Erosional Landforms 2

Geography: Edexcel A Level, topic 2.4.3

Arêtes and Pyramidal Peaks

Arêtes and pyramidal peaks result when corries back into the same mountain.

As corries develop, they eat back into the mountain mass in which they have developed.
When several corries lie close to one another, the divide separating two corries may become progressively narrowed until it is reduced to a narrow precipitous ridge called an arête.

If glaciers in corries continue to erode away at the mountain from three or more sides, the result is the formation of a sharp pyramidal peak, sometimes called a horn.

Glacial troughs are a result of large glaciers flowing through valleys.

Glacial troughs, also called U-shaped valleys, develop where glaciers flow into pre-existing V-shaped river valleys.
Glaciers widen and deepen the original valley making it steep sided with a wide, flat base.
Glaciers tend to straighten the valley, cutting off spurs and leaving cliffs called truncated spurs.
At the upper end of the valley where the glacier has entered the valley from the corries above, there is often a steep wall called the trough end.

Glacial flow is uneven and where erosion has over-deepened a section of the valley (e.g. where there is softer rock which is more easily eroded) it forms a rock basin.
These rock basins often fill with water post-glaciation, forming a ribbon lake.

Hanging valleys forms where ice in a tributary valley cannot erode effectively because its movement is blocked by ice in the main valley (or it may be smaller in size).
So, it remains ‘higher’ and smaller than the main glacial trough (hanging above it).
Post-glaciation, a hanging valley may be identified from a waterfall into the main valley below.

What are the narrow ridges between corries that back into the same mountain called?
Which of the following form when corries back into the same mountain?
Which of these are features you might find in glacial troughs?