Internal Structure of an Aeolian Dune using Ground-Penetrating Radar

  1. K. Pye2 and
  2. N. Lancaster3
  1. C. J. Schenk,
  2. D. L. Gautier,
  3. G. R. Olhoeft and
  4. J. E. Lucius

Published Online: 8 APR 2009

DOI: 10.1002/9781444303971.ch5

Aeolian Sediments: Ancient and Modern

Aeolian Sediments: Ancient and Modern

How to Cite

Schenk, C. J., Gautier, D. L., Olhoeft, G. R. and Lucius, J. E. (1993) Internal Structure of an Aeolian Dune using Ground-Penetrating Radar, in Aeolian Sediments: Ancient and Modern (eds K. Pye and N. Lancaster), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303971.ch5

Editor Information

  1. 2

    Reading, UK

  2. 3

    Reno, Nevada, USA

Author Information

  1. US Geological Survey, MS 971, Box 25046, Denver, CO 80225, USA

Publication History

  1. Published Online: 8 APR 2009
  2. Published Print: 27 MAY 1993

ISBN Information

Print ISBN: 9780632035441

Online ISBN: 9781444303971

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Keywords:

  • aeolian dune internal structure using ground-penetrating radar;
  • ground-penetrating radar in determining internal structures and geometry of large aeolian dune;
  • ground-penetrating radar and radio-frequency electromagnetic energy;
  • large dune radar survey;
  • sand-carrying wind directions with larger dune orientation;
  • dune structure evolution;
  • dune internal structure and sand-transporting wind complexity;
  • quantification of length-scales from radar cross-section

Summary

A ground-penetrating radar survey was made on a large complex aeolian dune along the margin of Great Sand Dunes National Monument, Colorado, to delineate the internal structures formed by dune migration in a complex wind regime. Radar waves were partially reflected from sediment interfaces that had differing densities or moisture contents. In this way bounding surfaces between sets could be interpreted from changes in the attitude of sets of reflectors. The radar reflectors were recorded to depths of 15 m, but the best resolution of bounding surfaces was obtained in the upper 5 m of the dune sand. Bounding surfaces interpreted from reflectors define a main dune set 5–8m thick, with foresets up to 23 m long. Thicknesses of other wedge-shaped and tabular planar sets range from 0.75 to 1.5 m, averaging 1 m; set lengths range from 6 to 12 m, averaging 8.5 m. Trough-shaped sets range in thickness from 0.5 to 3m, averaging 1.1m, and range in width from 5 to 22 m, averaging 10 m. These trough structures may have been caused by the migration of scour pits associated with small superimposed dunes, or may be the result of scour fills formed during reversing winds. Reversing winds also formed numerous subtle bounding surfaces (reactivation surfaces) along the leading edge of the dune as it migrated, defining sets ranging in thickness from 0.5 to 2 m, averaging 1 m, and with foreset lengths ranging from 15 to 23 m, averaging 20 m. This study demonstrates the usefulness of ground-penetrating radar in resolving the internal structures of damp to dry, clay-free, aeolian dune sand. The numerous sets and bounding surfaces resolved with radar indicate a relationship between the complexity of internal structure and the multiple directions of sand-carrying or sand-scouring winds. In a tectonically active basin such as the San Luis Valley, these complex aeolian dune sand bodies have excellent preservation potential.