Geomorphology and geomorphological responses to climate change in the interior of sub-Antarctic Marion Island
The influence of climate change on the geomorphology of the interior of Marion Island (above 750m a.s.l.) is investigated as climatic amelioration is thought to be responsible for the observed rapid melt out of the summit regions. Records have shown that the climate on Marion Island is warming and,...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | unknown |
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University of Pretoria
2013
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| Online Access: | http://hdl.handle.net/2263/26025 http://upetd.up.ac.za/thesis/available/etd-07032007-144008/ |
| Summary: | The influence of climate change on the geomorphology of the interior of Marion Island (above 750m a.s.l.) is investigated as climatic amelioration is thought to be responsible for the observed rapid melt out of the summit regions. Records have shown that the climate on Marion Island is warming and, as it represents a maritime periglacial environment characterised by small seasonal temperature ranges and steep temperature profiles, it is particularly sensitive to climate change. Marion Island is, therefore, an ideal location to address the poor understanding of periglacial environments in the Southern Circumpolar Region in the context of environmental conditions governing permafrost, seasonally frozen ground, and frost processes. To ascertain the influence of climatic amelioration on the geomorphology of Marion Island’s interior, thermokarst, periglacial, and rudimentary aeolian features were identified and mapped. Geomorphological features were documented to determine the extent of landscape response to climate change in the island’s interior. In addition, identification and mapping of geomorphological features were, in some cases, used to provide evidence for the previous existence of permafrost. Ground temperatures were also monitored to determine the present state and possible existence of permafrost above 750m a.s.l. Landscape development in the certain areas of the interior of Marion Island where glacial ice persists beneath sediment (scoria) and where permafrost previously existed has resulted in the manifestation of thermokarst features and the creation of a unique undulating topography. In parts of the study area, thermal erosion and subsidence of the thermokarst are identified as processes that are important agents of landscape evolution. Thermokarst processes, indicative of climate change are, however, limited to areas where buried glacial ice persists and permafrost existed. Thermokarst features studied were also noted to be ephemeral and easily destroyed through erosion by wind and water. Aeolian ... |
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