PHYSICAL GEOGRAPHY
FIRST-YEAR SUBJECT TERMINOLOGY
A
Abrasion
Acid rain
Actual evapotranspiration
Aeolian transport
Aluminium
Amplitude
Andesitic lava
Angle of repose
Aquiclude
Aquifer
Arch
Aridity index
The wearing away of a substance by rasping action, e.g. the
scouring of bedrock by the boulders carried in the base of a
glacier.
Pollutants in rainfall which are produced mainly by the
burning of fossil fuels and other human economic activities.
These activities release carbon dioxide, sulphur dioxide and
nitrogen oxide into the atmosphere, which form an acidic
solution in rain water.
The amount of water that is removed from a surface due to
evaporation and transpiration. The amount of water
available for evapotranspiration nearly always exceeds the
amount
which takes place.
The movement of particles due to wind activity. Wind can
move material by three processes: suspension, saltation and
surface creep.
A light metal, and the most abundant metal in the Earth’s
crust. It resists oxidation and is and a good conductor of
electricity.
The height of a wave above the still‐water line. This is usually
equal to half the wave height.
Acidic lava that is produced from the process of subduction.
Occurs at island arcs or at destructive plate margins where
oceanic crust is being destroyed.
The steepest angle at which a sloping surface formed of
loose material is stable and will not slide. This angle can
range between 0o to 90o.
An impermeable body of rock or layer of sediment that acts
as a barrier to the flow of groundwater.
Any subsurface material that holds a relatively large quantity
of groundwater and is able to transmit that water readily.
A formation resulting from erosion of cliff rocks due to wave
activity. Eventually waves cut through the headland
completely to form an arch.
A numerical measure of the degree of dryness of the climate
at a location. This is based on the relationship between the
input of water as precipitation (P), the output of moisture
resulting from evapotranspiration (E), and changes in the
water stored in the ground.
1
Asthenosphere
Attrition
Avalanche
The lower mantle in the internal structure of the Earth.
These semi‐molten rocks lie below the mantle’s rigid top
layer. It is composed mainly of silicate rocks, rich in iron and
magnesium.
One of the four main processes of erosion in rivers. As the
bedload moves downstream, boulders collide with other
material and the impact may break the rock into smaller
pieces. In time, angular rocks become rounded in
appearance.
A sudden downhill movement of snow, ice or rock. It occurs
like a landslide, when the weight of the material overcomes
the friction.
B
Backshore
Backwash
Bankfull discharge
Barrier island
Basaltic lava
Baseflow
Batholith
Bedding plane
Bedload
Bifurcation ratio
Big bang theory
The upper section of the beach. Usually above the influence
of waves.
Water from a wave returning to the sea after rushing up the
beach.
Occurs when a river’s water level reaches the top of its
channel; any further increase will result in flooding of the
surrounding land.
A series of sandy islands detached from, but running almost
parallel to, the mainland. They may extend for several
hundred kilometres.
Basic lava produced by the upward movement of material
from the mantle. Located at constructive plate margins:
along mid‐ocean ridges, over hotspots and alongside rift
valleys.
The portion of streamflow contributed by groundwater; it is
a steady flow that is slow to change even during rainless
periods.
Large igneous intrusive features. Formed when rising acidic
magma at destructive margins solidifies within the earth’s
crust.
Horizontal levels separating different layers/strata in
sedimentary rock and indicating different phases of
deposition.
One of the three ways in which river load is transported. It
involves larger particles which cannot be picked up by the
current. Therefore, they are moved along the riverbed by
saltation (bouncing) or traction (rolling).
The relationship between the number of streams of one
order and those of the next highest order. It is obtained by
dividing the number of streams in one order by the number
in the next highest order.
A scientific notion describing how the universe began with
an explosion of matter and energy about 14 billion years
ago.
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Biological weathering
Block fields
Blowhole
Braiding
Breaking waves
After the explosion, the universe began to cool and expand,
and eventually atoms, stars, galaxies and solar systems
formed.
The disintegration and decomposition of rocks due to
natural and living factors, such as plants and animals.
When block disintegration occurs due to frost shattering. If
this is on gentle slopes or flat land, it results in individual
large boulders, creating a field of rocks.
As a cliff is eroded by waves, a hollow formation may occur
along a joint or fault in the rock. This vertical erosion allows
water to rise up the joint and be ejected by a hole at the top
of the cliff.
When a river is divided into a series of diverging and
converging segments.
