| Term | Explanation of the term |
|---|---|
| Moraine | Moraine is a term used to describe the material which has been carried and deposited at the end of it’s route. There are three variatons of moraine to remember. The first one is terminal moraine. These occur where the Recessional morain occur where the glacier has retreated Medial moraine can be found where two glaciers have converged into |
| Nevée | Nevée is a french word used to describe ice which has been compressed so much that it has no air left inside. It can be recognised by it’s blue colour |
| Pyramidal peak | A pyramidal peak occurs when a piece of harder rock is eroded on three sides or more to create a pyramid. Two examples would be the Materhorn in Zermat and Mt Blanc above Chamonix. |
| Cirque | Cirque are caused over time by glaciers when snow has accumulated over the years and through it’s rotational movement has hollowed out and scoured the back wall to create a bowl like shape. At the back a fairly steep wall can be found. |
| Arêtes | Aretes is a french word to describe the top of the outward facing rock formations from a pyramidal peak. |
The term glaciation is used to describe the process which occurs when
ice accumulated into a large volume in one location from accumulated precipitation
over the years. In certain depressions the snow accumulates when the temperature
is too low for the snow to melt. Over the years the amount of ice increases
and with it the wheight of the volume of ice. This increasing mass begins
to exert on the soil below it and this pressure begins to erode the surface.
There may be a rotational movement which rips away rock smoothing the
formation and creating a cirque over time. A feature of the cirque is
firstly it’s formation of a hollow but is recognisable by the rock face
behind it being quite steep.
Over time this may help to form a pyramidal peak such as the Materhorn
in Zermat or the Mt Blanc above Chamonix. The process continues down the
mountain with gravity’s force with the result being the formation of a
glacier flowing down like a river. There are several key terms to remember
when talking of glaciers which you may find above.
When speaking of glacier it is interesting to remember that they behave
according to the same laws of fluid motion as a river. The center of the
glacier is moving faster than the outside because there is less friction
slowing it down.
It is one of the most destructive of geographic occurences
because of the sheer wheight contained within the ice. To illustrate the
movement of rock a simple experiment is to place several sticks at the
same height on the glacier and watch the movement of these sticks over
time. As the ice moves at different rates you will find that a v shape
is forming pointing downwards. It begins it’s trip downwards and anything
in it’s way is covered and surrounded by the ice over a period of time
and trapped. The material is ripped out of it’s place even if it’s a rock
as large as your house. It acts like sandpaper and leaves bare rock.
What remains from the passage of a glacier is a U shaped valley as can
be seen by the Lac Leman (lake Geneva) in Switzerland. Boulder clay which
is the ground stone is ubiquitous within the region and a rich soil is
a possitive side effect of all the materials which have been moved.
The speed of the glacier is not constant as you may be led to believe.
It is dependant on various factors such as precipitation, temperature,
angle of the slope and more. As the temperature increases the glacier
slows down and may begin to retreat. Precipitation helps add material
and mass which give the glacier enough momentum to begin flow back down
the slope. Finally the aspect of the slope may affect speed since the
steeeper it is the faster it will move down hill.