| Abstract: | The legacy of repeated Pleistocene glaciations has endowed many Welsh river valleys with locally thick successions of glacial and alluvial sediments. Investigations of a well-preserved flight of terraced sediments with good exposures at Capel Bangor, on the Afon Rheidol, mid-Wales, has allowed its Quaternary valley fill stratigraphy to be examined in detail. Study has revealed five terraced fills consisting of seven distinct sedimentary units. These range from Late Devensian ice-contact and ice-marginal deposits, to Holocene high-sinuosity stream sediments with episodes of man-induced accelerated deposition of fine-grained alluvium, and to aggradation and subsequent incision associated with historic metal mining. Examination of general sedimentary properties (e.g., granulometry, sedimentary structures, terrace surface morphology) show both differences in the pattern and controls of deposition and also progressive changes over Late Devensian and Holocene times. The sediments of the Rheidol Valley record the response and subsequent recovery of a drainage basin to glaciation, and the increasing influence of man on sediment yields, channel processes, and sediment quality. |
