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The development of landforms during the transition from a glacially dominated system to a fluvially dominated system

Rebecca Larking
Department of Geography, University of Otago, Dunedin, New Zealand


Abstract

Quaternary history, with regard to the role of glacial processes in landscape development, has been considered as unimportant in New Zealand.  Previous studies of landscape development in New Zealand have focused on the influence of geology and contemporary processes such as rainfall to explain patterns of landscape development.  From studies in British Columbia, it is postulated by the paraglacial model, that glacial history may influence the sedimentary processes of contemporary alpine environments.  However, there has been no work to examine this concept in New Zealand.  This thesis reports the results of an investigation on landform development during the transition from a glacial system to a fluvial system to examine the role that Quaternary history and glaciation may have on the contemporary fluvial system.  A model of landscape development during this transition period is constructed and evaluated by a field study of the morphology and stratigraphy of glacial and postglacial landforms, mainly alluvial fans, in the Hawea Valley, Central Otago, New Zealand.    Results from this study show that the construction of alluvial fans in the Hawea Valley, was dependent upon the influence of Quaternary glaciations during the transition from glacial to non-glacial conditions.  Glacial deposits and periglacial deposits were reworked by debris and fluvial processes to develop two types of alluvial fan: tributary fans and outwash-derived fans.  Both types of fans are defined as being paraglacial in origin because their formation was from either the direct remobilisation of glacigenic sediments, or their formation has been influenced by paraglacial processes such as base level change.  Where fan building has continued during repeated transitions from glacial to non-glacial conditions, multiple fans have developed.

Reference

Larking, R. 1999. The development of landforms during the transition from a glacially dominated system to a fluvially dominated system. Unpublished MSc thesis, in Geography, at the University of Otago, Dunedin, New Zealand. 133 pp.

© 2009 Department of Geography, University of Otago, Dunedin, New Zealand