Morphological and morphometric analyses of drumlin bedforms in the omagh basin, north central ireland

Knight, Jasper

doi:10.1111/j.0435-3676.1997.00021.x

Cited by 21 publications

(12 citation statements)

References 10 publications

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“…The notion of a residual ice block also helps to account for the scale difference between the terrestrial and lake basin ice flow indicators. This theory conflicts with the conclusion by Knight (1997) that at the end of the last glacial an ice centre located in the Omagh Basin migrated into the Lower Lough Erne basin.…”

Section: Discussion and Limitationscontrasting

confidence: 71%

Subglacial imprints associated with the isolation and decay of an ice mass in the Lower Lough Erne basin, Co. Fermanagh, NW Ireland

Lafferty

Quinn

Breen

2006

JGS

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High-resolution Chirp sub-bottom profiler and side-scan sonar data record the final phases of ice margin activity in the Lower Lough Erne basin at the end of the last cycle of Quaternary glaciations in Ireland. Relative to the terrestrial glacial landforms the features in the Lough are smaller in scale and are considered to represent local ice mass dynamics that followed regional-scale events. Four phases are identified.(1) After the last ice sheet-wide readvance associated with the Killard Point Stadial (between 15.0 and 14.1 14 C ka bp), stagnation zone retreat resulted in isolation of a residual ice block in the Lower Lough Erne basin.(2) Proglacial waters developed coeval with retreat of the western margin of the ice block. Drawdown induced localized surging and the generation of push features and lineations. (3) Squeeze-up features, reflecting a heavily crevassed ice margin, mark the quiescent phase of the local surge cycle. (4) Iceberg grounding pits and keel marks record calving and rapid disintegration of the Lough Erne ice margin. The well-preserved glacigenic features observed in the lake basin suggest formation by a succession of mechanisms that were too short lived to obliterate the underlying evidence of ice margin dynamics. Reconstructions of regional deglacial dynamics of the Irish Ice Sheet using terrestrial and marine signatures are extensive

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Section: Discussion and Limitationscontrasting

confidence: 71%

Subglacial imprints associated with the isolation and decay of an ice mass in the Lower Lough Erne basin, Co. Fermanagh, NW Ireland

Lafferty

Quinn

Breen

2006

JGS

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“…(, ), Jansson & Glasser (), Johnson (, b) Johnson et al . (), Jordan (, ), Jowett (), Jowett & Charlesworth (), Kendall (, ), Kilfeather (), Kinahan (), King & Gage (), Knight (, , , , b, ), Knight et al . (, ), Knowles (), Lamb & Ballantyne (), Lawson (), Letzer (, ), Lewis (), Lewis & Richards (), Lintern (), Livingstone et al .…”

Section: References For Britice Glacial Map V2unclassified

BRITICE Glacial Map, version 2: a map and GIS database of glacial landforms of the last British–Irish Ice Sheet

