On Different Types of Unglaciated Areas During the Ice Ages and Their Significance to Phytogeography

Dahl, Eilif

doi:10.1111/j.1469-8137.1946.tb05058.x

Cited by 51 publications

(43 citation statements)

References 11 publications

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“…Apart from the theoretical challenge by Dahl (1946 and1947) who suggests that the coastal summits above 3,000 feet must have remained as nunataks on a consideration of the marginal surface slope of inland ice sheets, the conclusions of Ode11 have remained largely undisputed (see, however, Mercer, 1956). Work in Iceland, where it was possible to prove conclusively that the high coastal mountains remained as nunataks throughout the glacial epoch, induced the writer to consider carefully the objections of Dahl, and to attempt to re-assess the field evidence before making a final conclusion.…”

Section: The Extent Of the Wisconsin Glaciationmentioning

confidence: 99%

“…Despite the slender evidence that Odell put forward, his concept, perpetuated by the writings of Tanner (1944) and Flint ( 1943 and1947), has gained almost universal acceptance. Odell's main criticism of Coleman is based on the assumption that the felsenmeere so widely distributed above the 2,000-to 2,200-foot level were formed by frost action in post-glacial times.…”

Section: Glaciation Of the Torjsgat Moc'ntaiksmentioning

confidence: 99%

“…As no definite evidence of the glaciation of these summits was obtained, the discussion must follow the theoretical lines of Dahl (1946 and1947).…”

Section: The Extent Of the Wisconsin Glaciation On The Coastal Summitsmentioning

confidence: 99%

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Glaciation of the Torngat Mountains, Northern Labrador

Ives¹

1957

ARCTIC

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Considers role of these mountains in glaciation of Labrador-Ungava, assessing particularly events in late-Wisconsin times with respect to final disappearance of both continental and local ice masses. Conflicting theories are discussed, and evidence presented, based on physiography and findings from summer 1956 field work, including unmistakable erratics on summits at 4,000-5,000 ft. The highest summits were completely submerged by eastward moving continental ice during the Wisconsin glaciation; local glaciers never reached significant dimensions; rapid melting in situ of thick masses of ice occurred during the final Wisconsin stages. Two or three separate glacial periods are recognized from the morphology of the area. Instantaneous glaciation of a large area of the Labrador-Ungava Plateau probably initiated a continental ice sheet in northeastern North America at the onset of each glacial period. Also pub. in International Union of Geodesy and Geophysics, Association of Scientific Hydrology, 11th assembly report of proceedings 1958, v. 4, p. 372-86.

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Section: The Extent Of the Wisconsin Glaciationmentioning

confidence: 99%

Section: Glaciation Of the Torjsgat Moc'ntaiksmentioning

confidence: 99%

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Glaciation of the Torngat Mountains, Northern Labrador

Ives¹

1957

ARCTIC

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“…The diminution of precipitation from west to east means a rise of the firn line in the same direction and it is eminently possible that in the southern Pennines, north-east Yorkshire and parts of Banffshire and Aberdeenshire, the elevation of the firn line lay throughout the Ice Age above that of the local hilltops, though ice of more westerly origin flooded the nearby lowlands. Even in the west, as Eilif Dahl 7 has pointed out, nunataks may exist where high mountains rise near the deep ocean. The writer believes that the field evidence is sufficient to demonstrate that Ben Loyal (2504 feet, 763 m.) in Sutherlandshire was a nunatak of this kind, and suspects that the mountains of Harris, which he has not had the opportunity of examining but which were thought by James Geikie 8 to have been the only Scottish summits to have projected above his all-enveloping "mer-de-glace," may prove to be an even better case.…”

Section: Unglaciated Enclaves In Glaciated Regionsmentioning

confidence: 99%

Unglaciated Enclaves in Glaciated Regions

Linton

1950

J. Glaciol.

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However, if air bubble elimination from large masses of ice after closing of communication between pores should exist (reports of Arctic and Antarctic expeditions on clear ice in "cold" glaciers are inconclusive), then the mechanism of elimination would have to be considered one of the major problems of glacier mechanics. Even elimination from narrow bands remains to be explained.The validity of the hypothesis suggested in this paper depends on the validity of the premises. It can reasonably be argued that we do not know how deformation of the crystals by basal translation will affect air bubble volume and pressure, and that we may not therefore assume that bubble pressure will lag behind hydrostatic pressure as the ice sinks, and will remain higher than hydrostatic pressure as the ice rises.The gra~n size of the Malaspina bubbly ice is of the order of magnitude of inches. The structure of this ice, which shows marked departure from random orientation, will be described elsewhere.MS.

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“…a geographical area where native biota of geographically isolated organisms were protected as a result of relatively stable environmental conditions during times of great environmental change such as glacialinterglacial cycles and sea-level variations on the island. Organisms may then re-colonise a region when the environmental conditions return to within the organism's tolerance levels (Bennett and Provan, 2008;Dahl, 1946). Thus, raised atolls may protect the specific biota of remote atolls during sea-level highstands and be a possible source of native pool species on the neighbouring atolls after the decline in sea level.…”

Section: Introductionmentioning

confidence: 99%

Native plant species richness on Eastern Polynesia’s remote atolls

Larrue

Butaud

Dumas

et al. 2015

Progress in Physical Geography: Earth and Environment

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Which abiotic factors influence the number of native plant species on remote atolls is an important question to understand better the spatial pattern of the species observed on these low and vulnerable coral islands. However, this issue is still very poorly documented, often due to human degradation, partial botanical surveys or the difficult geographic access of remote atolls for researchers. The remote atolls of Eastern Polynesia, which are among the most isolated in the world, are of great interest for studies of native species' distribution due to their isolation, low human density and urbanisation. In this study, we selected 49 remote atolls of Eastern Polynesia with complete botanical surveys to test the relative influence of eight abiotic factors on native plant species richness (i.e. indigenous and endemic species). Abiotic factors used as potential predictors included atoll area (km 2 ), shoreline length (km), atoll elevation (m) and index of isolation (UNEP), but also the coastal index of the atoll (I c ), the distance to the nearest similar atoll (km), the distance to the nearest large volcanic island ! 1000 km 2 (here, Tahiti as a potential stepping-stone island) and the distance to the nearest raised atoll ! 15 m a.s.l. (here, Makatea or Henderson as a potential refugium during sea-level highstands). Spearman's rank correlation, linear regression analysis and frequency diagrams were used to assess the relative influence of these factors on native species richness. No relationship was found between the species richness and the index of isolation or the distance to the nearest similar atoll. Atoll area and distance to the nearest raised atoll of Makatea explained 47.1% and 40%, respectively, of the native species richness variation observed on the remote atolls. The distance to the volcanic island of Tahiti and the coastal index explained 36.9% and 27.3% of the variation, while elevation and shoreline length explained 23.3% and 18.4% of the variation, respectively. Native species richness on the atolls surveyed increased with the

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On Different Types of Unglaciated Areas During the Ice Ages and Their Significance to Phytogeography

Cited by 51 publications

References 11 publications

Glaciation of the Torngat Mountains, Northern Labrador

Glaciation of the Torngat Mountains, Northern Labrador

Unglaciated Enclaves in Glaciated Regions

Native plant species richness on Eastern Polynesia’s remote atolls

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