Tors, felsenmeer, and glaciation in northern Cumberland Peninsula, Baffin Island

1977 ◽  
Vol 14 (12) ◽  
pp. 2817-2823 ◽  
Author(s):  
D. E. Sugden ◽  
S. H. Watts
Keyword(s):  
Case Studies ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Baffin Island

On the basis of two case studies in eastern Baffin Island it is suggested that tors and felsenmeer have survived beneath the Laurentide ice sheet. These features, therefore, need not be diagnostic of areas that escaped glaciation. Rather, the existence of tors and felsenmeer may reflect situations where the overlying Laurentide ice sheet was cold-based.

scholarly journals GIS analyses of ice-sheet erosional impacts on the exposed shield of Baffin Island, eastern Canadian Arctic

2015 ◽  
Vol 52 (11) ◽  
pp. 966-979 ◽  
Author(s):  
Karin Ebert
Keyword(s):  
Ice Sheet ◽  
Canadian Arctic ◽  
Laurentide Ice Sheet ◽  
Baffin Island ◽  
Glacial Erosion ◽  
Ice Sheet Erosion ◽  
The Impact ◽  
Exposure Ages ◽  
Eastern Canadian Arctic ◽  
Sheet Erosion

The erosional impacts of former ice sheets on the low-relief bedrock surfaces of Northern Hemisphere shields are not well understood. This paper assesses the variable impacts of glacial erosion on a portion of Baffin Island, eastern Canadian Arctic, between 68° and 72°N and 66° and 80°W. This tilted shield block was covered repeatedly by the Laurentide Ice Sheet during the late Cenozoic. The impact of ice-sheet erosion is examined with GIS analyses using two geomorphic parameters: lake density and terrain ruggedness. The resulting patterns generally conform to published data from other remote sensing studies, geological observations, cosmogenic exposure ages, and the distribution of the chemical index of alteration for tills. Lake density and terrain ruggedness are thereby demonstrated to be useful quantitative indicators of variable ice-sheet erosional impacts across Baffin Island. Ice-sheet erosion was most effective in the lower western parts of the lowlands, in a west–east-oriented band at around 350–400 m a.s.l., and in fjord-onset zones in the uplifted eastern region. Above the 350–400 m a.s.l. band and between the fjord-onset zones, ice-sheet erosion was not sufficient to create extensive ice-roughened or streamlined bedrock surfaces. The exception — where lake density and terrain ruggedness indicate that ice-sheet erosion had a scouring effect all across the study area — was in an area from Foxe Basin to Home Bay with elevations <400 m a.s.l. These morphological contrasts link to former ice-sheet basal thermal regimes during the Pleistocene. The zone of low glacial erosion surrounding the cold-based Barnes Ice Cap probably represents the ice cap’s greater extent during successive Pleistocene cold stages. Inter-fjord plateaus with few ice-sheet bedforms remained cold-based throughout multiple Pleistocene glaciations. In contrast, zones of high lake density and high terrain ruggedness are a result of the repeated development of fast-flowing, erosive ice in warm-based zones beneath the Laurentide Ice Sheet. These zones are linked to greater ice thickness over western lowland Baffin Island. However, adjacent lowland surfaces with similar elevations of non-eroded, weakly eroded, and ice-scoured shield bedrock indicate that—even in areas of high lake density and terrain ruggedness—the total depth of ice sheet erosion did not exceed 50 m.

Subglacially precipitated carbonates record geochemical interactions and pollen preservation at the base of the Laurentide Ice Sheet on central Baffin Island, eastern Canadian Arctic

2014 ◽  
Vol 81 (1) ◽  
pp. 94-105 ◽  
Author(s):  
Kurt A. Refsnider ◽  
Gifford H. Miller ◽  
Marilyn L. Fogel ◽  
Bianca Fréchette ◽  
Roxane Bowden ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Ice Sheet ◽  
The Arctic ◽  
Laurentide Ice Sheet ◽  
Geochemical Data ◽  
Baffin Island ◽  
Columnar Crystal ◽  
Ice Cap ◽  
Basal Ice ◽  
Isotopic Analyses

