Holocene floodplain diachronism and inherited downstream variations in fluvial processes: A study of the river Perry, Shropshire, England
作者:
Antony G. Brown,
期刊:
Journal of Quaternary Science
(WILEY Available online 1990)
卷期:
Volume 5,
issue 1
页码: 39-51
ISSN:0267-8179
年代: 1990
DOI:10.1002/jqs.3390050105
出版商: John Wiley&Sons, Ltd
关键词: Floodplain sediments;floodplain development;residence time;palaeoenvironments;Holocene
数据来源: WILEY
摘要:
AbstractThis paper attempts to explain downstream variations in the rates and processes of Holocene floodplain formation in a small to medium‐sized, lowland catchment in Central England. Four macro‐reaches were identified and horizons from at least one stratigraphic cross‐section from each were radiocarbon dated. Considerable diachronism was revealed with the basal age and hence minimum residence time of the top two metres varying from 1000‐9000yrs. The trend, adecreasein minimum residence time downstream, is explained by the basin‐and‐gorge bedrock long‐profile inherited from the Devensian glaciation of the area. This is illustrated by a positive relationship between the mean floodplain accumulation rate and the SL index (slope‐stream length product). Pollen analysis of the organic sediments shows that floodplain clearance took place around 1 300 BP, but probably locally, pre‐dated and post‐dated accelerated alluviation associated with agricultural expansion in the catchment. This study concludes that (a) different macro‐reaches in this small to medium‐sized catchment have adjusted in different ways to long‐term catchment changes as part of autogenic floodplain evolution, (b) this has involved a change in the catchment's sediment conveyance characteristics during the Holocene, and (c) an important control on channel behaviour and floodplain sedimentation throughout the Holocene (as well as at present) has been the valley slopes inherited from the Quaterna
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