Chapter 2: Glaciated Landscapes
Table of Contents
CHAPTER 2: GLACIATED LANDSCAPES............................................................................................................ 1
GLACIERS AS SYSTEMS............................................................................................................................... 1
GLACIAL PROCESSES.................................................................................................................................. 2
HOW A GLACIER FORMS.............................................................................................................................. 2
THE GLACIAL BUDGET AND MASS BALANCE..................................................................................................... 2
TYPES OF GLACIER AND MOVEMENT............................................................................................................... 3
FACTORS AFFECTING THE MICROCLIMATE........................................................................................................ 3
HOW ARE GLACIAL LANDFORMS DEVELOPED?.................................................................................................. 4
GLACIAL PROCESSES............................................................................................................................ 5
GLACIAL EROSIONAL LANDFORMS.................................................................................................................. 6
FACTORS AFFECTING GLACIAL EROSIONAL LANDFORMS......................................................................................8
DEPOSITIONAL LANDFORMS....................................................................................................................... 10
CASE STUDY: A LANDSCAPE ASSOCIATED WITH THE ACTION OF VALLEY GLACIERS- LAKE DISTRICT.........................12
CASE STUDY: A LANDSCAPE ASSOCIATED WITH THE ACTION OF ICE SHEETS- LAURENTIDE....................................15
Erosional Impact............................................................................................................................. 15
Depositional Impact........................................................................................................................ 15
GLACIO-FLUVIAL LANDFORMS..................................................................................................................... 17
PERIGLACIAL LANDFORMS.......................................................................................................................... 20
Types of Mass Movement................................................................................................................ 22
HUMAN ACTIVITY IN GLACIAL AND PERIGLACIAL LANDSCAPE SYSTEMS................................................................24
CASE STUDY: Oil extraction in Alaska (periglacial)..........................................................................24
CASE STUDY: HUMAN ACTIVITY CHANGE GLACIATED LANDSCAPE SYSTEM- GRANDE DIXENCE DAM.........................26
Glaciers as Systems
(A system with many stores, processes, inputs & outputs = open system).
Inputs Outputs (ablation=melting)
- Precipitation (snowfall) - Evaporation
- Material from deposition, weathering - Sublimation
& mass movement
- Avalanches - Meltwater
- Kinetic energy + thermal energy - Wind erosion
(from sun).
Stores
- Ice
- Water
- Debris
,Glacial Processes
(Dependant on the type of glacier- warm-based/cold-based)
Glacial movement (mechanisms of flow):
Warm-based Cold-based
Basal sliding- temp causes meltwater to Internal deformation- gravity and
lubricate contact between base layers of ice pressure of ice in the accumulation zone
and bedrock. Increased pressure when cause ice to slide over each other, in a
basal ice meets resistant bedrock = pressure ‘crumbling deformation’ (intergranular
melting point (basal ice melts). flow) = deep crevasses at surface.
Extensional flow- gradient becomes steeper, so ice moves faster = ice mass is stretched and
becomes thinner through a series of fractures = crevasses are formed in direction of flow.
Compressional flow- gradient becomes less steep, so ice mass backs up, crevasses close and
fractures as the ice mass compresses. The thicker ice then exerts pressure on bedrock =
more extensive erosion.
Creep- ice deforms under pressure due to obstructions on the valley floor. Then it can
spread around and over the obstruction, before re-freezing.
How a glacier forms
A glacier forms when-> temp is low enough so that snow exceeds
summer melt in an area. Resulting in an accumulation of snow and ice
year after year. Typically in a hollow on a mountain.
Over time, snow is compacted and turns into glacial ice. Then when its
40cm thick, the intense pressure causes it to begin flowing.
Process of snow into glacial ice:
Snowflakes- granular snow- neve- firn- glacial ice.
The Glacial budget and mass
balance
Mass balance= total sum of all
accumulation (snow, ice etc.) and
melt or ice loss across the entire
glacier.
, Positive balance- Accumulation is greater than ablation
Negative balance- Accumulation is less than ablation
*An equilibrium is reached when accumulation and ablation are equal.
Types of glacier and movement
Ice sheet= mass of snow and ice, greater than 50,000km2. There’s only 2-
Antarctica & Greenland.
Valley glacier= one bound by valley walls. They follow the course of existing river
valleys or corridors of lower ground.
Cold based cant move by
Cold-based (polar) glaciers: basal sliding, as basal temp
is below PMP.
- SLOW movement (<5m/year)
- Located in extreme LATITUDE polar regions So they move through
- Low basal temp, stuck to bedrock below PMPinternal deformation.
- Generally flat
Warm-based (alpine) glaciers:
- FAST movement (20-200m/year)
- High ALTITUDE mountainous regions
- Basal temp at/above PMP
- In areas of steep relief
Factors affecting the microclimate
Factor Effect
Relief Steeper relief = faster movement
Climate (4) wind- more wind = more ablation. Wind also affects erosion,
transportation & deposition
ppt- high ppt= more accumulation (main input of glaciers)
temp- higher temps = more ablation, + more meltwater
increases movement rate. Temp determines movement,
shape, size mass balance etc.
seasonal variations- positive net balance in winter, negative
net balance in summer.
Latitude High lat areas have lower temps, flatter relief, cold, dry
climates with little seasonal variation in PPT.
