Retreat of the last ice sheet from the maritime provinces, Gulf of St Lawrence Region

Prest, V K; Grant, Douglas

doi:10.4095/103337

Cited by 55 publications

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“…The ice-movement direction of the last glaciation in Nova Scotia is complex, and, as explained by Prest and Grant (1969), this complexity is probably related to a prolonged period of late, active ice flow from local centres in the Maritimes. They concluded that loc(ll ice caps may have formed in some Maritime areas prior to the advance of the continental ice sheet and that during glacier recession local ice activity was resumed with ice flow in diverse directions.…”

Section: Discussionmentioning

confidence: 99%

“…The terminal zone of the glacier would then form a topographic high which, bordering the ocean, would provide an area of excessive accumulation analogous to the situation which Prest and Grant ( 1969) postulated for the uplands of south-western Nova Scotia and elsewhere in the Maritimes. Under these conditions, there could have been a short period when the ice reversed its direction of flow until the continuing rise of sea-level dissipated the ice.…”

Section: Discussionmentioning

confidence: 99%

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The Yarmouth Drumlin Field, Nova Scotia, Canada

Gravenor¹

1974

J. Glaciol.

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ABSTRACT. The Yarmouth drumlinized area is a relatively small field of about 150 drumlins located south and south-east of the town of Yarmouth, Nova Scotia. An analysis of the drumlin shapes indicates that in the majority of cases the stoss end is on the southern extremity of the drumlin. This would suggest that the ice moved in from the south, a concept which is contradictory to pebble lithology and fabric 'analysis of the till in the drumlins and surrounding ground moraine. The drumlin field is anomalous in other respects in that the drumlin density is very low compared with other fields, and granulometric analysis shows that the drumlins are composed of coarse-grained material with only minor amounts of clay.It is suggested that the drumlins were originally formed by south to south-easterly flowing ice but during a later phase of glaciation a local centre of outflow, probably short-lived, developed south of Yarmouth on the continental shelf, and the drumlins were reshaped by ice flowing toward the north prior to the disappearance of this centre. Thus this area of drumlins was presumably not affected by the later area of outflow centred on the interior upland of western Nova Scotia which was hitherto believed to account for the Yarmouth drumlins. On suggere que les drumlins furent a I'origine, formes par de la glace coulant vers le Sud-Est; mais au cours d'une phase ulterieure'de la glaciation, un centre local d'ecoulement, probablement de courte duree, se developpa au Sud de Yarmouth sur la calotte continentale et les drumlins furent refa<;onnes par de la glace s'ecoulant vers le Nord, avant la disparition de ce centre. Par consequent, on presume que cette zone de drumlins ne fut pas affectee par I'ecoulement qui fut centre plus tard sur le plateau interieur de la Nouvelle Ecosse occidentale et que I'on croyait jusqu'ici Clre en cause dans la formation des drumlins de Yarmouth.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Yarmouth Drumlin Field, Nova Scotia, Canada

Gravenor¹

1974

J. Glaciol.

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“…Research primarily during the last ten years has demonstrated that much of the Laurentide ice sheet in southern Québec, Maine, and portions of the Maritime Provinces was a "marine-based ice sheet," that is, it was an ice sheet grounded below the prevailing sea level (PREST and GRANT, 1969;BORNS, 1973;STUIVER and BORNS, 1975).…”

Section: Current Understandingmentioning

confidence: 99%

The implications of the Pineo Ridge readvance in Maine

Borns

Hughes

2011

gpq

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Much of the Laurentide ice sheet in Maine, Atlantic Provinces, and southern Quebec was a "marine ice sheet," that is it was grounded below the prevailing sea level. When proper conditions prevailed, calving bays progressed into the ice sheet along ice streams partitioning it, leaving those portions grounded above sea level as residual ice caps. At least by 12,800 yrs. BP a calving bay had progressed up the St. Lawrence Lowland at least to Ottawa while a similar, but less extensive calving bay developed in Central Maine at approximately the same time. Concurrently, ice draining north into the St. Lawrence and south into the Central Maine calving bays rapidly lowered the surface of the intervening ice sheet until it eventually divided over the NE-SW trending Boundary and Longfellow Mountains and probably over other highland areas as well. A major consequence of these nearly simultaneous processes was the separation of an initial large ice cap over part of Maine, New Brunswick, and Québec which was bounded on the west by the calving bay in Central Maine, to the north by the calving bay in the St. Lawrence Lowland, to the south by the Bay of Fundy, and to the east by the Gulf of St. Lawrence. In coastal Maine, east of the calving bay, the margin of the ice cap receded above the marine limit at least 40 km and subsequently read-vanced terminating at Pineo Ridge moraine approximately 12,700 yrs. BP. These events are the stratigraphie and chronologic equivalent of the Cary-Pt. Huron recession/Pt. Huron readvance of the Great Lakes region.La plus grande partie de l’inlandsis laurentidien qui couvrait le Maine, les Maritimes et le sud du Québec était une « calotte glaciaire marine », sa base étant sous le niveau marin de l’époque. Les conditions le permettant, des baies de vêlage se sont développées le long de courants de glace et ont morcelle la calotte, si bien que les parties au-dessus du niveau de la mer sont devenues des calottes résiduelles. Vers 12 800 ans BP une baie de vêlage a occupé les basses terres du Saint-Laurent jusqu’à Ottawa. En même temps, une baie plus petite se développait dans le centre du Maine. Le drainage simultané de la glace, au nord, dans la baie de vêlage du Saint-Laurent et, au sud, dans celle du Maine a abaissé la surface de la calotte glaciaire jusqu’à ce qu’elle se divise le long des monts frontaliers et Longfellow (NE-SO) ainsi qu’en d’autres régions de hautes terres. Cette calotte glaciaire, d’abord très étendue, a donc été isolée au-dessus d’une partie du Maine, du Québec et du Nouveau-Brunswick. Elle était limitée à l’ouest par la baie de vêlage du centre du Maine, au nord par celle des basses terres du Saint-Laurent, au sud par la baie de Fundy et à l’est par le golfe du Saint-Laurent. Dans la région côtière du Maine, à l’est de la baie de vêlage, la marge glaciaire a reculé au-dessus de la limite marine sur au moins 40 km, puis a réavancé jusqu’à la moraine de Pineo Ridge vers 12 700 BP. Ces événements sont les équivalents stratigraphiques et chronologiques de la récession de Cary-Po...

