Rhind, David W.

2019-02-15T14:18:16Z

2019-02-15T14:18:16Z

1968

This study is concerned with an analysis of terrace forms in recently glacierised areas and in particular those existing in the Tweed Valley. It attempts to establish how significant terrace fragments are as records of geoaorphological evolution of an area, how easily they can be grouped and what has been the Late- and Post-Glacial history of the Tweed Valley. A review of some of the relevant literature on other, broadly comparable areas is followed by proposals for new definitions and a new classification of terrace fragments based on surface morphology and on downvalley gradient with cress valley height relationship respectively. The limits at which down and cross valley correlation can be carried out are discussed, along with the usual interpretations laid on the terrace sequences reported in the literature. A full discussion of both the possible and the employed means of mapping and heighting terrace fragments leads to the conclusion that, for the present purposes, only mapping on a scale of 1/10,560 and accurate levelling or tacheoraetric survey is suitable. As no recent account has summarised the geomorphological knowledge pertaining to the field area, the available literature has been summarised and added to in an analysis of the pre-terrace landscape elements, A detailed description of all of the mapped terrace fragments and associated fluvioglacial features is provided, arranged by splitting the Tweed Valley into three sub-areas. Virtually all of these terrace fragments were accurately heighted and the 11,000 resultant spot heights are reproduced in ap endix form and also on a series of vertical linear projection planes. The 'representative nature' of these results has been tested by taking a sample from the total number of fragments and statistically testing the variations in projected height and gradient possible by systematically excluding certain heights on a fragment. Correlation of individual fragments was carried out wherever possible, viewed in the light of distortions caused by the forms and distribution of the projection planes involved. A successful experiment involving the fitting of low order trend surfaces to individual fragments and the attempted correlation of these surfaces is reported. This employed spot heights in rectangular grid layouts on well-preserved fragments in the Fleurs Castle area. The value of steering these trend surfaces around valley meanders by changing the geographical coordinate system and the variation in trend surface form due to different point distribution patterns have also been investigated. The terrace sequence obtained for the whole valley is markedly different to those sequenoes often obtained in comparable areas, particularly in other parts of the British Isles. It consists essentially of several laterally-disparate suites of high gradient, ice-proximal outwash terraces, truncated at lower levels by low gradient ice-distant outwash terraces and Post-Glacial river terraces. The upstream extremities of the high gradient forms is believed to mark the approximate positions of still-stands or readvances of the downwasting ice mass formerly occupying the Tweed Valley.

http://hdl.handle.net/1842/33672

The University of Edinburgh

Annexe Thesis Digitisation Project 2019 Block 22

Already catalogued

Terraces of the Tweed Valley

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy