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The topography of drumlins; assessing their long profile shape

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

Spagnolo, M, Clark, C.D, Hughs, A.L.C and Dunlop, P (2011) The topography of drumlins; assessing their long profile shape. Earth Surface Processes and Landforms, 36 (6). pp. 790-804. [Journal article]

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URL: http://onlinelibrary.wiley.com/doi/10.1002/esp.v36.6/issuetoc

DOI: 10.1002/esp.2107

Abstract

The literature on drumlins is pervaded by the notion that their longitudinal profile is usually highly asymmetric with a stoss steeper end and a lee gentler end, and that this can be used to infer the palaeo ice flow direction. The idea is built up in many papers covering more than a century of research. However, most of the early published papers were qualitative in nature and more recent quantitative papers appear to challenge the ubiquity of the classical stoss–lee shape. Here the shape of the drumlin longitudinal profile of 29,238 drumlins in the British Isles has been analysed. Drumlins were grouped into flowsets for which a palaeo ice flow direction was inferred independently of the drumlin shape. Given such ice flow directions it was then possible to identify the upflow and downflow ends of each drumlin and to trace and extract its longitudinal profile. Results indicate that the highest point of the drumlin is usually found around half way along the profile. The mean slope angles at the stoss and lee ends were found to be very similar. Finally, the average profile built from all mapped drumlins appears almost symmetric. In conclusion, drumlin longitudinal profile is far from being the classically asymmetric shape widely reported in text-book descriptions. Drumlins are mostly symmetrical in shape with a very slight tendency towards the classical shape. Highly asymmetric drumlins do exist but are rare and with an almost equal numbers of drumlins that are the reverse of this. These findings are verified both at the entire population level and the flowset level. This demonstrates that the idealized stoss–lee shape of classically-asymmetric drumlins is not representative of the population and should be replaced with that of mostly symmetric bumps. Drumlin shape is not a good indicator of the palaeo ice flow direction.

Item Type:Journal article
Keywords:drumlins, morphometry, longitudinal profile, asymmetry, shape
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Environmental Sciences
Research Institutes and Groups:Environmental Sciences Research Institute
Environmental Sciences Research Institute > Quaternary Environmental Change
ID Code:15934
Deposited By:Dr Paul Dunlop
Deposited On:24 May 2011 08:50
Last Modified:24 May 2011 08:50

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