glacial landscapes Flashcards
describe the formation of a corrie
- snow accumulates on high north facing mountains and compresses into ice
- snow continues to fall and goes into cracks in the rock overnight and freezes these cracks widen and deepen over and over again until the rock cracks and freezes to the back of the corrie ( freeze thaw )
- more ice compresses o top and causes the glacier to slide due to the weight around 25cm per day
- back wall increases steepness due to plucking. This occurs when rocks is pulled away as the corrie moves
- then there is a decrease in erosion and a rock lip is formed and sediment is deposited here
- eventually this leaves a steep basin with a rock lip and a lake at the bottom
what are interlocking spurs
as the river erodes the landscape in the upper course winds and bends avoiding hard rocks and eroding softer rocks creating interlocking spurs
what are truncated spurs
when a valley fills with a glacier any land which is in the way will be eroded away. Interlocking spurs will have the ends eroded away and from truncated spurs that will have steep sides to show this erosion
what is abrasion (glaciaction)
eroded rock frozen in the ice grind the rock below and erodes it away
what is plucking
meltwater freezes at the base back or sides of the glacier freezes onto the rock. As the glacier moves it pulls out pieces of rock
what is freeze thaw weathering
water gets into cracks and freezes. The water expands putting pressure on the rock then the ice thaws and the rocks comes loose
what is the depostion material called
till
what is bulldozing
the glacier pushes the loose material infront of them
what is an arete
a narrow steep-sided ridge formed when two glaciers flow in parallel ways
what is a pyramidal peak
pointed mountain peak with at least three sides and is formed when three or more back to back glaciers erode the mountain
what is a corrie
a steep sided armchair shaped hollow with a lip at the bottom
when the ice melts it can leave a small circular lake called a tarn
what is a ribbon lake
long thin lakes that form after a glacier retreats
what are glacial troughs
steep sided valleys with flat floors
start off as v shaped valley but changes to a U shaped valley
what are hanging valleys
valleys that are formed by tributary glaciers that flow into the main glacier but the trough of the main glacier erodes much deeper so when the glacier melts the tributary glaciers are left at a higher level leaving a hanging valley
what are moraines
landforms made out of till deposited by a melting glacier
