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Implications of till deformation on glacier dynamics

  • Martin Truffer (a1), Keith A. Echelmeyer (a1) and William D. Harrison (a1)

Abstract

The dynamics of glacier motion are governed to a large extent by the properties of the basal interface. In this paper we address the interaction of a glacier with a layer of till at its bed in an attempt to test whether our physical understanding of till is sufficient to explain general features of the observed flow field and changes in geometry of Black Rapids Glacier, Alaska, U.S.A. We also investigate whether or not a till layer has a clear surface-observable signature in the dynamics of the glacier. Towards this end we use a finite-element ice-flow model with a Coulomb failure criterion within the basal till layer. We find that simple “till physics” can be used to describe decadal, seasonal and short-term (hours to days) velocity variations, and possibly uplift events. Mechanisms for each of these variations involve an increase in the extent of till at failure, a transfer of shear stress across the bed, and a consequent increase in ice deformation. “Effective shape factors” are calculated that permit a simple incorporation of this boundary condition into glacier response models. Our analyses, however, have not resulted in the identification of a clear and unique signature of a till layer in the surface dynamics of a glacier.

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References

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Balise, M. J. and Raymond, C. F.. 1985. Transfer of basal sliding variations to the surface of a linearly viscous glacier. J. Glaciol., 31(109), 308318
Boulton, G. S. and Dobbie, K. E.. 1998. Slow flow of granular aggregates: the deformation of sediments beneath glaciers. Philos. Trans. R. Soc. London, 356, 27132745.
Boulton, G. S. and Hindmarsh, R. C. A.. 1987. Sediment deformation beneath glaciers: rheology and geological consequences. J. Geophys. Res., 92(B9), 90599082.
Budd, W. F., Keage, P. L. and Blundy, N. A.. 1979. Empirical studies of ice sliding. J. Glaciol., 23(89), 157170.
Clarke, G. K. C. 1987. Subglacial till: a physical framework for its properties and processes. J. Geophys. Res., 92(B9), 90239036.
Cochran, O. D. 1995. The subglacial hydraulics of the surge-type Black Rapids Glacier, Alaska: a schematic model. (M.Sc. thesis, University of Alaska Fairbanks.)
De Marsily, G. 1986. Quantitative hydrogeology. San Diego, CA, Academic Press Inc.
Echelmeyer, K. A. 1983. Response of Blue Glacier to a perturbation in ice thickness: theory and observations. (Ph.D. thesis, California Institute of Technology.)
Echelmeyer, K. A., Harrison, W. D., Larsen, C. and Mitchell, J. E.. 1994. The role of the margins in the dynamics of an active ice stream. J. Glaciol., 40(136), 527538.
Fischer, U. H., Clarke, G. K. C. and Blatter, H.. 1999. Evidence for temporally varying “sticky spots” at the base of Trapridge Glacier, Yukon Territory, Canada. J. Glaciol., 45(150), 352360.
Fountain, A. G. and Walder, J. S.. 1998. Water flow through temperate glaciers. Rev. Geophys., 36(3), 299328.
Freeze, R. A. and Cherry, J. A.. 1979. Groundwater. Englewood Cliffs, NJ, Prentice-Hall.
Gades, A. M. 1998. Spatial and temporal variations of basal conditions beneath glaciers and ice sheets inferred from radio echo soundings. (Ph.D. thesis, University of Washington.)
Gudmundsson, G. H. 1999. A three-dimensional numerical model of the confluence area of Unteraargletscher, Bernese Alps, Switzerland. J. Glaciol., 45(150), 219230.
Gudmundsson, G. H., Iken, A. and Funk, M.. 1997. Measurements of ice deformation at the confluence area of Unteraargletscher, Bernese Alps, Switzerland. J. Glaciol., 43(145), 548556.
Harbor, J. M. 1992. Application of a general sliding law to simulating flow in a glacier cross-section. J. Glaciol., 38(128), 182190. (Erratum: 38(129), p. 316.)
Harrison, W. D., Kamb, B. and Engelhardt, H.. 1986. Morphology and motion at the bed of a surge-type glacier. [Abstract.] Eidg. Tech. Hochschule, Zürich. Versuchsanst. Wasserbau, Hydrol. Glaziol. Mitt. 90, 5556.
Harrison, W. D., Echelmeyer, K. A., Cosgrove, D. M. and Raymond, C. F.. 1992. The determination of glacier speed by time-lapse photography under unfavourable conditions. J. Glaciol., 38(129), 257265.
