Late Wisconsinan and Holocene Retreat of the Laurentide Ice Sheet

Dyke, A S; Prest, V K

doi:10.4095/122842

Cited by 134 publications

(116 citation statements)

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“…However, the new chronology is not consistent with existing chronologies for western New England (Davis and Jacobson, 1985;Hughes et al, 1985;Stone and Borns, 1986;Dyke and Prest, 1987) based on bulk sediment 14 C ages from cores of small lakes (Table II). Our atmospheric 14 C chronology indicates that deglaciation of New Hampshire and Vermont began at 12.6 ka in southern Vermont and ended with ice receding into Québec at about 11.5 ka (Fig.…”

Section: Evaluation: Calibrated Varve and Paleomagnetic Chronologymentioning

confidence: 71%

Varve, paleomagnetic, and 14 C Chronologies for late Pleistocene events in New Hampshire and Vermont (U.S.A.)

Ridge¹,

Bensonen²,

Brochu³

et al. 2002

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A deglacial chronology for northern New England has been formulated using an atmospheric 14 C calibration of the New England Varve Chronology and paleomagnetic records. This 14 C chronology is based on 14 C ages from macrofossils of non-aquatic plants and is about 1 500 yr younger than existing chronologies that are based primarily on 14 C ages of bulk organic samples. The lower and upper Connecticut Valley varve sequences of Ernst Antevs (NE varves 2 701-6 352 and 6 601-8 500) overlap (lower 6 012 = upper 6 601) based on their crudely matching varve records and their similar paleomagnetic records. Three 14 C ages at Canoe Brook, Vermont (NE varve 6 150 = 12.3 14C ka) calibrate the lower Con necticut Valley sequence. New AMS and con ventional 14 C ages on woody twigs from Newbury, Vermont calibrate the upper se quence from 11.6-10.4 14 C ka (NE varves 7 440-8 660) and are consistent with the over lapping varve and paleomagnetic records, and the Canoe Brook 14 C ages. Deglaciation of the Connecticut Valley in southern Vermont began at 12.6 14 C ka (15.2 cal ka) and the Littleton-Bethlehem Readvance in northern New Hampshire and Vermont reached its maximum at11.9-11.8 14 C ka (14.0-13.9 cal ka) followed by recession of ice into Québec at about 11.5 14 C ka (13.4 cal ka). A lake persisted in the upper Connecticut Valley until at least 10.4 14 C ka (12.3 cal ka) and may have been seen by the first humans in the area.

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Section: Evaluation: Calibrated Varve and Paleomagnetic Chronologymentioning

confidence: 71%

Varve, paleomagnetic, and 14 C Chronologies for late Pleistocene events in New Hampshire and Vermont (U.S.A.)

Ridge¹,

Bensonen²,

Brochu³

et al. 2002

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“…It is well known that a residual ice cap developed over northern Maine and adjacent Québec, but this ice cap did not extend much farther southwest than Thetford Mines (Parent and Occhietti, 1988). In the area from the Frontier Moraine west to Sherbrooke, the lobation of moraines and meltwater flow directions (including eskers) consistently record the northwestward recession of the Laurentide ice margin (Gadd et al, 1972;Dyke and Prest, 1987;Parent and Occhietti, 1988). Similarly, there is no indication that a late-glacial local ice mass formed over northern New Hampshire or adjacent parts of Maine and Vermont.…”

Section: Deglaciation Chronology Of the White Mountainsmentioning

confidence: 99%

“…If this reconstruction is correct, the ice margin must have readvanced at least the 12 km from the Dalton Range to the southern limit of the Bethlehem Moraine complex. Davis and Jacobson (1985), Dyke and Prest (1987), and Occhietti (1989) have proposed regional deglaciation chronologies for New England and adjacent Canada. These authors synthesized radiocarbon dates that provide minimum limits on the time of ice retreat, and they prepared paleogeographic maps showing the inferred extent of glacial ice at various times following the Late Wisconsinan glacial maximum.…”

Section: Bethlehem Moraine Complex and The Littleton-bethlehem Readvancementioning

