Geology Reference
In-Depth Information
Figure
8.6.
Pseudomorphs associated with thaw of ice wedges, Western Arctic Canada. (A) A
pseudomorph above partially-thawed ice wedge. (B) A partially-thawed composite (sand) wedge
comprises icy sand and sandy ice that is truncated along a planar, horizontal thaw contact. (C) An
ice-wedge pseudomorph with a tunnel comprising the middle section. From Murton and French
(1993b). Reproduced by permission of John Wiley & Sons Ltd.
that has formed above one wedge. This is a typical feature of the thaw-transformation
from an ice wedge to an ice-wedge pseudomorph (Harry and Gozdzik, 1988).
A fully developed ice-wedge pseudomorph is characterized by the penetration of mate-
rial into the fi ssure from above and from the sides, the downward infl ection of layers if
the enclosing sediments are stratifi ed, and various systems of miniature faults and dis-
placements. However, the majority of ice-wedge pseudomorphs are much more complex
than this. It must be stressed that the melt of the wedge ice and the release of any excess
ice (water) from the enclosing sediment may result in considerable deformation of the
original structure. Thus, a shape far removed from the simple wedge-like form can result.
A fuller discussion of ice-wedge pseudomorphs is given in Part III.
