Substratum control on tunnel-valley formation in Denmark

Peter B.E. Sandersen, Flemming Jørgensen

Research output: Chapter in Book/Report/Conference proceedingChapter in bookResearchpeer-review

22 Citations (Scopus)

Abstract

Tunnel valleys formed by meltwater erosion underneath the margins of the Pleistocene ice sheets are present in high numbers in the Danish onshore area. The geographical distribution of the buried tunnel valleys is uneven, but when comparing with the substrata lithology we find a large number of valleys in areas dominated by low-permeable sediment and a smaller number in areas with highly permeable substrata. The observations point to the drainage capacity of the ice-sheet substratum as an important factor controlling tunnel-valley formation. Tunnel-valley formation appears to be favoured in areas with low-permeable substrata because meltwater drainage through the sediments is impeded, leading to the formation of a channelized subglacial drainage system. The high transmissivity in areas dominated by permeable substrata facilitates drainage of a part of the meltwater as groundwater. This causes a lowering of the subglacial meltwater pressures, and tunnel-valley formation is less likely. Once formed and filled, the tunnel valleys cause a change of the hydraulic properties of the substratum and if subglacial water pressures underneath a subsequent ice advance are sufficiently high, old tunnel valleys will be prone to reactivation.

Original languageEnglish
Title of host publicationGlaciogenic reservoirs and hydrocarbon systems
EditorsM. Huuse, J. Redfern, D.P. le Heron, R.J. Dixon, A. Moscariello, J. Craig
Place of PublicationLondon
PublisherGeological Society of London
Pages145-157
Number of pages13
ISBN (Electronic)978-1-86239-348-6
DOIs
Publication statusPublished - 2012

Publication series

NameGeological Society, London, Special Publications
PublisherGeological Society of London
Volume368
ISSN (Electronic)0305-8719

Programme Area

  • Programme Area 2: Water Resources

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