Table of Contents
CHAPTER 2: GLACIATED LANDSCAPES............................................................................................................ 1
GLACIERS AS SYSTEMS............................................................................................................................... 1
GLACIAL PROCESSES.................................................................................................................................. 2
HOW A GLACIER FORMS.............................................................................................................................. 2
THE GLACIAL BUDGET AND MASS BALANCE..................................................................................................... 2
TYPES OF GLACIER AND MOVEMENT............................................................................................................... 3
FACTORS AFFECTING THE MICROCLIMATE........................................................................................................ 3
HOW ARE GLACIAL LANDFORMS DEVELOPED?.................................................................................................. 4
GLACIAL PROCESSES............................................................................................................................ 5
GLACIAL EROSIONAL LANDFORMS.................................................................................................................. 6
FACTORS AFFECTING GLACIAL EROSIONAL LANDFORMS......................................................................................8
DEPOSITIONAL LANDFORMS....................................................................................................................... 10
CASE STUDY: A LANDSCAPE ASSOCIATED WITH THE ACTION OF VALLEY GLACIERS- LAKE DISTRICT.........................12
CASE STUDY: A LANDSCAPE ASSOCIATED WITH THE ACTION OF ICE SHEETS- LAURENTIDE....................................15
Erosional Impact............................................................................................................................. 15
Depositional Impact........................................................................................................................ 15
GLACIO-FLUVIAL LANDFORMS..................................................................................................................... 17
PERIGLACIAL LANDFORMS.......................................................................................................................... 20
Types of Mass Movement................................................................................................................ 22
HUMAN ACTIVITY IN GLACIAL AND PERIGLACIAL LANDSCAPE SYSTEMS................................................................24
CASE STUDY: Oil extraction in Alaska (periglacial)..........................................................................24
CASE STUDY: HUMAN ACTIVITY CHANGE GLACIATED LANDSCAPE SYSTEM- GRANDE DIXENCE DAM.........................26
Glaciers as Systems
(A system with many stores, processes, inputs & outputs = open system).
Inputs Outputs (ablation=melting)
- Precipitation (snowfall) - Evaporation
- Material from deposition, weathering - Sublimation
& mass movement
- Avalanches - Meltwater
- Kinetic energy + thermal energy - Wind erosion
(from sun).
Stores
- Ice
- Water
- Debris
,Glacial Processes
(Dependant on the type of glacier- warm-based/cold-based)
Glacial movement (mechanisms of flow):
Warm-based Cold-based
Basal sliding- temp causes meltwater to Internal deformation- gravity and
lubricate contact between base layers of ice pressure of ice in the accumulation zone
and bedrock. Increased pressure when cause ice to slide over each other, in a
basal ice meets resistant bedrock = pressure ‘crumbling deformation’ (intergranular
melting point (basal ice melts). flow) = deep crevasses at surface.
Extensional flow- gradient becomes steeper, so ice moves faster = ice mass is stretched and
becomes thinner through a series of fractures = crevasses are formed in direction of flow.
Compressional flow- gradient becomes less steep, so ice mass backs up, crevasses close and
fractures as the ice mass compresses. The thicker ice then exerts pressure on bedrock =
more extensive erosion.
Creep- ice deforms under pressure due to obstructions on the valley floor. Then it can
spread around and over the obstruction, before re-freezing.
How a glacier forms
A glacier forms when-> temp is low enough so that snow exceeds
summer melt in an area. Resulting in an accumulation of snow and ice
year after year. Typically in a hollow on a mountain.
Over time, snow is compacted and turns into glacial ice. Then when its
40cm thick, the intense pressure causes it to begin flowing.
Process of snow into glacial ice:
Snowflakes- granular snow- neve- firn- glacial ice.
The Glacial budget and mass
balance
Mass balance= total sum of all
accumulation (snow, ice etc.) and
melt or ice loss across the entire
glacier.
, Positive balance- Accumulation is greater than ablation
Negative balance- Accumulation is less than ablation
*An equilibrium is reached when accumulation and ablation are equal.
Types of glacier and movement
Ice sheet= mass of snow and ice, greater than 50,000km2. There’s only 2-
Antarctica & Greenland.
Valley glacier= one bound by valley walls. They follow the course of existing river
valleys or corridors of lower ground.
Cold based cant move by
Cold-based (polar) glaciers: basal sliding, as basal temp
is below PMP.
- SLOW movement (<5m/year)
- Located in extreme LATITUDE polar regions So they move through
- Low basal temp, stuck to bedrock below PMPinternal deformation.
- Generally flat
Warm-based (alpine) glaciers:
- FAST movement (20-200m/year)
- High ALTITUDE mountainous regions
- Basal temp at/above PMP
- In areas of steep relief
Factors affecting the microclimate
Factor Effect
Relief Steeper relief = faster movement
Climate (4) wind- more wind = more ablation. Wind also affects erosion,
transportation & deposition
ppt- high ppt= more accumulation (main input of glaciers)
temp- higher temps = more ablation, + more meltwater
increases movement rate. Temp determines movement,
shape, size mass balance etc.
seasonal variations- positive net balance in winter, negative
net balance in summer.
Latitude High lat areas have lower temps, flatter relief, cold, dry
climates with little seasonal variation in PPT.
