The Melville Moraine: sea-level change and response of the western margin of the Foxe Ice Dome, Melville Peninsula, Northwest Territories

1990 ◽  
Vol 27 (9) ◽  
pp. 1215-1224 ◽  
Author(s):  
L. A. Dredge
Keyword(s):  
Sea Level ◽  
Climatic Factors ◽  
Outer Part ◽  
Baffin Island ◽  
Ice Flow ◽  
Radiocarbon Dates ◽  
Western Margin ◽  
Level Change ◽  
Emergence Patterns ◽  
Lowland Area

Marine-limit elevations and radiocarbon dates from Melville Peninsula suggest rapid deglaciation of Committee Bay about 9100 years ago when sea level was 235 m higher than present. During deglaciation, an extensive prominent moraine with both terrestrial and glaciomarine segments developed along the western margin of the Foxe Ice Dome. It developed between 8500 and 6500 years ago as glaciologic response to the opening of the bay. By the time ice had receded from the moraine, sea level had dropped to about 140 m. Garry Bay was not deglaciated until ice lay east of the Melville Moraine. Lithologic evidence and the persistence of ice in this lowland area suggest that the outer part of Garry Bay was the calving terminus of a major ice stream flowing westwards across the peninsula. Four well-controlled emergence curves, based on 37 radiocarbon dates, are presented. The Baker Bay and Brevoort curves depict disjunct emergence patterns in which the disjunction corresponds in time and elevation to the formation of the moraine; the other two cover only the last 7000 years and depict a normal exponential style of emergence. Differences in timing and amount of emergence in the curve from Fury and Hecla Strait are attributed to a late ice flow southwards from Baffin Island. The Melville Moraine is younger than the age initially proposed for the Cockburn moraine system, of which it forms a part. It formed as a glaciodynamic response to a shift from marine-based to terrestrially grounded ice margin, rather than to climatic factors.

scholarly journals Long-term regional trend and variability of mean sea level during the satellite altimetry era

2019 ◽  
Vol 83 (2) ◽  
pp. 111
Author(s):  
Quang-Hung Luu ◽  
Qing Wu ◽  
Pavel Tkalich ◽  
Ge Chen
Keyword(s):  
Sea Level ◽  
Climatic Factors ◽  
Sea Level Change ◽  
Climate System ◽  
Regional Trend ◽  
Mean Sea Level ◽  
Level Change ◽  
The Pacific ◽  
Change In Mean

The rise and fall of mean sea level are non-uniform around the global oceans. Their long-term regional trend and variability are intimately linked to the fluctuations and changes in the climate system. In this study, geographical patterns of sea level change derived from altimetric data over the period 1993-2015 were partitioned into large-scale oscillations allied with prevailing climatic factors after an empirical orthogonal function analysis. Taking into account the El Niño–Southern Oscillation (ENSO) and the Pacific Decadal Oscillations (PDO), the sea level change deduced from the multiple regression showed a better estimate than the simple linear regression thanks to significantly larger coefficients of determination and narrower confidence intervals. Regional patterns associated with climatic factors varied greatly in different basins, notably in the eastern and western regions of the Pacific Ocean. The PDO exhibited a stronger impact on long-term spatial change in mean sea level than the ENSO in various parts of the Indian and Pacific Oceans, as well as of the subtropics and along the equator. Further improvements in the signal decomposition technique and physical understanding of the climate system are needed to better attain the signature of climatic factors on regional mean sea level.

Microfossil analyses and radiocarbon dating of depositional sequences related to Holocene sea-level change in the Forth valley, Scotland

1993 ◽  
Vol 84 (1) ◽  
pp. 1-60 ◽  
Author(s):  
Marie Robinson
Keyword(s):  
Sea Level ◽  
Radiocarbon Dating ◽  
Sea Level Change ◽  
Radiocarbon Dates ◽  
Depositional Sequences ◽  
Level Curves ◽  
Level Change ◽  
South Central ◽  
Different Parts ◽  
Holocene Sea Level

ABSTRACTMicrofossil (pollen and diatom) evidence is presented from sites in the Forth valley, south-central Scotland, where alternating organic and estuarine minerogenic deposits record the influence of the changing Holocene sea level. Radiocarbon dating confirms the age of the Main and Low Buried Beaches, and of the Main Postglacial Transgression, in different parts of the Forth valley. Radiocarbon dates on shells from beds in the carse sediment and a Mesolithic shell midden near Grangemouth relate to the falling sea level in the 4th and 5th millennia BP. Sea-level curves are constructed for the western and eastern Forth valley.

