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Erosional and depositional subglacial streamlining processes at Skálafellsjökull, Iceland: an analogue for a new bedform continuum model

Erosional and depositional subglacial streamlining processes at Skálafellsjökull, Iceland: an analogue for a new bedform continuum model
Erosional and depositional subglacial streamlining processes at Skálafellsjökull, Iceland: an analogue for a new bedform continuum model
We combine the use of the unique Glacsweb in situ embedded sensors, surface velocity measurements (from dGPS and remote sensing), and UAV and field photographic surveys, to understand the subglacial processes responsible for the formation of a series of subglacial bedforms composed of both till and
bedrock. There is till deformation throughout the year, with spatial and temporal variations. We estimate the ice velocity associated with the formation of a range of subglacial bedforms (9.2–31 m a−1) and the erosion rate on the bedrock flutes (2.13 mm a−1). We show that there is simultaneous deposition and erosion (either at the base of till or directly by ice) which generates flutes, large flutes and drumlins (rather than just depositional processes required by the instability theory). The flutes form behind obstacles associated with mobile till. Where a stationary obstacle is below a threshold height (which at this site is 1.56 m), either till tails will form behind the obstacle or a large flute will develop. Where a stationary obstacle is above a threshold height, then drumlins may form. Using these results as an analogue for larger bedforms, we discuss the bedform continuum in relation to elongation ratio, height, glacier velocity and bed mobility.These bedforms form associated with an overall net erosional regime, and once bedforms are produced, they may become fixed due to the presence of stationary obstacles, and so the resultant bedforms result from the most recent, as well as legacy, processes as they evolve over time.
glaciers, wireless sensor network, dGPS, remote sensing, UAV photography, Structure from motion (SfM), subglacial bedforms, flutes, subglacial proceses, till, drumlins
153-169
Hart, Jane
e949a885-7b26-4544-9e15-32ba6f87e49a
Clayton, Alexander
bb78b742-1324-4aa1-b6af-f75a1e60e01c
Martinez, Kirk
5f711898-20fc-410e-a007-837d8c57cb18
Robson, Benjamin
63357635-4f8e-4420-a528-92eeb764db62
Hart, Jane
e949a885-7b26-4544-9e15-32ba6f87e49a
Clayton, Alexander
bb78b742-1324-4aa1-b6af-f75a1e60e01c
Martinez, Kirk
5f711898-20fc-410e-a007-837d8c57cb18
Robson, Benjamin
63357635-4f8e-4420-a528-92eeb764db62

Hart, Jane, Clayton, Alexander, Martinez, Kirk and Robson, Benjamin (2018) Erosional and depositional subglacial streamlining processes at Skálafellsjökull, Iceland: an analogue for a new bedform continuum model. Geologiska Foreningens i Stockholm Forhandlingar (GFF), 140 (2), 153-169. (doi:10.1080/11035897.2018.1477830).

Record type: Article

Abstract

We combine the use of the unique Glacsweb in situ embedded sensors, surface velocity measurements (from dGPS and remote sensing), and UAV and field photographic surveys, to understand the subglacial processes responsible for the formation of a series of subglacial bedforms composed of both till and
bedrock. There is till deformation throughout the year, with spatial and temporal variations. We estimate the ice velocity associated with the formation of a range of subglacial bedforms (9.2–31 m a−1) and the erosion rate on the bedrock flutes (2.13 mm a−1). We show that there is simultaneous deposition and erosion (either at the base of till or directly by ice) which generates flutes, large flutes and drumlins (rather than just depositional processes required by the instability theory). The flutes form behind obstacles associated with mobile till. Where a stationary obstacle is below a threshold height (which at this site is 1.56 m), either till tails will form behind the obstacle or a large flute will develop. Where a stationary obstacle is above a threshold height, then drumlins may form. Using these results as an analogue for larger bedforms, we discuss the bedform continuum in relation to elongation ratio, height, glacier velocity and bed mobility.These bedforms form associated with an overall net erosional regime, and once bedforms are produced, they may become fixed due to the presence of stationary obstacles, and so the resultant bedforms result from the most recent, as well as legacy, processes as they evolve over time.

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Accepted/In Press date: 15 May 2018
e-pub ahead of print date: 11 June 2018
Published date: 2018
Keywords: glaciers, wireless sensor network, dGPS, remote sensing, UAV photography, Structure from motion (SfM), subglacial bedforms, flutes, subglacial proceses, till, drumlins

Identifiers

Local EPrints ID: 421518
URI: https://eprints.soton.ac.uk/id/eprint/421518
PURE UUID: 5318895c-a962-4317-9dea-317b8448b607
ORCID for Jane Hart: ORCID iD orcid.org/0000-0002-2348-3944
ORCID for Kirk Martinez: ORCID iD orcid.org/0000-0003-3859-5700

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Date deposited: 14 Jun 2018 16:30
Last modified: 08 Aug 2018 00:36

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Contributors

Author: Jane Hart ORCID iD
Author: Alexander Clayton
Author: Kirk Martinez ORCID iD
Author: Benjamin Robson

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