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TitleCoastal peats from northwest Ireland: implications for late-Holocene relative sea-level change and shoreline evolution
AuthorShaw, J; Carter, R W G
SourceBoreas vol 23, 1994 p. 74-91,
Alt SeriesGeological Survey of Canada, Contribution Series 43992
Mediapaper; on-line; digital
File formatpdf
AreaCounty Donegal; Aranmore Island; Clonmass estuary; Roshin Point; Gweebarra Bay; Helgoland; Naran; Loughros More; Ballyness spit; Trawenagh Bay; Ireland
Lat/Long WENS -9.0000 -7.0000 55.3333 54.6667
Subjectssurficial geology/geomorphology; paleontology; marine geology; coastal environment; coastal studies; peat; Holocene; sea level changes; sedimentation; pollen; pollen analysis; palynology; Cenozoic
Illustrationssketch maps; histograms
Released2008 01 16
AbstractPeat and organic rich sediments at coastal sites in extreme northwest Ireland have accumulated in a wide variety of environments, often strongly influenced by late Holocene changes in relative sea level and by geomorphic processes. A deep peat sequence on the coast of Aranmore Island accumulated initially in a lake and subsequently in a freshwater marsh environment. The long pollen record serves as a template for regional events. It extends over much of the Holocene and shows relatively high levels of Pinus pollen up to just before the disappearance of this taxon at c. 3600 BP. Coastal peat occurrences elsewhere are much thinner and have accumulated over shorter periods; they contain further evidence to show that coastal areas were well-wooded compared with today, and that Pinus was an important woodland component prior to c. 4000 BP. At sites in Gweebarra Bay intertidal peats record the closure of small estuaries by geomorphological events during the past 5000 years. Coastal sites at Ballyness, Clonmass, and Trawenagh display regressive stratigraphies ˜ minerogenic marine sediments are overlain by silty peats capped by highly organic freshwater peats. Basal radiocarbon dates range from 4500 to 3300 BP. The silty peats are interpreted as having formed in salt-marsh environments and contain distinctive pollen spectra, marked by high levels of Pinus and Compositae Liguliflorae pollen. The data suggest that relative sea level attained levels close to that of today by the mid-Holocene in this region. The pattern of relative sea-level change agrees well with that predicted by geophysical modelling.