Connectivity analyses of valley patterns indicate preservation of a preglacial fluvial valley system in the Dyfi basin, Wales

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dc.contributor.author Sahlin, Eva A. U.
dc.contributor.author Glasser, Neil F.
dc.contributor.author Jansson, Krister N.
dc.contributor.author Hambrey, Michael J.
dc.date.accessioned 2009-12-22T16:23:28Z
dc.date.available 2009-12-22T16:23:28Z
dc.date.issued 2009-12-01
dc.identifier.citation Sahlin , E A U , Glasser , N F , Jansson , K N & Hambrey , M J 2009 , ' Connectivity analyses of valley patterns indicate preservation of a preglacial fluvial valley system in the Dyfi basin, Wales ' Proceedings of the Geologists' Association , vol 120 , pp. 245-255 . , 10.1016/j.pgeola.2009.10.001 , 10.1016/j.pgeola.2009.10.001 en
dc.identifier.issn 0016-7878
dc.identifier.other PURE: 142753
dc.identifier.other dspace: 2160/3898
dc.identifier.uri http://hdl.handle.net/2160/3898
dc.description Sahlin, E. A. U., Glasser, N. F., Jansson, K., Hambrey, M. J. (2009). Connectivity analyses of valley patterns indicate preservation of a preglacial fluvial valley system in the Dyfi basin, Wales. Proceedings of the Geologists’ Association 120, pp. 114-127 Sponsorship: Countryside Council for Wales (CCW); Aberystwyth University en
dc.description.abstract Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, acted as corridors for ice which drained the Welsh Ice Cap during the Devensian. Analyses of detailed digital elevation models, and interpretation of satellite images and aerial photographs, show the existence of large variations in the amount of glacial modification between these valleys. Although all the valleys are glacially over-deepened along late Caledonian fault lines, only the Dyfi basin exhibits a dendritic pattern, with V-shaped cross-profiles and valley spurs typical of valleys formed by fluvial processes. Connectivity analysis of the Dyfi basin shows that it exhibits an almost completely dendritic pattern with connectivity and values of 0.74 and 1.01, respectively, with little glacial modification of the preglacial fluvial valley pattern in the form of glacial valley breaching. Several examples of glacial meltwater incision into a well-developed pre-existing river valley system, causing river capture across watersheds, have been identified in the Dyfi basin. The degree of preservation of the preglacial fluvial valley system within the Dyfi basin indicates limited modification by glacial processes, despite the area being subjected to glacier activity during the Late Devensian at least. It is possible that major parts of the basin were covered by cold-based or slow-moving ice, close to, or under, a migrating ice-divide, with the major ice drainage occurring along the weaker zone of the Pennal Fault along which teh Dyfi valley is located, causing minor adjustments to the surrounding interfluves and uplands. It is proposed here that the general river valley morphology of the Dyfi basin is of a pre-Late Devensian age. en
dc.format.extent 11 en
dc.language.iso eng
dc.relation.ispartof Proceedings of the Geologists' Association en
dc.title Connectivity analyses of valley patterns indicate preservation of a preglacial fluvial valley system in the Dyfi basin, Wales en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.identifier.doi http://dx.doi.org/10.1016/j.pgeola.2009.10.001
dc.contributor.institution Institute of Geography & Earth Sciences en
dc.contributor.institution Centre for Glaciology en
dc.description.status Peer reviewed en


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