Lesson 3:

Formation of a Corrie

What you should know by the end of this lesson:

Formation of a Corrie

Important!!

When explaining the formation of Glacial features you NEED to discuss the processes involved. This is a very easy way to pick up marks! As you get a mark for naming the process and a mark for explaining how the process works. You get credited for up to 2 glacial processes per feature.

For the erosional features, all of the processes are the same. Regardless of the erosional feature make sure you discuss Abrasion and Plucking!

Corrie

REMEMBER!

When answering these as a full Higher Question you need to explain the processes which are involved in these formations. A well-explained process can gain you 2 marks, 1 mark for naming the process and 1 mark for explaining the process, but you need to have both to gain both marks.

The same goes for every process term you say

Lochnagar - A Corrie

These features are straight forward and your task is simply to try and understand the processes which explain how they form

Digital Workbook and Paper Jotter

Draw the annotated diagram into your jotter
Write the full explanation to your notes below your diagram

Diagram

During Glaciation

After Glaciation

Explanation

Before Glaciation

Snow accumulates in north-facing hollows when more snow falls in winter than melts in the summer
North and North-East slopes are more shaded so snow lies longer.
As snow accumulates it is compressed down (neve) squeezing out air and eventually forming glacial ice
Glacial ice is really heavy and begins to flow downhill due to gravity.

During Glaciation

As the glacier moves in a rotational movement because of the slope it erodes the hollow downwards.
Erosion occurs through the processes of Plucking (Explain term) and Abrasion(explain term)
The maximum vertical erosion is under the deepest part of the ice.
This creates a steep back wall and a hollow known as a Corrie.
As the hollow deepens a gap appears between the glacier and the back wall of the Corrie. Known as a bergschrund, this gap allows more rocks and boulders to be taken into the glacier.
As the glacier becomes shallow it loses energy and rocks get deposited creating a rock lip.

After Ice Age

As the glacier melts, this rock lip traps water in the hollow creating a tarn or lochan.
The steep back wall is still exposed to Freeze-thaw weathering (+ explanation) becoming jagged as rocks break away.
These fallen rocks also create a scree slope in the hollow.

A well known Corrie is, Lochnagar

Top Tip!

for erosional processes, you can get an extra mark for a named example of the feature!