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Title: An investigation into the relationship between joint and drainage patterns in selected drainage basins in South Wales
Author: Bent, P. F.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1983
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It has been repeatedly maintained that large parts of the rivers and streams of South Wales are not related to the inherent geological structure. This study is concerned with the identification of the jointing pattern in Devonian and Carboniferous strata for a region of the North Crop of the South Wales Coalfield between Ammanford (in the west) and Glynneath (in the east), which includes the complete Amman catchment and the upper reaches of the Tawe and Neath. Once such joint orientations had been recorded by intensive fieldwork, their influence on drainage development and evolution was attempted. Before the fieldwork programme was planned in detail, a pilot study was carried out to investigate the influence of joints on the guidance of stream networks. A positive response to such an investigation suggested that a more detailed study would be worthwhile. The joints at 168 sites were recorded, adopting a sampling design proposed by the author. This data was quantitatively analysed to derive values of preferred orientation for each joint site and to obtain a classification of joint orientations at the individual basin and inter-network levels, and thus examine the spatial variation of the dominant joint trends. The orientations of stream patterns were examined using the O.S. 1:10,560 maps and, once again, the derived data was carefully analysed in a similar fashion to that of the joint information. Comparisons between both types of orientational data during the course of fieldwork and, later, statistical analysis, revealed that large areas of the drainage network exhibited a high degree of structural adaptation. Other elements of the landscape considered were the orientations of valleys and those cave passages that are typical of the Carboniferous Limestone topography of the Tawe, Neath, Mellte, and Hepste river valleys. Once again, when the characteristic features of both these latter forms of orientational data were compared statistically with the joint trends, a high level of association was readily observed. Although this study did not discover any firm evidence that allowed a detailed chronological sequence of drainage development to be proposed, it did provide numerous examples where the geological structure, in the form of joint planes, has played a critical part in the development and subsequent evolution of the fluvial landscape of this sector of the South Wales Coalfield. Thus, while not suggesting the absence of the Chalk initially, its significance in drainage evolution was not thought to be that considerable.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available