Newton, M. and Evans, D.J.A. and Roberts, D.H. and Stokes, C.R. (2018) 'Bedrock mega-grooves in glaciated terrain : a review.', Earth-science reviews., 185 . pp. 57-79.
Bedrock mega-grooves are assemblages of straight and parallel troughs eroded in bedrock, typically over 1000 m in length; most sites occur within the limits of the Last Glacial Maximum, both on- and off-shore. In this paper, we review the current understanding of these important yet enigmatic landforms and propose a framework for their future research. Mega-grooves are important to our understanding of ice sheet dynamics, ice–bedrock interactions and bedrock landscape evolution in glaciated areas. The overall straightness of mega-grooves across the landscape, their parallel alignment to palaeo-ice flow direction, and occurrence below the general land-surface level, has led to their unanimous interpretation as landforms of subglacial erosion. Scenarios proposed for mega-groove formation focus on either glacier ice or subglacial meltwater as the principal agent of erosion, yet none offers a comprehensive explanation. At locations where mega-grooves occur along lines of structural geology, their location, formation and morphology were largely controlled by the bedrock characteristics. Where no underlying structural control is apparent, mega-grooves were likely initiated through glacial abrasion, and subsequently modified through a range of erosional processes, potentially involving multiple morphogenetic agencies and feedbacks operating between bedrock topography and basal ice flow. In the absence of absolute dates, morphostratigraphic analyses suggest mega-groove survival through multiple glacial cycles. No specific ice-flow characteristics have been identified as a condition for bedrock grooving, but it has been suggested that some bedrock mega-grooves are related to ice streaming, which deserves further study. An initial analysis of bedrock grooves with seemingly similar morphology at a range of scales hints at a bedrock – groove landform size continuum, which could be a useful framework for exploring process landform relationships. Future research could usefully focus on quantitative analysis of mega-groove morphology, augmented with detailed field analysis of landform relationships to bedrock structure and lithology, and thereby potentially provide further insight into the age and glaciological significance of these landforms.
|Full text:||(AM) Accepted Manuscript|
Available under License - Creative Commons Attribution Non-commercial No Derivatives.
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|Publisher Web site:||https://doi.org/10.1016/j.earscirev.2018.03.007|
|Publisher statement:||© 2018 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/|
|Date accepted:||14 March 2018|
|Date deposited:||27 March 2018|
|Date of first online publication:||24 March 2018|
|Date first made open access:||24 March 2019|
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