Skip to main content
Article thumbnail
Location of Repository

Glacial erosion and bedrock properties in NW Scotland : abrasion and plucking, hardness and joint spacing

By Maarten Krabbendam and Neil F. Glasser


Subglacial erosion beneath glaciers occurs predominantly by abrasion and plucking, producing distinct erosional forms. The controls on the relative importance of abrasion vs. plucking are poorly understood. On the one hand, glacial conditions that favour or suppress cavity formation (ice velocity, ice thickness, and water pressure) are thought to favour plucking or abrasion, respectively. Conversely, bedrock properties are also known to control landforms, but this has rarely been analysed quantitatively. In this study we compare landforms and bedrock properties of sandstone and quartzite at the bed of a palaeo-ice stream near Ullapool in NW Scotland. The boundary between the rock types is at right angles to the westward palaeo-ice flow, and palaeoglacial conditions on both rock types were similar. We report quantitative parameters for bedrock properties (Schmidt hammer hardness and joint spacing) and use morphometric parameters to analyse the landforms. Torridon sandstone is soft but thick-bedded and with a wide joint spacing. Erosional bedforms include roche moutonnées with smoothed tops and concave stoss sides, whalebacks, and elongate p-forms, indicating a high proportion of abrasion over plucking. Cambrian quartzite is hard but thin-bedded with narrow joint spacing. Erosional landforms are angular to subangular with abundant plucked lee faces, suggesting a high proportion of plucking over abrasion. Hardness and joint spacing thus exert a strong control on subglacial erosional landforms and the mechanisms that formed them. Thus glacial conditions (ice velocity, ice thickness) can only be inferred from glacial erosional landforms if the effects of bedrock properties of the substrate are considere

Topics: Glaciology, Earth Sciences
Publisher: Elsevier
Year: 2011
DOI identifier: 10.1016/j.geomorph.2011.04.022
OAI identifier:

