The movement of the glacier is called flow.
It is a slow and complex process, which is basically of 2 types:
1.- PLASTIC FLOW: is the movement inside the ice. It occurs below 50 meters from the surface of the glacier due to pressure. It begins to behave like a plastic material and the ice sheets slide past each other.
2.- BASAL SLIP: is the movement along the ground. It occurs because, as
a consequence of the pressure, the melting point of the ice decreases and in
deep areas it can melt, despite being below 0 degrees. Then that liquid water
acts as a lubricant that favors the movement of ice along the ground. The
presence of liquid water inside is also influenced by 3 factors that generate
heat:
1. The frictional heat of movement by plastic flow.
2. The added heat of the earth's interior emanated
through the ground
3. By the refreezing of the water that drains into the
glacier (this change of state generates heat).
 |
https://player.slideplayer.com/78/12867277/slides/slide_10.jpg
Fracture zone: it is the upper part of the glacier (approximately 50
meters above). It has not plastic flow because there isn´t enough pressure.
This ice is transported on horseback
by the one in the lower area.
If the soil is not regular, this upper area is highly stressed and multiple
fractures are produced, which are called crevices.
These cracks can reach depths of 50 meters. For this reason it is very
dangerous to move on the surface of a glacier.
https://player.slideplayer.com/25/8107034/data/images/img3.jpg |
MOVEMENT SPEED FEATURES:
/ The speed is very slow
(several meters/day or even less) and varies greatly from one glacier to
another.
/ It is not the same in all parts of the glacier. It is faster in the central area as a result
of the friction generated when its sides rub against the walls of the valley.
/ The advance of some glaciers occurs in waves, that is, there are periods of time in which they move faster and other stages in which the movement is slower. In a wave the speed can be up to 100 times the normal speed.
In the following video we can see how the movement of the glacier occurs.
