Glossary of Terms
Ablation zone
The area of a glacier, below the equilibrium-line altitude (ELA), that has a net loss in ice
mass due to melting, sublimation, evaporation, ice calving, aeolian processes like
blowing snow, avalanche, and any other ablation.
Acclimatization
The process in which an individual organism adjusts to a gradual change in its
environment (such as a change in altitude), allowing it to maintain performance across a
range of environmental conditions.
Accumulation zone
The area of a glacier, above the equilibrium-line altitude (ELA), where snowfall
accumulates and exceeds the losses from ablation (melting, evaporation, and
sublimation).
Acute mountain sickness
The body’s reaction to a lack of oxygen, caused by ascent at a faster pace than
acclimatisation. Often shortened to AMS.
Albedo
A measure of the reflectivity of the Earth's surface indicating the proportion of solar
energy (shortwave radiation) reflected back into space. White surfaces (clean snow or
ice) have a high albedo, while dark surfaces have a low albedo.
Allopatric speciation
Speciation occurring when biological populations of the same species become
geographically isolated
Alpine treeline
The highest elevation that sustains trees. Treeline marks the low-temperature limit of tree
growth and occurs in mountains worldwide.
Altitude
The vertical distance between an object, such as a bird, aircraft, or cloud, and a reference
point, where the object is not in direct contact with the reference point.
Alveoli
The many tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide
occurs
Amenity migration
The movement of people based on the draw of natural and/or cultural amenities.
Amplifier
Something that increases the power of another event or function.
Annuals
Vascular plants that complete their entire life cycle in one year and then die.
Arête
A sharp, narrow mountain ridge, created by glacial erosion.
Asthenosphere
The upper layer of the Earth's ductile mantle, just below the lithosphere (or the Earth's
crust).
Atmospheric circulation
Temperature imbalance created by uneven solar radiation across latitudes that controls
global patterns of wind and precipitation.
Atmospheric pressure
The downward force of air in the atmosphere caused by gravity pulling molecules of air
toward the Earth. Lower air density leads to lower atmospheric pressure because the more
spread out the molecules are, the less force they exert.
Autonomic nervous system
A control system that acts largely unconsciously and regulates bodily functions, such as
heart rate, digestion, respiratory rate, pupillary response, and urination.
Barometric pressure
Another term for ‘atmospheric pressure’.
Basaltic magma
Basaltic magma is molten rock enriched in iron and magnesium and depleted in silica.
Basaltic magmas tend to be fairly fluid (low viscosity) in contrast to other types of
magma.
Basal sliding
The act of a glacier sliding over its bed surface en masse due to meltwater under the ice
acting as a lubricant.
Bed deformation
The deformation of a soft-sediment bed surface by a glacier, which contributes to glacier
flow.
Bed surface
The surface over which a fracture and subsequent avalanche release occurs. Can be either
the ground or a snow surface.
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Behavioural adaptations
Decisions that organisms make in response their physical and social environment to
increase survival, reproduction or condition.
Bioclimatic belts
Areas of the Earth with distinct climates, which can be classified using different
environmental parameters and occur in an east-west direction around the planet.
Biodiversity
The number of species in a certain area and the genetic variation within populations, or
the role that species play within the ecosystem.
Biogeography
The study of the distribution of species in geographical space.
Biological corridors
Connecting isolated habitats, or protected areas, all allowing species the critical space
they need to migrate and thrive.
Boundary layer
A thin layer of air above the surface of the ground surface or a plant leaf that retains some
warmer thermal properties.
Brown fat
A tissue that is specialized for heat generation and is an important source of heat during
periods of hibernation.
Carbon dioxide
A colorless, odourless gas that is present in the atmosphere and is formed when any fuel
containing carbon is burned. It is breathed out of an animal's lungs during respiration, is
produced by the decay of organic matter, and is used by plants in photosynthesis. As a
greenhouse gas, carbon dioxide is the main contributor to climate change.
