Glacial Systems and Processes Flashcards
What is accumulation?
Accumulation: The addition of mass
(precipitation, usually snow) to the glacier.
Mainly occurs at higher altitudes at the
source of the glacier
What is ablation?
Ablation: The loss of mass from the glacier.
This includes meltwater, avalanches,
sublimation, evaporation, and other
processes.
What is the glacial budget?
Glacial budget: The mass balance of a glacier, i.e the difference between accumulation and
ablation.
What is a positive glacial budget?
A positive glacial budget shows accumulation exceeds ablation , so the glacier is
advancing.
What is a negative glacial budget?
A negative glacial budget shows ablation exceeds accumulation , to the glacier is
retreating.
How do glacial budgets fluctuate?
Glacial budgets fluctuate yearly, with more ablation in the summer months and more accumulation
in winter months.
How are glaciers natural systems?
Glaciers are natural systems, meaning there are specific interactions
within their development and sustaining that allow glaciers to work.
How do open systems work?
In an open system, there are inputs from outside the system’s set area
How does a close system work?
In a closed system, all of the inputs and processes occur within the
system’s set area
What are the inputs into a glacier?
Additions to the glacier
(accumulation). Precipitation such as
snow or hail are inputs to the glacier, as well
as avalanches from other areas entering the
system.
Debris that has been eroded can
also fall into a glacier’s system and
consequently can be transported and
deposited elsewhere.
What are the stores in the glacial system?
Also known as components.
Stores are the mass that glaciers hold.
The majority of stores within the glacier are
ice, but sediment from erosion and meltwater
lakes/channels also contribute to stores.
There are 3 types of glacial stores:
subglacial (underneath the glacier),
englacial (within the glacier), and
supraglacial (on top of the glacier)
What are the outputs of the glacial system?
Things that leave the
glacier system, usually in the form of
meltwater. All ablation processes are
outputs. Calving is also a common output, in
which large pieces of glacier break off at the
snout (the end).
What are the flows in the glacial system?
Flows occur in glaciers through the
transfer of mass or energy. There are
flows in mass and energy from ice on the
glacier to meltwater leaving the glacier. The
glacier also moves through flows, such as
compressional flow.
Describe the energy in glacial systems
Glaciers all have varying
amounts of energy dependent on their
mass, their environment, their composition
and other factors. For example, a glacier with
more meltwater underneath it would move
faster, giving it more energy. Glacial energy
is usually in the form of kinetic energy as the
glacier moves. This energy allows erosion to
occur. Gravity allows the glacier to have
energy, as it forces the glacier downhill.
What is dynamic equilibrium and how does it work within glacial systems?
Equilibrium refers to a state of balance. This balance is dynamic when the processes causing the balance are continual (always occuring). For example, even if the glacier is constantly gaining inputs and losing outputs, if the amount of these are the same, the mass of the glacier does not change annually and the glacier is at dynamic equilibrium. The area where mass gain = mass loss on a glacier is called the equilibrium line.
What is a feedback loop?
Feedback Loops: A feedback loop is a type of chain reaction, where one process leads to
another process, leading to another process, and so on. There are two types of feedback loops:
positive and negative.
Describe the positive feedback loop in a glacial system
In positive feedback, a process occurs, which causes another
process to occur, which starts a chain reaction that heightens the
first process.
1. Temperatures rise - 2. Permafrost melts - 3. Greenhouse effect - 4. CO2 released
Describe the negative feedback loop in a glacial system.
In negative feedback, the process that occurs is counteracted
by an opposing process, causing the effects to cancel each other
out and nothing to change.
1. Temperatures rise -2.Permafrost melts- 3.More plants to take in CO2- 4.Greenhouse effect lessens
-5.Temperatures fall
Describe the distribution of polar environments
Polar environments are located at the poles (high latitudes) of the Earth within the Arctic Circle
(66°N) and the Antarctic Circle (66°S) .
Describe the conditions of polar environments
These environments can also be described as being within
the 10°C isotherm, which means in the hottest month, the average temperature stays below 10°C.
However, the first definition is the most common.
In polar regions, the maximum extent of ice sheets occurs within the coldest, winter months. The
Arctic Winter (northern hemisphere) occurs from December - March, and the Antarctic Winter
(southern hemisphere) occurs from March - October.
Why is the soil in polar environments deprived of nutrients?
Due to the consistently below freezing temperatures with little rainfall, polar environments have slow nutrient cycles, meaning the soil is usually deprived of nutrients.
What are the winter temperatures and precipitation levels? Polar
.Winter temperatures average -40°C in some polar regions and precipitation almost never exceeds 100mm per year.
Describe the vegetation in polar regions
The cold, harsh climate with little rainfall also means only highly adapted vegetation can grow, such as mosses and lichen. These plants rarely decompose as there are a
lack of decomposers. When plants eventually decompose, the cold temperatures cause this process to be extremely slow.
Describe the soil in polar regions
This lack of nutrient rich vegetation from the harsh climate causes the soil to be low in nutrients. The nutrient deprived, frozen soil further limits nutrient rich plant growth. This creates a cycle where poor vegetation causes poor soil, and poor soil causes poor vegetation.
