Identification of Loess by Particle Size Distribution Using the Coulter Counter Ta Ii1

Lewis, G. C.; Fosberg, M. A.; Falen, A. L.; Miller, B. J.

doi:10.1097/00010694-198403000-00006

Cited by 8 publications

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“…Based on the data presented here, the differences in emission factors can be ascribed to mineralogical and textural (particle size) properties of the dust, which are related to the bedrock geology as well as erosion, deposition, weathering and soil forming processes. The two Yakima (YTC) samples contain more than 50% silt, as they comprise largely mechanically generated loess from the Last Glacial period (Bettis III et al, 2003;Lewis et al, 1984). The samples contain mineral particles of amphibole, pyroxene and plagioclase, typical of igneous rocks of the underlying Columbia River Basalt Group in the Yakima Valley (Busacca et al, 2008), together with approximately 7% clays.…”

Section: Particle Size Distributions Of Re-suspensions By Scanning Elmentioning

confidence: 99%

Controls on mineral dust emissions at four arid locations in the western USA

et al. 2012

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Section: Particle Size Distributions Of Re-suspensions By Scanning Elmentioning

confidence: 99%

Controls on mineral dust emissions at four arid locations in the western USA

et al. 2012

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AMS Radiocarbon Age of the Upper Mississippi Valley Roxana Silt

Leigh

Knox

1993

Quat. res.

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Accelerator mass spectrometer radiocarbon ages of the Roxana Silt (loess) along the Upper Mississippi Valley of Wisconsin and Minnesota indicate that loess sedimentation of the Roxana Silt occurred between about 55,000 and 27,000 14 C yr B.P. However, due to local environmental controls, the basal age at any given site may range from 55,000 to 35,000 14C yr B.P. The radiocarbon ages presented here are in agreement with previous radiocarbon ages for the Roxana Silt in its type area of west-central Illinois, but indicate that long-term sedimentation rates along the bluffline of the Upper Mississippi Valley were very slow (4-8 cm/1000 yr) compared to long-term sedimentation rates along the bluffline of the type area (40-70 cm/1000 yr). Comparison of radiocarbon ages for midcontinent middle Wisconsinan loess deposits indicates that sedimentation along the Mississippi River valley may have preceded loess sedimentation along the Missouri River valley by as much as 20,000 yr or that basal ages for middle Wisconsinan loess along the Missouri Valley are erroneously young. The bracketing ages for the Upper Mississippi Valley Roxana Silt indicate that the Mississippi River valley was receiving outwash sedimentation between 55,000 and 27,000 14C yr B.P.

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Loess of the Upper Mississippi Valley Driftless Area

Leigh

Knox

1994

Quat. res.

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Loess of the Driftless Area includes four distinct late Quaternary lithostratigraphic units: the Wyalusing (new), Loveland, Roxana, and Peoria formations. Erosion has removed parts or all of the pre-late Wisconsian loess at many sites. These formations consist largely of loess and retransported loess that typically occurs on uplands, terraces, and valley margins in the region. The oldest widespread formation (probably > 125,000 yr B.P.) is here formally named the Wyalusing Formation. The three younger formations correlate with the Loveland (probably > 125,000 yr B.P.), Roxana (55,000-25,000 yr B.P.), and Peoria (25,000-12,000 yr B.P.) loesses recognized elsewhere in the midcontinental United States. The soil/stratigraphic morphology of the Wyalusing-Loveland and Roxana-Peoria couplets appears to represent two distinct loess sedimentation sequences related to major expansion and contraction of the Laurentide Ice Sheet during oxygen isotope stages 6 and 3-2, respectively. The occurrence-frequency of loess units is inversely related to age, illustrating the erosional nature of the Driftless area landscape. The occurrence of four loess units at some sites in Driftless Area stratigraphic sections corroborates loess stratigraphy along the length of the Mississippi Valley, where typically not more than four or five loess units are found and they represent only the late and middle Pleistocene (<790,000 yr B.P.). Past climatic conditions, which favored erosion of loess, as well as a temporally erratic spatial extent of former continental ice sheets in North America, which provided the dust supply, probably account for the low number of loess units along the Mississippi Valley.

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Identification of Loess by Particle Size Distribution Using the Coulter Counter Ta Ii1

Cited by 8 publications

References 0 publications

Controls on mineral dust emissions at four arid locations in the western USA

Controls on mineral dust emissions at four arid locations in the western USA

AMS Radiocarbon Age of the Upper Mississippi Valley Roxana Silt

Loess of the Upper Mississippi Valley Driftless Area

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