Catastrophism
The theory that changes in the earth's crust during geological history have resulted chiefly
from sudden violent and unusual events.
Chronic mountain sickness
A disease in which the proportion of blood volume that is occupied by red blood cells
increases and there is an abnormally low level of oxygen in the blood. CMS can develop
during extended time living at a high altitude.
Cinder cone volcano
A cinder cone, also called a scoria cone, is a volcano composed of volcanic cinders
(scoria), or small, rough particles of hardened lava.
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Circulation cells
Formed by air moving across the surface of the Earth toward the equator the same time as
warm air that rises near the equator moves towards the poles.
Circumambulation
The act of moving or walking around a sacred object or idol. Circumambulation of
temples or deity images is an integral part of Hindu and Buddhist devotional practice.
Cirque glacier
A glacier formed in a cirque, a bowl-shaped depression, on the side of or near mountains.
Snow accumulation often occurs as the result of avalanching from higher surrounding
slopes.
Climate
The average weather in a place over many years. While the weather can change in just a
few hours, climate takes hundreds, thousands, even millions of years to change.
Climate change
A change in the statistical distribution of weather patterns when that change lasts for an
extended period of time (i.e., decades to millions of years).
Climax avalanche
The culmination of the build up of several layers on top of a weak one. Large climax
avalanches occur in the spring, when the whole of the season's snowpack may release
right down to ground.
Co-evolution
The influence of closely associated species on each other in their evolution.
Concentration gradient
The gradual difference in concentration of a substance between a region of high density
and one of lower density.
Condensation
The process in which air molecules move slower, causing many of them to convert back
to a liquid state at lower temperatures.
Coniferous trees
A type of woody plant that reproduces from seeds in cones and can easily be recognized
by their needle-like leaves.
Continentality
Proximity or distance of land to large water bodies, such as oceans.
Continental rift zone
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Places where the continental crust is extending and thinning. As the crust thins, the hot,
buoyant upper mantle (the asthenosphere) rises.
Convective cooling
A decrease in the amount of heat that is lost due to wind.
Convective storms
These storms tend to form in afternoons and evenings from strong daytime heating on the
landscape, which causes evaporation and eventually condensation as the water vapour
rises and cools.
Convergent mountains
Convergent mountains are those formed when two tectonic plates collide with each other
at convergent boundaries.
Convergent plate boundary
In plate tectonics, a convergent boundary is an actively deforming region where two (or
more) tectonic plates or fragments of the lithosphere move toward one another and
collide.
Coriolis Effect
When the rotation of the Earth deflects winds so that they do not flow directly north and
south.
Crevasse
A crack in the surface of a glacier caused by tensional stress within the ice. Stress can be
caused by stretching if the glacier is speeding up as it flows down the valley. Crevasses
can also be caused by the ice flowing over bumps or steps in the bedrock.
Crown
In the context of slab avalanches, a crown is the distinctive upper fracture line where the
avalanche releases on a mountain slope. It is perpendicular to the slope and extends down
to a well-defined sliding surface or bed surface.
Cryoprotectants
A substance that prevents the freezing of tissues, or prevents damage to cells during
freezing.
Cushion growth form
Plants that are tightly packed clusters of many smaller stems.
Cuticle
The waxy coating on a needle that helps to retain moisture and provides protection from
UV radiation.
Death zone
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The name used by climbers in reference to extreme altitudes (usually above 8,000m),
where acclimatization is virtually impossible and humans can't survive for long.
Debris flow
A moving mass of loose mud, sand, soil, rock, water, and air that travels down a slope
under the influence of gravity.
Detritus
Dead organic material that includes decomposing organisms.
Diffusion
Specifically the movement of oxygen and other gases between the alveoli and the
bloodstream.
Divergent plate boundary
In plate tectonics, a divergent boundary is a linear feature that exists between two
tectonic plates that are moving away from each other. Divergent boundaries within
continents initially produce rifts, which eventually become rift valleys, while divergent
boundaries between oceanic plates produce oceanic spreading ridges.
