Glaciation Flashcards
Define the term glaciation
The process or state of being covered by ice glaciers or ice sheets
What is an ice age
A long period in time when the Earth’s temperature was reduced resulting in the expansion of continental and polar ice sheets and glaciers
When did the last ice age end
18,000 years ago
What is an ice sheet
A chunk of glacier ice that covers the land surrounding it and is greater than 50,000 km wide
What is an ice cap
Covers less than 50,000 square kilometres
Feeds a series of glaciers around its edges
Ice flows away from this highest point towards the caps edge
What is a glacier
A slowly moving mass or river of ice formed by accumulation and compaction of snow on mountains or near the poles
What are interglacial periods
During an ice age there are intermittent periods of colder and warmer average global temperatures, the warmer periods are called interglacial periods
What is freeze thaw weathering ( frost shattering)
Water that enters cracks in rocks freezes and when it does, it expands
Repeated freeze and thaw means cracks in the rock expand until the rock is fractured
What is abrasion ( striations )
The glacier scours and scrapes the valley floor, this is a sandpapering effect
What is plucking
The water at the bottom of the glacier freezes onto rock on the valley base
As the glacier moves, the rock is pulled away from the valley base
Plucking mainly occurs when the rock is well-jointed
What causes an avalanche?
Unstable layers can also slip because of
Skis
Snow boarders
Earthquakes
Name the impacts of avalanches
Roads and railways can be blocked Power supplies cut off Tears down trees and ski lifts Destroy buildings People can be killed
How would you protect against avalanches
Build wooden fences Avalanche sheds Wedges Walls on steep slopes Moulds Plant trees
What is a crevasse
Deep cracks in the glacier caused when it moves down the slope
What is a tarn
A lake that forms in the Corrie when the glacier disappears