Heinrichs, T. A., Mayo, L. R., Echelmeyer, K. A. and Harrison, W. D.. 1996. Quiescent-phase evolution of a surge-type glacier: Black Rapids Glacier, Alaska, U.S.A. J. Glaciol., 42(140), 110122.
Hobbs, P.V. 1974. Ice physics. Oxford, Clarendon Press.
Hodge, S. M. 1974. Variations in the sliding of a temperate glacier. J. Glaciol., 13(69), 349369.
Hooke, R. LeB. 1981. Flow law for polycrystalline ice in glaciers: comparison of theoretical predictions, laboratory data, and field measurements. Rev. Geophys. Space Phys., 19(4), 664672.
Hooke, R. LeB. 1998. Principles of glacier mechanics. Upper Saddle River, NJ, Prentice Hall.
Hooke, R. LeB., Hanson, B., Iverson, N. R., Jansson, P. and Fischer, U. H.. 1997. Rheology of till beneath Storglaciären, Sweden. J. Glaciol., 43(143), 172179
Hubbard, A., Blatter, H., Nienow, P., Mair, D. and Hubbard, B.. 1998. Comparison of a three-dimensional model for glacier flow with field data from Haut Glacier d’Arolla, Switzerland. J. Glaciol., 44(147), 368378.
Iken, A. and Truffer, M.. 1997. The relationship between subglacial water pressure and velocity of Findelengletscher, Switzerland, during its advance and retreat. J. Glaciol., 43(144), 328338.
Iken, A., Röthlisberger, H., Flotron, A. and Haeberli, W.. 1983. The uplift of Unteraargletscher at the beginning of the melt season — a consequence of water storage at the bed? J. Glaciol., 29(101), 2847.
Iken, A., Fabri, K. and Funk, M.. 1996. Water storage and subglacial drainage conditions inferred from borehole measurements on Gornergletscher, Valais, Switzerland. J. Glaciol., 42(141), 233248.
Iverson, N. R., Hooyer, T. S. and Baker, R. W.. 1998. Ring-shear studies of till deformation: Coulomb-plastic behavior and distributed strain in glacier beds. J. Glaciol., 44(148), 634642.
Kamb, B. 1987. Glacier surge mechanism based on linked cavity configuration of the basal water conduit system. J. Geophys. Res., 92(B9), 90839100.
Kamb, B. 1991. Rheological nonlinearity and flow instability in the deforming bed mechanism of ice stream motion. J. Geophys. Res., 96(B10), 16,58516,595.
Kamb, B., Engelhardt, H., Fahnestock, M. A., Humphrey, N., Meier, M. and Stone, D.. 1994. Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier. 2. Interpretation. J. Geophys. Res., 99(B8), 15,23115,244.
Lliboutry, L. 1968. General theory of subglacial cavitation and sliding of temperate glaciers. J. Glaciol., 7(49), 2158.
Nolan, M. and Echelmeyer, K.. 1999a. Seismic detection of transient changes beneath Black Rapids Glacier, Alaska, U.S.A.: I. Techniques and observations. J. Glaciol., 45(149), 119131.
Nolan, M. and Echelmeyer, K.. 1999b. Seismic detection of transient changes beneath Black Rapids Glacier, Alaska, U.S.A.: II. Basal morphology and processes. J. Glaciol., 45(149), 132146.
Paterson, W. S. B. 1994. The physics of glaciers. Third edition. Oxford, etc., Elsevier.
Raymond, C. F. 1971. Flow in a transverse section of Athabasca Glacier, Alberta, Canada. J. Glaciol., 10(58), 5584.
Raymond, C. F. and Harrison, W. D.. 1988. Evolution of Variegated Glacier, Alaska, U.S.A., prior to its surge. J. Glaciol., 34(117), 154169.
Reynaud, L. 1973. Flow of a valley glacier with a solid friction law. J. Glaciol., 12(65), 251258.
Shreve, R. L. 1972. Movement of water in glaciers. J. Glaciol., 11(62), 205214.
Truffer, M., Motyka, R. J., Harrison, W. D., Echelmeyer, K. A., Fisk, B. and Tulaczyk, S.. 1999. Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions. J. Glaciol., 45(151), 495505.
Truffer, M., Harrison, W. D. and Echelmeyer, K. A.. 2000. Glacier motion dominated by processes deep in underlying till. J. Glaciol., 46(153), 213221.
Tulaczyk, S. M., Kamb, B. and Engelhardt, H. F.. 2000. Basal mechanics of Ice Stream B, West Antarctica. I. Till mechanics. J. Geophys. Res., 105(B1), 463481.
Walder, J. S. and Fowler, A.. 1994. Channelized subglacial drainage over a deformable bed. J. Glaciol., 40(134), 315.
Weertman, J. 1957. On the sliding of glaciers. J. Glaciol., 3(21), 3338.
Willis, I. C. 1995. Intra-annual variations in glacier motion: a review. Prog. Phys. Geogr., 19(1), 61106.
Wood, D. M. 1990. Soil behaviour and critical state soil mechanics. Cambridge, Cambridge University Press.
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Journal of Glaciology
  • ISSN: 0022-1430
  • EISSN: 1727-5652
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