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G. G. Fredlund

Publications and source records attributed to G. G. Fredlund.

3 recordsLinked to original sources

Holocene stratigraphy and chronology of the Casper Dune Field, Casper, Wyoming, USA

Activation chronologies of dune fields within the North American Great Plains are significant sources of paleoclimate information. Although many regional chronologies exist, several dune fields have been understudied, including the Casper Dune Field of central Wyoming. This study investigated aeolian dune sediment and buried soils of the Casper Dune Field. Complex parabolic and hairpin parabolic dunes dominate the eastern dune field, while simple parabolic and linear dunes dominate the western dune field. Buried soils are found throughout the dune field, though their distribution and degree of development varies. Buried soils in the eastern dune field are weakly developed with typical A-C profiles, whereas soils in the western dune field typically exhibit A-Bt-C profiles. Optically stimulated luminescence (OSL) and radiocarbon ages were used to provide a chronology of dune field activation that spans most of the Holocene. At the onset of the Holocene, alluvium was deposited first, followed by widespread dune activity ~ 10.0—6.2 ka. Following activity, the dune field stabilized until about 4.1 ka. During this stabilization period, however, reactivation occurred in at least one locality within the dune field at 5.1 ka. Subsequent aeolian activity occurred at 4.1 ka and between 1.0 ka and 0.4 ka. The resulting activation chronology is compared with those obtained from elsewhere in Wyoming and from other west-central Great Plains dune fields.

Wyoming

Mid-Wisconsinan environments on the eastern Great Plains

Few sites on the eastern Great Plains contain paleobotanical records for the mid-Wisconsin. We report on four sites, two stream cutbanks and two quarry exposures, ranging in age from >50 to ???23.4 ka. The oldest site at >50 ka contains a suite of macrofossils from prairie and disturbed ground habitats, with no representation of trees, indicating an open prairie. By ???38 ka the assemblages include aquatic, wetland, mudflat, and prairie elements with rare specimens of Populus, Betula cf. papyrifera, Salix and at the most northerly site, Picea. This assemblage suggests a prairie/parkland with interspersed marshes, cooler temperatures and increased moisture. Populus and Salix continued to be represented from ???36 to ???29 ka, but the only other taxon was Carex. A hiatus may be present at some time during this interval. After ???29 ka, Picea became dominant on the uplands and it was joined by sedges in local wetlands. At sites near riverine loess sources, loess accumulation began to fill in the wetlands and organic deposition ceased some time after 29 ka. ?? 2009 Elsevier Ltd. All rights reserved.

Quaternary Science Reviews

Aeolian cliff-top deposits and buried soils in the White River Badlands, South Dakota, USA

Aeolian deposits in the North American Great Plains are important sources of Holocene palaeo-environmental records. Although there are extensive studies on loess and dune records in the region, little is known about records in aeolian cliff-top deposits. These are common on table (mesa) edges in the White River Badlands. These sediments typically have loam and sandy-loam textures with dominantly very fine sand, 0.5-1% organic carbon and 0.5-5% CaCO3. Some of these aeolian deposits are atypically coarse and contain granules and fine pebbles. Buried soils within these deposits are weakly developed with A-C and A-AC-C profiles. Beneath these are buried soils with varying degrees of pedogenic development formed in fluvial, aeolian or colluvial deposits. Thickness and number of buried soils vary. However, late-Holocene soils from several localities have ages of approximately 1300, 2500 and 3700 14C yrs BP. The 1300 14C yr BP soil is cumulic, with a thicker and lighter A horizon. Soils beneath the cliff-top deposits are early-Holocene (typically 7900 but as old as 10000 14C yrs BP) at higher elevation (???950 m) tables, and late-Holocene (2900 14C yrs BP) at lower (???830 m) tables. These age estimates are based on total organic matter 14C ages from the top 5 cm of buried soils, and agreement is good between an infrared stimulated luminescence age and bracketing 14C ages. Our studies show that cliff-top aeolian deposits have a history similar to that of other aeolian deposits on the Great Plains, and they are another source of palaeoenvironmental data.

Holocene