, W.E., Bradbury, J.P., Anderson, R.Y. and Barnosky, C.W.1984: The variability of Holocene climate change: Evidence from varved lake sediments. Science226, 1191-94.
9.
Forman, S.L., Goetz, A.F.H. and Yuhas, R.H.1992: Large-scale stabilized dunes on the High Plains of Colorado: Understanding the landscape response to Holocene climates with the aid of images from space. Geology20, 145-48.
10.
Forman, S.L., Oglesby, R., Markgraf, V. and Stafford, T.1995: Paleoclimatic significance of Late Quaternary eolian deposition on the Piedmont and High Plains, Central United States. Global and Planetary Change11, 35-55.
11.
Fritts, H.C.1991: Reconstructing large-scale climatic patterns from tree-ring data. Tucson, Arizona: University of Arizona Press.
12.
Fritz, S.C., Engstrom, D.R. and Haskell, B.J.1994: 'Little Ice Age' aridity in the North American Great Plains: A high resolution reconstruction of salinity fluctuations from Devils Lake, North Dakota. The Holocene4, 69-73.
13.
Holliday, V.T.1989: Middle Holocene drought on the Southern High Plains . Quaternary Research31, 74-82.
14.
— 1995: Stratigraphy and paleoenvironments of Late Quaternary valley fills on the southern High Plains. Geological Society of America, Memoir 186.
15.
Houghton, J.T., Jenkins, G.J. and Ephranums, J.J.1991: Climate change: the IPCC scientific assessment . Cambridge: Cambridge University Press.
16.
Karlstrom, E.T. and Karlstrom, T.N.V.1986: Late Quaternary alluvial stratigraphy and soils of the Black Mesa - Little Colorado river areas, northern Arizona. In Nations, J.D., Conway, C.M. and Swann, G.A. , editors, Geology of central northern Arizona, Geological Society of America: Rocky Mountain Section Guidebook, 71-91.
17.
Kutzbach, J.E. and Wright, Jr. H.E.1985: Simulation of the climate of 18,000 years BP; results for the North American/North Atlantic/European sector and comparison with the geologic record of North America: Quaternary Science Reviews4, 147-87.
18.
Loope, D.L., Swinehart, J.B. and Mason, T.P.1995: Dune-dammed paleovalleys of the Nebraska Sand Hills - intrinsic versus climatic control on the accumulation of lake and marsh sediments . Geological Society of America Bulletin107, 396-406.
19.
Lugn, A.L.1968: The origin of loesses and their relation to the Great Plains in North America. In Schultz, C.B. and Frye, J.C., editors, Loess and related eolian deposits of the world, Lincoln, Nebraska: University of Nebraska Press, 139-82.
20.
Madole, R.F.1994: Stratigraphic evidence of desertification in the west-central Great Plains within the past 1000 yr. Geology22, 483-86.
21.
— 1995: Spatial and temporal patterns of late Quaternary aeolian deposition, eastern Colorado, USA. Quaternary Science Reviews14, 155-77.
22.
Madole, R.F. and Stokes, S.1992: Preliminary chronology of dune and sheet sand south and east of the South Platte River near Greeley, Colorado. American Quaternary Association, Program and Abstracts 31, 71.
23.
Martin, C.W.1992: Late Holocene alluvial chronology and climate change in the Central Great Plains. Quaternary Research37, 315-22.
24.
— 1993: Radiocarbon ages on late Pleistocene loess stratigraphy of Nebraska and Kansas, Central Great Plains. Quaternary Science Reviews12, 179-88.
25.
Mason, J.P., Swinehart, J.B. and Loope, D.B.1997: Holocene history of lacustrine and marsh sediments in a dune-blocked drainage, Southwestern Nebraska Sand Hills, USA. Journal of Palaeolimnology, in press.
26.
May, D.W.1989; Holocene alluvial fills in the South Loup Valley, Nebraska . Quaternary Research32, 117-20.
27.
May, D.W. and Holen, S.R.1993: Radiocarbon ages of soils and charcoal in Late Wisconsin loess, south-central Nebraska. Quaternary Research39, 55-58.
28.
May, D.W., Swinehart, J.B., Loope, D.L. and Souders, V.L.1995: Late Quaternary fluvial and eolian sediment: Loup River Basin and the Nebraska Sand Hills. In Flowerday, C.A., editor, Geolc gic field trips in Nebraska and South Dakota, Conservation and Survey Division, University of Nebraska-Lincoln, Guide Book No. 10, 13-31.
29.
Meko, D.M.1995: Dendroclimatic evidence from the Great Plains of the United States. In Bradley, R.S. and Hondes, P.D., editors, Climate since AD 1500 , London: Routledge , 312-30.
