1. FEATURES OF GLACIAL EROSION
Features of erosion
These slide-shows are all on the Geography Blog, if you wish to copy any notes from them; we will not be stopping in class for you to do this
FEATURES OF GLACIAL EROSION
These are the features you will need to be able to describe, explain their formation, draw a labelled sketch of and recognise on an OS map.
CORRIES
PYRAMIDAL PEAKS
ARETES
U-SHAPED VALLEYS
HANGING VALLEYS
TRUNCATED SPURS
RIBBON LAKE

2. A corrie is a deep, rounded hollow with a steep back wall.
Features of erosion
CORRIES
Snow collects in hollows, especially on the less sunny north and east facing slopes, turns to glacial ice and moves downwards under the force of gravity
Rocks are plucked out and the hollow is widened by abrasion to become a corrie.
A corrie is a deep, rounded hollow with a steep back wall.

3. Also learn how to draw and label sketches.
Features of erosion
Read the in formation on the formation of corries in your notes and textbook page 91
There is a bullet-pointed list of actions explaining in order how a corrie is created.
Learn this at home!
Also learn how to draw and label sketches.

4. Features of erosion
MAXIMISE
YOUR
MARKS !
NOTE;- the labels on the first two sketches are not just naming the features, like in sketch c).
They describe what is happening in the sketch, naming the processes.
This makes these labels -and the diagram- worth more marks than one where bits only are named!

5. Answer these questions in the usual way;-
Features of erosion
Answer these questions in the usual way;-
Q1. Where is the bergshrund and what causes it?
A. It is at the top of the back-wall, where the ice is ripping away from the rock because of gravity pulling the ice downhill.
Q2.What erosion process greatly affects the backwall, and how does this affect the rock texture here?
A.Plucking is the main process here and it leaves the rock jagged and rough.

6. Features of erosion
Q3.The debris created by plucking is active elsewhere in the corrie- where and with what results?
A.Abrasion uses the plucking products to smooth, deepen and enlarge the floor/ basin of the corrie.
Q4. Describe how corries, aretes and pyramidal peaks are all related features.
A. To create an arete, there has to be more than one corrie eroding the land between them into an arete. The eroded corrie back-walls eat into the summit of the mountain creating a pyramidal peak, where several aretes come together.

7. Features of erosion
Formation of a corrie 12
Recap – this is the sort of diagram that you should be able to draw under exam conditions. Practice doing this.

8. Features of erosion
Back wall
scree
lip
Once the glacier retreats, the corrie may be filled with water. A small, generally circular loch is formed. This is known as a tarn or corrie lochan.

9. On an OS map, corries are shown as horseshoe-shaped features.
Features of erosion
On an OS map, corries are shown as horseshoe-shaped features.
scree
Note the east-facing aspect; snow lasts longer before melting. N
Note the contours are very close together, especially on the steep backwall. Note also the bare rock symbol.
tarn

10. Features of erosion
Red Tarn

11. Features of erosion
ARETE
An arete is a narrow, sharp-edged ridge which forms the side walls of corries or separates different glacial valleys.

12. The red lines mark the spines of the three aretes.
Features of erosion
On a map an arete is hard to see. It is a long ridge between to corries or valleys.
scree
= arete
The red lines mark the spines of the three aretes.
horn
bare rock
These corries and arete are in the Cairngorms.

13. Striding Edge arete on Helvellyn, Lake District arete
Features of erosion
Striding Edge
Striding Edge arete on
Helvellyn,
Lake District

14. Pyramidal peaks are also called horns.
Features of erosion
MATTERHORN
Pyramidal peaks are also called horns.

15. Features of erosion
A VALLEY GLACIER
The next few slides will help to explain the formation of this feature.

16. Stages in the formation of a U-shaped valley
Features of erosion 13
Stages in the formation of a U-shaped valley
Take the handout and use page 284 of ‘Wider World’ to add the labels.

17. These are the actions that form this feature.
Features of erosion
These are the actions that form this feature.
a) A glacier flows into an earlier 'V' shaped valley.
b) The glacier abrades and plucks the sides and floor of the river valley.
c) The valley is greatly deepened, widened and straightened.
d) When the ice melts the valley is 'U' shaped.
e) It now has very steep sides and a fairly flat floor.
f) Any rivers are called 'misfit streams’ because they are far too small to have cut the valley.

18. Features of erosion
Truncated spurs
Former hill spurs are ‘truncated’- their ends are cut off by the ice action to form steep, sheer cliffs.
The yellow lines show where the spurs were before they were chopped off! Note how they defined a V-shaped valley.

19. A U-shaped valley in Canada.
Features of erosion
A U-shaped valley in Canada.

20. Features of erosion
When a glaciated valley is submerged or drowned by a rise in sea level, a fiord is formed.
The sea lochs of western Scotland are the best examples of fiords in the British Isles.
Fiord/fjord

21. Features of erosion
A hanging valley
Vertical erosion in the main glacier is far greater than in the tributary glaciers. So the valleys are not the same depth.
After the glacier has retreated, rivers flowing down the tributary join the main valley via a waterfall
Can you spot the river delta,too?

22. U-shaped valleys have few contours on their floors.
Features of erosion
Truncated spur
U-shaped valleys have few contours on their floors.
There is a hanging valley here.
Note the very steep sides.
waterfall
Misfit stream

23. Features of erosion
When a glacier moves along the valley, some parts are deepened more than others.
When the glacier retreats, the deepest parts fill with water and become lakes.
The English Lake
District owes its
character to these
narrow ribbon lakes
along its valley
floors.
Ribbon lakes

24. Material is dropped at the ‘break of slope’ to form this fan shape.
Erosion/ deposition
Caused when a stream falling from a side valley reaches flatter ground on the valley floor.
Material is dropped at the ‘break of slope’ to form this fan shape.
An alluvial fan
(This is really a depositional feature.)
alluvium = silt deposited by a river

25. These are partly erosional, partly depositional features.
Erosion/ deposition
A crag and tail
Edinburgh Castle
crag
tail
Plug of volcanic rock
These are partly erosional, partly depositional features.
The rock face facing the ice is steepened by glacial erosion. Softer rock on the other slope is protected from erosion to form a tail of boulder clay.

26. Features of erosion
Identify the features marked on the diagram by matching them to the names of features listed below.
Arête; Hanging Valley; Corrie;
'U' shaped Valley; Alluvial Fan; Pyramidal Peak;
Corrie Tarn; Misfit Stream;
Ribbon Lake; Truncated Spur; Screes.