Loess of the Upper Mississippi Valley Driftless Area

1994 ◽  
Vol 42 (1) ◽  
pp. 30-40 ◽  
Author(s):  
David S. Leigh ◽  
James C. Knox
Keyword(s):  
United States ◽  
Late Quaternary ◽  
Ice Sheets ◽  
Climatic Conditions ◽  
Laurentide Ice Sheet ◽  
Middle Pleistocene ◽  
Mississippi Valley ◽  
Driftless Area ◽  
Lithostratigraphic Units ◽  
Continental Ice Sheets

AbstractLoess 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.

Aeolian influx and related environmental conditions on Gran Canaria during the early Pleistocene

2018 ◽  
Vol 91 (1) ◽  
pp. 35-50 ◽  
Author(s):  
Inmaculada Menéndez ◽  
José Mangas ◽  
Esperança Tauler ◽  
Vidal Barrón ◽  
José Torrent ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Textural Analysis ◽  
Climatic Conditions ◽  
Saharan Dust ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Quartz Content ◽  
Gran Canaria ◽  
Climatic Oscillations ◽  
Climatic Variations

AbstractThe island of Gran Canaria is regularly affected by dust falls due to its proximity to the Saharan desert. Climatic oscillations may affect the Saharan dust input to the island. Geochemical, mineralogical, and textural analysis was performed on a well-developed and representative early Pleistocene paleosol to examine Saharan dust contribution to Gran Canaria. Significant and variable Saharan dust content was identified in addition to weathering products such as iron oxides and clay minerals. Variations in quartz and iron oxide concentrations in the paleosol likely reflect different Saharan dust input in more/less-contrasted rhexistasic/biostatic climatic conditions. Linking the quartz content in Canarian soils, the Ingenio paleosol, and two Canarian loess-like deposits to different ages from the Quaternary, we hypothesized that the dust input should be lower (about 33–38%) throughout the early to middle Pleistocene than during the late Quaternary. The Saharan dust input to the Gran Canaria profile in the Pleistocene persisted in spite of climatic variations.

Late Tertiary to late Quaternary record in the Mackenzie Mountains, Northwest Territories, Canada: stratigraphy, paleosols, paleomagnetism, and chlorine - 36

1996 ◽  
Vol 33 (6) ◽  
pp. 875-895 ◽  
Author(s):  
A. Duk-Rodkin ◽  
R. W. Barendregt ◽  
C. Tarnocai ◽  
F. M. Phillips
Keyword(s):  
Late Quaternary ◽  
Ice Sheet ◽  
Climatic Conditions ◽  
Unconsolidated Sediments ◽  
Laurentide Ice Sheet ◽  
Stratigraphic Sequence ◽  
Late Tertiary ◽  
Mackenzie Mountains ◽  
Late Wisconsinan ◽  
Stratigraphic Succession

A stratigraphic sequence of unconsolidated sediments ranging in age from Late Pliocene to Late Pleistocene is recorded in the Canyon Ranges of the Mackenzie Mountains. Three of the sections (Katherine Creek, Little Bear River, and Inlin Brook) expose bedrock and Tertiary gravel overlain by colluvium and a multiple till sequence of montane origin, separated by paleosols and capped by a till of Laurentide origin. The sections are correlated on the basis of lithology, paleosol development, paleomagnetism, and chlorine dating of surface boulder erratics. A formal stratigraphic nomenclature is proposed for the deposits of this region. The sequence of glacial tills separated by paleosols reflects a long record of glacial–interglacial cycles. Soil properties from the oldest paleosol to modern soil show a general decrease in the degree of soil development, suggesting a progressive deterioration of interglacial climatic conditions. A normal–reverse–normal sequence of remanent magnetization was determined within the stratigraphic succession and assigned to the Gauss–Matuyama–Brunhes chrons, respectively. A Gauss age was assigned to the basal colluvium, an early Matuyama age (including Olduvai) to the first two tills, and a Brunhes age to the last three tills. Laurentide deposits are of Late Wisconsinan age and are restricted to the uppermost part of the stratigraphic succession. Chlorine dates for surface boulders place the all-time limit of the Laurentide Ice Sheet at about 30 ka. The Late Wisconsinan Laurentide Ice Sheet was the only continental ice to reach the Mackenzie and Richardson mountains of the northern Cordillera.

