HOLOCENE FLOODPLAIN DIACHRONISM AND INHERITED DOWNSTREAM VARIATIONS IN FLUVIAL PROCESSES - A STUDY OF THE RIVER PERRY, SHROPSHIRE, ENGLAND

被引：27

作者：

BROWN, AG

机构：

[1] Soils and Sediments Research Laboratory, Geography Department, University, Leicester

来源：

JOURNAL OF QUATERNARY SCIENCE | 1990年 / 5卷 / 01期

关键词：

floodplain development; Floodplain sediments; Holocene; palaeoenvironments; residence time;

D O I：

10.1002/jqs.3390050105

中图分类号：

P9 [自然地理学];

学科分类号：

0705 ; 070501 ;

摘要：

This 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, a decrease in 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 Quaternary glaciation of the area. Copyright © 1990 John Wiley & Sons, Ltd

引用

页码：39 / 51

页数：13

共 43 条

[1] Allen J.R.L., A review of the origin and characteristics of ancient alluvial sediments, Sedimentology, 5, pp. 89-191, (1965)
[2] Barber K.E., Twigger S.N., Late Quaternary Palaeoecology of the Severn Basin, Palaeohydrology in Practice, pp. 217-250, (1987)
[3] Beales P.W., The Late Devensian and Flandrian vegetational history of Crose Mere, Shropshire, New Phytologist, 85, pp. 133-161, (1980)
[4] Boulton G.S., Worsley P., Late Weichselian glaciation in the Cheshire‐Shropshire basin, Nature, 207, pp. 704-706, (1965)
[5] Bowen D.Q., (1977)
[6] Brakenridge G.R., Late Quaternary floodplain sedimentation along the Pomme de Terre River, southern Missouri, Quaternary Research, 15, pp. 62-76, (1981)
[7] Bridge J.S., Paleochannel patterns inferred from alluvial deposits: a critical evaluation, Journal of Sedimentary Petrology, 55, pp. 579-589, (1985)
[8] Brown A.G., Human impact on former floodplain woodlands of the Severn, Archaeological Aspects of Woodland Ecology, pp. 93-105, (1982)
[9] Brown A.G., Long‐term sediment storage in the Severn and Wye catchments, Palaeohydrology in Practice, pp. 307-332, (1987)
[10] Brown A.C., The palaeoecology of Alnus (alder) and the postglacial history of floodplain vegetation: pollen percentage and influx data from the West Midlands, UK, New Phytologist, 110, pp. 425-436, (1988)

← 1 2 3 4 5 →