Connectivity analyses of valley patterns indicate Devensian glacial drainage activity in Mid-Wales Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, are believed to have acted as corridors for ice which drained the Welsh Ice Cap during the Devensian1,...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.617.4284 http://www.hig.se/download/18.51c1f7d3123eb47ebf580007522/connectivity+poster_sahlin.pdf |
| Summary: | Connectivity analyses of valley patterns indicate Devensian glacial drainage activity in Mid-Wales Coastal valleys in the west part of Mid-Wales, such as the Mawddach, Dysynni, Tal-y-llyn and Dyfi, are believed to have acted as corridors for ice which drained the Welsh Ice Cap during the Devensian1, 2. However, analysis of digital elevation models (DEMs) and interpretation of satellite images and aerial photographs reveal large variations in the amount of glacial modifi-cation between these valleys. Although all the valleys are glacially over-deepened along Silurian 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 little glacial modification of the preglacial fluvial valley pattern. Compared with the river valleys to the north it is unlikely that powerful ice streams existed in the Dyfi basin for significant parts of the Late Devensian. The general river valley morphology of the Dyfi basin is thus interpreted to be at least of a pre-Late Devensian age, the preservation due to cold-based ice. |
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