Diversity-stability hypothesis
Based on the observation that species vary in their morphology and physiology, and that
in a highly diverse system there will be some species that can compensate for the loss of
others following disturbance.
DNA barcoding
A technique for characterizing species using a short DNA sequence.
Dome mountains
Mountains formed from magma rising from the Earth's mantle into the crust that pushes
overlying sedimentary rock layers upward to form a 'dome' shape. Unlike a volcano, the
magma typically does not reach the Earth's surface. Instead, the magma cools underneath
the surface and forms the core of the mountains.
Dry snow zone
A place where it is too cold at any time of the year for melting to occur. They are
restricted largely to very high latitudes and/or altitudes.
Earth creep
The slow downslope movement of individual soil particles under the influence of gravity.
It is mostly imperceptible except to long-term measurements, and there is little
mechanical disruption of the material, which can form small-scale soil creep terracettes.
Earthflow
The downslope viscous flow of fine-grained materials that have been saturated with water
and moves under the pull of gravity.
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Ecotones
The transitional boundary between distinct plant communities.
Ectotherms
Animals that primarily regulate their temperatures using external sources of heat.
Elevation
The vertical distance between a point on the land surface and a reference point, usually
the mean sea level.
Elevation-dependent warming
An acceleration in the rate of change in mountain ecosystems, cryospheric systems,
hydrological regimes and biodiversity as elevation increases.
Endemic
Species that have evolved in isolation over millennia to inhabit specialized alpine
environments.
Endothelin Receptor Type B
A gene that is associated with high altitude adaptation and can improve cardiac tolerance
to hypoxia in Ethiopian highlanders.
Equilibrium-line altitude
The average elevation of the zone on a glacier where accumulation equals ablation over a
one-year period. Often referred to as the ELA.
Erosion
A process by which earth is worn away, often by water, wind, or ice. A similar process,
weathering, breaks down or dissolves rock, weakening it or turning it into tiny fragments.
Evaporation
The process in which water is converted from its liquid state to a gaseous state.
Evaporative cooling
Helps animals keep cool through evaporation of water from the body. This can be
accomplished through sweating or panting.
Fault-block mountain
Mountains formed by the movement of large crustal blocks when forces in the Earth's
crust pull it apart. Some parts of the Earth are pushed upward and others collapse down.
Feedback effects
Effects that either amplify or diminish the initial process, such as warming.
Firn
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An intermediate stage in the transformation of snow to glacier ice.
Flagging
Where tree limbs on the windward side of mountains are unable to survive the high winds
so branches only form in alignment with the prevailing winds.
Foehn/Chinook winds
The result of dry warm winds that flow downslope on the lee side of a continental
mountain range.
Freezing-point depression
A process that allows plants to increase the concentration of soluble sugars in their tissues
in order to reduce the temperature at which they will freeze.
Frontal rainfall
Where low-pressure systems move in from elsewhere and are forced to travel over the
mountains.
Frontier, myth
An enduring myth deeply connected to the American psyche, the "frontier" in popular
imagination is a region of endless possibilities, a vast, magnificent, ideal stage for the
national drama of liberty, equality, and the pursuit of happiness.
Geographical area hypothesis
The hypothesis that suggests that larger areas can support more species.
Glacial lake outburst flood
The sudden and in some cases cyclic release of meltwater from a glacier-dammed lake,
which can result in a catastrophic flood.
Glacier
A mass of relatively slow-moving ice created by the long-term accumulation of snow.
Greenhouse effect
Much like the glass of a greenhouse, gases in our atmosphere sustain life on Earth by
trapping the sun's heat. These gases allow the sun's rays to pass through and warm the
earth, but prevent this warmth from escaping our atmosphere into space.
Greenhouse gas
A gas in the atmosphere that absorbs and emits radiation. The primary greenhouse gases
in Earth's atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and
ozone.
Groundwater
Water that fills the pore spaces and fractures in rocks and sediment.
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Habitat
An ecological or environmental 'space' that is inhabited by a particular species of animal,
plant or organism.
