Fluvioglacial Processes And Landforms Flashcards
How does surface meltwater get underneath the glacier? What does it do there?
Surface meltwater filters through crevasses and then flows through the tunnels underneath the glacier before running out of the snout.
What is a meltwater stream?
When glacial ice melts, water runs out and forms streams of meltwater. Warm based glaciers and retreating glaciers produce lots of meltwater.
What do meltwater streams cause a lot of?
Erosion.
Why do meltwater streams cause a lot of erosion?
The pressure of ice means that meltwater streams flow very quickly and therefore can carry a lot of material that can erode the landscape.
What’s a meltwater channel? How is it formed?
A meltwater channel is a deep and wide trough in the landscape. It is formed because of the erosive power of the meltwater stream.
What shape are meltwater streams often? And why?
They are often braided as they split into lots of mini streams that cross over each other. This is because when the meltwater is flowing more slowly it can’t carry it’s load so it deposits the sediment on the ground and splits into two streams to get around it.
What’s the difference between fluvioglacial deposits and glacial deposits?
Fluvioglacial deposits are sorted whereas glacial deposits are unsorted.
What’s an outwash plain?
A layer of gravel, sand and clay that forms in front of where the snout of the melting glacier used to be.
Are the sediments on outwash plains sorted into layers?
Yes they are sorted into layers. Gravel is the bottom layer as it’s the heaviest, clay gets dropped last and the farthest away from the snout as it is the lightest.
How are kettle holes formed?
Blocks of ice that have been broken off the glacier can get surrounded/partly buried by the fluvioglacial deposits. When the blocks of ice melt they leave the kettle holes in the outwash plain.
What’s an esker?
A long winding ridge of sand and gravel that runs parallel to the valley sides/ the same direction as the glacier. Eskers are deposited by meltwater streams flowing in tunnels underneath the glacier as when the glacier retreats and the stream dries up the load remains as the esker.
What meltwater streams form eskers?
The meltwater streams flowing in tunnels underneath the glacier.
What is a kame?
A kame is a mound of sand and gravel found on the valley floor. Meltwater streams on top of glaciers collect in depressions and deposit layers of debris. When the ice melts, the debris is dumped on the valley floor.
What’s a kame terrace?
A kame terrace is a pile of deposit left against the valley wall by meltwater streams that run between the glacier and valley sides. They are different to lateral moraine as they are sorted into layers- gravel at the bottom, then sand then clay at the top.
What’s a proglacial lake?
This lake forms in front of glaciers for example when the meltwater stream gets dammed by terminal moraine.