30.
Muhs, D.R.1985: Age and paleoclimatic significance of Holocene sand dunes in northeastern Colorado. Annals of the Association of American Geographers75, 566-82.
31.
Muhs, D.R. and Holliday, V.T.1995: Evidence of active dune sand on the Great Plains in the 19th century from accounts of early explorers. Quaternary Research43, 198-208.
32.
Muhs, D.R. and Maat, P.B.1993: The potential response of eolian sands to greenhouse warming and precipitation reduction on the Great Plains of the USA. Journal of Arid Environments25, 351-61.
33.
Nambi, K.S.V. and Aitken, M.J.1986: Annual dose conversion factors for TL and ESR dating . Archaeometry28, 202-205.
34.
Pye, K., Winspear, N.R. and Zhou, L.P.1995: Thermoluminescence ages of loess and associated sediments in central Nebraska, USA. Palaeogeography, Palaeoclimatology, Palaeoecology118, 73-87.
35.
Sarnthein, M.1978: Sand deserts during glacial maximum and climatic optimum . Nature272, 43-46.
36.
Schulman, E.1959: Tree-ring evidence for climatic changes. In Shapley, H., editor, Climatic change: evidence, causes, and effects, Cambridge, MA: Harvard University Press, 207-19.
37.
Smith, B.W., Rhodes, E.J., Stokes, S. and Spooner, N.A.1991: Optical dating of quartz. Radiation Protection Dosimetry17, 229-33.
38.
Smith, H.T.U.1965: Dune morphology and chronology in central and western Nebraska. Journal of Geology73, 557-78.
39.
Spaulding, W.G.1991: A Middle Holocene vegetation record from the Mojave Desert of North America and its palaeoclimatic significance. Quaternary Research35, 427-37.
40.
Stokes, S.1992: Optical dating of young (modern) sediments using quartz: results from a selection of depositional enviornments. Quaternary Science Reviews11, 153-59.
41.
— 1994: Optical dating of selected Late Quaternary aeolian sediments from the Southwestern United States. Unpublished D. Phil. thesis, Oxford University.
42.
— 1997: The effects of pre-heating on the natural OSL of sedimentary quartz from Nebraska. Ancient TL, in press.
43.
Stokes, S. and Breed, C.S.1993: A chronostratigraphic re-evaluation of the Tusayan dunes, Moenkopi Plateau and southern Ward Terrace, northeastern Arizona. In Pye, K., editor, The dynamics and environmental context of aeolian sedimentary systems, London: Geological Society of London, Special Publication No. 72, 75-90.
44.
Stokes, S. and Gaylord, D.1993: Optical dating of Holocene dune sands in the Ferris dune field, Wyoming. Quaternary Research39, 274-81.
45.
Stuiver, M. and Long, A. , editors, 1993: Calibration 1993. Radiocarbon35, 244 pp.
46.
Swinehart, J.B.1990: Wind-blown deposits. In Bleed, A. and Flowerday, C., editors, An atlas of the Sand Hills, Lincoln, Nebraska : University of Nebraska, Conservation and Survey Division, Resource Atlas No. 5a, 43-56.
47.
Van Devender, T.R., Betancourt, J.L. and Wimberly, M.1984: Biogeographical implications of a pack rat midden . Quaternary Research44, 345-60.
48.
Warren, A.J.1976: Morphology and sediments of the Nebraska Sand Hills in relation to Pleistocene winds and the development of aeolian bed forms . Journal of Geology84, 685-700.
49.
Weakly, H.E.1962: History of drought in Nebraska. Journal of Soil and Water Conservation17, 271-74.
50.
Wells, G.L.1983: Late-glacial circulation over North America revealed by aeolian features. In Street-Perrot, A. , Beran, M. and Ratcliffe, R., editors, Variations in the global water budget, Dordrecht, Netherlands: D. Reidel, 317-30.
51.
Wells, S.G., McFadden, L.D. and Schultz, J.D.1990: Eolian landscape evolution and soil formation in the Chaco dune field, southern Colorado Plateau, New Mexico. Geomorphology3, 517-46.
52.
Wolfe, S.A., Huntley, D.J. and Ollerhead, J.1995: Recent and late Holocene sand dune activity in southwestern Saskatchewan. Reserches en cours (Geological Survey of Canada) B, 131-40.
53.
Wright, H.E. Jr, Almendinger, J.C. and Gruger, J.1985: Pollen diagram from the Nebraska Sand Hills and the age of the dunes. Quaternary Research24, 115-20.
