North American Deglacial Marine- and Lake-Limit Surfaces*

Dyke, Arthur S.; Dredge, L A; Hodgson, D A

doi:10.7202/014753ar

Cited by 26 publications

(15 citation statements)

References 239 publications

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“…It is important to note that the elevation values presented here are not corrected for glacio-isostatic adjustment (GIA), which may skew the results where long eskers stretch from areas of pronounced uplift (especially in the Keewatin sector) to areas of more subdued uplift (see Peltier, 2004;Dyke et al, 2005). The effect of GIA also has implications for the nature of the bed on which the eskers formed, compared with the bed observed today.…”

Section: Topography/slopementioning

confidence: 84%

Morphometry and pattern of a large sample (>20,000) of Canadian eskers and implications for subglacial drainage beneath ice sheets

Storrar¹,

Stokes²,

Evans³

2014

Quaternary Science Reviews

109

120

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a b s t r a c tIce sheet flow is strongly influenced by the nature and quantity of meltwater entering the subglacial system. Accessing and monitoring contemporary drainage systems beneath ice sheets is notoriously difficult, but it is possible to utilise the exposed beds of palaeo-ice sheets. In particular, eskers record deposition in glacial drainage channels and are widespread on the exposed beds of former ice sheets. However, unlike some other common glacial landforms (e.g. drumlins) there have been relatively few attempts to investigate and quantify their characteristics at the ice sheet scale. This paper presents data on the distribution, pattern, and morphometry of a large (>20,000) sample of eskers in Canada, formed under the Laurentide Ice Sheet, including quantification of their length, fragmentation, sinuosity, lateral spacing, number of tributaries, and downstream elevation changes. Results indicate that eskers are typically very long (hundreds of km) and often very straight (mean sinuosity approximates 1). We interpret these long esker systems to reflect time-transgressive formation in long, stable conduits under hydrostatic pressure. The longest eskers (in the Keewatin sector) are also the least fragmented, which we interpret to reflect formation at an ice margin experiencing stable and gradual retreat. In many locations, the lateral distance between neighbouring eskers is remarkably consistent and results indicate a preferred spacing of around 12 km, consistent with numerical models which predict esker spacing of 8e25 km. In other locations, typically over soft sediments, eskers are rarer and their patterns are more chaotic, reflecting fewer large R-channels and rapidly changing ice sheet dynamics. Comparison of esker patterns with an existing ice margin chronology reveals that the meltwater drainage system evolved during deglaciation: eskers became more closely spaced with fewer tributaries as deglaciation progressed, which has been interpreted to reflect increased meltwater supply from surface melt. Eskers show no preference to trend up or down slopes, indicating that ice surface was an important control on their location and that the conduits were, in places, close to ice overburden pressure.

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Section: Topography/slopementioning

confidence: 84%

Morphometry and pattern of a large sample (>20,000) of Canadian eskers and implications for subglacial drainage beneath ice sheets

Storrar¹,

Stokes²,

Evans³

2014

Quaternary Science Reviews

109

120

View full text Add to dashboard Cite

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“…We inspected beaches between modern sea level and the highest accessible terrain (range: 50-160 m) in each area. The limit of postglacial marine submergence on southeast Somerset Island is about 160 m, but it rises southward from there along the Gulf of Boothia coast, reaching about 250 m (Dyke et al, 2005). We concentrated our search on middle and late Holocene relict shorelines, generally the lower 30 -40 m, where archaeological sites are most abundant.…”

Section: Methodsmentioning

confidence: 99%

Paleoeskimo Demography and Holocene Sea-level History, Gulf of Boothia, Arctic Canada

Dyke¹,

Savelle²,

Johnson³

2011

ARCTIC

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Surveys in six areas along the Gulf of Boothia produced large collections of radiocarbon samples from raised beaches that yield six new relative sea-level curves and information on Holocene bowhead whale ranges. In addition, on the lower beaches, we documented 482 Paleoeskimo dwelling features spanning about 3500 years (4200-800 14 C years BP). Spatial densities of sites are only about half those reported by us from adjacent regions, but other attributes are remarkably similar. On the basis of feature elevation, corroborated by radiocarbon dates, Paleoeskimo occupation appears to have passed through a series of boom-and-bust cycles, the first being the most prominent. After the first peopling about 4200 BP, populations rose between about 3900 and 3600 BP to their all-time maximum, which was followed by a dramatic crash. Population recoveries after the initial crash were small and perhaps temporary. A final increase between 1900 (1500) and 800 14 C years BP was followed by the disappearance of the Paleoeskimo. No compelling evidence yet points to the cause of the population declines; climate change and resource over-exploitation are equally plausible. The frequency distributions of dwelling sizes and numbers of dwellings per site closely resemble those in adjacent regions, suggesting similar social dynamics. Specifically, dispersed nuclear families or small extended families characterized Paleoeskimo settlement patterns for most of the year, but annual aggregations involved 100 or more people. The only significant architectural change coincides with the arrival of Late Dorset people bringing distinctive triangular midpassages and soapstone lamp supports.

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“…at the head of Steensby Inlet (Dyke 2007(Dyke , 2008. The marine limit elevation varies between 109 m west of Igloolik Island (Dredge 1995) and 54 m at the head of Steensby Inlet ( Dyke 2005;Dyke et al 2005). Thus all of the areas that we examined became exposed through isostatic rebound during the middle and late Holocene.…”

Section: Relative Sea-level Historymentioning

confidence: 97%

Paleoeskimo Occupation History of Foxe Basin, Arctic Canada: Implications for the Core Area Model and Dorset Origins

Savelle¹,

Dyke²

2014

Am. antiq.

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This paper presents the first detailed record of Paleoeskimo occupation history of Foxe Basin, Nunavut, Arctic Canada, the traditional Paleoeskimo “core area.” Rather than continuous, stable occupations from approximately 4000–1000 B.P. traditionally assumed for the core area, the region has undergone a series of demographic oscillations, including several instances of abandonment of key areas, most notably Igloolik. The Foxe Basin demographic trends are reminiscent of Paleoeskimo “boom and bust” cycles recognized elsewhere, but show no consistent chronological pattern either within Foxe Basin or inter-regionally. Equally important, our results bear on the critical question of the Pre-Dorset to Dorset transition. Rather than having been a gradual in situ process centered within the core area, the demographic patterns, including the abrupt and widespread appearance of semi-subterranean dwellings during earliest Dorset, are consistent with newly arrived populations from outside of Foxe Basin. While there is no obvious “parent” culture to Dorset within the Eastern Arctic, it is suggested that a Western Arctic origin, specifically Norton Culture, invoking to some extent Jorgen Meldgaard’s “smell of the forest”, may have played a significant role.

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North American Deglacial Marine- and Lake-Limit Surfaces*

Cited by 26 publications

References 239 publications

Morphometry and pattern of a large sample (>20,000) of Canadian eskers and implications for subglacial drainage beneath ice sheets

Morphometry and pattern of a large sample (>20,000) of Canadian eskers and implications for subglacial drainage beneath ice sheets

Paleoeskimo Demography and Holocene Sea-level History, Gulf of Boothia, Arctic Canada

Paleoeskimo Occupation History of Foxe Basin, Arctic Canada: Implications for the Core Area Model and Dorset Origins

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