Glacial Landscapes Flashcards
What is a glacier?
A large accumulation of snow and ice which moves under its own weight.
How does a glacier form?
Precipitation falls as snow.
Each Layer becomes heavier and compresses the layers underneath.
This is called diagenesis
Real glacial ice is when there is only 20% of air as bubbles
What is an open system?
A system that allows the transfer of both matter and energy to neighbouring systems
What is a glacial period
Periods of very cold and dry climate in which land ice and valley glaciers have grown to their maximum levels
The last one ended 10,000 years ago
What is an interglacial period
Warmer periods during which much of the ice has retreated
Current interglacial period is known as the Holocene
Inputs of a glacial system
Snow, hail, avalanches, rock debris, solar energy
Outputs of a glacial system
Calving, melting, sublimation, evaporation, previously eroded material that has been transported and deposited by the glacier
Give an example of a positive feedback loop in a glacial environment
Temperature rises - Permafrost melts - Co2 released - Greenhouse effect - Temp rises
Give an example of a negative feedback loop in a glacial environment
Temp rises - Permafrost melts - Plants absorb more co2 - Reduces greenhouse effect - Temp cools
Name the 4 types of polar environments
Polar, Periglacial/tundra, alpine, glacial
What is the albedo effect
When incoming solar radiation is reflected back into space due to light colours such as ice
This causes it to be cooler in these areas
Outline the characteristics of the climate in periglacial environments
Very cold and dry all year round
little seasonality
What are the main features of soil in periglacial environments?
Lack of clearly defined layers
Thin organic layer, often acidic
Waterlogged in summer
What are the main features of vegetation in periglacial environments?
Low level of production
Low levels of biodiversity
Vegetation close to the ground
What does aspect mean?
The direction the slope faces
What does accumulation mean
The addition of snow and ice over time
What does ablation mean?
The loss of snow and ice overtime
What is the net balance of a glacier
The difference between accumulation and ablation
What is pressure melting point
That temperature at which ice is on the verge of melting
Outline the characteristics of a warm based glacier
Found at high altitude locations
Meltwater means the glacier is more mobile
More rates of erosion, transportation and deposition
Athabasca Glacier
Outline the characteristics of a cold based glacier
Found at high latitude locations
Less meltwater so often does not move much
Much less erosion, transportation and deposition
Meserve Glacier
Outline the process of internal deformation
Explains the movement of cold based glaciers
Under great pressure at the base of a glacier the ice crystals allign themselves to the direction of movement of the glacier
Most likely near the bed as pressures are highest
Cracks can emerge leading to the formation of crevasses
Glacier remains frozen to the bedrock
Corries
Form when snow continues to build up in a nivation hollow and eventually compacts to form a glacier
Glacier becomes trapped within the hollow, only way it can move is rotational slip
Back wall eroded through plucking and frost shattering, hollow deeped via abtasion
Water can fill corries to make tarns
Arêtes
A knife edged ridge formed between two corries (when two steep backwalls meet)
If three meet they create a pyrmaidal peak
Glacial Troughs
A u-shaped valley formed by a glacier bulldozing and eroding through a river valley
The glacier has enough force to erode a rivers interlocking spurs leaving smooth but steep truncated spurs
aswell as a wide flat valley floor
The original river will continue to flow but now as a misfit stream due to the difference in its size with its surroundings
Hanging Valleys
A smaller u-shaped valley caused by a tributary glacier. The smaller glacier does not have enough energy to erode to the valley floor leaving a hanging valley where waterfalls usually form
Roche mountonees
Glacier hits an obstacle that is too large/hard to pluck
Hitting the obstacle creates pressure and friction increasing melting as the lower ice reaches PMP
The meltwater allows the glacier to slide over the rock and smaller rocks abrade the stoss side
When the glacier reaches the top of the obstacle friction and pressure drop
Meltwater refreezes
Frozen rocks are plucked from the lee side
Till plains
Unsorted glacial material formed through erosion and weathering
Form when an ice sheet detaches from the main glacier and melts causing all of the till on top of and within the glacier to deposit on the valley floor
Erratics
A large boulder that is of a different rock type to the surrounding rock
Would have been broken off by weathering and erosion then transported by a glacier and deposited when it has been moved to a different location
Moraines
Deposits of eroded material that are transported with the glacier
Lateral: Material deposited on the sides of a glacier leaving a ridge when the ice melts
Medial: Formed when two lateral morains meet in the middle of a glacier and deposit material
Ground: Carried under the glacier and abraded between glacier and valley floor. Only sorted moraine
Recessional: Forms at the end of a glacier
Drumlins
When a glacier hits an obstacle that cannot be eroded deposition from underneath the glacier builds up behind the obstacle
The glacier moves over the large mound and drags excess deposition to the other side
Tear drops shape with a long tapered edge
Blunt end - stoss side
Tapered end - Lee side
Why is plant growth difficult in the Tundra?
Waterlogged soils - thawed soils can’t infiltrate through permafrost and evaporation rates are low
Strong winds
Low levels of precipitation
Low insulation
Short growing season - no more than 60 days
Vegetation and soil characteristics in cold environments - polar
Slow nutrient cycles
Climate means decomposers can’t thrive
Cold, harsh climate with little rainfall - only highly adapted vegetation can grow such as mosses and lichen
Overall there is a cycle where poor vegetation creates poor soil and poor soil causes poor vegetation
Vegetation and soil characteristics in cold environments - Alpine
Heavy snowfall in winter
In summer there is heavy rainfall aswell meltwater
Mild temps stimulate plant growth, thawing and decomposition
Alpine vegetation is decomposed more quickly than in a polar climate, and grows quicker too due to soil fertility and climate.
The nutrient rich vegetation allows a more fertile soil to develop when it decomposes, as the nutrients are transferred into the soil. This fertile soil allows more nutrient rich plants to grow.
Vegetation and soil in cold environments - periglacial tundra
Temperatures are consistently below freezing.
The latitude of some permafrost regions also assists in the consistently cold temperatures, as winters in higher latitudes last longer with less daylight hours, making them colder.
Vegetation is more prevalent than in polar regions, but only highly adapted plants can survive in the cold temperatures with little rainfall.
The temperatures and poor soil leads to a slow nutrient cycle. The lack of nutrient rich plants contributes to the soil infertility.
The cold climate causes the lower ground to be frozen all year around. However, slightly warmer summer temperatures cause the thawing of upper soil called the active layer. Soil is usually extremely waterlogged in summer due to thawing, which means plants become deoxygenated within the soil and cannot survive, and any nutrients are often leached out.
Vegetation adaptions to tundra environment
Vegetation grows close to ground - protects from strong winds
Shallow roots - To allow it to get nutrients from the active layer
Can photosynthesise at low temps - due to low temps from albedo effect, they can create energy
Perennial plants - store food to allow them to survive during harsh winters
