Scottish late-glacial moraines: debris supply, genesis and significance

Moraines;Sedimentation and deposition;Erosion

Benn, Douglas I. ; Ballantyne, C. K. ; Ballantyne, C. K.

University:University of St Andrews

Department:Earth & Environmental Sciences and Geography & Sustainable Development (Schools of)

关键词: Moraines;    Sedimentation and deposition;    Erosion;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/2676/DouglasIBennPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

A variety of moraine forms were deposited by glaciers during theLoch Lomond Stadial. Study of such moraines and related landformsprovides a valuable source of data on patterns of landscape evolutionand climatic change. This thesis presents detailed case-studies ofmoraines in geologically and topographically contrasting areas on theIsland of Skye, Scotland. Geomorphological mapping,sedimentological analyses and mathematical modelling techniqueswere employed to determine the principal controls on morainemorphology, composition and distribution. Particular emphasis wasplaced on the provenance, transport and deposition of debris, andtheir spatial variation. The results were used to construct a summarymodel of glacial landform evolution, which relates differentsediment-landform associations to spatial and temporal controls,particularly basin lithology and structure, topography, position ofdeposition and ice-margin activity.The initial stage of deglaciation in the study area was marked by aseries of readvances and/or stillstands. During this stage, thelower-lying glaciers were more sensitive to climatic ameliorationthan the higher glaciers. The subsequent phase was characterised bymore rapid deglaciation. Evidence for one instance of late-stage insitu glacier stagnation is described. The results indicate thatlandforms hitherto grouped as 'hummocky -moraine' formed by avariety of processes. Such moraines formed by (a) uneven depositionof supraglacially and/or -subglacially-derived debris at active icemargins, (b) deposition at the stagnant margins of otherwise activeglaciers, and (c) deposition during uninterrupted glacier retreat orareal stagnation. Differentiation and analysis of so-called 'hummockymoraine' enables glacier behaviour, during the Lateglacial to beinterpreted in great detail.