Glaciers Flashcards
what is a glacier?
land was permanently frozen with some melt water rivers
ice covered much of the landscape and carved out deep glacial valleys
what is the main weathering process in a cold environment?
FREEZE THAW
- when water seeps into cracks and freeze causing them to expand and break the rock the process the repeats multiple times till eventually parts of the rock or mountain breaks of
how do glaciers move?
- meltwater lubricates the glacier so it can slide downhilll
- the movement is called basal slip high up in the valley side where the movement is more curved this is rotational slip
how do glaciers transport material?
ice eroded as a result of freeze-thaw , the sediment (morraine) can be transported on, inside or bellow the ice
as the glacier move forward it pushes loose debris which transports it down hill this is known as the bulldozing effect
what causes deposition?
most of the deposition takes place at the snout of the glacier (the front) as it retreats it leaves behind the bed of broken rock fragments as a boulder clay
ahead of the glacier meltwater rivers rock fragments transporting them and causing them to become rounded
what is abrasion?
- “sandpaper effect”
- weight of the ice scores the valley which leaves a smooth polished surface
what is plucking?
meltwater beneath a glacier freezes and bonds the the base of the glacier and the rocky surface and as it moves it plucks up fragment of rock
what is an arrete?
- knife edge ridge found at the back of a corrie or separating two glacial valleys
- narrow
- forms when erosion takes place between two back to back corries causing the land in between them to narrow
what is a corrie?
- large hollowed out depression found on the upper slopes of a glacial valley
- has a steep back wall and a raised lip
- may have a lake called a tarn
how is a corrie formed ?
- over a long period of time snow accumulates in a a small hollow and compresses into ice
- freeze thaw above the glacier
- plucking steepens the back wall
- the pressure of the ice melts the bottom of the glacier and allows it to move causing a slip of slop and the hollow to deepen
- after the glaciated period usually a tarn is left in a deep rock basin, rock lip and steep back wall
what is a pyramidal peak ?
three or more corries formed on a mountain and erosion leads to the formation of a single peak
what is a truncated spur ?
unable to flow around interlocking spurs it cuts straight through them
- the truncated spur is STEEP EDGED
what is a hanging valley?
small tributary valleys above the main glacial trough where smaller glaciers weren’t able to erode down to the same level as the main glacier
- usually marked by a waterfall
what is a glacial trough?
steep-sided, wide, and flat-bottomed valley
- start as a v shaped valley
- abrasion causes them to make u shaped glacial troughs
what is a ribbon lake ?
long, deep and narrow lakes
- as a result of severe erosion of a glacial trough that occurs when a tributary joins causing ice to get thicker or a weaker band of rock erodes more easily
