Glaciers transport and deposit materialAs I looked at in the previous post, glaciers erode rock, creating distinctive landforms. This eroded material is then transported and deposited by the glacier, forming different landforms. A glacier works like a conveyor belt, constantly transporting material downhill. The ice continues to move downhill, even when the zone of ablution at the bottom of the glacier is receding. The material can be frozen inside the glacier, carried on its surface or bulldozed, which means material is pushed in front of the glacier. Material can include rock, gravel, sand and clay, but even ancient human remains have been found transported in glaciers. Deposition occurs when the ice melts at the snout (or end) of the glacier, which is why this part of the glacier, the zone of ablution, often looks grey and dirty, or if the ice is overloaded with material. Glacial deposits are deposited when the ice melts, and unlike river deposits which are sorted by weight, glacial deposits can be rocks of all shapes and sizes, from fine clay to rocks the size of a house. Fluvo-glacial deposits are washed out of the ice by meltwater, and these are sorted by weight, with heavier materials deposited first. Landforms produced by transportation and depositionMoraines These are piles formed from material deposited by the glacier as it melts. There are four different types depending on their position.
Drumlins Elongated hills of glacial deposits. They can be 1km long and 500m wide, and often occur in groups. They are formed from the debris carried along and then accumulated under a glacier, which was deposited when the ice became overloaded with sediment. One end is round, blunt and steep and the other tapered, pointed and gently sloping, showing the direction the glacier moved in. There is still disagreement among glaciologists as to how exactly drumlins were formed. Erratics As I said, glacial deposits come in a mix all shapes and sizes. Extremely big deposits are called erratics. They are large rocks or boulders and are often found on their own. They are often unusual shapes and a rock type which is uncommon in the area they were deposited in. This video from the BBC gives more information about and examples of erratics: Erratics in Switzerland Till Till is a poorly sorted mix of mud, sand and gravel-sized material deposited directly by glacier ice. Outwash plain A flat spread of sediment deposited by meltwater streams from a glacier. Photo examples of these landforms are shown in the slideshow below. Sources:
Coordination Group Publications LTd. (CGP) (2010) GCSE Geography: The Revision Guide. CGP. Royal Geographical Society (no date) 'How glaciers shape the land and what they leave behind' Teaching resources: KS3 teaching resources. [Accessed on 24/08/15] 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 BBC (2014) 'Landscapes of glacial deposition' Geography: Glaciation. [Accessed on 24/08/15] Available from: http://www.bbc.co.uk/bitesize/standard/geography/glaciation/glacial_deposition/revision/4/
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AuthorMy name is Heather and I am going to begin my SCITT course to train as a Geography teacher. ArchivesCategories
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