scholarly journals Glacier-Bed Landforms of The Prairie Region of North America

1980 ◽  
Vol 25 (93) ◽  
pp. 457-476 ◽  
Author(s):  
S. R. Moran ◽  
Lee Clayton ◽  
R. Leb Hooke ◽  
M.M Fenton ◽  
L.D. Andriashek
Keyword(s):  
United States ◽  
Shear Strength ◽  
North America ◽  
Pore Pressure ◽  
Marginal Zone ◽  
Ice Sheets ◽  
The United States ◽  
A Value ◽  
Basal Sliding ◽  
Continental Ice Sheets

AbstractTwo major types of terrain that formed at or near the bed of Pleistocene continental ice sheets are widespread throughout the prairie region of Canada and the United States. These are (1) glacial-thrust blocks and source depressions, and (2) streamlined terrain.Glacial-thrust terrain formed where the glacier was frozen to the substrate and where elevated pore-pressure decreased the shear strength of the substrate to a value less than that applied by the glacier. The marginal zone of ice sheets consisted of a frozen-bed zone, no more than 2–3 km wide in places, within which glacial-thrust blocks are large and angular. Up-glacier from this zone, the thrust blocks are generally smaller and smoothed. Streamlined terrain begins 2–3 km behind known ice-margin positions and extends tens of kilometres up-glacier Streamlined terrain formed in two ways: (1) erosion of the substrate as a consequence of basal sliding in the sub-marginal thawed-bed zone, and (2) erosional smoothing accompanied by emplacement of till in the lee of thrust blocks where they were deposited and subsequently exposed to thawed-bed conditions as a result of further advance of the glacier.

Preservation and Recognition of Middle and Early Pleistocene Loess in the Driftless Area, Wisconsin

1997 ◽  
Vol 47 (2) ◽  
pp. 147-154 ◽  
Author(s):  
Peter M. Jacobs ◽  
James C. Knox ◽  
Joseph A. Mason
Keyword(s):  
Environmental Conditions ◽  
Early Pleistocene ◽  
Middle Pleistocene ◽  
Mississippi Valley ◽  
Apparent Absence ◽  
Driftless Area

An exceptional stratigraphic and pedologic record of Pleistocene environmental conditions occurs at the Kieler Site in the Driftless Area of southwestern Wisconsin. Peoria, Roxana, Loveland, and pre-Loveland loesses overlie weathered bedrock residuum. The pre-Loveland unit previously has been included as part of the residuum at other Driftless Area sites. Early and middle Pleistocene loesses in the Mississippi Valley are normally absent at most localities. Rather than nondeposition, we suggest the apparent absence of pre-Illinoian loess units is due in part to erosion, but also to weathering that renders loesses unrecognizable so they are classified as “residuum.”

Basal Temperatures in Polar Ice Sheets: A Qualitative Review

1977 ◽  
Vol 7 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Roger LeB. Hooke
Keyword(s):  
Thermal Regime ◽  
Accumulation Rate ◽  
Ice Sheets ◽  
Climatic Conditions ◽  
Laurentide Ice Sheet ◽  
Polar Ice ◽  
Qualitative Review ◽  
Ablation Area ◽  
Polar Ice Sheets ◽  
Basal Melting

In recent years glacial geologists have become increasingly interested in the thermal regime at the bases of polar ice sheets, and have attempted to interpret certain Pleistocene glacial features in terms of this thermal regime. This effort has suffered from a lack of a reasonably comprehensive but qualitative review of factors controlling the temperature at the base of a polar glacier; this paper attempts to fill this void. Using the Laurentide Ice Sheet as an example, it is shown that under cold climatic conditions basal melting is likely to occur only beneath the lower part of the ablation area. If the climate is somewhat warmer, or if the accumulation rate is sufficiently low, basal melting may also occur beneath the accumulation area. The zone of greatest basal melt-water production is probably beneath the lower part of the ablation area.