Late Holocene Sea-Level Change on Rota and Guam, Mariana Islands, and Its Constraint on Geophysical Predictions

1993 ◽  
Vol 40 (2) ◽  
pp. 189-200 ◽  
Author(s):  
Hajime Kayanne ◽  
Teruaki Ishii ◽  
Eiji Matsumoto ◽  
Nobuyuki Yonekura
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Sea Level Change ◽  
Mariana Islands ◽  
Present Level ◽  
Sea Level Changes ◽  
Radiocarbon Dates ◽  
Level Change ◽  
Sea Level Variations ◽  
Holocene Sea Level

AbstractHolocene emergent reefs and notches are well distributed on Rota and Guam. Relative sea-level changes at these islands are reconstructed based on geomorphological observations and borings on present and emergent reefs, together with 54 radiocarbon dates. Sea level rose gradually to a maximum of 1.8 m between 6000 and 4200 yr B.P. and reached its highest level by 4200 yr B.P. on both islands. After 3200 yr B.P. abrupt uplift caused emergence of the reef. By subtracting the tectonic effect, we obtained the sea-level change in the Marianas: sea level reached its present level by 4200 yr B.P. and has remained almost stable since then. Reconstructed late Holocene sea-level change in the Mariana Islands provides constraints on geophysical models of sea-level variations.

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.

Late Holocene diatom biostratigraphy and sea-level changes in the southeastern Beaufort Sea

2000 ◽  
Vol 37 (1) ◽  
pp. 63-80 ◽  
Author(s):  
Stéphane Campeau ◽  
Arnaud Héquette ◽  
Reinhard Pienitz
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Beaufort Sea ◽  
Sea Level Changes ◽  
Diatom Assemblages ◽  
Radiocarbon Dates ◽  
Sea Levels ◽  
Temporal Precision ◽  
Level Change ◽  
Paleoenvironmental Changes

Late Holocene sediments from the Atkinson Point area were analysed to provide quantitative reconstructions of recent sea-level changes in the southeastern Beaufort Sea. The succession of diatom assemblages in five cores revealed paleoenvironmental changes induced by the transgression of the Beaufort Sea during successive periods of lacustrine conditions, breaching and flooding of thermokarst lakes by the sea, and the landward migration of sandy spits. Based on radiocarbon dates and quantitative paleodepth determinations, a relative sea-level curve for the late Holocene has been developed. Despite a loss of temporal precision due to old carbon contamination, an envelope of sea-level change has been defined for the last 2 ka BP, suggesting a sea-level rise in the order of 1.1 mm a-1 for the last millennium. This paper presents the first sea-level reconstruction inferred from a diatom-based transfer function. It represents an improvement over traditional methods which were limited to qualitative estimates of past sea levels.

Radiocarbon Ages from Two Submerged Strandline Features in the Western Gulf of Maine and a Sea-Level Curve for the Northeastern Massachusetts Coastal Region

1993 ◽  
Vol 40 (1) ◽  
pp. 38-45 ◽  
Author(s):  
Robert N. Oldale ◽  
Steven M. Colman ◽  
Glen A. Jones
Keyword(s):  
Sea Level ◽  
Gulf Of Maine ◽  
Coastal Region ◽  
Sea Level Change ◽  
Level Curve ◽  
Radiocarbon Dates ◽  
Level Change ◽  
The North ◽  
Rapid Changes ◽  
Late Wisconsinan

AbstractNew radiocarbon dates provide ages for two submerged strandline features on the Massachusetts inner shelf. These ages provide limited control on a relative sea-level (RSL) curve for the late Wisconsinan and Holocene. The curve indicates a late Wisconsinan high stand of RSL of +33 m about 14,000 yr ago and a very short-lived relative low stand of about -43 m at about 12,000 yr ago followed by a rise to present sea level. Rapid changes of RSL around 12,000 yr ago may be related to changes in global glacial meltwater discharge and eustatic sea-level change shown by dated corals off Barbados. Variations in the magnitude and timing of RSL change from south to north along the coast of the western Gulf of Maine are due to greater crustal depression and later deglaciation to the north.

Late glacial and post-glacial history and emergence of the Ottawa Islands, Hudson Bay, Northwest Territories: Evidence on the deglaciation of Hudson Bay

1969 ◽  
Vol 6 (5) ◽  
pp. 1263-1276 ◽  
Author(s):  
J. T. Andrews ◽  
G. Falconer
Keyword(s):  
Northwest Territories ◽  
Sea Level ◽  
Late Glacial ◽  
Hudson Bay ◽  
Baffin Island ◽  
Glacial History ◽  
The West ◽  
Radiocarbon Dates ◽  
Northeastern Part ◽  
Present Rate

The Ottawa Islands are in the northeastern part of Hudson Bay. Evidence from crossing striations suggests that the earliest recorded glacial movement was toward the northeast. With deglaciation of Hudson Strait and central Hudson Bay the ice movement shifted progressively in an anti-clockwise direction, with the final movement being toward the west–southwest. The islands were deglaciated between 7610 and 7250 radiocarbon years ago. The marine limit is 158 m above sea level. Deltaic deposits below the marine limit are grouped into sets that correlate with glacial advances in Labrador–Ungava and Baffin Island, and with palynological results from Keewatin, suggesting that they reflect climatically induced processes rather than a balance in eustatic–isostatic movements. Radiocarbon dates on marine molluscs enable postglacial uplift and emergence curves to be drawn, which agree closely with predicted curves. Rates of uplift were about 0.06 m yr−1 at 6500 yr B.P., whereas the present rate is about 0.008 m yr−1. The deglaciation of Hudson Bay was marked by the splitting of the ice sheet along the submarine deep that trends southward between Mansel and Coats islands toward the southwest coast of the bay.

