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Title: The boulder bed group (Dalradian) of Co. Donegal, Eire
Author: Howarth, Richard J.
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 1966
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The Dalradian Boulder Bed Group is particularly complete and well exposed at Glencolumbkille, Kiltyfanned, and Fanad in Co. ' Donegal. The succession consists of graphitic schists followed successively by striped schist, dolomite, dolomitic boulder bed, semipelitic boulder bed and increasingly psammitic boulder bed with interbedded quartzites, dolomitic schist, and finally the thick Slieve Tooey Quartzite. The till-like Boulder Bed has been cited as evidence for Eocambrian glaciation. Recently, the glacial origin of similar deposits has been seriously questioned, and this study is a critical re-examination of the Group, and of the Boulder Bed in particular, in order to appraise the hypothesis of a glacial origin. The Boulder Bed is described in special detail with emphasis on the sedimentary structures, and composition of the clasts and matrix. The digital computer techniques of cluster and factor analysis have been used as an aid to achieving an objective analysis of quantitative data on the mineralogical and chemical composition of the Boulder Bed, and the Kiltyfanned Schist which lies at the junction of the Boulder Bed and the Slieve Tooey Quartzite. The presence of ice-rafted clasts and a matrix probably containing rock flour in the original sediment is established, and most of the evidence points to an origin as a till deposited beneath a wet-base glacier in a glacio-marine environment. It is suggested that the source area may have lain to the south or south-east of the present regional strike, and probably consisted of a granitic and metamorphic basement complex overlain by sedimentary cover.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available