scholarly journals Glacier-Bed Landforms of The Prairie Region of North America

1980 ◽  
Vol 25 (93) ◽  
pp. 457-476 ◽  
Author(s):  
S. R. Moran ◽  
Lee Clayton ◽  
R. Leb Hooke ◽  
M.M Fenton ◽  
L.D. Andriashek
Keyword(s):  
United States ◽  
Shear Strength ◽  
North America ◽  
Pore Pressure ◽  
Marginal Zone ◽  
Ice Sheets ◽  
The United States ◽  
A Value ◽  
Basal Sliding ◽  
Continental Ice Sheets

Abstract Two major types of terrain that formed at or near the bed of Pleistocene continental ice sheets are widespread throughout the prairie region of Canada and the United States. These are (1) glacial-thrust blocks and source depressions, and (2) streamlined terrain. Glacial-thrust terrain formed where the glacier was frozen to the substrate and where elevated pore-pressure decreased the shear strength of the substrate to a value less than that applied by the glacier. The marginal zone of ice sheets consisted of a frozen-bed zone, no more than 2–3 km wide in places, within which glacial-thrust blocks are large and angular. Up-glacier from this zone, the thrust blocks are generally smaller and smoothed. Streamlined terrain begins 2–3 km behind known ice-margin positions and extends tens of kilometres up-glacier Streamlined terrain formed in two ways: (1) erosion of the substrate as a consequence of basal sliding in the sub-marginal thawed-bed zone, and (2) erosional smoothing accompanied by emplacement of till in the lee of thrust blocks where they were deposited and subsequently exposed to thawed-bed conditions as a result of further advance of the glacier.

Cosmogenic 36Cl dating of the maximum limit of the Laurentide Ice Sheet in southwestern Alberta

1999 ◽  
Vol 36 (8) ◽  
pp. 1347-1356 ◽  
Author(s):  
Lionel E Jackson, Jr. ◽  
Fred M Phillips ◽  
Edward C Little
Keyword(s):  
Rocky Mountains ◽  
Erosion Rate ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Canadian Shield ◽  
Laurentide Ice Sheet ◽  
Glacial Deposits ◽  
Glacial Ice ◽  
Continental Ice Sheets ◽  
Glacial Advance

Cosmogenic 36Cl ages were determined on 11 glacial erratics from the summits of Porcupine Hills and Cloudy Ridge, Waterton valley, and the Foothills south of Cardston, Alberta. These erratics were derived from the Canadian Shield and the Rocky Mountains of the Waterton area. They were laid down by (1) the most extensive advance of a Canadian Shield centred continental ice sheet into this region (stratigraphically oldest glacial deposits); (2) a montane glacial advance from the Waterton valley (stratigraphically intermediate glacial deposits); and (3) an advance of continental glacial ice that overrode deposits of the intermediate-age montane advance. Zero erosion rate 36Cl ages of the erratics, uncorrected for snow cover, range between about 12 and 18 ka. They support the hypothesis that the Laurentide Ice Sheet reached farther into the southwestern Foothills than did all the previous continental ice sheets.

scholarly journals Glacier-Bed Landforms of the Prairie Region of North America

1979 ◽  
Vol 23 (89) ◽  
pp. 423-424 ◽  
Author(s):  
S. R. Moran ◽  
Lee Clayton ◽  
R. LeB. Hooke ◽  
M. M. Fenton ◽  
L. D. Andriashek
Keyword(s):  
United States ◽  
Marginal Zone ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ice Sheets ◽  
The United States ◽  
Future Issue ◽  
A Value ◽  
Basal Sliding ◽  
Continental Ice Sheets