Hadley cell
A large-scale atmospheric convection cell in which air rises at the equator and sinks at
medium latitudes, typically about 30° north or south.
Head scarp
The steep, nearly vertical region of exposed soil and rock at the head of a landslide,
where the failure surface ruptures the ground surface.
Heath
A shrub-land habitat that can be found on free-draining acidic soils and are more
common in cooler, damp climates.
Height
The vertical distance between the top of an object, such as a tree, building, or person, and
the land surface where the object is in direct contact with the ground.
Heliotropic
A plants' motion in response to the sun's movement.
Haemoglobin
A protein found in red blood cells that facilitates the transport of oxygen.
Hibernation
An adaptation that saves animals energy by reducing their activity levels.
High altitude cerebral edema
A potentially fatal form of AMS where the brain swells and stops functioning in the
normal way. Often referred to as HACE.
High altitude pulmonary edema
A potentially fatal form of AMS where excess fluid develops in the lungs, either in the
lung tissue itself or in the space normally used for gas exchange. Often referred to as
HAPE.
Hotspot
In geology, the places known as hotspots are volcanic regions thought to be fed by
underlying mantle that is anomalously hot compared with the surrounding mantle.
Hotspots of biodiversity
Regions containing high concentrations of endemic species that are also facing threats of
rapid species loss.
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Hydrogen sulphide
Colorless gas that has a foul smell similar to that of rotten eggs. It's heavier than air and is
poisonous.
Hydrology
The science concerned with the properties of the Earth's water, especially its movement
in relation to land.
Hyperventilation
To breath faster, deep and rapid breathing.
Hypoxia
A condition where the rate of diffusion of oxygen into our blood is slower at high
altitudes.
Ice cap
An ice mass that covers less than 50,000 km² of land area (usually covering a highland
area). Ice caps are not constrained by topographical features (i.e. they will lie over the top
of mountains).
Ice sheet
An ice mass that is greater than 50,000 km² of land area (usually covering a highland
area). Ice sheets are not constrained by topographical features (i.e. they will lie over the
top of mountains).
Icefield
Icefields are similar to ice caps, except that their flow is influenced by the underlying
topography, and they are typically smaller than ice caps.
Infiltration
The process where the soils in a watershed act a sponge, soaking up precipitation.
Krummholz
Trees become crooked and stunted and are only able to survive by growing horizontally
near the upper limits of their distribution.
Lagomorphs
Species of hares and rabbits and pikas
Lahar
A type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky
debris, and water. The material flows down from a volcano, typically along a river valley.
Landslide
A form of mass wasting that includes a wide range of ground movements, such as
rockfalls, earthflows, and debris flows, under the influence of gravity.
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Lateral moraine
A type of moraine that forms along a glaciers long, lateral edges.
Latitude
Distance from the equator towards the poles.
Lava
Lava is the molten rock, or magma, expelled by a volcanic eruption.
Leeward side
The side of a mountain that is sheltered from the wind.
Legacy pollutants
Contaminants that are often no longer in use and have accumulated in glaciers.
Lithosphere
The crust and the uppermost mantle, which constitute the hard and rigid outer layer of the
Earth.
Loose snow avalanche
A loose snow avalanche, or point release avalanche, is an avalanche formed in snow with
little internal cohesion among individual snow crystals.
Mantle
The mantle is the mostly solid bulk of Earth’s interior, lying between Earth’s dense,
super-heated core and its thin outer layer, the crust. The mantle is about 2,900 kilometers
(1,802 miles) thick, and makes up 84% of planet’s total volume.
Marcescent leaves
Leaves that senesce but not fall off the plant and provide protection from the cold.
Mass balance
Mass balance is the gain and loss of ice from the glacier system. It can be thought of as
the ‘health of a glacier’; glaciers losing more mass than they receive will be in negative
mass balance and so will recede. Glaciers gaining more mass than they lose will be in
positive mass balance and will advance.
