摘要:

The two dominant environmental factors on Macquarie Island are the constantly low temperatures and the high wind velocities. The low temperatures represent the overall limiting factor for the vegetation as a whole, while exposure to wind determines the distribution of the vegetation types and of small‐scale geomorphological features. A hard cushion formation (feldmark) occupies most of the exposed plateau area. With decreasing exposure the hard cushions are replaced by herbfields, bogs or ferns, depending on the height of the water table. The coastal areas, which are generally less exposed, are covered by aPoa foliosagrassland. While the macro‐relief of the island is largely glacial in origin the micro‐relief of the slopes is the product of past and recent periglacial solifluction and its interrelationship with vegetation development. While exposed slopes exhibit a high degree of slope mobility lee slopes are much more stable and are characterized by large, stable terraces. The latter are considered to be relict features formed when permafrost conditions prevailed. If such terraces ever existed on the windward slopes they could not have survived because neither the riser nor the terrace surfaces gave any shelter from the wind and shallow solifluction movements tended to smooth out the slopes. Oblique terraces occur on slopes that display neither a clear leeward nor windward orientation and represent transitional forms between the unterraced slopes and the terraced less slopes.

ISSN:0273-8457    

DOI:10.1080/10889378409377228

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

In this second part of his study of the glaciation of the continental shelves during the Wurm glaciation the author first examines in detail the evidence for glacio‐isostatic depression (and subsequent rebound) of the various glaciated shelves and demonstrates how this evidence substantiates the geomorphological evidence of former glaciation. This leads to a detailed discussion of “marine”; ice sheets in terms of their formation, morphology and dynamics. Using the West Antarctic Ice Sheet as his model, as being the only existing example, the author demonstrates how such ice sheets consist of several interlocking components, namely ice sheets whose bases lie well below sea level on isostatically depressed shelf areas, contiguous glacier complexes on islands and mountainous coasts, and ice shelves in both interior and fringing configurations. In addition to a larger version of and Antarctic Ice Sheet the author argues for the existence during the Würm glaciation of two further major integrated (and contiguous) ice sheets of this type, namely a Panarctic Ice Sheet, including the Laurentide, Innuitian, Greenland, Scandinavian and Barents‐Kara ice sheets, with associated ice shelves on Baffin Bay, the Norwegian‐Greenland Sea and the Arctic Ocean; and a Cordilleran‐Bering Ice Cap on the North American Cordillera, Southern Beringia and the mountains of Kamchatka and Koryakiya, with an ice shelf in the southern, deep section of the Bering Sea.

ISSN:0273-8457    

DOI:10.1080/10889378409377229

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0273-8457    

DOI:10.1080/10889378409377230

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0273-8457    

DOI:10.1080/10889378409377227

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor