Lecture 10 Flashcards
What type of glacier makes a āUā shaped valley
Alpine glacier
What is a glacier?
A large long lasting accumulation of snow and ice that develops on land, they flow due to weight and gravity
What is bigger a alpine or continental glacier?
Continental
What is ablation?
Surface removal of ice or snow from a glacier or snow field
What separates glaciers from large ice sheets?
Movement
What makes glaciers move?
The ice becoming too heavy and gravity pulls them in a plastic flow
What is a temperate glacier?
A glacier that has a layer 10-20m beneath snow that is at the pressure melting point
Define basal sliding.
The sliding over a glacier over a surface
Why does the bottom of a glacier melt when in contact with the surface of the earth?
It melts due to the overwhelming pressure on the bottom. The water reduces friction and the glacier will increase pace
True or False
Glaciers can be considered a system.
True
What makes glaciers a system?
They have inputs and outputs
What are the glacier inputs?
Water and sediment
What are the glacier outputs?
Water, vapour and sediment
What is till?
Heterogeneous sediment deposited directly by a glacier. Particles have not been sorted.
What is a moraine?
A hill of glacial till deposited directly by a glacier. Terminal moraines mark a glaciers furthest point
What is a firm limit? Where is it located on a glacier?
The firm limit is the lower boundary of the zone of accumulation where snow accumulates on an annual basis. It it the middle of the top of the glacier
True or False:
Glaciers size remain constant
False, they change size with the seasons
If the input of a glacier is equal to its output what happens?
The glacier appears to be standing still.
What is calving?
The loss of glacier mass when ice breaks off into a water body
How do glaciers pick up sediment?
As they move they pick up sediment by the freezing and and melting of bottom ice.
What is scouring?
When glaciers move across bedrock dragging sediment they create scratches in the surface
Name two features caused by scouring?
Striations and glacial polish
What are striations?
An erosional landform that creates grooves caused by sediment dragged on bedrock.
What is glacial polish?
A glacial erosional feature caused by abrasion and scouring smoothing a rocks surface. This grinds rock into fine clay.
What is glacial milk?
Glacier fed water that is filled with fine texture
What is plucking?
A glacial erosional process that detaches particles from a surface by pulling sediment off a rock face
What side of a hill will be more likely to have plucking?
The lee-side
What is Roche moutonnee?
A feature caused by abrasion and plucking. A smoothed side and a rough side
How do glaciers flow?
On the path of least resistance pulled by gravity
What shape do alpine glaciers make?
U
What are hanging valleys caused by?
A smaller glacier meeting a larger glacier creating a cliff. It can also be caused by a second glacier passing through one tunnel multiple times and widening the valley
What are cirques?
Bowl shaped valleys at the head of a glacier valley.
What are horns?
The peak of a mountain surrounded by cirques.
What is an Aretes?
A narrow ridge between two glacier valleys
True or False:
Alpine glacier features are more subtle than continental glacier features
False, continental glaciers make more subtle features due to sheer size
What is a common continental glacier feature?
Lakes
What are glaciofluvial deposits?
The sediment carried by melt water.
What creates a recessional moraine?
A retreating glacier
What are lateral moraines?
Cause by sediment along side a glacier
What are medial moraines?
Two combined lateral moraines
What are some examples of outwash deposits?
Sand erosion, deposition and transport by meltwater. Outwash plain caused by many meltwater streams are carrying sand in front of a glacier.
What is a kame?
Steep conical hill made of glaciofluvial sediment that piles up in a glacial crevasse transported by meltwater
What is an esker?
Long twisting ridges of sediment found on earths surface, these are remains of glacier streams that are placed on the ground prior to the ice melt
What is a drumlin?
A teaspoon shaped hill indicating flow direction made of glacial deposits
What is a kettle hole?
Created by rapid melting of ice when pieces of a glacier break off and melt they form bodies of water
True or False:
Glacial systems are closed systems
False they are open
What does negative balance mean?
A receding glacier
What are glacial erratics?
Large rocks carried by glaciers
Pro glacial lakes are filled with what?
Glacial milk
Define paleoclimatic.
Climate conditions in the geological past reconstructed from a direct or indirect source.
