The deglaciation of the northern White Mountains of New Hampshire

Gerath, Robert F.; Fowler, Brian K.; Haselton, George M.

doi:10.1130/spe197-p21

Cited by 14 publications

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“…ited during deglaciation, this rate of retreat also provides preliminary ages for recessional morainic belts in the region. These estimated ages are in broad agreement with the deglacial chronology proposed for the adjacent regions of northern New Hampshire (Thompson et al, 1996;Gerath et al, 1985) and for the Lake Champlain valley (Connally and Sirkin, 1973).…”

Section: Resultssupporting

confidence: 78%

Late Wisconsinan deglaciation and glacial lake development in the Appalachians of southeastern Québec

Parent¹,

Occhietti²

2002

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Late Wisconsinan deglaciation in southeastern Québec was preceded by a northward ice-flow reversal that was recorded in the northeastern part of the region. The reversal event was generated by flow convergence toward the St. Lawrence Ice Stream, a northeastward-flowing ice stream which formed in the St. Lawrence estuary prior to 13 000 years BP and lasted until at least 12 400 years BP. In the Bois-Francs uplands, the flow reversal event led to the formation of a semi-detached ice mass that underwent widespread stagnation and downwasting. In the southwestern region, northward retreat of the margin of the Laurentide Ice Sheet was marked by the formation of a series of discontinuous recessional moraines and by the development of ice-dammed lakes in the main valleys. The level of these lakes fell as progressively lower outlets became ice-free. The main episodes are (1) the Sherbrooke Phase of Glacial Lake Memphremagog, (2) an unnamed transitional lake and (3) Glacial Lake Candona, a large lake which had expanded northeastward from the deglaciated regions of the Upper St. Lawrence (Lake Iroquois) and Ottawa valleys to the Lake Champlain (Glacial Lake Vermont) basin. As recorded by the Danville Varves, Lake Candona lasted about 100 years following deposition of the Ulverton-Tingwick Moraine. Subsequent ice retreat along the Appalachian piedmont led to final drainage of Lake Candona and allowed Champlain Sea waters to invade much of these glaciolacustrine terrains about 12 000 years BP. On the basis of the Danville Varves record, a regional rate of ice retreat of about 200 m·a -1 is inferred. The age of the earliest moraine, the Frontier Moraine, is thus about 12 550 years BP, while the ages of the subsequent Dixville, Cherry River-East-Angus, Mont Ham and Ulverton-Tingwick moraines are estimated at 12 500, 12 325, 12 200 et 12 100 years BP, respectively.La déglaciation du Wisconsinien supérieur a été précédée d'une inversion d'écoulement glaciaire vers le nord. Cette inversion, enregistrée dans le nordest de la région, résulte de la convergence des glaces vers le Courant glaciaire du Saint-Laurent, lequel s'était formé dans l'estuaire du Saint-Lau- rent avant 13 000 ans BP et a duré au moins jusque vers 12 400 ans BP. Dans les hautes-terres des Bois-Francs, cette inversion d'écoulement a mené à l'isolement d'une masse glaciaire partiellement détachée et qui se dissipa tardivement. Dans le secteur sud-ouest, le retrait de l'Inlandsis est ponctué par la mise en place d'ensembles morainiques discontinus et par le développement de lacs proglaciaires barrés dans les vallées principales. Le niveau de ces lacs chutait à mesure que le retrait glaciaire libérait des cols de plus en plus bas. Les principaux épisodes sont : la Phase Sherbrooke du Lac glaciaire Memphrémagog ; un lac de transition ; le Lac glaciaire Candona, formé de la coalescence des lacs glaciaires endigués dans les vallées du haut Saint-Laurent, des Outaouais, du lac Champlain (Lac Vermont) et du Saint-François. Le Lac Candona a subsisté quelque ...