In shallower water the height and steepness of the wave
increases until the upper part of the wave spills over and
breaks.
C
Capacity
Carbonation
Cave
Channel flow
Chemical change
Chemical weathering
Clay
Cliff
Cliff retreat
The total load of material transported by a river.
A form of chemical weathering. Rainwater contains carbon
dioxide which produces carbonic acid. This weak acid reacts
with rocks that are composed of calcium carbonate, such as
limestone. The limestone dissolves and weathers due to this
reaction.
A formation in a cliff resulting from erosion by wave action.
Sometimes the sea can widen the weakness in the cliff and
undercut part of the rock to form a cave.
A combination of three transfer processes bringing water into
a river channel: surface runoff, through‐flow or groundwater
flow. Once in the river, water flows towards the sea and is lost
from the drainage basin.
When the composition of minerals, or chemicals, that make up
a rock is altered due to environmental factors, such as
temperature. These changes modify the composition and
structure of the rock.
One of the two major types of weathering and generally
considered to be the more effective one; it involves the
chemical decomposition of rock by a variety of chemical
processes including dissolution, chelation and hydrolysis.
The finest‐grained soil – less than 0.002mm in diameter. Clay
soils are sticky and hold more water than other soils due to
their numerous micro‐pores.
A vertical, or nearly vertical, rock exposure. They are formed as
erosion landforms due to weathering and erosion. Cliffs are
common along coasts, rivers and in mountainous areas.
Continuous undercutting increases stress and tension in the
cliff until it collapses. This process is repeated until the cliff
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moves back (retreats).
Collision zones
Competence
Compressional waves
Condensation nuclei
Consequent
Constructive plate margins
Constructive waves
Continent
Continental drift
Continental shelf
Convection current
Convergent
Core
Coriolis force
Corrosion
Creep
Two continental crusts collide and, as neither can sink, are
forced up to produce fold mountains.
The maximum size of material which a river is capable of
transporting.
As energy passes through the solid, liquid or gas, the material
condenses in the same direction the wave is moving, and then
extends back to its original thickness once the wave has
passed.
Microscopic particles in the air that attract water. These are
the surfaces for water vapour molecules. The particles include
dust, smoke and salt.
The main river, which is a result of the initial land uplift or
slope. It flows in the same direction as the dip of the rocks.
As two tectonic plates move away from each other new
oceanic crust appears, forming mid‐ocean ridges with
volcanoes.
Small or low ocean waves; flat in form with a long wavelength
and low frequency. Moves sand and shingle up the beach.
One of Earth’s seven main divisions of land. A result of sub‐
oceanic forces that sent land masses wandering away from the
supercontinent of Pangaea that existed 200 million years ago.
Alfred Wegener’s theory that all continents were once joined
together in one large supercontinent. Later, the landmasses
split up and the various continents moved apart.
A broad, shallow region (less than 500m) where the
continental crust is thinner than normal. It is on the edge of
the continent and lies underneath the ocean. It runs from the
coastline to the drop‐off point (shelf break).
A process involving the movement of heat energy from one
place to another. These currents are created because of the
differences occurring within the densities and temperature of
a specific gas or liquid. The mantle within the Earth’s surface
flows due to convection currents.
When two things move toward each other. A convergent plate
boundary is where two plates move toward each other so that
one plate sinks beneath the other.
The innermost of the two major divisions of the solid Earth,
the other being the mantle; the core includes the outer core,
which is liquid and the inner core which is solid; the core is the
densest part of the Earth.
Wind deviation as a result of earth’s rotation. It causes all free‐
moving objects, including wind, to be deflected to the right of
their path of motion in the Northern Hemisphere, and to the
left in the Southern Hemisphere.
One of the four main processes of erosion in rivers. This is
related to the chemical composition of the water, e.g. the
concentration of carbonic acid. This concentration can dissolve
certain types of rocks such as limestone.
Soil creep is the slowest of downhill mass movements and
occurs on slopes of about 5o. It takes place at a rate of less
than 1cm per year. It is a continuous process and occurs in
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humid climates where there is vegetation cover.
Crest
The highest point of a wave.
Crust
The outermost layer of a planet. Earth’s crust includes both
oceanic crust (sima) and continental crust (sial).
A three‐dimensional geometric pattern in which the atoms in
crystals are arranged.
Crystal lattice
D
Debris fall
Debris flow
Debris slide
Decomposition
Deflation
Deflation hollows
Delta
Dendritic
Deposition
Desert pavement
Desertification
Spontaneous, rare and very rapid movement of
unconsolidated material on slopes that exceed 40o. The fall
may result from extreme physical or chemical weathering in
mountains, pressure release, storm wave action on sea cliffs,
or earthquakes.