Medial moraine
A type of moraine that runs down the center of a valley floor. It forms when two glaciers
meet and the debris on the edges of the adjacent valley sides join and are carried on top of
the enlarged glacier.
Mercury barometer
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Consists of a mercury-filled glass tube, with a closed top and bottom. This tube sits in a
container, also filled with mercury and open to the atmosphere. When the mercury level
in the tube falls, it creates a vacuum in which gas pressure is less the atmospheric
pressure. The barometer works by equalizing the pressure.
Microbes
A microscopic living organism such as bacteria.
Microclimates
A sheltered growing environment for plants to find refuge from the wind. For example:
plants that grow close to a boulder that blocks the wind or provides shade from intense
sun may be more likely to survive and reproduce.
Moraine
A moraine is an accumulation of dirt and rocks that has fallen onto the glacier surface or
have been pushed along by the glacier as it moves. The dirt and rocks composing
moraines can range in size from powdery silt to large rocks and boulders. A receding
glacier can leave behind moraines that are visible long after the glacier retreats.
Mountain mass effect
Large mountains that influence regional climates.
Mutualistic association
Of benefit to both organisms.
Non-shivering thermogenesis
The release of a hormone that increases an animal's metabolic rate and is found mostly in
mammals.
Oceanic spreading ridge
An oceanic spreading ridge is the fracture zone along the ocean bottom where molten
mantle material comes to the surface, thus creating new crust.
Ogives
The alternating bands of light and dark ice that form on some glaciers just below icefalls.
The ice flows faster down the center of the glacier, forming ridged arcs of ice that bend
downstream.
Orogenesis
The geological process of mountain building.
Orographic precipitation
Precipitation that occurs when topographical barriers force air to rise.
Pacific ring of fire
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The Ring of Fire, or circum-Pacific belt, is a major area in the basin of the Pacific Ocean
where a large number of earthquakes and volcanic eruptions occur. In a 40,000 km
horseshoe shape, it is associated with a nearly continuous series of oceanic trenches,
volcanic arcs, and volcanic belts and/or plate movements.
Paleomagnetism
The study of the earth's magnetic field.
Pangea
A supercontinent that existed during the late Palaeozoic and early Mesozoic eras. It
assembled from earlier continental units approximately 300 million years ago, and it
began to break apart about 175 million years ago.
Partial pressure
The pressure a gas exerts independent of others in a mixture.
Perennials
Plants that persist for more than two years.
Phenology
The periodicity of animal and plant life cycle and the influence of seasonal and
interannual variations associated with climate and elevation.
Photosynthesis
The process in which plants use light energy to convert carbon dioxide and water into
sugar and oxygen.
Piedmont glacier
A valley glacier that spills out onto a relatively flat plain and fans out into a bulb-like
lobe.
Piloerection
Involuntary reflex caused by a muscle contraction near the surface of the skin.
Plasma
The liquid component of blood.
Plate tectonics
A theory explaining the structure of the earth's crust and many associated phenomena as
resulting from the interaction of rigid lithospheric plates that move slowly over the
underlying mantle.
Plateau
A high plain or tableland usually consisting of relatively flat terrain that is raised
significantly above the surrounding area.
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Polychlorinated biphenyls
Any of a class of toxic aromatic compounds whose molecules contain two benzene rings
in which hydrogen atoms have been replaced by chlorine atoms: often formed as waste in
industrial processes,
Polycyclic aromatic hydrocarbons
Organic compounds containing only carbon and hydrogen and that are composed of
multiple aromatic rings.
Polymorphism
More than one form in the same population group or species.
Positive feedback
A scientific concept that describes a cycle where one event causes another event to occur,
the second re-enforcing the first, causing it to become greater and so forth.
Productivity hypothesis
Proposes that the amount of primary productivity, which forms the resource base of food
webs, determines the number of species that can be supported in an area.
Pubescence
A dense, hairy surface in alpine plants.
Pyroclastic flow
A dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively
from a volcano and typically flowing downslope at great speed.
