Glaciated Landscapes SG1

Question 1

Define Glacier

Answer 1

A land based ice mass that is thick enough to ‘flow’ under its own weight

Question 2

Define Glaciated Landscape

Answer 2

Landscapes that have been shaped by the action of glaciers (current and past glaciers)

Question 3

Define Valley Glacier

Answer 3

River of ice which flows down from high mountains, following the course of existing river valleys

Question 4

How long are valley glaciers?

Answer 4

10-30km

Question 5

Define Ice Sheet

Answer 5

Areas of thick ice spread out over land and sea

Question 6

How far do ice sheets extend for?

Answer 6

> 50,000km3

Question 7

What % of today’s ice is in ice sheets?

Answer 7

69%

Question 8

What % of the earth is covered by ice?

Answer 8

10%

Question 9

What is the last glacial period called?

Answer 9

The Pleistocene

Question 10

How long ago was the Pleistocene?

Answer 10

2 million - 11,000 years ago

Question 11

What is the current interglacial period called?

Answer 11

Holocene

Question 12

When did the Holocene start?

Answer 12

11,000 years ago (at the end of the Pleistocene)

Question 13

Define Ice Age

Answer 13

An extended period of time where the earth experienced a cycle of very cold phases (glacials), interspersed with warmer phases (interglacials)

Question 14

Define Glacial

Answer 14

A very cold phase where global temperatures dropped by approximately 5 degrees C resulting in the spread of ice

Question 15

Define Interglacial

Answer 15

Warm phase where temperatures increased to present level or above

Question 16

Define Accumulation

Answer 16

Input of snow and ice to a glacier

Question 17

Define Ablation

Answer 17

The loss of ice and snow through melting, evaporation and sublimation

Question 18

Define Equilibrium Line

Answer 18

Balance between inputs and outputs

Question 19

Define Net Balance

Answer 19

Difference between accumulation and ablation

Question 20

Define Glacial Mass Balance (or Budget)

Answer 20

The difference between the amount of snow and ice accumulation and the amount of ablation occurring in a glacier over a one year period

Question 21

Is the glacial mass balance positive or negative in winter?

Answer 21

Positive - accumulation exceeds ablation

Question 22

Is the glacial mass balance positive or negative in summer?

Answer 22

Negative - ablation exceeds accumulation

Question 23

Define System

Answer 23

A set of interrelated elements comprising of components (stores) and processes (links) that are connected together to form a working unit

Question 24

What three things does a glacier comprise of?

Answer 24

Inputs, Throughputs/Processes, Outputs

Question 25

Define Potential Energy

Answer 25

Energy stored in the glacier's height

Question 26

Define Kinetic Energy

Answer 26

The capacity to do work as a result of motion

Question 27

Define Thermal Energy

Answer 27

The capacity to do work as a result of heat

Question 28

Define Diagenesis

Answer 28

How snow turns into ice

Question 29

Where are cold based glaciers found?

Answer 29

At high latitude locations and in places of low relief

Question 30

Where are warm based glaciers found?

Answer 30

At high altitude locations and in places of high relief

Question 31

What is another name for a warm based glacier?

Answer 31

Temperate glaciers

Question 32

What is another name for a cold based glacier?

Answer 32

Polar glaciers

Question 33

What is the velocity of warm based glaciers?

Answer 33

20m to 200m per year

Question 34

What is the velocity of cold based glaciers?

Answer 34

Only a few meters per year

Question 35

Define Pressure Melting Point

Answer 35

The temperature at which ice is at the verge of melting, at a given pressure

Question 36

What is the main movement of warm based glaciers?

Answer 36

Basal sliding

Question 37

What is the main movement of cold based glaciers?

Answer 37

Internal deformation

Question 38

What are the three mechanisms of basal sliding?

Answer 38

Slippage, Regelation, Substrate deformation

Question 39

Define Slippage

Answer 39

If the basal temperature is above pressure melting point a thin film of melt water exists between the glacier and valley floor so friction is reduced

Question 40

Define Regelation (or Creep)

Answer 40

On the up-valley side of an obstruction the ice will have increased pressure, creating higher temperatures. This causes the ice to deform around the obstruction. It refreezes on the downhill side

Question 41

Define Substrate Deformation

Answer 41

When meltwater is present beneath a glacier it can seep into any sediment below. When the sediment becomes saturated it will act as a lubricant and the ice will slide on it

Question 42

What are the two mechanisms of internal deformation?

Answer 42

Intergranular slip, Laminar flow

Question 43

Define Intergranular Slip

Answer 43

The overlying weight of ice can result in the individual ice crystals changing shape due to compaction. Ice crystals become flattened and so slide over each other

Question 44

Define Laminar Flow

Answer 44

The layers of snow, firn, neve and glacial ice create planes of weakness. This combined movement allows the ice to move down-slope under the effect of gravity

Question 45

Define The Rigid Zone

Answer 45

The upper zone of the glacier where the ice is brittle and breaks

Question 46

Define The Plastic Zone

Answer 46

The lower zone of the glacier where under the pressure the ice deforms

Question 47

Define Extending Flow

Answer 47

When ice moves over a steep slope it is unable to deform quickly enough so it fractures forming crevasses. The leading ice pulls away from the ice behind it

Question 48

Define Compressing Flow

Answer 48

When the gradient decreases, ice thickens and the flowing ice pushes over the slower moving leading ice

Question 49

Define Closed System

Answer 49

Have transfers of energy into and beyond the system but not matter

Question 50

Define Open System

Answer 50

Have transfers of matter and energy beyond the system

Question 51

Are glaciers open or closed systems?

Answer 51

Open

Question 52

Define Dynamic Equilibrium

Answer 52

A state of balance between continually changing processes

Question 53

Define Negative Feedback

Answer 53

Acts to minimise or dampen the effect on change

Question 54

Define Positive Feedback

Answer 54

Acts to reinforce or amplify the effect on change

Question 55

What are the three physical factors affecting glaciated landscape systems?

Answer 55

Climate, Latitude and Altitude, Relief and Aspect, Geology