confidence: 99%

Deglaciation of the northwestern White Mountains, New Hampshire

Thompson¹,

Fowler²,

Dorion³

2002

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The mode of deglaciation in the northwestern White Mountains of New Hampshire has been controversial since the mid 1800's. Early workers believed that active ice deposited the Bethlehem Moraine complex in the Ammonoosuc River basin during recession of the last ice sheet. In the 1930's this deglaciation model was replaced by the concept of widespread simultaneous stagnation and downwastage of Late Wisconsinan ice. The present authors reexamined the Bethlehem Moraine complex and support the original interpretation of a series of moraines deposited by active ice. We found other moraine clusters of similar age to the northeast in the Johns River and Israel River basins. Ice-marginal deposits that probably correlate with the Bethlehem Moraine also occur west of Littleton. The Bethlehem Moraine complex and equivalent deposits in adjacent areas were formed by readvance and oscillatory retreat of the Connecticut Valley lobe of the Laurentide Ice Sheet. This event is called the Littleton-Bethlehem Readvance. Throughout the study area, sequences of glaciolacustrine deposits and meltwater drainage channels indicate progressive northward recession of the glacier margin. Radiocarbon dates from nearby New England and Québec suggest that the ice sheet withdrew from this part of the White Mountains between about 12 500 and 12 000 14 C yr BP. We attribute the Littleton- Bethlehem Readvance to a brief climatic cooling during Older Dyas time, close to 12,000 BP.Le mode de déglaciation du nord-ouest des White Mountains a fait l'objet de contro- verses depuis le milieu du XIX e siècle. Les premiers chercheurs ont supposé que le complexe morainique de Bethlehem dans le bassin de l'Ammonoosuc River avait été mis en place par la glace active au cours du recul du dernier Inlandsis. Au cours des années 1930, ce modèle de déglaciation a été remplacé par le concept selon lequel il y aurait eu stagnation simultanée sur une grande étendue et fonte de l'inlandsis du Wisconsinien supérieur. Les présents auteurs ont réétudié la Moraine de Bethlehem et appuient l'interprétation originelle selon laquelle il s'agit d'un ensemble de moraines terminales mises en place par une glace active. Ils ont aussi découvert d'autres ensembles morainiques d'âge similaire au nord-est, dans les bassins de Johns River et Israel River. Quelques dépôts de marge glaciaire, probablement de la même époque que celle du complexe morainique de Bethlehem, ont aussi été identifiés à l'ouest de Littleton. Le complexe morainique de Bethlehem et les dépôts équivalents dans les zones adjacentes ont été mis en place par récurrence et retrait oscillatoire du lobe de la vallée du Connecticut appartenant à l'Inlandsis laurentidien. Il s'agit de la récurrence de Littleton-Bethlehem. Les dates obtenues en Nouvelle-Angletterre et dans le Québec limitrophe laissent supposer que l'Inlandsis laurentidien s'est retiré de cette partie des White Mountains vers 12 500-12 000 14 C BP. Les auteurs attribuent la récurrence à une refroidissement climatiqu...

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“…During glacial periods, large ice sheets covering present-day Canada and northwestern Eurasia (Dyke and Prest, 1987;Clark et al, 1993;Peltier, 2004;Svendsen et al, 2004;Lambeck et al, 2006;Tarasov et al, 2012) exerted a strong influence on climate. Several studies highlighted the importance the climatic changes induced by continental-scale ice sheets (e.g.…”

Section: Introductionmentioning

confidence: 99%

How might the North American ice sheet influence the northwestern Eurasian climate?

et al. 2015

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Abstract.It is now widely acknowledged that past Northern Hemisphere ice sheets covering Canada and northern Europe at the Last Glacial Maximum (LGM) exerted a strong influence on climate by causing changes in atmospheric and oceanic circulations. In turn, these changes may have impacted the development of the ice sheets themselves through a combination of different feedback mechanisms. The present study is designed to investigate the potential impact of the North American ice sheet on the surface mass balance (SMB) of the Eurasian ice sheet driven by simulated changes in the past glacial atmospheric circulation. Using the LMDZ5 atmospheric circulation model, we carried out 12 experiments under constant LGM conditions for insolation, greenhouse gases and ocean. In these experiments, the Eurasian ice sheet is removed. The 12 experiments differ in the North American ice-sheet topography, ranging from a white and flat (present-day topography) ice sheet to a fullsize LGM ice sheet. This experimental design allows the albedo and the topographic impacts of the North American ice sheet onto the climate to be disentangled. The results are compared to our baseline experiment where both the North American and the Eurasian ice sheets have been removed. In summer, the sole albedo effect of the American ice sheet modifies the pattern of planetary waves with respect to the no-ice-sheet case, resulting in a cooling of the northwestern Eurasian region. By contrast, the atmospheric circulation changes induced by the topography of the North American ice sheet lead to a strong decrease of this cooling. In winter, the Scandinavian and the Barents-Kara regions respond differently to the American ice-sheet albedo effect: in response to atmospheric circulation changes, Scandinavia becomes warmer and total precipitation is more abundant, whereas the Barents-Kara area becomes cooler with a decrease of convective processes, causing a decrease of total precipitation. The gradual increase of the altitude of the American ice sheet leads to less total precipitation and snowfall and to colder temperatures over both the Scandinavian and the Barents and Kara sea sectors. We then compute the resulting annual surface mass balance over the Fennoscandian region from the simulated temperature and precipitation fields used to force an ice-sheet model. It clearly appears that the SMB is dominated by the ablation signal. In response to the summer cooling induced by the American ice-sheet albedo, high positive SMB values are obtained over the Eurasian region, leading thus to the growth of an ice sheet. On the contrary, the gradual increase of the American ice-sheet altitude induces more ablation over the Eurasian sector, hence limiting the growth of Fennoscandia. To test the robustness of our results with respect to the Eurasian ice sheet state, we carried out two additional LMDZ experiments with new boundary conditions involving both the American (flat or full LGM) and high Eurasian ice sheets. The most striking result is that the Eurasian ice sheet is...

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Late Wisconsinan and Holocene Retreat of the Laurentide Ice Sheet

Cited by 134 publications

References 0 publications

Varve, paleomagnetic, and 14 C Chronologies for late Pleistocene events in New Hampshire and Vermont (U.S.A.)

Varve, paleomagnetic, and 14 C Chronologies for late Pleistocene events in New Hampshire and Vermont (U.S.A.)

Deglaciation of the northwestern White Mountains, New Hampshire

How might the North American ice sheet influence the northwestern Eurasian climate?

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