Introduction Polycrystalline aggregates in pure shear dynamic recrystallisation Grain shape and preferred orientation changes Grain shape and preferred orientation changes Fabric Evolution of glacial ice during deformation Movies References List of figures Acknowledgements Home
Figure 1. 1. 1
Figure 1. 1. 2
1. 1. 1. Quartz crystal showing location of main
crystal faces and principal crystallographic axes.
1. 1. 2. Schematic representation of the basal glide plane (0001) in ice in relation to non-basal glide planes and glide directions.
 
Figure 1. 1. 3
Figure 1. 2. 1
1. 1. 3. The flattening of a single crystal.
1. 2. 1. A Pure shear deformation.
 
Figure 1. 2. 2
Figure 1. 2. 3
1. 2. 2. Four undeformed polygonal grains with basal planes (0001) oriented at high-angle to the viewing plane.
1. 2. 3. A pure-shear deformation with 20% bulk
shortening and the relationship to the finite strain ellipse.
 
Figure 1. 2. 4
Figure 1. 4. 1
1. 2. 4. Principal-stress distribution.
1. 4. 1. Polycrystalline aggregates of
undeformed and deformed grains.
 
Figure 1. 4. 2
Figure 1. 4. 3
1. 4. 2. Random c-axis preferred-orientation in
undeformed verses strong fabric in deformed sample.
1. 4. 3. The c-axis distributions in pure shear
versus a simple shear regime.
 
Figure 1. 6. 1
Figure 1. 6. 2
1. 6. 1. Flow lines in an outlet glacier in the
Framnes Mountains, Antarctica (Marmo & Wilson 1998).
1. 6. 2. Longitudinal section parallel to the flow
lines in the Framnes Mountains glacier.
 
Figure 1. 6. 3
Figure 2. 1. 1
1. 6. 3. Divergent, parallel and convergent flow regimes and observed c-axes fabric associated with each.
2. 1. 1. In-situ simple shear deformation apparatus.
 
Figure 2. 1. 2
Figure 2. 2. 1
2. 1. 2. Plan view of in-situ pure shear deformation rig.
2. 2. 1. Simulated fabric development in flow lines
from an outlet glacier in the Framnes Mountains, Antarctica.
 
Figure 2. 3. 1
Figure 2. 3. 2
2. 3. 1. The crystal structure of ice Ih.
2. 3. 2. The propagation of a dislocation through
the basal plane of an ice lattice.
 
Figure 2. 5. 1
Figure 2. 6. 1
2. 5. 1. A Frank-Read source for the multiple
initiation of dislocation loops.
2. 6. 1. The Ice Ih lattice.
 
Figure 2. 8. 1
Figure 2. 9. 1
2. 8. 1. Deformation style of a single
crystal of ice using a cantilever.
2. 9. 1. Creep curves in ice.
 
Figure 2. 9. 2
Figure 2. 10. 1
2. 9. 2. A schematic sketch of stress-time curve
for deformation in a single crystal of ice at -10°C.
2. 10. 1. Two separated portions of a crystal with a model for calculating the resolved shear stress in a single crystal.
 
Figure 2. 11. 1
Figure 2. 14. 1
2. 11. 1. Data for glide on basal and non-basal systems, and in isotropic polycrystalline ice by Duval et al, (1983).
2. 14. 1. Schematic creep curve for
polycrystalline ice under constant load.
 
Figure 2. 15. 1
Figure 2. 15. 2
2. 15. 1. Plots of strain rate as a function of strain
for creep of granular polycrystalline ice in uniaxial compression.
2. 15. 2. The minimum strain rate is uniaxial creep tests on granular polycrystalline ice as functions of stress at various temperatures.
 
Figure 2. 17. 1
Figure 2. 19. 1
2. 17. 1. Deformation mechanism maps for
isotropic polycrystalline ice by Goodman et al. (1981).
2. 19. 1. Grain size reduction occurs in a shear
zone developed in coarse ice deformed at -2°C
 
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Created: August 23, 1999
Last modified: March 15, 2004
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