Radiative heat gain
One way that alpine plants stay warm by increasing the amount of heat that they absorb
from the sun.
Rain shadow
Produced from the leeward side of a mountain receiving much less rain.
Respiration
The process in which oxygen is transported from the air into our tissues.
Respiratory system
In humans, consists of our lungs and a series of connected tubes that transfer air to and
from the lungs.
Rhizomes
Modified underground stems that extend away from the plant and grow new shoots.
Rhyolitic magma
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Molten rock enriched with silica. Rhyolitic magmas tend to have a high viscosity (low
fluidity) in contrast to other types of magma.
Romanticism
An artistic and intellectual movement that ran from the late eighteenth century through
the nineteenth century. It stressed strong emotion as a source of aesthetic experience,
placing emphasis on such emotions as trepidation, horror, and the awe experienced in
confronting the sublimity of Nature.
Rosette growth form
A circular, basal arrangement of leaves that is common in alpine plants.
Scenesce
The aging process in plants.
Seasonality
When latitude controls how much temperatures fluctuate within a year.
Shear strength
Breaking strength. Bond or anchorage of a snow layer to its adjacent surfaces, under
surface, and sides.
Shear stress
The downward force, gravity, acting parallel to the under surface on a slab layer.
Shield volcano
A type of volcano usually built almost entirely of fluid lava flows. They are named for
their low profile, resembling a warrior's shield lying on the ground. This is caused by the
highly fluid lava they erupt, which travels farther than lava erupted from stratovolcanoes.
Shivering
Small, involuntary contraction of skeletal muscles.
Silica
Silica is a very common mineral composed of silicon and oxygen (SiO2). It makes up
about 95% of the Earth's crust. Magma types are defined by their silica content.
Sintering
The process of compacting and forming a solid mass of material by heat or pressure
without melting it to the point of liquefaction.
Slab avalanche
The simultaneous rupture of a coherent mass of snow over an extended area. A distinct
fracture line is left at the upslope limit of the avalanche, and a clearly defined sliding
surface is often revealed.
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Slump
A form of mass wasting that occurs when a coherent mass of loosely consolidated
materials or rock layers moves a short distance down a slope. Movement is characterized
by sliding along a concave-upward or planar surface.
Snowpack
The accumulated snow that falls onto the ground and does not melt until temperatures
warm up in the spring.
Speciation
Evolutionary process that creates new species.
Species diversity
Accounts for both species richness and evenness. Species diversity can provide some
insights about how ecosystems function in mountain environments.
Species richness
A count of the total number of species present in a prescribed area.
Starting zone
The uppermost part of the avalanche path; for a loose snow avalanche, it's where the first
snow grain starts to move downhill; for a slab avalanche, it's where the crown is located.
Stomata
Specialized pores that diffuse carbon dioxide into leaves as water diffuses out.
Stratosphere
The region of the upper atmosphere extending upward from the
tropopause to about 50 km above the Earth, characterized by little vertical change in
temperature.
Stratovolcano
A conical volcano built up by many layers (strata) of hardened lava, tephra, pumice, and
volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep
profile and periodic explosive eruptions and effusive eruptions, although some have
collapsed craters called calderas. Also known as a "composite volcanos."
Subduction zones
Regions where one tectonic plate moves under another at convergent plate boundaries.
Subnivian space
A space below the snow.
Supercooling
When water inside living tissues can cool below its freezing point.
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Supervolcano
A volcano that erupts and throws magma and rocky particles over an area greater than
240 cubic miles (1000 cubic kilometers).
Sustainable development
A process of meeting human development goals while sustaining the ability of natural
systems to continue to provide the natural resources and ecosystem services upon which
life depends.
Taproot systems
Plants that have a large main root with smaller roots branching off of the side.
Tectonic plates
Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as
the lithosphere.
Temperature inversion
An increase in temperature with elevation because cold air descends to the valley floor in
winter.
Terminal moraine
A type of moraine that forms at the terminus or snout of a glacier, marking its maximum
advance. Also called an ‘end moraine.’