Suggested articles


  1. (2001). A quantitative study of the influence of pre-existing compositional and fabric heterogeneities upon fracture-zone development during basement reactivation.
  2. (1979). A theoretical model of glacial abrasion.
  3. (1996). Abraded rock landforms (whalebacks) developed under ice streams in mountain areas.
  4. (1988). Are roches moutonnées mainly preglacial forms?
  5. (2010). Bedrock fracture control of glacial erosion processes and rates.
  6. (1998). Beyond Power: Bedrock River Incision Process
  7. (2005). Boulder edge-roundness as an indicator of relative age: a Lochnagar case study.
  8. (2008). British Geological Survey,
  9. (1996). Cavities and the effective pressure between abrading clasts and bedrock.
  10. (1982). Controls on the stability and inclinations of hillslopes formed on hard rock.
  11. (1999). Coupled ice-till dynamics and the seeding of drumlins and bedrock forms.
  12. (2001). Development of joint-controlled rock basins in Bohus granite,
  13. (2004). Differences between veins and joints using the example of the Jurassic limestones of Somerset In:
  14. (2009). Dynamic cycles, ice streams and their impact on the extent, chronology and deglaciation of the British–Irish ice sheet.
  15. (2010). Edge-roundness of boulders of Torridonian Sandstone (northwest Scotland): applications for relative dating and implications for warm and cold climate weathering rates.
  16. (1966). Engineering Classification and Index Properties for Intact Rock. Air Force Weapons Laboratory
  17. (1992). Evolution of large roches moutonnées.
  18. (1998). Exposure dating and validation of periglacial weathering limits, northwest Scotland. doi
  19. (1930). Geologic history of the Yosemite Valley. doi
  20. (1989). Glacial erosion: Abrasion vs Plucking. MS for doi
  21. Glacial erosion: Abrasion vs Plucking. MS for Geomorphology Iverson, N.R., 1991a. Morphology of glacial striae: implications for abrasion of glacier beds and fault surfaces.
  22. (2004). Glacial erosional landforms; origins and significance for palaeoglaciology.
  23. (1996). Glacial quarrying: a simple theoretical model.
  24. (1996). Glacial striae and former ice movement; the evidence from Assynt, Sutherland. doi
  25. (2008). Ice caps existed throughout the lateglacial interstadial in northern Scotland.
  26. (1981). Ice-scoured topography and its relationship to bedrock structure and ice movements in parts of northern Scotland and west Greenland. Geografiska Annaler 63A,
  27. in press. Lateral plucking as a mechanism for elongate erosional glacial bedforms: explaining megagrooves doi
  28. (2009). Influence of rock mass strength on the erosion rate of alpine cliffs. doi
  29. (2001). Inherited landforms and glacial impact of different palaeosurfaces in southwest Sweden. Geografiska Annaler 83A,
  30. (1996). Is erosion by deforming subglacial sediments significant? (Toward till continuity).
  31. (1994). Joint control in the formation of rock steps in the subglacial environment. In:
  32. (2010). Keanchulish P-forms. In:
  33. (1996). Landscapes of aerial scouring in NW Scotland.
  34. (2009). Lateglacial ice-cap dynamics in NW Scotland: evidence from the fjords of the Summer Isles region. doi
  35. (2009). Laurentian palaeostress trajectories and ephemeral fracture permeability, Cambrian Eriboll Formation sandstones west of the Moine Thrust Zone, NW Scotland. doi
  36. (1998). Lithological and structural controls on the surface wear characteristics of glaciated metamorphic bedrock surfaces: Ossian Sarsfjellet, Svalbard.
  37. (1990). Medium scale landforms of glacial erosion in south Greenland; process and form.
  38. (2008). Megagrooves and streamlined bedrock in NW Scotland: the role of ice streams in landscape evolution.
  39. (1995). Nunataks of the last ice sheet in Northwest Scotland. doi
  40. (1995). Periglacial features in Assynt
  41. (2010). Polythermal ice in the Assynt Mountains: Ice sheet thickness, deglaciation and differential erosion.
  42. (1991). Potential effects of subglacial water-pressure fluctuations on quarrying.
  43. (1979). Processes of glacier erosion on different substrata.
  44. (2000). River incision into bedrock; mechanics and relative efficacy of plucking, abrasion, and cavitation. doi
  45. (1981). Rock jointing and abrasion forms on roches moutonnées, SW Finland.
  46. (1991). Rock resistance to erosion: some further considerations.
  47. (2004). Rock strength and development of glacial valley morphology
  48. (1999). Scotland: Cambrian and Ordovician of the Hebridean Terrane.
  49. (2001). Sediment and rock strength controls on river incision into bedrock. doi
  50. (1943). Sheet structure in granites: its origin and use as a measure of glacial erosion in New England.
  51. (1996). Sliding of till over bedrock: scratching, polishing, comminution and kinematic-wave theory.
  52. (2003). Stac Pollaidh: A Late Devensian Nunatak? Quaternary Newsletters 100,
  53. (2005). Streamlined bedrock terrain and fast ice flow, Jakobshavns Isbrae, West Greenland; implications for ice stream and ice sheet dynamics.
  54. (1996). Structural geology of rocks and regions.
  55. (2004). The feedback between joint-zone development and downward erosion of regularly spaced canyons in the Navajo Sandstone, Zion National Park,
  56. (2010). The geology and landscape of the Northwest Highlands: an introduction. In:
  57. (1999). The glacial impact on an exhumed subMesozoic etch surface in southwestern Sweden.
  58. (1968). The influence of glacial erosion and rock structure on corries
  59. (1992). The influence of rock mass strength on glacial valley cross-profile morphometry: a case study from the Southern Alps, New Zealand.
  60. (1998). The last ice sheet in northwest Scotland; reconstruction and implications.
  61. (2002). The later Proterozoic Torridonian Rocks of Scotland: Their Sedimentology, Geochemistry and Origin. doi
  62. (2005). The Minch palaeo-ice-stream: NW sector of the British-Irish Ice Sheet. doi
  63. (2008). The northern sector of the last British Ice Sheet: maximum extent and demise.
  64. (1996). The role of bedrock topography, structure, ice dynamics and preglacial weathering in controlling subglacial erosion beneath a high-latitude, maritime ice field.
  65. (2005). The Schmidt hammer in rock material characterization.
  66. (2002). The significance of rock structure, lithology and pre-glacial deep weathering for the shape of intermediate-scale glacial erosional landforms. doi
  67. (2011). The use of the Schmidt Hammer and Equotip for rock hardness assessment in geomorphology and heritage science: a comparative analysis. doi
  68. (1990). Tidal and storm influenced sedimentation from a Cambrian transgressive passive margin sequence. doi
  69. (1998). Using inherited cosmogenic 36Cl to constrain glacial erosion rates of the Cordilleran ice sheet.

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.