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Section: Resultssupporting

confidence: 78%

Late Wisconsinan deglaciation and glacial lake development in the Appalachians of southeastern Québec

Parent¹,

Occhietti²

2002

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“…Bradley (1981) challenged the Goldthwaits' view of the timing for cirque glaciation in the Presidential Range by noting that large boulders and diamicts at the mouths of northfacing cirques were composed of lithologies derived from bedrock to the south. However, Gerath and Fowler (1982), Fowler (1984), Gerath et al (1985), Davis and Waitt (1986), and Waitt and Davis (1988) examined the diamicts at the cirque mouths and concluded that the sediments are not till, but rather debris flow deposits. Bradley (1981) also noted fresh grooves across the painted surface on the Tuckerman Ravine headwall, suggesting that if recent snow/ice avalanches could erode bedrock, then perhaps cirque glaciers could also striate cirque headwalls.…”

Section: Presidential Range New Hampshirementioning

confidence: 99%

Cirques of the Presidential Range, New Hampshire, and surrounding alpine areas in the northeastern United States

Davis¹

2002

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Evidence for rejuvenation of cirque glaciers following wastage of continental ice remains elusive for the Presidential Range and Mount Moosilauke of New Hampshire, Mount Katahdin and the Longfellow Mountains of Maine, and the Adirondack Mountains of New York. At Ritterbush Pond in the northern Green Mountains of Vermont, radiocarbon ages from lake sediment cores suggest that a low-altitude valley head, located up- valley of a series of cross-valley moraines, was ice-free by 11,940 14 C yrs BP (Bierman et al. , 1997). Although some workers argue that these moraines in Vermont are evidence for cirque glaciation, the moraines could have been formed by a tongue of continental ice during deglaciation. At Johnson Hollow Brook valley in the Catskill Mountains of New York, a radiocarbon age from basal sediments in a pond dammed by a moraine suggests that glacier ice may have persisted until 10,860 14 C yrs BP (Lederer and Rodbell, 1998). Because this moraine appears to have been deposited by a cirque glacier, the radiocarbon age provides the best evidence in the northeastern United States for cirque glaciation post-dating recession of continental ice. Cirque morphometric data, compiled from newly available topographic maps, add to the conundrum that these two sites in the Green and Catskill Mountains should not be nearly as favorable for maintaining local glaciers post- dating icesheet recession as higher-altitude and better-developed cirques in the Presidential Range and Mount Katahdin, where evidence for post-icesheet cirque glaciers is lacking.Les signes de rajeunissement des glaciers de cirque après le retrait de l'inlandsis demeurent ambigus au Presidential Range (New Hampshire), au mont Katahdin et dans les Longfellow Mountains (Maine), ainsi dans les Adirondack (New York). Au Ritterbush Pond, dans le nord des Green Mountains du Vermont, les datations au radiocarbone de sédiments lacustres ont établi que l'extrémité d'une vallée de basse altitude, située en amont d'une série de moraines transversales, était libre de glace vers 11 940 BP. Bien que certains chercheurs croient que ces moraines témoignent d'une glaciation de cirque, il est aussi possible que les moraines aient été mises en place par une langue glaciaire pendant la déglaciation. Dans la vallée du Johnson Hollow Brook dans les Catskill (New York), une datation au radiocarbone de sédiments de base dans un étang fermé par une moraine indique que la glace pourrait avoir persisté jusqu'à vers 10 860 BP (Lederer et Rodbell, 1998). Comme cette moraine semble avoir été mise en place par un glacier de cirque, la datation fournit le meilleur indice de glaciation de cirque survenue après le retrait de l'inlandsis dans le nord-est des États-Unis. Les données sur la morphométrie des cirques, compilées à partir des nouvelles cartes topographiques, creusent le mystère en établissant que les deux sites des Green Mountains et des Catskill seraient moins propices au maintien des glaciers locaux après le retrait de l'inlandsis que...

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“…Recent descriptions of moraines and glaciotectonic structures in the northeastern White Mountains have shown that active ice persisted during deglaciation in areas that were topographically favorable for sustained glacial flow (e.g. Gerath, 1978;Gerath et al, 1985;and Thompson and Fowler, 1989). …”

Section: Introductionmentioning

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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The deglaciation of the northern White Mountains of New Hampshire

Cited by 14 publications

References 0 publications

Late Wisconsinan deglaciation and glacial lake development in the Appalachians of southeastern Québec

Late Wisconsinan deglaciation and glacial lake development in the Appalachians of southeastern Québec

Cirques of the Presidential Range, New Hampshire, and surrounding alpine areas in the northeastern United States

Deglaciation of the northwestern White Mountains, New Hampshire

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