Topic 2 - Glaciation: EQ2

Question 1

What is the accumulation zone?

Answer 1

Where there is a net gain of ice over the course of a year. Here, inputs exceed outputs

Question 2

What is the ablation zone?

Answer 2

Where there is a net loss of ice during a year. Here, outputs exceed inputs

Question 3

When is ablation at its highest?

Answer 3

During the summer (due to rapid melting of the ice)

Question 4

When is accumulation at its highest?

Answer 4

During the winter (high amounts of snowfall and limited melting)

Question 5

What is mass balance?

Answer 5

The year-to-year change between accumulation and ablation

Question 6

What happens when accumulation exceeds ablation?

Answer 6

A positive mass balance occurs, the glacier’s mass increased and it advances

Question 7

What happens when ablation exceeds accumulation?

Answer 7

A negative mass balance occurs, the glacier’s mass decreases and it retreats

Question 8

What are the inputs in a glacial system?

Answer 8

Precipitation
Avalanches
Wind Deposition

Question 9

What are the outputs in a glacial system?

Answer 9

Sublimation
Calving
Water

Question 10

What is dynamic equilibrium?

Answer 10

The boundary between the accumulation zone and the ablation zone

Question 11

What are the flows/transfers in a glacial system?

Answer 11

Evaporation
Sublimation
Meltwater Flow
Internal deformation
Basal Sliding

Question 12

What are negative feedback loops?

Answer 12

Negative feedback loops regulate systems to establish balance and equilibrium

Question 13

What is an example of a negative feedback loop?

Answer 13

The presence of ice decreases the albedo effect

When the temperature increases, ice melts and this increases the albedo and lowers the temperature, refreshing the water back into ice

Question 14

What is an example of a positive feedback loop?

Answer 14

The Albedo affect

Snow reflects the sun’s rays, reducing ground temperature, leading to a decrease in temperature

Question 15

What processes can a warm-based glacier move by?

Answer 15

Basal slip
Internal deformation

Question 16

What processes can a cold-based glacier move by?

Answer 16

Internal Deformation only

Question 17

What is Basal slip?

Answer 17

When the base of the glacier is at PMP, and meltwater present (lubricant) allows the glacier to slide at a quicker pace over the bedrock

Question 18

What is internal deformation?

Answer 18

When the weight of the glacier ice and gravity causes the ice crystals to deform, so that the glacier moves downslope very slowly

Question 19

What are the 3 types of basal slip?

Answer 19

Enhanced basal creep and regelation creep
Extensional and compressional flow
Surges

Question 20

What is enhanced basal creep?

Answer 20

Whereby basal ice deforms around irregularities on the underlying bedrock surface

Objects are greater than 1m

Question 21

What is regelation creep?

Answer 21

Basal ice deforms under pressure when encountering obstructions such as rock steps.
As the pressure increases, the ice reforms in a plastic state as a result of PMP.

Once it’s flowed over the obstruction, the pressure is lowered and the meltwater refreezes

Question 22

What is extensional flow?

Answer 22

Over steep slopes, the rate of basal slip will increase and the ice will accelerate and thin

Question 23

What is compressional flow?

Answer 23

Over shallower slopes, basal slip slows and the ice decelerates and thickens

Question 24

What are Surges?

Answer 24

Short-lived events where a glacier can advance substantially, moving up to 100times faster than normal.
One cause are volcanic eruptions (especially in iceland) where the glacier turns into a toothpaste-like substance and can move 300-400m

Question 25

What are the 2 types of internal deformation?

Answer 25

Intra-granular flow Internal-granular flow

Question 26

What is intra-granular flow?

Answer 26

Individual ice crystals fracture or deform due to the intense stresses within the ice. The mass of the ice will gradually deform and move downhill

Question 27

What is inter-granular flow?

Answer 27

Individual ice crystals will slip and slide over each other, causing the mass of the ice to deform

Question 28

What factors control the rate of movement?

Answer 28

Altitude Slope Lithology Precipitation Ice temperature

Question 29

How does lithology affect the rate of movement?

Answer 29

If a glacier sits on permeable rock, some of the meltwater created by PMP will percolate through the rocks. This means that it won’t be kept in a glacial system and a decrease in meltwater and glacial movement

Question 30

How does slope affect the rate of flow?

Answer 30

If a glacier sits in a steeper gradient, the rate of movement will increase due to more gravitational force

Question 31

How does rates of ablation affect the rate of movement?

Answer 31

The more meltwater there is, the faster the movement as basal slippage increases

Question 32

How does precipitation affect the rate of movement?

Answer 32

Higher snowfall leads to greater accumulation and faster movement

Question 33

How does ice temperature affect the rate of movement?

Answer 33

In some environments, ice is so cold that it’s frozen to the bedrock which means that it will move much more slowly

Question 34

How does altitude affect the rate of movement?

Answer 34

The greater the precipitation and lower the temperature, the greater the chance of supply of snow and ice, and an increase sim mass balance

Question 35

What are the 4 types of crevasse?

Answer 35

Transverse crevasse Longitudinal crevasse Radial crevasse Marginal crevasse

Question 36

What is a transverse crevasse?

Answer 36

Cut across the glacier at approximately 90 degree angles

Question 37

What is a longitudinal crevasse?

Answer 37

Oriented parallel to the flow direction of the ice

Question 38

What is a radial crevasse?

Answer 38

Form in a splayed pattern at the snout of the glacier

Question 39

What is a marginal crevasse?

Answer 39

Form near sides of glaciers