Radiocarbon Isochrones on the Disintegration of the Laurentide Ice Sheet

Bryson, Reid A.; Wendland, Wayne M.; Ives, Jack D.; Andrews, John T.

doi:10.2307/1550356

Cited by 182 publications

(76 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This pattern shows a similar timing for advance and retreat as derived from the proxy field evidence, e.g. GOLDTHWAITE (1958); PREST (1969); BRYSON et al (1969); DENTON and HUGHES (1981); PREST (1984).…”

Section: Advance and Retreat Ratessupporting

confidence: 76%

Conditions for Growth and Retreat of the Laurentide Ice Sheet

Budd¹,

Smith²

2008

gpq

View full text Add to dashboard Cite

Results of three dimensional numerical modelling of the North American ice sheets in response to the Earth's orbital radiation variations are reviewed in relation to the conditions for formation and retreat of the ice sheets. The last interglacial develops as a clear result of the preceding high summer radiation levels and is not very dependent on the climatic paramaterisation. The magnitude and timing of the last glacial maximum provides a means of fine tuning the climatic parameterisation. In between these two periods the extent of ice sheet advances and retreat is strongly sensitive to the magnitude of the ice sheet albedo feedback parameter. The time changes of the radiation, climate, ice sheet cover and bedrock depression are out of phase and as a result equilibrium is not attained. The distribution of land surface elevation plays a key role in the pattern of seeding of the ice sheet growth and the subsequent advances, coalescence and retreat. The dispersal pattern of bedrock in till can be expected to reflect the growth and advance phases of the ice sheet development rather than the maximum configuration. Finally, the cycles of ice ages over the last 500,000 years from the modelling follows the occurrence of extreme summer radiation levels over a wide latitude band of 40-80°N due to coincidence of obliquity and perihelion features superimposed on the hysteresis effects of the ice cover.Les résultats obtenus à partir de la modélisation numérique tri-dimensionnelle des calottes glaciaires de l'Amérique du Nord selon les variations de l'insolation des latitudes sont examinés en fonction des conditions à l'origine de la formation et du retrait des inlandsis. L'existence du dernier interglaciaire est nettement le résultat des hauts niveaux antérieurs d'insolation estivale et très peu celui des paramètres climatiques. L'ampleur et la durée du dernier maximum glaciaire permettent de préciser les paramètres climatiques en cause. Entre ces deux périodes, l'importance de la progression des glaciers et de leur retrait subséquent est grandement influencée par l'albédo de la calotte glaciaire. Les changements temporels de l'insolation, du climat, de la couverture de glace et de l'enfoncement du substratum sont décalés les uns par rapport aux autres, résultant en un déséquilibre. La répartition des altitudes de la surface terrestre joue un rôle clé dans le processus de formation de la calotte glaciaire, ainsi que des récurrences, de la coalescence et du retrait subséquents. On peut s'attendre à ce que le mode de dispersion des dépôts glaciaire expriment davantage les phases de croissance et de récurrence de la calotte glaciaire que sa configuration maximale. En dernier lieu selon le modèle, les cycles de glaciation au cours des 500 000 dernières années suivent l'apparition de niveaux extrêmes d'insolation le long d'une large bande de 40° à 80° de latitude, en raison de l'obliquité de l'écliptique et des caractéristiques du périhélie surimposés à l'effet d'hystéréris causé par la couverture de glace.Die Ergebnisse eines d...

show abstract

Section: Advance and Retreat Ratessupporting

confidence: 76%

Conditions for Growth and Retreat of the Laurentide Ice Sheet

Budd¹,

Smith²

2008

gpq

View full text Add to dashboard Cite

show abstract

“…The o uter coa st e:nerged from th e retreating glaciers about 10000 years ago (Andrews and o th ers, 1970;Bryson and others, 1969 ) . R etrea t th ereaft er' was relatively slow ( < 2 7 m year-I) and there is good eviden ce that some glaciers from the inl and ice sheet were sti ll in contact with the sea about 4 300 years ago (Andrews, 1969) .…”

Section: Home Baymentioning

confidence: 99%

An Inventory of the Present and Past Glacierization of Home Bay and Okoa Bay, East Baffin Island, N.W.T., Canada, and some Climatic and Palaeoclimatic Considerations

