Anatomy and Facies Association of a Drumlin in Co. Down, Northern Ireland, from Seismic and Electrical Resistivity Surveys

  1. Michael J. Hambrey4,
  2. Poul Christoffersen4,5,
  3. Neil F. Glasser4 and
  4. Bryn Hubbard4
  1. Bernd Kulessa1,
  2. Gordon Clarke2,
  3. David A. B. Hughes2 and
  4. S. Lee Barbour3

Published Online: 24 MAR 2009

DOI: 10.1002/9781444304435.ch11

Glacial Sedimentary Processes and Products

Glacial Sedimentary Processes and Products

How to Cite

Kulessa, B., Clarke, G., Hughes, D. A. B. and Barbour, S. L. (2007) Anatomy and Facies Association of a Drumlin in Co. Down, Northern Ireland, from Seismic and Electrical Resistivity Surveys, in Glacial Sedimentary Processes and Products (eds M. J. Hambrey, P. Christoffersen, N. F. Glasser and B. Hubbard), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304435.ch11

Editor Information

  1. 4

    Centre for Glaciology, Institute of Geography & Earth Sciences, Aberystwyth University, Wales, Ceredigion SY23 3DB, UK

  2. 5

    Scott Polar Research Institute, University of Cambridge, Lensfield Road, Cambridge, CB2 1ER, UK

Author Information

  1. 1

    School of the Environment and Society, University of Wales Swansea, Singleton Park, Swansea, SA2 8PP, UK

  2. 2

    School of Planning, Architecture, and Civil Engineering, Queen's University Belfast, Belfast, BT9 5AG, UK

  3. 3

    Department of Civil and Geological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, SK S7N 5A9, Canada

Publication History

  1. Published Online: 24 MAR 2009
  2. Published Print: 14 DEC 2007

Book Series:

  1. Special Publication Number 39 of the International Association of Sedimentologists

Book Series Editors:

  1. Isabel Montanez

Series Editor Information

  1. University of California, Davis, USA

ISBN Information

Print ISBN: 9781405183000

Online ISBN: 9781444304435

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Keywords:

  • anatomy and facies association of Drumlin in co. down, northern Ireland, from seismic and electrical resistivity surveys;
  • seismic refraction and electrical resistivity geophysical techniques;
  • seismic refraction surveys;
  • field site and methods;
  • electrical resistivity surveys creating electrical current in ground using two electrodes and measure;
  • borehole logs and relevant field observations;
  • calibration of geophysical data;
  • topsoil and glacial till units

Summary

Seismic refraction and electrical resistivity geophysical techniques were used to reconstruct the internal architecture of a drumlin in Co. Down, Northern Ireland. Geophysical results were both validated and complemented by borehole drilling, flow modelling of ground water, and geological mapping. The geophysical anatomy of the drumlin consists of five successive layers with depth including; topsoil, partially saturated and saturated glacial tills, and weathered and more competent greywacke bedrock. There are numerous, often extensive inclusions of clay, sand, gravel, cobbles, and boulders within the topsoil and the till units. Together geophysical and geotechnical findings imply that the drumlin is part of the subglacial lodgement, melt-out, debris flow, sheet flow facies described by previous authors, and formed by re-sedimentation and streamlining of pre-existing sediments during deglaciation of the Late Devensian ice sheet. Seismic refraction imaging is particularly well suited to delineating layering within the drumlin, and is able to reconstruct depths to interfaces to within ±0.5 m accuracy. Refraction imaging ascertained that the weathered bedrock layer is continuous and of substantial thickness, so that it acts as a basal aquifer which underdrains the bulk of the drumlin. Electrical resistivity imaging was found to be capable of delineating relative spatial changes in the moisture content of the till units, as well as mapping sedimentary inclusions within the till. The moisture content appeared to be elevated near the margins of the drumlin, which may infer a weakening of the drumlin slopes. Our findings advocate the use of seismic refraction and electrical resistivity methods in future sedimentological and geotechnical studies of internal drumlin architecture and drumlin formation, owing particularly to the superior, 3-D spatial coverage of these methods.