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Title: Beach form and process variation in South Georgia, a sub-Antarctic island
Author: Hansom, James D.
ISNI:       0000 0000 2628 2369
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1979
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Four beach types have been identified in South Georgia. These are beaches associated with outwash, moraine, relict outwash and cliff. They can be distinguished on the basis of their site, morphology and materials. Generally, the outwash type occupies larger sites and has low, flat and sandy beaches; the moraine type occupies any size of site and has steep pebble beach's of medium height; the relict outwash type occupies medium sized sites and has high yet low angled beaches of mixed sands and pebbles; the cliff type occupies small sites and is characterised by high steep pebble, beaches. A marked contrast in distribution of beach types is evident since cliff-backed beaches are located on any coast whilst the other types, especially the outwash-backed beaches, tend to be located on the north coast. Identification and analysis of beach variables indicates that the beach environment of South Georgia is highly active. Waves derived by hindcasting from meteorological data indicate that 55% of all waves approach from the south-west with dominant periods of 8-14 seconds whilst 32% and 13% approach from the north-west and east respectively with periods of 12-14 seconds. However, refraction of these waves into the bays shows that much of the deepwater wave energy is lost and that the remainder is focused towards specific points on the beaches. The terrestrial environment of South Georgia is also highly active since the cold wet climate allows- vigorous operation of glacial and subaerial processes which both generate and transport much debris to the beach zones. However, the intensity of operation of marine and terrestrial processes varies from place to place. The windward south coast is highly active in terms of wave energy yet of low activity in terms of debris generation and the opposite is the case on the north coast. Variation in the intensity of process largely accounts for the variation in beach form in South Georgia. Classification of beaches by energy and form supports the idea that high energy beaches are located on the exposed sides of islands. From a quantitative and qualitative analysis of form and process, the south coast emerges as a high energy coast with small, steep and high beaches whilst the north coast is mainly a lower energy coast with large, flat and low beaches in the sheltered inlets. This variation is generalised to produce models of beach type and evolution in South Georgia. If South Georgia is assumed to be typical of sub-Antarctic environments then these models suggest that the sub-Antarctic is one of the most active beach environments in the world. Seen in the context of Quaternary climate change, the beaches of South Georgia can be viewed as a model of beach development following deglaciation. If ergodicity in beach development is accepted then the model South Georgia beach may be an analogue of Late glacial mid-latitude beach development.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available