1970

View full text Add to dashboard Cite

. An a ir-photogr a ph inventor y of the present glacieriza tion of a reas of east Ba Rl n Isla nd a dj oining Hom e Bay a nd Okoa Ba y is d escribed. I ce fi elds c ha racterize the broad mounta in su m mits of the for mer, while the la tter is a n a rea of cirque glaciers. The extent of g lacieriza tion is sta tisti ca ll y rel a ted to va rio us topogra phic pa rameters. It is found that there is a 4 : 1 rat io between H ome Bay a nd O koa Bay in t he a rea of ice as a p ercen t of the la nd a rea a bove 6 00 m a .s.l. Trend-surface a na lyses a r e m a d e of the distribution of snow-ba nks a nd of cirques (empty a nd with ice bodi es) in th e two a reas. Th e ori enta tion of the cirques a nd of the ice-field glaciers in H om e Bay is a lso exam in ed. 39% of empty cirques in O koa Bay face sou th, whereas those with existing glaciers a r e restricted to orienta ti ons with azimuths between 3 10°-145°. Neither glac ier length nor the observable recession in the H o me Bay a rea show a n y sig nifica nt difference with rega rd to aspect.C onsidera ti on of clima tic pa ra meters (sn owfa ll a nd d egree d ays) a nd syn optic-clima tologica l results p rovide n o reason for th e strong contrast between t he two a reas. Cool, cloud y su m mer conditions a re assoc ia ted with easterl y Row components tha t should a ffect both a reas. A possibl e mod el for the inception of the m ounta in ice field s of H o m e Bay c. 2 000-4 000 years a go is outlin ed a nd it is suggested tha t differentia l lag effects between the ice bodi es in the two a reas may be responsible for som e of th e observed difference. The m a n y pa radoxica l rela t ionships between g lacierizat ion, topogra phy a nd cl ima te in these a reas, and t he ra ther negati ve results, emphasize t he d a ngers of fac ile pa laeoclima tic interpreta tions. R ESUME.

show abstract

“…The timing and pattern of the preceding ice retreat on the peninsula were poorly known until recently because few dates indicating local déglaciation time were available from the interior. Several déglaciation chronologies for the region have been published (PREST, 1969;BRYSON et al, 1969;IVES et al 1975;HILLAIRE-MARCEL and OCCHIETTI, 1980;MAYEWSKI et al, 1981), but these reconstructions are imprecise because of the lack of data from the interior.…”

Section: Introductionmentioning

confidence: 99%

A Standard Method for Evaluating Radiocarbon Dates of Local Deglaciation: Application to the Deglaciation History of Southern Labrador and Adjacent Québec

King¹

2007

gpq

View full text Add to dashboard Cite

Sixty-two radiocarbon dates of marine shells, basal lake sediments, and basal peat deposits from the southeastern part of the Labrador-Ungava Peninsula, Canada, were evaluated for their accuracy and precision in estimating local deglaciation time. A procedure for the consistent evaluation of basal dates of lake sediments was developed after consideration of the problems with dating early-postglacial sediments. Of the 62 dates, 42 were selected to construct the regional déglaciation chronology, interpreted in the context of the glacial geology of the area. Late Wisconsin ice stretched to or beyond the present-day coastline throughout the study area, except in southeastern Labrador where the extreme southeastern coast was probably ice-free during Late Wisconsin time. Déglaciation began in southeastern Labrador by 13.OK. It proceeded slowly at first, and between 9.7K and 10.5K the retreating ice formed the Paradise Moraine, which parallels the southeastern Labrador coastline. In contrast, the coast at Sept-îles was not ice-free until about 9.4K. Shortly thereafter the extensive Québec North Shore Moraine System developed, although its precise age is uncertain. The position of the ice margin at 8.0K is uncertain, but may still have been near the Québec North Shore Moraine System. After 8.0K ice retreat was rapid, although extensive ice persisted at 6.5K in western Labrador and adjacent Québec. Final wastage of ice occurred in two localities in the center of the Labrador-Ungava Peninsula just after 6.OK. The precision of the well-dated glacial isochrones is estimated to be about ± 23 km.On a évalué la précision, relativement au moment de la déglaciation, de 62 datations au radiocarbone, effectuées sur des coquillages marins, de sédiments lacustres de base et des dépôts de tourbe de base prélevés dans le sud de la péninsule du Labrador-Ungava. On a ainsi élaboré un mode d'évaluation de la datation des sédiments lacustres qui tient compte des problèmes reliés à la datation des premiers sédiments postglaciaires. Quarante-deux des 62 datations ont servi à établir la chronologie de la déglaciation, à la lumière de la géologie glaciaire de la région. Au Wisconsinien supérieur, les glaciers ont partout progressé jusqu'à la côte, sauf dans l'extrême sud-est du Labrador où la côte était probablement libre de glace. La déglaciation du sud-est du Labrador a commencé vers 13 000 BP. Lent au début, le retrait glaciaire a ensuite mis en place, entre 9700 et 10 500 BP, la moraine Paradise parallèlement à la côte sud-est du Labrador. Par contre, la glace ne s'est pas retirée de la côte aux environs de Sept-îles avant 9400 BP. Peu après, mais sans qu'on puisse en préciser la date, s'est formé le système morainique de la Côte-Nord. On ne connaît pas la situation exacte de la marge glaciaire vers 8000 BP. mais elle devait encore se trouver à proximité du système morainique de la Côte-Nord. À partir de ce moment. Ie recul a été rapide; cependant, vers 6500 BP, les glaciers occupaient encore de vastes étendues dans l'ouest du Labrador et ...

show abstract

Radiocarbon Isochrones on the Disintegration of the Laurentide Ice Sheet

Cited by 182 publications

References 21 publications

Conditions for Growth and Retreat of the Laurentide Ice Sheet

Conditions for Growth and Retreat of the Laurentide Ice Sheet

An Inventory of the Present and Past Glacierization of Home Bay and Okoa Bay, East Baffin Island, N.W.T., Canada, and some Climatic and Palaeoclimatic Considerations

A Standard Method for Evaluating Radiocarbon Dates of Local Deglaciation: Application to the Deglaciation History of Southern Labrador and Adjacent Québec

Contact Info

Product

Resources

About