Glacial landforms Flashcards
What is a drumlin?
mound of glacial debris, that has been streamlined into an elongated hill. formed beneath a glacier or ice sheet. It’s stratified
What are erratics?
Rocks that are geologically out of place
What is the formation of an erratic?
Freeze thaw weathering at the back of the corrie, causes rock to fall onto the ice. Glacier starts to move by basal sliding so bolder moves with the ice (transportation) and then it is deposited as the ice melts.
What are the two types of pingos?
open system= rounded ice-cored hills, formed in valley bottoms where water from surrounding slopes collect, freezes and expands.
Closed system= rounded ice cored hills, developed beneath lake beds, the groundwater beneath a lake is trapped by the permafrost. The unfrozen ground is compressed and forces up the overlying sediment
What is patterned ground?
collective term for a number of small scale features that are a result of frost heave. Larger stones eventually reach the surface and that the ground surface is doomed
What are periglacial features [environment located on the margin of past glaciers]?
Pingos and patterned ground
What are outwash plains?
formed in front of a glacier and are where material is deposited over a wide area, carried out from the glacier by meltwater.
What is the formation of outwash plains?
Meltwater carries sediment away from the snout, sediment gets deposited when it loses energy into sections and is sorted.
Clay is last
Gravel is first
What is a corrie?
armchair-shaped hollow found on the side of a mountain
How is a corrie formed?
Snow is collected in a hollow of a mountain and gets compacted into ice. The ice then moves slowly down hill, abrasion results in a deep hollow, the ice then melts and forms a corrie
What are the three types of moraine and what are they?
Terminal moraine= when the glacier has reached its furthest point and stopped, unstratified
Lateral moraine= ridge of till running along the side of a glacier formed by frost shattering
Recessional moraine= series of ridges running transversely across glacial troughs and are parallel to each other as the glacier retreats, its unsorted
How are lateral moraines formed?
Glacier moves through valley, it erodes the sides by plucking
How are terminal moraines formed?
glacier loses energy resulting in deposited material, it then retreats
How are recessional moraines formed?
When accumulation is equal to ablation, recessional moraines form
