Glaciation Flashcards
Niche glaciers
- Very small
- Occupy hollows
- North-facing slopes
Piedmont glacier
- Valley glacier extent
- On lowland areas
- Spread out and merge
Snowline
- The point above which snow and ice cover the ground throughout the year
- Snow and ice has survived summer melting
Aspect
The direction in which a slope faces
Negative balance
Ablation exceeds accumulation = more mass is lost than gained
Positive balance
Accumulation exceeds ablation = more mass is gained than lost
Feedback
Balance in a system between inputs and outputs, then the system is said to be in a state of dynamic equilibrium
Positive feedback
Where the effects of an action are multiplied by subsequent knock-on or secondary effects
Negative feedback
Where the effects of an action are nullified by its subsequent knock-on effects
Glacial budget
Net balance between accumulation and ablation within a glaciers system
Glacier
Mass of ice that flows down hill due to gravity
Valley glacier
- Fill valleys
- Several KM long
Corrie glacier
- Small glacier
- Bowl shaped hollows
- High up in mountains
Ice sheets
Domes of ice covering huge areas of land
Five types of glacier
- Valley
- Corrie
- Niche
- Piedmont
- Ice sheets
What can glaciers be classified as?
- Morphology
- Thermal Regime
Thermal Regime
How they move
- Temperate glaciers
- Polar glaciers
Temperate glaciers
- Occurs in areas with milder summers = melting
- Meltwater acts as a lubricant = steep relief
- Move by basal flow, extending/compressing flow, creep and surges
- More likely to erode, transport and deposit material
Polar glaciers
- Occur in very cold areas = below 0 degrees so no meltwater occurs
- Frozen to beds = move by internal flow
- Less erosion, transportation and deposition
Relationship between snowline, latitude and altitude
Higher the latitude, lower the snowline in elevation
Glacier inputs
- Snow
- Ice
- Water vapour
- Rock debris
- Geothermal heat
- Gravity
Glacier outputs
- Water vapour
- Meltwater
- Glacial debris
- Iceburgs
Glacier stores
- The glacier
Glacier transfers
- Ice flow
Accumulation
Inputs = mass is gained
Ablation
Outputs = mass is lost
How snow becomes ice
- Snow initally falls as flakes which trap air
- Snow accumulates, lower layers are slowly compressed by the upper layers, turns into FIRN
- Melt-water seeps into gaps between snow particles + freezes, further compacting mass
- Further accumulation squeezes out air from lower layer, after time solid ice develops
- Ice forms which changes colour, blue = no ice present
- If mass of ice becomes large enough = glacier
Mer de Glace, France
- Retreating glacier
- Longest glacier in the French Alps
- Temperate glacier
Hubbard Glacier, Alaska
- Advancing glacier
- 38 miles long
- Temperate glacier
Historical patterns of ice advance and retreat
- Little ice age , 1644 = annual temp across the northern hemisphere declined by 0.6c
- Medival warming period followed = period of warming began in the late 19th century
Calving
- Breaking off of ice from the snout
Sublimation
- The process of snow/ice changing into water vapour
Desublimation
- The process where water vapour changes directly into ice.
Example of positive feedback
- Arctic ice melts
- Land and water exposed
- Darker and duller surfaces = Lower albedo
- More solar radiation absorbed
= Surface warms = More arctic ice melts
