Sediments exposed at Flintstone Hill in a Souris River cutbank provide the most complete postglacial stratigraphic section in the Glacial Lake Hind Basin (GLHB), southwestern Manitoba. Four lithologic units, A-D, are observed: A1 (~2 m thick), glaciolacustrine silts and clays that grade upward to peat and record final regression of Glacial Lake Hind (~10 500-9300 BP); A2 (~1.5 m thick), low energy fluvial marl and silts grading to O-horizon(s) (by 6700 BP); B (1.5 m thick), dune sands that migrated from the southwest, contrary to the modern wind regime (after ~6700 BP); C (1.0 m thick), thin fluvial deposit between eolian sand sheets (~5500-3200 BP); D (up to 7 m thick), parabolic dune on the modern landscape oriented consistent with the modern wind regime, blowouts suggest episodic dune reactivation (~3200 BP to present). Overall, Flintstone Hill deposits record draining of Glacial Lake Hind, establishment of the Souris River channel through the GLHB, mid-Holocene eolian activity / landscape instability greater than present, and a return to nearly modern conditions by ~5400 BP. Native inhabitants in the GLHB focused on exploiting wetlands and wet meadows before 9300 BP and a landscape similar to the present thereafter.Les sédiments à découvert de la Flintstone Hill, sur la berge escarpée de la rivière Souris, offrent la séquence stratigraphique postglaciaire la plus complète du bassin du Lac glaciaire Hind. Quatre unités lithologiques, de A à D, y sont observées : A1 (~2 m d’épaisseur), silts et argiles glaciolacustres au granoclassement vertical progressif jusqu’à la tourbe témoignent de la dernière régression du Lac glaciaire Hind (~10 500-9300 BP) ; A2 (~1,5 m d’épaisseur), marnes fluviatiles de faible énergie et silts jusqu’à un horizon O (vers 6700 BP) ; B (1,5 m d’épaisseur), sables dunaires en provenance du sud-ouest, contrairement au régime des vents actuel (après ~6700 BP) ; C (1,0 m d’épaisseur), dépôt fluviatile mince entre des couches de sable (~5500-3200 BP) ; D (jusqu’à 7 m d’épaisseur), dune parabolique faisant partie du paysage moderne et orientée selon le régime des vents actuel, avec des creux de déflation témoignant de réactivations dunaires épisodiques (~3200 BP à aujourd’hui). En résumé, les dépôts de la Flintsone Hill attestent d’abord de la vidange du Lac glaciaire Hind, puis de l’établissement du chenal de la rivière Souris à travers le bassin, d’une activité éolienne et d’une instabilité des paysages à l’Holocène moyen plus grande que maintenant et de l’établissement de conditions quasi contemporaines vers 5400 BP. Les premiers habitants du bassin ont d’abord exploité les terres humides et les prés humides avant 9300 BP, puis un paysage semblable à celui d’aujourd’hui par la suite.Los sedimentos expuestos en la zona de Flinstone Hills en la ribera del Souris River proporcionan el registro estratigráfico post-glaciar más completo de la cuenca del Lake Hind, al sudoeste de Manitoba. Se distinguen cuatro unidades litológicas: A-D. La unidad A1, de unos 2 m de grosor, está compuesta por limo...
Stratigraphic and paleoecologic (palynomorph, macrobotanical) data obtained from a cutbank of the Souris River in southwestern Manitoba establish some fundamental parameters of Folsom land‐use in association with a proglacial lake on the Canadian Prairies. By dating the regression of glacial Lake Hind, we observed that recorded Folsom sites are restricted to areas of the Hind basin drained shortly before 10,400 yr B.P. This pattern may therefore record the interception of seasonal resources on recently‐drained proglacial lake surfaces. Based on paleovegetation reconstructions, we note that these surfaces were rapidly colonized by emergent and aquatic vegetation following regression, generating a viable resource base for Folsom hunter‐gatherers. However, low plant productivity and diversity may have greatly limited the extent to which this locale was exploited, in contrast to nonperiglacial regions on the Plains. We also suggest that wetland plant succession during the Pleistocene‐Holocene transition was due, at least locally, to climate‐forced fluctuations in groundwater levels. © 2003 Wiley Periodicals, Inc.
Our study adds to the Quaternary history of eolian systems and deposits in western Wisconsin, USA, primarily within the lower Chippewa River valley. Thickness and textural patterns of loess deposits in the region indicate transport by west-northwesterly and westerly winds. Loess is thickest and coarsest on the southeastern flanks of large bedrock ridges and uplands, similar in some ways to shadow dunes. In many areas, sand was transported up and onto the western flanks of bedrock ridges as sand ramps, presumably as loess was deposited in their lee. Long, linear dunes, common on the sandy lowlands of the Chippewa valley, also trend to the east-southeast. Small depressional blowouts are widespread here as well and often lie immediately upwind of small parabolic dunes. Finally, in areas where sediment was being exposed by erosion along cutbanks of the Chippewa River, sand appears to have been transported up and onto the terrace treads, forming cliff-top dunes. Luminescence data indicate that this activity has continued throughout the latest Pleistocene and into the mid-Holocene. Together, these landforms and sediments paint a picture of a locally destabilized landscape with widespread eolian activity throughout much of the postglacial period.
A stream cut-bank at Flintstone Hill, Lauder Sandhills, Glacial Lake Hind Basin, southwestern Manitoba, exposes an extensive Holocene sedimentary sequence. Ground penetrating radar (GPR) is used to determine lateral continuity of four major stratigraphic units (wetland complex, Mid-Holocene aeolian dune, sandsheet/fluvial, Late Holocene aeolian dune) and to image primary sedimentary features within the dune strata. Depth of GPR signal penetration is only about 5 m. Signal attenuation is attributed to the presence of primarily pedogenic silts/clays and carbonate-and iron sesquioxide-rich horizons within the sandier units. Nevertheless, the stratigraphic units are shown by GPR, and confirmed by core data, to be laterally continuous within the survey area. Finer-scale dune strata are not well displayed in the aeolian units. Signal attenuation above the Mid-Holocene unit and relatively high iron sesquioxide concentrations within the unit limit imaging of well-preserved dune foreset strata. In the Late Holocene unit, depositional strata are poorly preserved and GPR primarily images soil A-horizons formed on surfaces of temporary stabilization within the dune sediment.1990s, when Schenk et al. (1993) published radar images of the internal stratigraphy of an area of the Great Sand Dunes in Colorado, USA. Some more
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