Optical ages indicate the southwestern margin of the Green Bay Lobe in Wisconsin, USA, was at its maximum extent until about 18,500years ago

Attig, John W.; Hanson, Paul R.; Rawling, J. Elmo; Young, Aaron R.; Carson, Eric C.

doi:10.1016/j.geomorph.2011.04.027

Cited by 20 publications

(37 citation statements)

References 27 publications

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“…High confidence in the sediment Baker et al (1992) A digital elevation model of the Devils Lake catchment along with maximum extent of Green Bay Lobe of the Laurentide Ice Sheet at~18.5 kya is shown (Attig et al, 2011). Contour lines at 50 m intervals.…”

Section: Chronologymentioning

confidence: 95%

“…The lake was formed when the northern and southeastern ends of the Devils Lake Gorge were plugged by the Johnstown moraine, deposited at the maximum extent of the Green Bay Lobe. It is likely that Devils Lake became a continually inundated basin by 21,000 cal yr BP but certainly by 18,500 cal yr BP, when OSL ages of sediment deposits suggest the Green Bay Lobe began thinning and retreating (Attig et al, 2011). Independent radiocarbon dating of lacustrine sediments just south of Devils Lake indicates that the position of ice here during the glacial maximum may have been quite prolonged, with the Green Bay Lobe at its maximum position from about 26,400 ± 5100 cal yr BP to 21,400 ± 3300 cal yr BP (Carson et al, 2012).…”

Section: Regional Setting and Study Sitementioning

confidence: 99%

“…We report our results for the lowest 270 cm of the sediment core on a depth scale. This enables a temporal context for post-maximum ice sheet events and dynamics that were previously untimed but postdate 18,500 cal yr BP (Attig et al, 2011).…”

Section: Chronologymentioning

confidence: 99%

“…The lake and surrounding landscape underwent significant and complex changes during the last glacial period, followed by deglaciation and transition into the Holocene period (Attig et al, 2011). Earlier debate focused on the vegetation composition during the cool Younger Dryas (YD) interval (12.8e11.5 ka) (Baker et al, 1992;Shuman et al, 2002;Grimm et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Because of its unusual setting (Lytwyn, 2010;Attig et al, 2011), Devils Lake has the potential to provide information about very early post-glacial ecosystem development, as well as additional information about the biogeochemical changes coinciding with previously documented climate and vegetation changes. We present geochemical, biological, and geophysical data from a new, 10 m long sediment core retrieved in February 2012 that describe the evolution of the catchment ecosystem.…”

Section: Introductionmentioning

confidence: 99%

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Ecosystem development following deglaciation: A new sedimentary record from Devils Lake, Wisconsin, USA

Williams

McLauchlan

Mueller

et al. 2015

Quaternary Science Reviews

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Processes and rates of ecosystem development can be reconstructed using lacustrine sedimentary sequences, but this approach often requires records that contain the start of primary succession. Most lakes in the upper Midwestern U.S. were formed by glaciers at the end of the last Ice Age approximately 11,700 cal yr BP. Devils Lake, Wisconsin is a rare example of a lake from this region whose sediments extend into the Pleistocene and may include the Last Glacial Maximum. Sediment magnetic, geochemical, pollen, and charcoal records were generated from a 10 m core whose basal sediments may be 28,000 years old. Together with a previously published pollen record, these proxies combine to reveal a history of long-term climatic, vegetative and geologic change during the late Pleistocene to Holocene. We identify six sedimentary units that indicate a series of consecutive events rather than a predictable trajectory of ecosystem development at the site. Productivity in the lake was low during the late Pleistocene and increased during the Holocene, as reflected by the sediment lithology, which shows a sudden shift from glacial vivianite-rich and organic-poor clastic-dominated sediments to Holocene diatomaceous sapropels. Several important processes initiated around 17,000 cal yr BP, including the onset of organic matter accumulation and fire in the terrestrial ecosystem. However, the post-glacial landscape was not devoid of vegetation because pollen assemblages indicate that terrestrial vegetation, likely a spruce tundra, survived near the site. A switch to a hardwood forest period during the Holocene also led to a change in the fire regime, with increased frequency of burning. Aquatic ecosystem productivity lagged terrestrial ecosystem productivity throughout the record. Nutrient cycling (as recorded by sedimentary ?15N) was variable but not directional, and appeared to be correlated with climate conditions early in the record, and terrestrial ecosystem processes later in the record. Throughout the Holocene magnetic mineral concentration decreased as productivity increased, and the source of magnetic material shifted from almost exclusively lithogenic to approximately 50% derived from soil or biogenic sources. Magnetic grain size, Ambrosia pollen percentages, and charcoal concentration increased and ?15N decreased in the most recent part of the record, due to anthropogenic influence in the region including agricultural activities.authorsversionPeer reviewe