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“…12,750 y BP (BROOKES 1974) or the Ten Mile Lake event ca. 11,000 y BP (GRANT, 1969). Locally diamictons spread downslope over pre-existing postglacial organic accumulations, such as the peat dating 10,250 ± 250 y BP (Y-762) on Port Hood Island (TERAS-MAE, 1974) and the peat dating 10,300 ± 150 y BP (GSC-1578) near East Bay (GRANT, 1975a).…”

Section: Inferred Quaternary Eventsmentioning

confidence: 99%

“…Incidental to studies of recent sea-level change, observation of glacial features yielded new evidence for an ice cap over southern Nova Scotia, and for a complex ice-flow sequence over southern Cape Breton (GRANT, 1967(GRANT, , 1968. Preparation of the Glacial Map of Canada (PREST, GRANT and RAMPTON, 1968) afforded an opportunity to examine airphotos of the entire region and this, together with a review of existing ice-flow data, culminated in a hypothesis that the topography and maritime setting prevented and confined the penetration by Labradorean ice, and promoted the growth and determined the retreat pattern of upland and lowland ice caps (PREST and GRANT, 1969).…”

Section: Glacial Stylementioning

confidence: 99%

Glacial style and ice limits, the Quaternary stratigraphic record, and changes of land and ocean level in the Atlantic Provinces, Canada

Grant

2011

gpq

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Evidence from scattered stratigraphie sections, from the relationship of a sequence of ice flow indicators to a raised interglacial marine platform, together with the limits of freshly glaciated terrain against weathered bedrock areas, indicates that late Wisconsinan glaciers spread weakly toward, and in many areas not beyond, the present coast. These were fed by a complex of small ice caps located on broad lowlands and uplands. The limiting factor was the deep submarine channels that transect the region. Thus, Laurentide ice was limited to northern Gulf of St. Lawrence. With this pattern of centripetal flow toward the Gulf, large areas remained unglacierized. There is now better geological corroboration of Fer-nald's hypothesis of nunatak botanic réfugia, though there was, perhaps during early Wisconsinan time, grounded ice in the Gulf and an outlet glacier in Laurentian Channel. Raised postglacial shorelines fit the model, with a general tilt toward the main shield ice sheet, but with two broad domes reflecting the ice complexes over New Brunswick and Newfoundland. Older emerged and submerged shorelines beyond the glacial limit complicate the pattern. At present northern regions are still rebounding while a zone of subsidence is migrating inland from the continental margin.Un certain nombre de faits prouvent que les glaciers, à la fin du Wisconsinien, se sont écoulés vers les côtes actuelles, et dans plusieurs cas, ne sont pas allés au-delà : les coupes stratigraphiques, les liens entre une série d’indicateurs de l’écoulement glaciaire et la plateforme marine interglaciaire relevée, ainsi que les rapports entre les limites des dernières régions englacées et les régions dont la roche en place a été altérée. Ces glaciers étaient nourris par un ensemble de petites calottes localisées sur de vastes étendues. Toutefois, les profonds chenaux qui entaillent la région, en ont empêché l’extension. Le glacier laurentidien s’est donc confiné au nord du golfe du Saint-Laurent. Ce mouvement centripète vers le golfe a d’ailleurs épargné de vastes secteurs. Les données géologiques appuient maintenant davantage l’hypothèse de Fernald au sujet des refuges biologiques des nunataks, bien qu’au début du Wisconsinien, une calotte et un glacier émissaire aient occupé le golfe et le chenal laurentien. Les lignes de rivages soulevés postglaciaires sont conformes au modèle d’ensemble, avec un relèvement différentiel davantage marqué vers le glacier laurentidien mais également avec la présence de deux larges dômes associés aux calottes du Nouveau-Brunswick et de Terre-Neuve. Toutefois des littoraux plus anciens, émergés et immergés, au-delà de la limite glaciaire, compliquent ce plan. Au nord, les régions se relèvent encore, alors qu’une zone de subsidence se déplace vers l’intérieur des terres

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Retreat of the last ice sheet from the maritime provinces, Gulf of St Lawrence Region

Cited by 55 publications

References 0 publications

The Yarmouth Drumlin Field, Nova Scotia, Canada

The Yarmouth Drumlin Field, Nova Scotia, Canada

The implications of the Pineo Ridge readvance in Maine

Glacial style and ice limits, the Quaternary stratigraphic record, and changes of land and ocean level in the Atlantic Provinces, Canada

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