104
Climatic Geomorphology
.'U";.<"
....
--.-_
Figure 4.16. Simplified block diagram of the Holmstrrmbreen push moraine in Spitsbergen, with faults
and overthrusting folds. It is composed of fine-grained sediments (black) and till (triangles). Vertical scale
exaggerated (Van der Wateren, 1992; in Ehlers (1996), Figure 35).
carried by the glacier. The size of the accumulations also depends on the time that the
glacier stays in the same place. Thus, the moraine ridges of the Franz Josef glacier of
New Zealand, located in a coastal plain at the foot of the mountains, reached heights of
up to 430 m during a stationary stage.
Push moraines (Figure 4.11) are the result of advances of ice at the frontal margins,
forcing forward the material previously deposited by the glacier. This bulldozer effect
causes the formation of small, asymmetric moraine ridges that do not usually surpass 2 m
in height, with the greater gradient on the ice-facing slopes. The deposits are constituted of
glacial till, as well as fluvioglacial material. As a consequence of the ice push, imbricated
folds and inverse faults can occur (Sharp, 1982; Van der Wateren, 1992) (Figure 4.16). It is
also well known that the glaciers tend to advance in winter when melting processes are at
a minimum; these annual advances in a glacier in continuous retreat result in small ridges
whose spacing is related to the melting balance (Hewitt, 1967; Worsley, 1974); these
ridges are known as annual or De Geer moraines (Hoppe, 1959). Glaciers of spasmodic or
surging flow can produce large push moraines when they advance, with moraine ridges of
much greater size and a pronounced internal deformation.
Finally, when stagnant ice melts, disintegration moraines develop (Figure 4.11). In
these stagnant glaciers the highest areas are covered by debris that protect the ice from
melting, and the particles flow or slide toward the depressions. When the ice disappears
an inversion of the relief occurs, and the oldest accumulations of the depressions result
in small hills (Boulton, 1972). This landscape constitutes a hummocky moraine, characterized by an undulating relief composed of small hills and closed depressions.
Climatic Geomorphology
.'U";.<"
....
--.-_
Figure 4.16. Simplified block diagram of the Holmstrrmbreen push moraine in Spitsbergen, with faults
and overthrusting folds. It is composed of fine-grained sediments (black) and till (triangles). Vertical scale
exaggerated (Van der Wateren, 1992; in Ehlers (1996), Figure 35).
carried by the glacier. The size of the accumulations also depends on the time that the
glacier stays in the same place. Thus, the moraine ridges of the Franz Josef glacier of
New Zealand, located in a coastal plain at the foot of the mountains, reached heights of
up to 430 m during a stationary stage.
Push moraines (Figure 4.11) are the result of advances of ice at the frontal margins,
forcing forward the material previously deposited by the glacier. This bulldozer effect
causes the formation of small, asymmetric moraine ridges that do not usually surpass 2 m
in height, with the greater gradient on the ice-facing slopes. The deposits are constituted of
glacial till, as well as fluvioglacial material. As a consequence of the ice push, imbricated
folds and inverse faults can occur (Sharp, 1982; Van der Wateren, 1992) (Figure 4.16). It is
also well known that the glaciers tend to advance in winter when melting processes are at
a minimum; these annual advances in a glacier in continuous retreat result in small ridges
whose spacing is related to the melting balance (Hewitt, 1967; Worsley, 1974); these
ridges are known as annual or De Geer moraines (Hoppe, 1959). Glaciers of spasmodic or
surging flow can produce large push moraines when they advance, with moraine ridges of
much greater size and a pronounced internal deformation.
Finally, when stagnant ice melts, disintegration moraines develop (Figure 4.11). In
these stagnant glaciers the highest areas are covered by debris that protect the ice from
melting, and the particles flow or slide toward the depressions. When the ice disappears
an inversion of the relief occurs, and the oldest accumulations of the depressions result
in small hills (Boulton, 1972). This landscape constitutes a hummocky moraine, characterized by an undulating relief composed of small hills and closed depressions.