Reconstructed ice-flow patterns and ice limits using drift pebble lithology, outer Nachvak Fiord, northern Labrador

1989 ◽  
Vol 26 (3) ◽  
pp. 577-590 ◽  
Author(s):  
Trevor Bell ◽  
Robert J. Rogerson ◽  
Flemming Mengel
Keyword(s):  
Sea Level ◽  
Ice Shelf ◽  
Ice Flow ◽  
Radiocarbon Dates ◽  
Ice Shelves ◽  
Ice Coverage ◽  
Local Material ◽  
Late Wisconsinan ◽  
Glaciomarine Sediments ◽  
Ice Model

The geology of outer Nachvak Fiord provides an opportunity to differentiate lithologies originating in the Churchill Structural Province (central and inner fiord) from those in the sedimentary Ramah Group and the Nain Structural Province (outer fiord). As a result, the distribution of glacial erratics from the central and inner fiord depicts the former presence of regional Laurentide ice in the outer fiord, whereas the distribution of glacial deposits characterized by locally derived lithologies delimits the area of local glacier expansion.Based upon these criteria, the suggestion is made that regional ice at some time covered the deeply weathered mountain summits (900 m asl) in outer Nachvak Fiord. A later advance, confined to the fiord and valleys, deposited the highest moraines and till (180–115 m asl) recorded in the area. On the basis of geomorphic relationships, this advance is considered a discrete glacial event, separate from a later glaciation that was responsible for moraines and sediments at lower elevations (130–80 m asl). Two hypotheses are presented to explain the character of glacial features and sediments in the lower valleys.Hypothesis I requires that regional ice advanced through the study area and floated as ice shelves in the outer fiord and adjacent distributary valley. Sea level at this time was approximately 70 m higher than at present. Radiocarbon dates and amino-acid ratios from the shells in associated marine and glaciomarine sediments suggest a Middle Wisconsinan age for this event. During the Late Wisconsinan, regional Laurentide ice was restricted to the inner fiord while the sea (29–40 m above present) occupied the outer fiord area. The expansion of local cirque glaciers in upland areas may have occurred during both regional glaciations.In hypothesis II, the Middle Wisconsinan was characterized by extensive local glacier activity, depositing predominantly local material in the lower valleys, south of the fiord. Related fossiliferous sediments (same as above) provide the dating framework for this event. Late Wisconsinan regional ice advanced to the outer fiord and entered the distributary valley south of the fiord. Till deposited during this event is distinguished from the earlier local glaciation by the predominance of regional lithologies. Both Middle and Late Wisconsinan glaciations resulted in the formation of ice-shelf moraines at similar elevations. This implies similar relative sea-level responses to loading of the crust during both events, and consequently it is suggested that regional Laurentide ice had also advanced during the Middle Wisconsinan.Neither hypothesis conforms to a recently proposed Late Wisconsinan ice model for northern Labrador that requires extensive regional ice coverage in the outer fiord and on the Labrador Shelf.

scholarly journals Relative Sea-Level Change in the Northern Strait of Georgia, British Columbia*

2007 ◽  
Vol 59 (2-3) ◽  
pp. 113-127 ◽  
Author(s):  
Thomas S. James ◽  
Ian Hutchinson ◽  
J. Vaughn Barrie ◽  
Kim W. Conway ◽  
Darcy Mathews
Keyword(s):  
British Columbia ◽  
Sea Level ◽  
Sea Level Change ◽  
Relative Sea Level ◽  
Radiocarbon Dates ◽  
Strait Of Georgia ◽  
Level Change ◽  
Decay Times ◽  
Crustal Uplift ◽  
Cordilleran Ice Sheet

Abstract Twenty-four new radiocarbon dates from isolation basin cores, excavations and natural exposures, and an archeological site, constrain relative sea-level change since the last glaciation in the northern Strait of Georgia, British Columbia. Relative sea level fell rapidly from about 150 m elevation to 45 m elevation from 11 750 to 11 000 BP (13 750 to 13 000 cal BP), then its rate of fall slowed. The initial rapid emergence began soon after the transition from proximal to distal glaciomarine sedimentation, when the glacial front retreated from the Strait of Georgia and the Earth’s surface was unloaded. A sea-level lowstand a few metres below present-day sea level may have occurred in the early Holocene, but sea level was near its present level by 2000 BP. Sea-level change in the northern Strait of Georgia lagged the mid Strait of Georgia, 80 km to the south, by a few hundred years during initial emergence. The lowstand in the northern strait was later and probably shallower than in the mid strait. Isostatic depression inferred from the sea-level observations can be fit with two decaying exponential terms with characteristic decay times of 500 and 2600 years. The faster decay time corresponds to a shallow mantle viscosity of about 1019 Pa s, consistent with previous glacio-isostatic modelling. The present-day crustal uplift rate from the residual isostatic effects of the Cordilleran Ice Sheet is about 0.25 mm/a. Crustal uplift is not expected to significantly ameliorate projected sea-level rise in the mid and northern Strait of Georgia because present-day vertical crustal movements are inferred to be small.

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