Abstract Two major types of terrain that formed at or near the bed of Pleistocene continental ice sheets are widespread throughout the prairie region of Canada and the United States. These are (1) glacial-thrust blocks and source depressions and (2) streamlined terrain. Glacial-thrust terrain formed where the glacier was frozen to the substrate and where elevated pore-water pressure decreased the shear strength of the substrate to a value less than that applied by the glacier. The marginal zone of ice sheets consisted of a frozen-bed zone, no more than 2 to 3 km wide in places, within which glacial-thrust blocks are large and angular. Up-glacier from this zone the thrust blocks are generally smaller and smoothed. Streamlined terrain begins 2 to 3 km behind known ice-margin positions and extends tens of kilometres up-glacier. Streamlined terrain formed in two ways: (1) erosion of the substrate as a consequence of basal sliding in the sub-marginal thawed-bed zone and (2) erosional smoothing accompanied by emplacement of till in the lee of thrust blocks where they were deposited and subsequently exposed to thawed-bed conditions as a result of further advance of the glacier. This paper has been accepted for publication in full in a future issue of the Journal of Glaciology.

Late Quaternary sedimentation in central Flemish Pass

1992 ◽  
Vol 29 (3) ◽  
pp. 535-550 ◽  
Author(s):  
David J. W. Piper ◽  
Christopher P. G. Pereira
Keyword(s):  
Late Quaternary ◽  
Ice Sheets ◽  
Seismic Profiles ◽  
Grand Banks ◽  
The Past ◽  
Labrador Current ◽  
Lithostratigraphic Units ◽  
History Of ◽  
Quaternary History ◽  
Late Wisconsinan

Flemish Pass is a basin in 1000 m water depth on the continental slope off the Grand Banks of Newfoundland and has a Quaternary fill principally of turbidites. The late Quaternary history of the pass has been investigated using mid-range side-scan sonargraphs, high-resolution seismic profiles, and cores dated using C-14. The sequence of facies in the cores reveals six lithostratigraphic units deposited in the past 40 ka. At 15–19 ka and ?25–30 ka, sedimentation was dominated by debris-flow and turbidite deposits, together with hemipelagic deposits of similar clay-size mineralogy, derived from the Grand Banks. At other times, ice-rafting and hemipelagic sedimentation, principally of carbonate-rich sediment transported by the Labrador Current, predominated. A late Quaternary regional unconformity on the slope may reflect the effects of ice sheets reaching the shelf break, probably in the Early Wisconsinan. Late Wisconsinan resedimentation was not related to ice-marginal processes and probably resulted from iceberg impacts.

scholarly journals Glacier-Bed Landforms of the Prairie Region of North America

1979 ◽  
Vol 23 (89) ◽  
pp. 423-424 ◽  
Author(s):  
S. R. Moran ◽  
Lee Clayton ◽  
R. LeB. Hooke ◽  
M. M. Fenton ◽  
L. D. Andriashek
Keyword(s):  
United States ◽  
Marginal Zone ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Ice Sheets ◽  
The United States ◽  
Future Issue ◽  
A Value ◽  
Basal Sliding ◽  
Continental Ice Sheets

AbstractTwo major types of terrain that formed at or near the bed of Pleistocene continental ice sheets are widespread throughout the prairie region of Canada and the United States. These are (1) glacial-thrust blocks and source depressions and (2) streamlined terrain.Glacial-thrust terrain formed where the glacier was frozen to the substrate and where elevated pore-water pressure decreased the shear strength of the substrate to a value less than that applied by the glacier. The marginal zone of ice sheets consisted of a frozen-bed zone, no more than 2 to 3 km wide in places, within which glacial-thrust blocks are large and angular. Up-glacier from this zone the thrust blocks are generally smaller and smoothed. Streamlined terrain begins 2 to 3 km behind known ice-margin positions and extends tens of kilometres up-glacier. Streamlined terrain formed in two ways: (1) erosion of the substrate as a consequence of basal sliding in the sub-marginal thawed-bed zone and (2) erosional smoothing accompanied by emplacement of till in the lee of thrust blocks where they were deposited and subsequently exposed to thawed-bed conditions as a result of further advance of the glacier.This paper has been accepted for publication in full in a future issue of the Journal of Glaciology.

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