Explain the formation of roches moutonnées. - AQA - A-Level Geography - Question 4 - 2019 - Paper 1

Roches moutonnées are erosional landforms found in previously glaciated valleys. They are formed when:

1. Glacial Movement: The movement of an advancing glacier plays a crucial role in shaping these features. As the glacier moves, it smooths and erodes more resistant portions of rock, creating the characteristic shapes of roches moutonnées.

2. Stoss and Lee Sides: The glacier's advancing edge creates a steep side, known as the stoss side, facing the direction of glacier movement. Conversely, the lee side is smoother and often more gently sloping because it experiences less impact from the glacier.

3. Plucking and Abrasion: The process of plucking occurs when the glacier freezes onto the rock and pulls pieces away as it moves. Along with abrasion, where the movement of debris within the glacier grinds down the rock surface, these processes contribute to the formation of the features.

4. Dynamic Ice Flow: The uneven ice flow over the rock features can result in both smoothing and shattering, depending on the rock's resistance to the glacier's pressure. Thus, roches moutonnées are shaped by both glacial erosion and the varying resistance of underlying rock.