A type of mass movement characterised by the downslope
flow of saturated mass of heterogeneous soil material and
rock debris.
A rapid movement where unconsolidated earth collectively
moves down a land mass. Slides may be planar or rotational.
Detrivores, such as ants and termites, begin this process by
either burying leaf litter (detritus) or eating it. Their faeces
increase the surface area of detritus upon which fungi and
bacteria can act to break down the organic compounds. This
releases nutrient ions essential for plant growth into the soil.
One of the two main processes of wind erosion. Silt and sand
are removed by wind, leaving behind stones. This results in a
desert pavement.
In deserts, dew may collect in depressions. Subsequent
chemical weathering may loosen material, which is then
removed by wind to leave depressions in the ground.
Forms when a river loses energy and competence as it flows
into an area of slow‐moving water (such as the sea) and
deposits fine sediment. The meeting of fresh and salt water
produces an electrical charge which causes clay particles to
coagulate and to settle on the seabed.
A tree‐like river drainage pattern in which the many tributaries
(branches) converge upon the main river (trunk).
A process where the input of sediment and deposits exceeds
the output. It results in the accumulation of these deposits on
a surface. Deposition occurs in many systems, such as coasts,
deserts, glaciers and rivers.
In deserts, vast areas of flat and colourless pavements are the
result of earlier, wetter climates. Pebbles were transported by
water from surrounding highlands and deposited on the
lowland plains along with other sands. Later, the wind
removed the sand, causing the remaining pebbles to settle and
interlock like cobblestones.
The turning of the land, often through physical processes and
human mismanagement, into desert.
Oceanic crust moves towards continental crust, but, being
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Destructive plate margins
Destructive waves
Disaster
Discharge
Disintegration
Dissolution
Divergent
Doppler effect
Drainage basin
Drainage density
Duricrust
Dyke
heavier, sinks and is destroyed. These forms deep‐sea trenches
and island arcs with volcanoes.
Large or high ocean waves; steep in form with a short
wavelength and high frequency. Have a powerful backwash,
moving sediment down the beach.
Natural events such as desertification, ozone depletion and
acid rain, which are caused by human activity and the
mismanagement of the environment.
The amount of water originating as precipitation which
reaches the stream channel by surface runoff, throughflow
and baseflow.
The physical break up of rocks into smaller fragments.
The dissolving of a compound in water. If the bedrock of a
river is readily soluble, like limestone, it is constantly dissolved
in flowing water and removed in solution.
When two things move in different directions from each other.
A divergent plate boundary is where two plates move apart
from each other.
The change in the observed frequency of a wave when there is
relative motion between the wave source and the observer.
The area that contributes runoff to a stream, river or lake.
The average length of stream within each unit area. This is
calculated by measuring the total length of all the streams
within the basin and dividing by the area of the whole basin.
Where salts accumulate near or on desert surfaces, particles
may become cemented together to form hard crusts.
A vertical sheet intrusion with horizontal cooling cracks. When
magma rises to the surface, it cuts across the bedding planes
of the sedentary rock to form a dyke.
E
Earthquake
Eckman spiral
Endoreic
Ephemeral
Erg (dune fields)
Results from a slow build‐up of pressure within crustal rocks. If
this pressure is suddenly released then parts of the surface
may experience a jerking movement.
When wind forces surface water molecules to move, they
drag deeper layers of water molecules. Each layer of water
molecules are moved by friction from the shallower layer, and
each deeper layer moves more slowly than the layer above it.
The movement stops at a depth of about 100m.
A water body or basin that is drained internally and has no
outlet.
Lasting only a short period of time. For example, the life‐cycle
of certain plants, or the existence of some streams after
precipitation.
Large areas of sand dunes in a desert region.
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Erosion
Evapotranspiration
Exogenous
Exposure
Extrusive
The removal of rock debris and soil by an agency such as
moving water, wind, or glaciers; generally, the sculpting or
wearing down of the land by erosional agents.
The loss of water from the soil through evaporation and
transpiration.
A river which flows permanently through a desert as it obtains
its water from mountains outside the desert environment.
Bedrock that is uncovered and visible on the Earth’s surface.
The rock may now be subject to environmental impacts, such
as the weather.
When lava and other material reach the surface and are no
longer underground.