AbstractThe mineralogy and isotopic compositions of subglacially precipitated carbonate crusts (SPCCs) provide information on conditions and processes beneath former glaciers and ice sheets. Here we describe SPCCs formed on gneissic bedrock at the bed of the Laurentide Ice Sheet (LIS) during the last glacial maximum on central Baffin Island. Geochemical data indicate that the Ca in the crusts was likely derived from the subglacial chemical weathering Ca-bearing minerals in the local bedrock. C and Sr isotopic analyses reveal that the C in the calcite was derived predominantly from older plant debris. The δ18O values of the SPCCs suggest that these crusts formed in isotopic equilibrium with basal ice LIS preserved in the Barnes Ice Cap (BIC). Columnar crystal fabric and the predominance of sparite over micrite in the SPCCs are indicative of carbonate precipitation under open-system conditions. However, the mean δ18O value of the calcite crusts is ~ 10‰ higher than those of primary LIS ice preserved in the BIC, demonstrating that SPCCs record the isotopic composition of only basal ice. Palynomorph assemblages preserved within the calcite and basal BIC ice include species last endemic to the Arctic in the early Tertiary. The source of these palynomorphs remains enigmatic.

scholarly journals Palaeo-ice streams in the northern Keewatin sector of the Laurentide ice sheet

2005 ◽  
Vol 42 ◽  
pp. 135-144 ◽  
Author(s):  
Hernán De Angelis ◽  
Johan Kleman
Keyword(s):  
Potential Role ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Baffin Island ◽  
Ice Streams ◽  
Relative Age ◽  
Ice Stream ◽  
Deep Interior ◽  
Ice Sheet Dynamics ◽  
Streaming Flow

AbstractEvidence for ice streams in the Laurentide ice sheet is widespread. In the region of northern Keewatin and the Boothia Peninsula, Nunavut, Canada, palaeo-ice streams have been recognized, but their location, size and potential role in ice-sheet dynamics are poorly constrained. Based on the interpretation of satellite imagery, we produce a palaeo-ice-stream map of this region. Glacial directional landforms, eskers and moraines were mapped and integrated into landform assemblages using a glacial geological inversion model. Palaeo-frozen bed areas were also identified. Relative age of the geomorphic swarms was assessed by cross-cutting relationships and radiocarbon ages where available. Using this information we obtained a glaciologically plausible picture of ice-stream evolution within the northernmost Laurentide ice sheet. On the M’Clintock Channel corridor, three generations of pure ice streams are found. On Baffin Island and the Gulf of Boothia, glaciation was dominated by frozen-bed zones located on high plateaus and ice streams running along the troughs, i.e. topographic ice streams. A massive convergent pattern at the head of Committee Bay drained ice from both the Keewatin and Foxe sectors and was probably one of the main deglaciation channels of the Laurentide ice sheet. Finally, our results indicate that streaming flow was present in the deep interior of the Laurentide ice sheet, as recently shown for the Greenland and Antarctic ice sheets.

Oriented lake-and-ridge assemblages of the Arctic coastal plains: glacial landforms modified by thermokarst and solifluction

Polar Record ◽  
1999 ◽  
Vol 35 (194) ◽  
pp. 215-230 ◽  
Author(s):  
Mikhail G. Grosswald ◽  
Terence J. Hughes ◽  
Norman P. Lasca
Keyword(s):  
Ice Sheet ◽  
Late Glacial ◽  
The Arctic ◽  
Laurentide Ice Sheet ◽  
Baffin Island ◽  
Mackenzie Delta ◽  
Space Images ◽  
The North ◽  
Arctic Ice ◽  
Glacial Landforms

