glacial landscapes Flashcards
what is erosion?
the wearing away of pieces of rock, soil or other solid materials
what is weathering?
breaking down of rocks in situ by the action of weather, plants, animals and chemical processes
what is transportation?
to move objects or people from one place to another
what is deposition?
when material is deposited or left behind- when a river loses its energy and is unable to carry its load any further
what are the two main types of erosion?
abrasion and plucking
what is abrasion?
as the glacier moves downhill, rocks that have been frozen into the base and sides of the glacier scrape the rock beneath.
the rocks scrape the bedrock like sandpaper, leaving scratches called striations behind
glaciers shape the land by what processes?
erosion, transportation, weathering and deposition
when does glacial abrasion occur?
when rock fragments that are frozen into the bottom of a glacier scrape and erode the valley floor
what is the second form of erosion?
plucking
what is plucking?
rocks become frozen into the bottom of the glacier as well as the sides.
when the glacier moves downhill it “plucks” the rocks from the ground into the glacier
what is the main type of weathering?
freeze- thaw weathering
what is freeze thaw weathering?
when temperatures are higher during the day, snow melts and water enters the cracks in the rock.
when temperatures drop below 0 degrees, the water in the crack freezes and expands- making the crack larger.
the process is repeated and the crack gets larger over time- pieces of rock then break off
what is a corrie?
bowl shaped hollows with a steep back wall and ridges, forming an armchair shape around a hollow sometimes containing a small round lake called a tarn
how does a corrie form?
1) snow accumulates in depressions high up, predominately on north facing slopes
2) over time, the snow becomes glacial ice and there is more ice than the depression can hold- some of it starts to flow to lower levels
3) freeze thaw weathering occurs at the top of the slope producing scree which becomes incorporated into the glacier
4) the hollow deepens where the ice is thickest due to abrasion- rock debris acts as tools to wear away the bottom of the hollow
5) ice becomes frozen to the back of the hollow and plucking occurs as blocks of rock are pulled away as the ice moves downhill- makes the back wall steeper and these rock fragments become incorporated into the glacier
what is water table?
current upper level of saturate rock/soil where no more water can be absorbed
