Although the main focus of the exam specifications is the current glaciated landscapes of the UK, the specifications do refer to the processes of erosion, transport and deposition that once took place in the UK. GCSE students should understand different types of erosion from previous geography topics such as rivers and coasts, but may not have studied them in the context of glaciers. How glaciers erode the landscapeAlthough glaciers move extremely slowly, they are incredibly powerful and have a huge effect on the landscape. One of the processes that it caused by the advance of a glacier is erosion. Note that 'weathering refers to the weakening and breakdown of rock in its position (without being moved); whereas erosion refers to the picking up and removal of the weathered rock, thereby wearing away the land' (Royal Geographical Society, no date) The weight of the ice in the glacier causes it to move downhill, and as it does it erodes the landscape in two main ways:
Then as the glacier moves, it rips out the pieces of rock.
of the glacier and wear it away, like sandpaper. The rock above glaciers is also weathered by freeze-thaw weathering. This is when water gets into cracks in rocks and freezes, causing the rock to expand and putting pressure on it. When it then thaws, the pressure is released. Repeated freezing and thawing widens cracks and causes parts of rock to fall off. At the top of the glacier, in the zone of accumulation, the ice doesn't move in a straighten line. Instead it turns in a circular motion called rotational slip. This erodes hollows and deepens them into bowl shapes. Landforms produced by glacial erosion
the valleys and forming a sharp edge between them.
eroding the mountain.
Formed by a hollow containing a small glacier which is eroded by rotational slip. It often contains a tarn - a small circular lake formed when the glacier melts.
eroded by a river are cut off as the glacier moves past, leaving truncated spurs.
tributary glaciers (similar to a river's tributaries) flow into the main glacier, but the glacial trough is eroded much more deeply by the larger glacier so when the glaciers melt the hanging valleys are left "hanging" at a higher level.
resistant rock was eroded more than the surrounding hard rock.
moutonnee can result. It often has a steep, jagged face as a result of plucking on the far side, and a gradual incline on the other side which is smoothed and polished by abrasion. Striations on the rock indicate the direction the glacier moved in. Examples of all these glaciated landforms in the UK can be seen in the slideshow below. Sources:
BBC (2014) 'Landscapes of glacial erosion' BBC Bitesize Geography: Glaciation. [Accessed 20/08/15] Available from: http://www.bbc.co.uk/bitesize/standard/geography/glaciation/glacial_erosion/revision/1/ Coordination Group Publications Ltd. (CGP) (2010) GCSE Geography: The Revision Guide. CGP Glaciers online (2015) Photoglossary: Alphabetic list. [Accessed on 20/08/15] Available from: http://www.swisseduc.ch/glaciers/glossary/ Royal Geographical Society (no date) 'Glaciation and geological timescales - How glaciers shape the land and what they leave behind.' Teaching resources: KS3 teaching resources. [Accessed on 20/08/15] Available from: http://www.rgs.org/OurWork/Schools/Teaching+resources/Key+Stage+3+resources/Glaciation+and+geological+timescales/How+glaciers+shape+the+land+and+what+they+leave+behind.htm
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