What is the distribution of alpine environments?
Alpine environments are areas of low temperatures in high altitude, mountainous regions, found
at any latitudes. These environments are found above the tree line.
What are the temperatures in the alpine environments like?
Temperatures in alpine areas fluctuate annually, and alpine summers are frequently above 0°C.
An example of an alpine environment is Mount Washington, The White Mountains. There is a large amount of fluctuation between seasonal temperatures, January -20 low, -10 high and in July 8 low, 12 high.
Describe the weather/climate conditions in the winter in alpine environments
In the winter, alpine environments receive heavy snowfall, more than in polar environments in most cases. In summer, milder temperatures can lead to sometimes heavy rainfall and a lot of meltwater from the melting of snow and ice. The climate allows adapted animals to move to higher altitudes. The milder temperatures also stimulate plant growth, thawing, and decomposition.
Describe the vegetation in the alpine environments
Vegetation that is adapted to the alpine climate thrives in milder alpine summers, and usually dies back in winter. The climate (and consequent wildlife) allows for a quicker nutrient cycle, as the wildlife use vegetation for food and the warmer climate encourages decomposing. Alpine vegetation is decomposed more quickly than in a polar climate, and grows quicker too due to soil fertility and climate.
Describe the soil in alpine environments?
Higher temperatures allow soils (usually at lower altitudes) to thaw, increasing the area that vegetation can grow in. 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. Soils usually freeze in winter, meaning less plants can grow in the colder conditions.
Describe the distribution of periglacial environments.
Periglacial environments are areas found on the edge of colder environments like polar and alpine
environments.These areas are consistently cold enough that the ground is permanently frozen
(permafrost). Permafrost can be continuous, discontinuous, sporadic or isolated, which
indicates the extent of permafrost cover. Although permafrost is also found on the fringes of glacial
and alpine environments, the majority of permafrost is located at high latitudes within the
northern hemisphere
Describe the weather/climate conditions in periglacial areas
Similar to polar environments, precipitation is low (but still occurs in summer months). 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.
Describe the vegetation in periglacial environments
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 permafrost makes it especially hard for plants to grow as plants cannot infiltrate the soil.
Describe the soil in periglacial environments
The cold climate causes the lower ground to be frozen all year around. However, slightly warmer summer temperatures causes 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.
What are glacial environments?
A glacial environment is an area where temperatures are consistently cold enough to sustain
glaciers or ice sheets. Glacial environments are in both polar and alpine areas (and sometimes
periglacial however temperatures are usually not cold enough). The climate, soil, and vegetation is
dependent on the region in which the glacier develops, but the temperatures must be below
freezing for long enough in the year that the glacier does not melt entirely.
When was the most recent major ice age?
Aside from an ice age around 300 million years ago, the most recent major ice age
occured in the Pleistocene era. The period spanned from around 2.5 million years ago
to 11,700 years ago.
During this ice age, there were many fluctuations in global temperatures:
● Glacial period: colder temperatures, causing glacial advances and sea levels to fall.
● Interglacial period: warmer temperatures, causing glacial retreats and sea levels to rise.
What were global temperatures in the most recent ice age/
During this ice age, there were many fluctuations in global temperatures:
● Glacial period: colder temperatures, causing glacial advances and sea levels to fall.
● Interglacial period: warmer temperatures, causing glacial retreats and sea levels to rise.
When was the most recent period of glacial advance?
The most recent period of glacial advance ( Last Glacial Maximum ) was around 21,000 years
ago, and the present distribution of cold environments is much more isolated in comparison to this
period.
What period is the world currently in and how are glaciers affected?
The world is currently in an interglacial period, meaning temperatures are higher and the majority
of our glaciers are retreating.
How has the movement of glaciers occured?
Glaciers have advanced and retreated in correlation with the world’s glacial and interglacial periods.
Describe the current global temperatures and the reason for this.
Historically, global temperatures have been
increasing since Last Glacial Maximum. However,
there have been smaller global coolings in
recent history that have affected the mass
balance of glaciers.
Which period in recent history has the most significant global cooling?
The ‘Little Ice Age ’ -
between 1300 and 1870 has been the most
significant global cooling in recent history. The
graph shows the length change in 5 different
glaciers in Mont Blanc in history. The period from
1818-1821 (during the Little Ice Age) shows that
all glaciers were at their largest point at this time.
Describe the glacial advance of the Alps during the Little Ice Age.
Glacial advance in the Alps was a very prevalent
issue during the Little Ice Age. Heavy snowfall
and avalanches were common and posed a risk
to life.
“Between 1627 and 1633 Chamonix lost a third if
its land through avalanches, snow, glaciers and
flooding, and the remaining hectares were under
constant threat. (Source: Fagan, 2010.
What are the two types of glacier?
There are two main types of glaciers that develop in glacial environments - warm based and cold
based glaciers. Each glacier type has a specific development and certain characteristics.
Describe warm based glaciers, environment, climate, features and processes.
Environment: Alpine
Climate: Fluctuating, warmer temperatures
Features: Lots of meltwater
Processes: High erosion from basal sliding,
internal deformation also present
