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Production and preservation of the smallest drumlins

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journal contribution
posted on 26.03.2018 by John Hillier, Ivar Benediktsson, Tom Dowling, Anders Schomacker
Few very small drumlins are typically mapped in previously glaciated landscapes, which might be an important signature of subglacial processes or an observational artefact. 143 newly emergent drumlins, recently sculpted by the Mulajokull glacier, have been mapped using high resolution LiDAR and aerial photographs in addition to field surveying. In this paper, these are used as evidence that few small drumlins (e.g. height H ≲ 4 m, width W ≲ 40 m, length L ≲ 100 m) are produced; at least, few survive to pass outside the ice margin in this actively forming drumlin field. Specifically, the lack of a multitude of small features seen in other landforms (e.g. volcanoes) is argued not to be due to i) Digital Elevation Model (DEM) resolution or quality, ii) mapper ability in complex (i.e. anthropogenically cluttered or vegetated) landscapes, or iii) post-glacial degradation at this site. So, whilst detection ability must still be at least acknowledged in drumlin mapping, and ideally corrected for in quantitative analyses, this observation can now be firmly taken as a constraint upon drumlin formation models (i.e. statistical, conceptual, or numerical ice flow). Our preferred explanation for the scarcity of small drumlins, at least at sites similar to Mulajokull (i.e. ice lobes with near-margin drumlin genesis), is that they form stochastically during multiple surge cycles, evolving from wide and gentle pre-existing undulations by increasing rapidly in amplitude before significant streamlining occurs.

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

GFF

Citation

HILLIER, J. ... et al, 2018. Production and preservation of the smallest drumlins. GFF, 140(2), pp. 136-152.

Publisher

© Geologiska Foreningen. Published by Taylor and Francis

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Acceptance date

12/03/2018

Publication date

2018-06-06

Notes

This is an original manuscript of an article published by Taylor & Francis in GFF, on 06 Jun 2018, available online: https://doi.org/10.1080/11035897.2018.1457714

ISSN

1103-5897

eISSN

2000-0863

Language

en

Exports