Stratigraphic evidence of desertification in the west-central Great Plains within the past 1000 yr

Chronology and geochemistry of late Holocene eolian deposits in the Brandon Sand Hills, Manitoba, Canada

“…Near Hudson Bay, James Bay, and in Pinery Provincial Park, Ontario, soils with Ae/BF/C or Ae/BM/C pro"les have developed in less than 2500 yr (Protz et al, 1984(Protz et al, , 1988VandenBygaart and Protz, 1995), under precipitation regimes ranging from 500 to 850 mm/yr. In the drier grasslands of the central and southern Great Plains, soils with only Ah/AC/C pro"les are developed on dunes of late Holocene age (Muhs, 1985;Holliday, 1990Holliday, , 1995aMadole, 1994Madole, , 1995Muhs et al, 1996Muhs et al, , 1997aArbogast, 1996;Muhs and Wolfe, 1999). These comparisons suggest that the minimally developed soils of the Brandon Sand Hills indicate that much of the dune "eld has been active in the past 2}3 millennia.…”

“…Dunes in many parts of this region were long perceived to be relict landforms of full-glacial time (Wright, 1970;Sarnthein, 1978;Kutzbach and Wright, 1985), but it is now known that most dune "elds were last active in the Holocene. Stratigraphic studies combined with radiocarbon and luminescence dating methods demonstrate that eolian sands over a wide range of mid-continental North America have been active in the past 3000 years (David, 1971a, b;Ahlbrandt et al, 1983;Swinehart and Di!endal, 1990;Madole, 1994Madole, , 1995Holliday, 1995aHolliday, , b, 1997Forman et al, 1995;Loope et al, 1995;Arbogast, 1996;Muhs et al, 1996Muhs et al, , 1997aWolfe et al, 1995;Stokes and Swinehart, 1997). Furthermore, most of these studies have stratigraphic data indicating multiple periods of eolian activity in the late Holocene.…”

Geologic map of the Masters 7.5' quadrangle, Weld and Morgan Counties, Colorado

“…Widespread deposition of eolian sand during the late Holocene is indicated by radiocarbon ages reported by Madole (1994Madole ( , 1995 and Madole and others (2005) 14 C ka B.P., Beta-62192) in Greasewood Lake 7.5′ quadrangle. Radiocarbon ages for soil carbonate rhizoliths collected from a quarry exposure north of Orchard are in good agreement, indicating a maximum-limiting age for uppermost eolian sand of about 1.44±0.13 cal ka B.P.…”

Geologic map of the Weldona 7.5' quadrangle, Morgan County, Colorado

“…Widespread deposition of eolian sand during the late Holocene is indicated by radiocarbon ages reported by Madole (1994Madole ( , 1995 and Madole and others (2005) for buried soils that provide maximum-limiting ages for uppermost sand deposits in and near Weldona 7.5΄ quadrangle: 0.64±0.11 cal ka B.P. 14 C ka B.P.)…”