| Summary: | A pronival (protalus) rampart is a ridge, series of ridges or ramp of unconsolidated debris formed at the downslope margin of a perennial or semi-permanent snowbed overlooked by an exposed bedrock cliff. These landforms were traditionally regarded as simple and easily understood since the mechanisms of debris transport were intuitively considered to include supranival debris transport whereby clasts dislodged from the exposed cliffs above roll, bounce and slide over a snowbed under the influence of gravity. However, most studies focus on relict examples and few accounts document debris transport, or investigate rampart genesis, at actively-accumulating sites. This has led to circular reasoning and assumptions about rampart morphology, site characteristics, constituent material, genesis and palaeo-environmental significance. A review of existing literature reveals that rampart development was conventionally thought to extend downslope or outward below snowbeds of increasing thickness and extent but not all actively-accumulating ramparts fit this model. Given the over-reliance of research on relict pronival ramparts, this thesis focusses on actively–accumulating examples in order to improve our understanding of their genesis, clarify rampart identification and re-evaluate their palaeo-environmental significance. Rampart genesis is addressed by focussing on active sites on sub-Antarctic Marion Island and at Grunehogna, Western Dronning Maud Land, Antarctica as well as all other actively-accumulating ramparts documented across the globe. An alternative model for genesis in the form of retrogressive (upslope) development under fluctuating, and possibly declining, snowbed volumes is presented and relative-age dating techniques are recognised as being particularly useful in aiding with the assessment of rampart genesis. It is also found that ramparts which exhibit a distal slope at repose do not necessarily develop below snowbeds which are increasing in extent and thickness. The different modes of rampart genesis ...
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