The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation.
Investigation of drumlins is significant to both glaciology and palaeoglaciology but the sheer diversity of their composition and internal structure is often cited as a major obstacle towards a satisfactory (unifying?) explanation of their formation. This paper presents the first systematic survey o...
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Online Access: | http://dro.dur.ac.uk/11135/ http://dro.dur.ac.uk/11135/1/11135.pdf https://doi.org/10.1016/j.earscirev.2011.05.001 |
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ftunivdurham:oai:dro.dur.ac.uk.OAI2:11135 2023-05-15T16:41:38+02:00 The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation. Stokes, C.R. Spagnolo, M. Clark, C.D. 2011-08-01 application/pdf http://dro.dur.ac.uk/11135/ http://dro.dur.ac.uk/11135/1/11135.pdf https://doi.org/10.1016/j.earscirev.2011.05.001 unknown Elsevier dro:11135 issn:0012-8252 doi:10.1016/j.earscirev.2011.05.001 http://dro.dur.ac.uk/11135/ http://dx.doi.org/10.1016/j.earscirev.2011.05.001 http://dro.dur.ac.uk/11135/1/11135.pdf NOTICE: this is the author’s version of a work that was accepted for publication in 'Earth science reviews'. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Earth science reviews, 107 (3-4), 2011, 10.1016/j.earscirev.2011.05.001 Earth science reviews, 2011, Vol.107(3-4), pp.398-422 [Peer Reviewed Journal] Drumlin Subglacial bedforms Ice sheet Palaeoglaciology Glaciology Article PeerReviewed 2011 ftunivdurham https://doi.org/10.1016/j.earscirev.2011.05.001 2020-05-28T22:29:55Z Investigation of drumlins is significant to both glaciology and palaeoglaciology but the sheer diversity of their composition and internal structure is often cited as a major obstacle towards a satisfactory (unifying?) explanation of their formation. This paper presents the first systematic survey of the vast literature on this subject, with the aim of concisely summarising observations and identifying any emergent patterns or commonality that theories of drumlin formation should be able to explain. Results confirm that investigations are often limited by availability of suitable sediment exposures (40% of studies report data from < 5 drumlins and 44% do not specify sample size), although borehole data and geophysical techniques can alleviate this problem. However, it is clear that the constituents of drumlins are incredibly diverse in terms of their composition (e.g. a range of lithologies, clast shapes, sizes and fabrics); structure (e.g. sediments that are sorted, homogeneous, surface conformable, unconformable); and evidence of deformation (e.g. ranging from pervasive, to non-pervasive/limited, to absent). Despite this diversity, our review leads us to suggest that drumlin composition can be simplified to five basic types: (i), mainly bedrock, (ii), part bedrock/part till; (iii), mainly till; (iv), part till/part sorted sediments; and (v), mainly sorted sediments. This is a potentially significant step, in that it reduces the oft-cited complexity of drumlin composition and provides a more realistic goal for theories or numerical models of drumlin formation to target. The various types can occur within the same drumlin field, which leaves us with two possible implications for drumlin formation. (1) Different types of drumlin are formed/seeded by different processes, despite being morphologically similar (equifinality?) — investigation of drumlin composition may, therefore, reveal diagnostic processes/explanations for these different types of drumlin and we argue that bedrock ‘drumlins’ are an example. (2) A single process occurs across large parts of the ice-bed interface to create drumlinised terrain in a variety of sediments — investigation of drumlin composition may, in this case, simply reflect pre-existing sediments but, importantly, the way in which the drumlin-forming mechanism modifies/is modified by them. We argue that the latter, simpler, explanation applies to all other types of drumlin (excluding purely bedrock forms) and conclude that the diversity in drumlin composition is no obstacle to a single unifying theory. Article in Journal/Newspaper Ice Sheet Durham University: Durham Research Online Earth-Science Reviews 107 3-4 398 422 |
institution |
Open Polar |
collection |
Durham University: Durham Research Online |
op_collection_id |
ftunivdurham |
language |
unknown |
topic |
Drumlin Subglacial bedforms Ice sheet Palaeoglaciology Glaciology |
spellingShingle |