Clark

Ely

Greenwood

et al. 2017

Boreas

127

118

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During the last glaciation, most of the British Isles and the surrounding continental shelf were covered by the BritishIrish Ice Sheet (BIIS). An earlier compilation from the existing literature (BRITICE version 1) assembled the relevant glacial geomorphological evidence into a freely available GIS geodatabase and map (Clark et al. 2004: Boreas 33, 359). New high-resolution digital elevation models, of the land and seabed, have become available casting the glacial landform record of the British Isles in a new light and highlighting the shortcomings of the V.1 BRITICE compilation. Here we present awholesale revision of the evidence, onshore and offshore, to produce BRITICE version 2, which now also includes Ireland. All published geomorphological evidence pertinent to the behaviour of the ice sheet is included, up to the census date of December 2015. The revised GIS database contains over 170 000 geospatially referenced and attributed elements -an eightfold increase in information from the previous version. The compiled data include: drumlins, ribbed moraine, crag-and-tails, mega-scale glacial lineations, glacially streamlined bedrock (grooves, roches moutonn ees, whalebacks), glacial erratics, eskers, meltwater channels (subglacial, lateral, proglacial and tunnel valleys), moraines, trimlines, cirques, trough-mouth fans and evidence defining ice-dammed lakes. The increased volume of features necessitates different map/database products with varying levels of data generalization, namely: (i) an unfiltered GIS database containing all mapping; (ii) a filtered GIS database, resolving data conflicts and with edits to improve geo-locational accuracy (available as GIS data and PDF maps); and (iii) a cartographically generalized map to provide an overviewof the distribution and types of features at the ice-sheet scale that can be printed at A0 paper size at a 1:1 250 000 scale. All GIS data, the maps (as PDFs) and a bibliography of all published sources are available for download from: https://www.sheffield.ac.uk/geography/staff/clark_chris/britice. Palaeo-ice sheets provide the opportunity to study icesheet behaviour over a longer time period (10 000s of years) than can be achieved by studying current ice sheets (10s of years) thereby permitting exploration of the long-term role of ice sheets in the climate system. The extent, geometry and dynamics of palaeo-ice sheets can be reconstructed from the geomorphological and geological evidence they leave behind, with the mapping, logging and description of such evidence being the vital ingredients. For many palaeo-ice sheets, such as the British-Irish Ice Sheet (BIIS), the accumulation of evidence at individual field-sites has been ongoing for well over 100 years (e.g. Geikie 1894) yielding thousands of publications. Using such work to build local to regional reconstructions of ice dynamics is feasible, but at the ice-sheet scale the volume of information becomes unmanageable. Often the information is spread across so many publications and across many decades of work, where...

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“…Many studies have examined the distribution (Vernon ; Hill ; Knight ; Greenwood and Clark ) and sedimentology of drumlins across Ireland, in particular where drumlins have been exposed by coastal erosion (McCabe et al . ; Hanvey ; McCabe and Dardis 1989a, ; Knight and McCabe ; Knight , , ).…”

Section: Introductionmentioning

confidence: 99%

“…McCabe ; Greenwood and Clark ). Bedrock‐cored drumlins with very little sediment cover are found in some hillslope settings (Knight ), and ‘hybrid’ drumlins containing fairly equal thicknesses of bedrock and sediments are also found in some coastal bedrock valleys (Knight ).…”

Section: Introductionmentioning

confidence: 99%

Subglacial hydrology and drumlin sediments in connemara, western ireland

Knight

2014

Geografiska Annaler: Series A, Physical Geography

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Sediment-cored drumlins are uncommon across the glacially eroded granite bedrock of Connemara (west County Galway, western Ireland). This paper describes the internal sediments from two significant drumlin exposures at Ardmore and Ballyconneely. Both drumlins show a lowermost lithofacies association comprising overconsolidated subglacial diamicton with clast lithology, strong fabrics and overfolds indicative of regional east/southeast to west/northwest late Weichselian ice flow. This lithofacies association is overlain at both sites by west-dipping, stratified, graded gravel and diamicton beds that downlap onto laminated silts. These beds reflect episodic debris flows into a leeside cavity developed following creation of relief by deposition and deformation of a subglacial diamicton nucleus located up-ice. Variations in substrate hydrological processes are identified in both drumlins based on the presence of clastic dikes, flame structures and debris flowdeposited gravels which are present at different locations spatially within the drumlin and at different stratigraphic levels. These features reflect the close connection between subglacial hydrological and sedimentary processes and their changes over time as the drumlin form develops.

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Morphological and morphometric analyses of drumlin bedforms in the omagh basin, north central ireland

Cited by 21 publications

References 10 publications

Subglacial imprints associated with the isolation and decay of an ice mass in the Lower Lough Erne basin, Co. Fermanagh, NW Ireland

Subglacial imprints associated with the isolation and decay of an ice mass in the Lower Lough Erne basin, Co. Fermanagh, NW Ireland

BRITICE Glacial Map, version 2: a map and GIS database of glacial landforms of the last British–Irish Ice Sheet

Subglacial hydrology and drumlin sediments in connemara, western ireland

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