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Section: Chronologymentioning

confidence: 95%

Section: Regional Setting and Study Sitementioning

confidence: 99%

Section: Chronologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Ecosystem development following deglaciation: A new sedimentary record from Devils Lake, Wisconsin, USA

Williams

McLauchlan

Mueller

et al. 2015

Quaternary Science Reviews

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LiDAR‐based semi‐automated mapping of drumlins and mega‐scale glacial lineations of the Green Bay Lobe, Wisconsin, USA: Ice sheet beds as glaciotribological systems

Eyles

Bukhari

Sookhan

et al. 2022

Earth Surf Processes Landf

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A machine learning methodology for processing and visualizing high-resolution LiDAR digital data is used to map drumlins and mega-scale glacial lineations (MSGLs) on the bed of the Late Wisconsin Green Bay Lobe in Wisconsin, USA, which exhibited surge-like behaviour during deglaciation. Previous work has shown that streamlined bedforms are the product of erosional streamlining of pre-existing sediment. Analysis of bedform height and elongation ratio using curvature-based relief separation (CBRS) and K-means clustering of 32,003 bedforms reveals a continuum of six morphotypes ranging from drumlins, through "channeled" more elongated multi-crested drumlins, to MSGLs. Further statistical analysis shows that morphotypes cluster into six types of streamlined surfaces (S1-S6) recording progressive elimination of an antecedent overridden topography to produce a smoother bed. Initial, relatively high-relief drumlinized surfaces (S1, S2) occur around the slowerflowing lateral flanks of the lobe, where a pre-existing hummocky morainal topography was only partially modified by subglacial erosion. More streamlined surfaces (S3, S4) dominated by multi-crested more elongate drumlins of reduced relief amplitude are transitional to flow sets of MSGL-dominated surfaces (S5, S6) indicative of much faster-flowing ice streaming along the lobe's axis. Estimates of basal drag based on roughness calculations for each surface type identify a 61% reduction in frictional retardation from poorly streamlined surfaces S1 and S2 to MSGL-dominated surfaces S5 and S6, with a step-like reduction between drumlins and channeled drumlins (S3, S4) possibly recording the rapid onset of fast flow. Subglacial streamlining is argued to be accomplished by a thin (<1 m) "third layer" of deforming subglacial debris between ice and its bed which functioned as an erodent layer. A thin (<3 m) till cap, formed by aggradation of deforming debris, rests unconformably on heterogeneous core sediments. Streamlined subglacial surfaces are comparable to the "functional" surfaces resulting from erosion by a "third layer" of wear debris in engineering tribological systems, and also by gouge on faults. Pleistocene ice sheets expanded over pre-existing landsystems, pointing to the broader relevance of the methodology and findings reported here.

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Soils of the Northern Lake States Forest and Forage Region: LRR K

Schaetzl

2016

The Soils of the USA

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Optical ages indicate the southwestern margin of the Green Bay Lobe in Wisconsin, USA, was at its maximum extent until about 18,500years ago

Cited by 20 publications

References 27 publications

Ecosystem development following deglaciation: A new sedimentary record from Devils Lake, Wisconsin, USA

Ecosystem development following deglaciation: A new sedimentary record from Devils Lake, Wisconsin, USA

LiDAR‐based semi‐automated mapping of drumlins and mega‐scale glacial lineations of the Green Bay Lobe, Wisconsin, USA: Ice sheet beds as glaciotribological systems

Soils of the Northern Lake States Forest and Forage Region: LRR K

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