Drumlin Subglacial bedforms Ice sheet Palaeoglaciology Glaciology Stokes, C.R. Spagnolo, M. Clark, C.D. The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation. |
topic_facet |
Drumlin Subglacial bedforms Ice sheet Palaeoglaciology Glaciology |
description |
Investigation of drumlins is significant to both glaciology and palaeoglaciology but the sheer diversity of their composition and internal structure is often cited as a major obstacle towards a satisfactory (unifying?) explanation of their formation. This paper presents the first systematic survey of the vast literature on this subject, with the aim of concisely summarising observations and identifying any emergent patterns or commonality that theories of drumlin formation should be able to explain. Results confirm that investigations are often limited by availability of suitable sediment exposures (40% of studies report data from < 5 drumlins and 44% do not specify sample size), although borehole data and geophysical techniques can alleviate this problem. However, it is clear that the constituents of drumlins are incredibly diverse in terms of their composition (e.g. a range of lithologies, clast shapes, sizes and fabrics); structure (e.g. sediments that are sorted, homogeneous, surface conformable, unconformable); and evidence of deformation (e.g. ranging from pervasive, to non-pervasive/limited, to absent). Despite this diversity, our review leads us to suggest that drumlin composition can be simplified to five basic types: (i), mainly bedrock, (ii), part bedrock/part till; (iii), mainly till; (iv), part till/part sorted sediments; and (v), mainly sorted sediments. This is a potentially significant step, in that it reduces the oft-cited complexity of drumlin composition and provides a more realistic goal for theories or numerical models of drumlin formation to target. The various types can occur within the same drumlin field, which leaves us with two possible implications for drumlin formation. (1) Different types of drumlin are formed/seeded by different processes, despite being morphologically similar (equifinality?) — investigation of drumlin composition may, therefore, reveal diagnostic processes/explanations for these different types of drumlin and we argue that bedrock ‘drumlins’ are an example. (2) A single process occurs across large parts of the ice-bed interface to create drumlinised terrain in a variety of sediments — investigation of drumlin composition may, in this case, simply reflect pre-existing sediments but, importantly, the way in which the drumlin-forming mechanism modifies/is modified by them. We argue that the latter, simpler, explanation applies to all other types of drumlin (excluding purely bedrock forms) and conclude that the diversity in drumlin composition is no obstacle to a single unifying theory. |
format |
Article in Journal/Newspaper |
author |
Stokes, C.R. Spagnolo, M. Clark, C.D. |
author_facet |
Stokes, C.R. Spagnolo, M. Clark, C.D. |
author_sort |
Stokes, C.R. |
title |
The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation. |
title_short |
The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation. |
title_full |
The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation. |
title_fullStr |
The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation. |
title_full_unstemmed |
The composition and internal structure of drumlins : Complexity, commonality, and implications for a unifying theory of their formation. |
title_sort |
composition and internal structure of drumlins : complexity, commonality, and implications for a unifying theory of their formation. |
publisher |
Elsevier |
publishDate |
2011 |
url |
http://dro.dur.ac.uk/11135/ http://dro.dur.ac.uk/11135/1/11135.pdf https://doi.org/10.1016/j.earscirev.2011.05.001 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Earth science reviews, 2011, Vol.107(3-4), pp.398-422 [Peer Reviewed Journal] |
op_relation |
dro:11135 issn:0012-8252 doi:10.1016/j.earscirev.2011.05.001 http://dro.dur.ac.uk/11135/ http://dx.doi.org/10.1016/j.earscirev.2011.05.001 http://dro.dur.ac.uk/11135/1/11135.pdf |
op_rights |
NOTICE: this is the author’s version of a work that was accepted for publication in 'Earth science reviews'. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Earth science reviews, 107 (3-4), 2011, 10.1016/j.earscirev.2011.05.001 |
op_doi |
https://doi.org/10.1016/j.earscirev.2011.05.001 |
container_title |
Earth-Science Reviews |
container_volume |
107 |
container_issue |
3-4 |
container_start_page |
398 |
op_container_end_page |
422 |
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1766032090556530688 |