As the glacier grows down slope it erodes away the sides of the valleys forming a u-shaped valley. Since the glacier can measure from a couple of hundred meters to a kilometer of width, it will push on the sides of the valley and carry with it pieces of the mountains (mainly rocks and trees). This debris is known as moraine, more precisely lateral moraine. The glacier also erodes the floor of the valley. This is because of the weight of the glacier that when it advances it scrapes the floor carrying with it anything on its passage. This is known as terminal moraine.
Glaciers also transport materials down hill. In many glaciers you can find rocks that can only be found at certain altitudes at the bottom of the valley. These are mainly erratics (large boulders).
Glaciers are found on the northern faces of mountains such as the Matterhorn and Mont Blanc. This is because these faces aren’t exposed to the sun and so it’s easier for the glacier to grow. These glaciers are found all around the world, for example in the French and Swiss Alps and in Scandinavian countries. They are also found in South America, Greenland, New Zealand, Antarctica, USA, Africa and all over Asia.
These are some examples of glaciers
At the start of the glacier (at the source) once the accumulation of snow has begun, the glacier erodes the back wall forming a sort of “armchair” as shown on the first diagram. These are called cirques but are also known as cwns’. When the glacier has retreated, the ice left in the cirque melts forming a lake called Tarn.
Nearly all glaciers are found on a pyramidal peak mountain. A very good example of a pyramidal peak is the Matterhorn. Three cirques formed on the three faces of the mountain. As these formed, they wore away the back wall making the slope from the cirque to the peak of the mountain steeper and steeper. This makes the higher part of the face very steep forming a shape very similar to a pyramid. This is why it’s called a Pyramidal Peak.
When two cirques erode the back wall and join back to
back they form a very sharp ridge, only a couple of
meters wide. These lead up to the peak of the mountain
and are called Arêtes.
When the glacier starts growing down hill or down slope, it follows the easiest path. The easiest path to get from the top of a mountain to the bottom at the mountain is following an already existing valley. This valley would be V-shaped and there would be a river at the bottom of it. As the glacier advances it erodes the side of the valley forming a U-shaped valley. The bottom of the valley is known as the Glacial Trough. It is a very flat and wide area of land. The sides of the valley are very high and steep. The valleys are very long and can stretch from a mountain to the sea side.
New U-Shaped valley
Old V-Shaped valley
In these U-shaped valleys you will find, once the glacier has retreated a misfit river. This is a river that used to flow under the glacier and that doesn’t follow very well the valley. It meanders a lot and this is where you find ribbon lakes, long narrow lakes.
Hanging valleys are valleys that used to be tributary valleys. As the glacier eroded away the valley sides, the tributary valleys have been isolated at high heights. You can see these when you see a waterfall. The river that flows down the valley has been cut and falls down a cliff. These valleys are hanging over an edge.
The hills that separate these hanging valleys are known as Truncated spurs. They are hills that divide two hanging valleys from each other.
Truncated Spur Hanging Valley
A scree slope or Talus is formed at the bottom of a very steep slope (i.e. Back wall of cwn). It is an accumulation of rocks. These rocks have fallen off the slope due to weathering and especially because of Freeze Thaw. Water enters tiny cracks in the rock and when the temperature drops, this water freezes and expands. The pressure put on the rock makes it explode and come off the mountain. These rocks roll down the slope and form a pile.
Erratics are large boulders which have been carried by the glacier when it was still growing. These masses can be carried for hundreds of kilometers and even across the seas (this only happens during ice ages). A good examples are the rocks found in East Anglia that can only be found in Scandinavia. These masses have been carried by a glacier in the last Ice Age.
In the past 10000 years there have been many glaciers which have retreated. This is because they only survived during Ice Ages and when these ended, the air temperature was too high for them to survive. Glaciers could be found in Wales and other similar countries where now they have disappeared.
Now glaciers are found in places such as the French and Swiss Alps, Scandinavia, New Zealand etc. (all mentioned in introduction). Many of them are disappearing because of the rise of temperature caused by the Green House effects. If the temperature keeps on rising at this rate, very soon all glaciers will disappear. This is a danger because the glaciers found on the South Pole will melt and cause the sea level to rise which will mean the world will flood.