F
Fetch
Flood plain
Fluvial landforms
Fold mountains
Foreshore
The maximum distance of open water over which the wind
can blow. Places with the greatest fetch receive the highest‐
energy waves.
Should a river continue to rise above the river bank, the
water will cover any adjacent flat land. The land susceptible
to flooding in this way is known as the flood plain.
Natural features associated with rivers. As the velocity of a
river increases, surplus energy transports material and
causes erosion. Where the velocity decreases, an energy
deficit results in deposition features.
Fold mountains form along both destructive and collision
plate boundaries. They form when two plates with
landmasses on them move towards each other. The plates
push layers of accumulated sediment in the sea into folds
between them. This becomes a fold mountain range.
The lower section of the beach. Also considered the inter‐
tidal or surf zone.
Fossils
The remains of a prehistoric plant or animal embedded in
rock, which is evidence of ancient life.
Frequency
The amount of time taken for one full wavelength to pass a
stationary point.
Frictional force
Impact of the Earth’s surface causing a drag on wind,
resulting in the wind slowing down.
Frost shattering
The most widespread form of mechanical weathering. In
daytime water enters the joints, but during cold nights it
freezes. When water freezes, it expands and pressure is
exerted on the joints. The alternating freeze‐thaw process
slowly widens the joints, and in time, the pieces of rock
shatter from the main body.
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G
Glaciation
Granite intrusion
Gravel
A period of time where temperatures drop below freezing and
ice forms across large areas.
When magma was forced into the Earth’s crust and cooled to
solid form. Having been formed at a depth and under pressure,
the rate of cooling was slow. This enabled large crystals of
quartz, mica and feldspar to form, making up granite.
A mass of rock fragments that are mostly larger than 2mm.
H
Hamada
High plateaus of bare rock, characteristic of most desert
landscapes.
Hazard
An event that affects, or threatens, people and property.
Headland
A coastal landform which extends out into the sea. It is
typically high and with a sheer drop.
Headward erosion
Humic acid
Hydration
Hydraulic action
Hydraulic pressure
Hydraulic radius
Hydrolysis
The wearing away of rock or soil at the origin of a stream
channel, which causes the origin to move away from the
direction of the stream flow. Therefore, the stream channel
lengthens.
A result of the decomposition of vegetation (humus). It aids in
the process of organic weathering and helps plant roots
receive water and nutrients.
A form of chemical weathering. Certain rocks, especially those
with salt minerals, are capable of absorbing water into their
structure, causing them to swell and to become vulnerable to
future breakdown.
One of the four main processes of erosion in rivers. The force
of the water as the turbulent current hits the river banks (on
the outside of a meander) pushes water into cracks. The air in
the cracks is compressed, pressure is increased, and, in time,
the bank will collapse.
When a parcel of air is trapped and compressed either in a
joint in a cliff, or between a breaking wave and a cliff. The
resultant increase in pressure may, over a period of time,
weaken and break off pieces of rock or damage sea defences.
The ratio between the area of the cross‐section of a river
channel and the length of its wetted perimeter.
A complex chemical weathering process or series of processes
involving the reaction of water and an acid on a mineral; it is
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considered to be the most effective process in the
decomposition of granite.
I
Igneous
Infiltration
Interception
Interlocking spurs
Intermittent
Internal derangement
Intrusive
Iron
Isotope
Relating to, or resulting from volcanic activity, specifically
when magma or lava has cooled to a solid state.
If there is enough water supply, soil will gradually take in
water from the surface, slowly allowing it to vertically seep
through pores in the soil.
The first raindrops of a rainfall event will fall on vegetation
which shelters the underlying ground from receiving these
drops. Vegetation stores the moisture on its leaves before it
evaporates back into the atmosphere.
Formed when the river is forced to follow a winding course
around the protrusions of the surrounding highland. As the
resultant spurs join, the view up or down the valley is
restricted.
Not continuous and occurring at irregular intervals. E.g.
ephemeral streams.
The loosening of rock and soil inside a landmass after the
land has become saturated with water. This results in a flow
mass movement, where there is no breakage of vegetation
or landmass cover.
Magma which solidifies inside Earth’s crust and does not
reach the surface. Often produces batholiths.
Originates from sedimentary rock, and people have used it
as an important source of metal. Along with nickel, iron
makes up the Earth’s core.
Atoms with the same atomic number but different mass
numbers (for example, carbon‐12, carbon‐13, and carbon‐14
all have six protons per atom, and thus have the same
atomic number, but different mass numbers).
