Glaciation Flashcards
When was the last time we had an Ice Age in the UK?
11-15,000 years ago (Quaternary Ice Age)
What is a glacier in its infancy?
A corrie, which is a pile of snow that builds up in a hollow part of a mountain until pressure from snow above creates melting at the bottom
Why do glaciers look dirty?
Glaciers contain lots of stones and mud that have simply been eroded down the mountain; rocks largely through plucking and freeze-thaw weathering
What is freeze-thaw weathering?
Freeze-thaw weathering is when water seeps into pre-existing cracks in rocks that freezes and consequently expands, usually due to a dip in temperature at night, and the constant cycle of thawing and freezing will augment the cracks and eventually break the rock into fragments
Why are pebbles on the beach so smooth?
By the time pebbles have reached the beach, they have already undergone a fair amount of abrasion (scraping and smashing into bodies of ice and other rocks, thus smoothening jagged edges)
How can you tell that abrasion has occurred?
Stritations will be left on rock or ice
What covered areas of high latitude during the Ice Age?
Large ice sheets
Why does the bottom of the glacier melt?
The pressure of the layers of snow creates friction which creates heat - the melt water acts as a lubricant
What is névé?
Compacted snow found around 10 metres down a glacier
How long does it take to create a glacier and how can you tell how old a glacier is?
20-30 years, and you can tell because of the melt lines inbetween the blocks of ice or snow - each block is a year of snow
What are crevasses?
Deep gashes that split open the surface of the ice
Why do crevasses form at the surface?
The bottom of the glacier has more friction than the top, so the bottom will move faster, which creates cracks, or crevasses and the top is more brittle
Why does a glacier flow faster in the middle?
There is less friction
How do glaciers shape the landscape?
Carve giant chunks out of mountains, shape the land via erosion, rocks are weathered and plucked
