Biogeographic and Geologic Indications of Unglaciated Areas in Scandinavia During the Glacial Ages

Dahl, Eilif

doi:10.1130/0016-7606(1955)66[1499:bagiou]2.0.co;2

Cited by 60 publications

(49 citation statements)

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“…The tors are seen as essentially preglacial forms (André, 2004), created prior to multiple glacial phases by differential weathering and erosion under periglacial or temperate environments. Tors have been used as evidence of former nunataks (Linton, 1949(Linton, , 1955Dahl, 1955;Ives, 1966) or that areas lay beyond glacial limits (Daveau, 1971;Veyret, 1980;Scourse, 1987). Alternatively, tors are accepted as indicators of the former presence of non-erosive ice covers (Linton, 1959;Godard, 1965Godard, , 1969Sugden, 1968;Sugden and Watts, 1977;Rapp, 1996).…”

Section: Introductionmentioning

confidence: 99%

Glacial modification of granite tors in the Cairngorms, Scotland

Hall

Phillips

2006

J Quaternary Science

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A range of evidence indicates that many granite tors in the Cairngorms have been modified by the flow of glacier ice during the Pleistocene. Comparisons with SW England and the use of a space-time transformation across 38 tor groups in the Cairngorms allow a model to be developed for progressive glacial modification. Tors with deeply etched surfaces and no, or limited, block removal imply an absence of significant glacial modification. The removal of superstructure and blocks, locally forming boulder trains, and the progressive reduction of tors to stumps and basal slabs represent the more advanced stages of modification. Recognition of some slabs as tor stumps from which glacial erosion has removed all superstructure allows the original distribution of tors to be reconstructed for large areas of the Cairngorms. Unmodified tors require covers of non-erosive, cold-based ice during all of the cold stages of the Middle and Late Pleistocene. Deformation beneath cold-based glacier ice is capable of the removal of blocks but advanced glacial modification requires former wetbased glacier ice. The depth of glacial erosion at former tor sites remains limited largely to the partial or total elimination of the upstanding tor form. Cosmogenic nuclide exposure ages together with data from weathering pit depths , from the surfaces of tors and large erratic blocks require that the glacial entrainment of blocks from tors occurred in Marine Isotope Stages (MIS) 4-2, 6 and, probably, at least one earlier phase. The occurrence of glacially modified tors on or close to, the main summits of the Cairngorms requires full ice cover over the mountains during these Stages. Evidence from the Cairngorms indicates that tor morphology can be regarded as an important indicator of former ice cover in many formerly glaciated areas, particularly where other evidence of ice cover is sparse. Recognition of the glacial modification of tors is important for debates about the former existence of nunataks and refugia.

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Section: Introductionmentioning

confidence: 99%

Glacial modification of granite tors in the Cairngorms, Scotland

Hall

Phillips

2006

J Quaternary Science

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“…Localisation du mont Gausta (Telemark). Dahl, 1955;Rudberg, 1984;Jansen, 1986;Nesje, 1989;Nesje étal., 1988Nesje étal., , 1990 (fig. 3a et b).…”

Section: Les éLéments Du Relief Et Le Cadre Structuralunclassified

“…par an . D'après E. Dahl (1955), les températu-res de l'air enregistrent 73 cycles de gel-dégel en moyenne par an (61 à 91 cycles annuels pour la période 1940-1944).…”

Section: L'environnement Bioclimatique Et Les Conditions De La Morphounclassified

“…• L'influence de processus holocènes et les témoignages d'un réaménagement périglaciaire E. Dahl (1955) a déjà utilisé les données météorologi-ques relatives au Gaustatoppen pour minimiser l'influence du gel à l'emplacement des champs de blocs de Norvège, en montrant que le nombre d'alternances gel-dégel était moindre sur de tels sommets que dans les vallées situées en contrebas. Ives (1966) a repris ces observations pour discuter du rôle des processus postglaciaires sur la genèse de certains champs de blocs de Scandinavie, en rappelant que la portée des cycles diurnes de gel-dégel se limitait à une faible profondeur dans les régions concernées.…”

Section: Les Conditions D'élaboration Du Felsenmeer Du Gaustarâenunclassified

“…Ces questions ont été débattues depuis longtemps dans le cadre de la Scandinavie, où elles ont été souvent confrontées à la théorie des refuges (WiIIe, 1905;Ahlmann, 1919 ;Linton, 1949Linton, , 1950E. Dahl, 1955 ;Rudberg, 1962aRudberg, et b, 1977Rudberg, , 1988R.…”

Section: Introductionunclassified

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