AbstractOriented assemblages of parallel ridges and elongated lakes are widespread on the coastal lowlands of northeast Eurasia and Arctic North America, in particular, in Alaska, Arctic Canada, and northeast Siberia. So far, only the oriented lakes have been of much scientific interest. They are believed to be formed by thermokarst in perennially frozen ice-rich sediments, while their orientation is accounted for either by impact of modern winds blowing at right angles to long axes of the lakes (when it concerns individual lakes), or by the influence of underlying bedrock structures (in the case of longitudinal and transverse alignment of lake clusters).En masseexamination of space images suggests that oriented lake-and-ridge assemblages, not the oriented lakes alone, occur in the Arctic. Hence any theory about their formation should account for the origin and orientation of the assemblages as a whole. The existing hypotheses appear inadequate for this end, so this paper proposes that the assemblages were initially created by glacial activity, that is, by ice sheets that drumlinized and tectonized their beds, as well as by sub- and proglacial meltwater, and then they were modified by thermokarst, solifluction, and aeolian processes. This assumption opens up an avenue by which all known features of oriented landforms in the Arctic can be explained. The paper suggests that the oriented landforms in Siberia and Alaska are largely signatures of a marine Arctic ice sheet that transgressed from the north, while the Baffin Island and Mackenzie Delta forms were created by the respective sectors of the Laurentide ice sheet. The oriented features discussed belong to the last Late Glacial through the Early Holocene.

scholarly journals First recognition of a Laurentide Ice Stream : Robert Bell on Hudson Strait

2010 ◽  
Vol 61 (2-3) ◽  
pp. 211-215 ◽  
Author(s):  
Ian A. Brookes
Keyword(s):  
Ice Sheet ◽  
Late Glacial ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Baffin Island ◽  
Ice Streams ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Ice Stream ◽  
Late Wisconsinan

Abstract In papers published in 1895 and 1901, and in undated notes for a 1907 paper he did not deliver or publish, Robert Bell of the Geological Survey of Canada interpreted the pattern of glacial striae, stossing of rock knobs, and surficial sediment composition along the margins of Hudson Strait, between Labrador, Ungava Bay and Baffin Island, as evidence of what he called an ice-stream, a long river-like glacier, fed from Hudson Bay and Foxe Basin, that had moved eastward along the Strait during the Late Glacial period. This was the earliest mention of such a glaciological feature within the Laurentide Ice Sheet (LIS). It was not until ice-streams were recognized in the West Antarctic Ice Sheet in the 1970’s that Bell’s concept was revived in the next decade and subsequently, in recognition of several ice-streams within the Late Wisconsinan LIS.

scholarly journals The Sangamonian Stage and the Laurentide Ice Sheet

2008 ◽  
Vol 41 (2) ◽  
pp. 189-198 ◽  
Author(s):  
Denis A. St-Onge
Keyword(s):  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Interglacial Period ◽  
Baffin Island ◽  
Cape Breton Island ◽  
Definitive Answer ◽  
Plant Fossils ◽  
North American Continent ◽  
The North ◽  
Ice Accumulation

ABSTRACT This review of the most recent studies (up to June 1986) dealing with the Sangamonian in some key areas clearly indicates that, as yet, there is no definitive answer to the question : "When did the ice which eventually became the Laurentide Ice Sheet begin to accumulate?" In most areas the stratigraphic record simply identifies a probable interglacial period; the record yields no information on when ice growth may have started following that warm climatic interval. However the deltaic glacial lake sediments of the Scarborough Formation in the Toronto area and the Bécancour Till in the Trois-Rivières area are thought to possibly date from the Sangamonian (marine isotope sub-stages 5d-b). The Adam Till in the James Bay Lowland may be correlative. In Atlantic Canada, mostly in Cape Breton Island, plant fossils suggest a mid-Sangamonian climate roughly comparable to that which prevailed 11-12 ka ago. On Baffin Island a marine transgression of mid-Sangamonian age is thought to result from important ice accumulation in the area. These stratigraphic interpretations suggest significant glacier expansion in several areas of the North American continent during part of the Sangamonian Stage. Whether or not any of this ice survived a warmer climate period near the end of the Sangamonian to become part of the Laurentide Ice Sheet is a matter of speculation.

