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Indications of Recent Extensive Glacierization in North–Central Baffin Island, N.W.T.*

  • J. D. Ives (a1)

Abstract

Studies of the geomorphology and rock lichen development north of the Barnes Ice Cap prompt the conclusion that 70 per cent of this extensive, interior region was covered by permanent ice some 300 to 400 yr. ago. Contemporaneously the northern Barnes Ice Cap was significantly larger than today; it dammed up a lake in the upper Isortoq valley, over 80 km. long and up to 300 m. deep. Excluding the ice cap less than 2 per cent of the area is glacierized today; this represents a dramatic reduction in surface area of the former ice cover. Similarly, significant recession of the ice cap implies that glaciers of the “Baffin type” are in a less healthy budgetary state than hitherto has been assumed.

Proof of former extensive ice cover rests largely upon restricted rock lichen development. When sufficient time has elapsed for complete colonization, few indications of the former existence of an ice cover will remain. This type of glacierization may have affected large areas in the high Arctic. Absence of evidence of glaciation, therefore, cannot be relied upon to delimit nunatak areas (plant refugia) during the last glaciation.

Résumé

Des études sur la morphologie et sur la croissance des lichens au nord de la calotte glaciaire de Barnes indiquent que 70 p.c. de cette vaste contrée intérieure était recouverte de glaces permanentes il y a de 300 à 400 ans. A cette époque, l’extrémité septentrionale de la calotte de Barnes était passablement plus étendue qu’elle ne l’est aujourd’hui et formait, dans la partie supérieure de la vallée Isortoq, un barrage à l’arrière duquel s’était formé un lac de plus de 80 km de longueur et dont la profondeur atteignait 300 m. Exception faite de la calotte glaciaire actuelle, moins de 2 p.c. de la région est aujourd’hui occupée par des glaciers ce qui représente une réduction très considérable de l’aire jadis recouverte par les glaces. En outre, l’amaigrissement sensible de la calotte laisse supposer que les glaciers de “type Baffin” ont un bilan beaucoup moins positif qu’on ne l’avait supposé jusqu’à présent.

Les preuves d’une ancienne glaciation de fortes proportions reposent principalement sur la croissance restreinte des lichens. Lorsque se sera écoulé un laps de temps suffisamment long pour permettre leur pleine croissance, l’on pourra difficilement retrouver de traces d’une glaciation antérieure. Ce genre de glaciation a peut–être touché de vastes étendues du Gravel Nord. En conséquence, une absence de vestiges de glaciation n’indique pas nécessairement une région à nunatak de la dernière glaciation.

Zusammenfassung

Untersuchungen über die Geomorphologie und die Entwicklung von Steinflechten nördlich des Barnes–Eisschildes führen zu dem Schluss, dass 70% dieses ausgedehnten inneren Gebietes vor 300–400 Jahren eine ständige Eisbedeckung trugen. Zur selben Zeit war das nördliche Barnes–Eisschild bedeutend grösser als heute; es staute im oberen Isortoq–Tal einen See von über 80 km Länge und his 300 m Tiefe auf. Abgesehen von dem Eisschild sind heute weniger als 2% des Gebietes vergletschert; dies bedeutet einen drastischen Flächenrückgang der früheren Eisbedeckung. Des weiteren lässt der beträchtliche Rückgang des Eisschildes vermuten, dass sich die Gletscher vom “Baffin-Typ” in einem weit schlechteren Ernährungszustand befinden als bisher angenommen.

Der Beweis für eine ausgedehnte frühere Vereisung ist vor allen in der beschränkten Entwicklung von Steinflechten zu erblicken. Wenn genügend Zeit für eine vollständige Besiedlung verstrichen ist, werden nur wenige Anzeichen der früheren Eisbedeckung übrig bleiben. Dieser Typ der Vergletscherung war möglicherweise in der hohen Arktis weit verbreitet. Der Nachweis für das Fehlen einer Vereisung kann deshalb nicht nur auf die beschränkten Nunatak–Flächen (Pflanzen–Zulhtchtsstätten) während der letzten Eiszeit gegründet werden.

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Copyright

Footnotes

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Published with permission of the Director, Geographical Branch, Ottawa.

Footnotes

References

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Baird, P. D. 1952. The glaciological studies of the Baffin Island Expedition, 1960. Part I: Method of nourishment of the Barnes Ice Cap. Journal of Glaciology, Vol. 2, No. 11, p. 29.
Beschel, R. E. 1957. Lichenometrie im Glestchervorfeld. Jahrbuch des Vereins zum Schulze der Alpenpflanzen und Tiere München, Bd. 22, p. 16485.
Beschel, R. E. 1961. Dating rock surfaces by lichen growth and its application to glaciology and physiography (lichenometry). (In Raasch, G. O., ed. Geology of the Arctic. Toronto, University of Toronto Press, 1961, Vol. 2, p. 104462.)
Falconer, G. 1962. Patterned ground under ice fields. Journal of Glaciology, Vol. 4, No. 32, p. 23840. [Letter.]
Grayson, J. F. Unpublished. The postglacial history of vegetation and climate in the Labrador–Quebec region as determined by palynology. [Ph.D. thesis presented to the University of Michigan, 1956.]
Goldthwait, R. P. 1951. Development of end moraines in east–central Baffin Island. Journal of Geology, Vol. 5g, No. 6, p. 56777.
Löve, A. 1959. Origin of the arctic flora. (In Problems of the Pleistocene epoch and arctic area; a selection of papers presented at a seminar held in Montreal. Montreal, p. 8295. (McGill University Museums Publication, No. 1.))
Savile, D. B. O. 1961. The botany of the northwestern Queen Elizabeth Islands. Canadian Journal of Botany, Vol. 39, No. 4, p. 90942.
Ward, W. H. 1952. The glaciological studies of the Baffin Island Expedition, 1950. Part II: The physics of deglaciation in central Baffin Island. Journal of Glaciology, Vol. 2, No. 11, p. 923.
Ward, W. H. 1953. Comments on Dr. Orvig’s paper. Journal of Glaciology, Vol. 2, No. 14, p. 24748.

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