The Grand Tour
The Grand Tour was the traditional trip of Europe undertaken by mainly upper-class
European young men of means, or those of more humble origin who could find a
sponsor. The custom flourished from about 1660 until the advent of large-scale rail
transport in the 1840s, and was associated with a standard itinerary.
Thermal basking
Specific spectral reflectance and absorbance properties of the body surface that lead to
increased heating when an animal exposes itself to solar radiation.
Thermogenesis
The process in which endotherms adapt to amplify their internal heat production under
cold conditions.
Thermoregulation
The process that allows animals to maintain stable body temperature.
Tidal volume
The amount of air that is moved in and out of the lungs in each breath during normal
respiration.
Tidewater glacier
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Valley glaciers that flow all the way down to the ocean. They often calve numerous small
icebergs, which can sometimes pose problems for shipping lanes.
Topography
The shape and features of the Earth's surface and other observable objects.
Topple
This type of landslides involves the forward rotation and movement of a mass of rock,
earth or debris out of a slope. This kind of slope failure generally occurs around an axis
(or point) at or near the base of the block of rock.
Torpor
A state of low metabolic rate and decreased body temperature.
Tracheids
A type of water-conducting cell in the xylem that lacks perforations in the cell wall.
Transboundary peace park
A transboundary protected area, or "peace park," is a protected area that spans boundaries
of more than one country or sub-national entity, where the political border sections that
are enclosed within its area are abolished.
Transform margin
A tectonic plate boundary that is neither divergent nor convergent; rather, here, plates are
grinding past one another in a mostly horizontal motion.
Translation/rotational slide
A type of landslide that occurs when a plane of weakness, of failure surface, in the rock
or sediment causes an overlying consolidated mass to move downslope along the surface
of the rupture.
Trigger
A disturbance that initiates fracture within a snowpack's weak layer causing an
avalanche. Most avalanches are “naturally” triggered, meaning that weather (wind, snow,
rain or sun) stresses the snowpack to its breaking point.
Tsunamis
A series of waves in a water body caused by the displacement of a large volume of water,
generally in an ocean or a large lake.
Uniformitarianism
The theory that changes in the earth's crust during geological history have resulted from
the action of continuous and uniform processes.
Valley glaciers
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Glaciers that are confined within steep walled valleys. They are often outlet glaciers that
provide drainage for icefields, ice caps or ice sheets.
Vasoconstriction
A process whereby blood vessels near the skin decrease in diameter at low temperatures.
Viscosity
Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends primarily on
the composition of the magma, and temperature.
Volcanic ash
Tiny jagged pieces of rock and glass created when solid rock shatters and magma
separates into minute particles during explosive volcanic activity.
Volcanic mountains
Mountains formed when gas-rich molten rock, or magma, from deep within the earth,
moves forcefully to the surface, erupts, and accumulates and cools in various sizes and
forms.
Volcanic winter
A volcanic winter is a reduction in global temperatures caused by volcanic ash and
droplets of sulphuric acid obscuring the Sun and raising Earth's albedo (increasing the
reflection of solar radiation) after a large particularly explosive volcanic eruption.
Water cycle
The movement of water between the Earth's oceans, atmosphere and land.
Water towers
Large, elevated tanks of fresh water. The store and provide a useable source of fresh
water for people that live near them. Frequently used as a metaphor for mountains.
Water-potential gradient
Liquid water moves from soil to and through roots, through the xylem of plants, to the
leaves, and eventually evaporates in the substomatal cavities of the leaf. The driving
force for this flow is a water potential gradient.
Watershed
The area of land where all of the water that falls in it and drains off of it goes to a
common outlet
Weather
Is the hour-to-hour and day-to-day variability in atmospheric conditions, including
temperature, precipitation, humidity, air pressure, and wind at any specific location.
Windward side
The side of a mountain that faces the prevailing winds.
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Zooplankton
Zooplankton are heterotrophic (sometimes detritivorous) plankton that live in seas,
oceans, and fresh water.
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