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Historical valley alluviation in mid‐Wales
Author(s) -
Lewin J.,
Bradley S. B.,
Macklin M. G.
Publication year - 1983
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350180406
Subject(s) - aggradation , overbank , geology , floodplain , alluvium , channel (broadcasting) , sediment , geomorphology , canyon , hydrology (agriculture) , archaeology , fluvial , geography , cartography , geotechnical engineering , engineering , structural basin , electrical engineering
Recent developments on a floodplain reach of the Afon Ystwyth are analysed with the aid of five sets of maps and ten of air photographs covering the period since 1800. The area has been subjected to around 3 m of aggradation and then incision in association with historic metal mining. Analysis of sediment texture and metal concentrations allows subdivision of the mining‐associated sediments; C/M plots and shape analyses allow a distinction between proglacial, mining aggradation, and wandering river phases. The distinctive style of aggradation, involving overbank gravel splays and interfingering fines, and the lagged response of channel and sedimentation, relate largely to alterations in sediment supply rates. This has relevance for the interpretation of Quaternary fills and river terraces and for contemporary river management.