Growth rate of the Laurentide Ice Sheet and sea Level Lowering (with Emphasis on the 115,000 BP Sea Level Low)

1976 ◽  
Vol 6 (2) ◽  
pp. 167-183 ◽  
Author(s):  
J.T. Andrews ◽  
M.A.W. Mahaffy
Keyword(s):  
Sea Level ◽  
Three Dimensional ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Baffin Island ◽  
Optimum Conditions ◽  
Ice Flow ◽  
Rapid Fall ◽  
Level Lowering

A physically plausible three-dimensional numerical ice flow model is used to examine the rate at which the Laurentide Ice Sheet could spread and thicken using as input likely values for the rate of fall of snowline and the amount of net mass balance over the growing ice sheet. This provides then both a test of the hypothesis of “instantaneous glacierization” and of the suggested rapid fall of world sea level to between −20 and −70 m below present at 115,000 BP. Two experiments are described: The first terminated after 10,050 years of model run with ice sheets centered over Labrador-Ungava and Baffin Island with a total volume of 3.0 × 106 km3 of ice, whereas the second was completed after 10,000 years and resulted in a significantly larger ice sheet (still with two main centers) with a volume of 7.78 × 106 km3 of ice. This latter figure is equivalent to the mass required to lower world sea level by 19.4 m. Our results indicate that large ice sheets can develop in about 10,000 years under optimum conditions.

scholarly journals Late Pleistocene and Holocene glaciation and deglaciation of Melville Peninsula, Northern Laurentide Ice Sheet

2004 ◽  
Vol 55 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Lynda A. Dredge
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
North Coast ◽  
Baffin Island ◽  
Ice Flow ◽  
Ice Caps ◽  
The North ◽  
Northern Areas ◽  
Controlled Flow

Abstract Melville Peninsula lies within the Foxe/Baffin Sector of the Laurentide Ice Sheet. Pre-Foxe/Pre-Wisconsin ice may have covered the entire peninsula. Preserved regolith in uplands indicates a subsequent weathering interval. Striations and till types indicate that, during the last (Foxe) glaciation, a local ice sheet (Melville Ice) initially developed on plateaus, but was later subsumed by the regional Foxe ice sheet. Ice from the central Foxe dome flowed across northern areas and Rae Isthmus, while ice from a subsidiary divide controlled flow on southern uplands. Ice remained cold-based and non-erosive on some plateaus, but changed from cold- to warm-based under other parts of the subsidiary ice divide, and was warm-based elsewhere. Ice streaming, generating carbonate till plumes, was prevalent during deglaciation. A late, quartzite-bearing southwestward ice flow from Baffin Island crossed onto the north coast. A marine incursion began in Committee Bay about 14 ka and advanced southwards to Wales Island by 8.6 ka. The marine-based ice centre in Foxe Basin broke up about 6.9 ka. Northern Melville Peninsula and Rae Isthmus were deglaciated rapidly, but remnant ice caps remained active and advanced into some areas. The ice caps began to retreat from coastal areas ~6.4 to 6.1 ka, by which time sea level had fallen from 150-180 m to 100 m.

scholarly journals The effects of flowline length evolution on chemistry–δ18O profiles from Penny Ice Cap, Baffin Island, Canada

2002 ◽  
Vol 35 ◽  
pp. 150-156 ◽  
Author(s):  
David A. Fisher ◽  
Roy M. Koerner ◽  
Gregory A. Zielinski ◽  
Cameron P. Wake ◽  
Christian M. Zdanowicz ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Early Holocene ◽  
Ice Age ◽  
Laurentide Ice Sheet ◽  
Simple Extension ◽  
Baffin Island ◽  
Ice Cap ◽  
Chemical Signatures ◽  
Usual Pattern ◽  
Present Site

AbstractThe isotopic and chemical signatures for ice-age and Holocene ice from Summit, Greenland, and Penny Ice Cap, Baffin Island, Canada, are compared. the usual pattern of low δ18O, high Ca2+ and high Cl– is presented in the Summit records, but Penny Ice Cap has lower than present Cl– in its ice-age ice. A simple extension of the Hansson model (Hansson, 1994) is developed and used to simulate these signatures. the low ice-age Cl– from Penny Ice Cap is explained by having the ice-age ice originating many thousands of km inland near the centre of the Laurentide ice sheet and much further from the marine sources. Summit’s flowlines all start close to the present site. the Penny Ice Cap early-Holocene δ18O’s had to be corrected to offset the Laurentide meltwater distortion. the analysis suggests that presently the Summit and Penny Ice Cap marine impurity originates about 500 km away, and that presently Penny Ice Cap receives a significant amount of local continental impurity.

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