L
Lag time
Laminar flow
The period between maximum precipitation and peak stream
discharge. Lag time varies according to conditions within the
drainage basin.
A horizontal movement of water so rarely experienced in
rivers that it is usually discounted. Such a form of flow, if
existed, would travel over sediment on the river bed without
disturbing it.
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Lamination
Lava
Levee
Limestone
Lithosphere
Longshore drift
A structure within a rock that consists of various fine layers
(laminae). These layers are parallel to each other and less than
1cm thick.
Molten rock that has reached the surface.
When a river overflows its banks the increase in friction with
the floodplain results in the coarsest/heaviest material being
deposited first alongside the channel forming a natural
embankment (levee).
A sedimentary rock consisting of at least 80% calcium
carbonate.
The earth’s crust and the rigid upper part of the mantle.
When a wave breaks (usually at an angle) the swash carries
material up the shore at the same angle of approach. The
backwash then returns the material at right angles to the
beach under the influence of gravity creating a longshore drift
current down the shoreline.
M
Magma
Magnesium
Magnetic pole
Mantle
Marine
Mass extinction
Mass movement
Meander
Mechanical weathering
Molten rock found below the surface of the earth.
The eighth most abundant element in the earth’s crust and a
key component of silicate rocks found within the mantle of the
earth.
Known as the North and South Poles, these represent the
intersection of the earth’s axis of rotation with the earth’s
surface.
One of the major layers of the earth’s interior that consists of a
rigid upper layer (lithosphere) with the remaining layers
existing in a semi‐molten state (asthenosphere). It extends
down to 2900km and temperatures can reach 5000°C. It is the
layer beneath the crust and surrounding the core.
Relating to or found in the sea.
Rare and extreme events can cause mass extinctions such as
the meteorite impact on earth more than 65 million years ago.
In these events lineages of plant and animal life are lost.
The downhill movement of weathered material including soil,
loose stones and rocks in response to gravity; it includes soil
creep, rock fall, landslides and mudflows also termed mass
wasting.
Asymmetrical winding portions of a river that migrate
downstream and are caused by erosion on the outer parts of a
river bend due to a higher velocity. Material is deposited on
the inside of bends, but the continuous erosion of the outer
bend causes the meander to migrate downstream.
The disintegration of rock into smaller particles without any
change in the chemical composition of the rock. It is common
in locations lacking in vegetation (deserts and high mountain
areas).
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Metamorphic
Mid‐Atlantic Ridge
Mud flow
Rock altered in physical structure and/or chemical (mineral)
composition by action of heat, pressure, shearing stress, or
infusion of elements. All taking place at a substantial depth
beneath the surface.
Created by a constructive plate margin where the North
American Plate and the Eurasian Plate (both continental
crusts) diverge, allowing for magma to rise and in the process
filling the gap and creating a new oceanic crust.
A rapid mass movement process that occurs on steep slopes
and is encouraged by the presence of water. Mudflows usually
occur after periods of intense rainfall where the soils increase
in volume and weight.
N
Nearshore
Nickel
A section of the beach where waves break and affect the
seabed.
A hard metal forming a key component of the earth’s core.
O
Organic weathering
Orthogonal lines
Oxbow lake
Oxidation
Bacteria and the respiration of plant roots increase
carbon dioxide levels in soils which helps accelerate
chemical weathering processes. Organisms and
organic acids are important weathering agents and
work to break down minerals in rocks.
Lines drawn at right angles to advancing wave crests to
illustrate advancements in waves as they approach the
nearest point of onshore contact.
A cut‐off, crescent‐shaped feature representing an old
meander where flooding followed by deposition has
resulted in the former meander being blocked off from
the main river.
A process of chemical weathering which occurs when
rocks are exposed to oxygen in the air or water, this
process causes rocks to crumble easily.
P
Parallel
Parent material
A river drainage pattern where rivers and streams flow
downhill almost parallel with each other.
Contributes to the depth, texture, drainage (permeability) and
quality (nutrient content) of a soil and also influences its
colour. Important for soil formation and is dependent on
underlying rock formation.
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Particle size
Influences wave steepness and morphology of a beach.
Passive
Also known as a conservative plate margin where two plates
move parallel to each other with the crust neither being
destroyed nor created.
Maximum water level during a precipitation event.
Peak flow
Pediment
Percolation
Perennial
Periglacial
Period
Permeability
Plates
Playa
Plunge pool
Point bar
Porosity
Potential evapotranspiration
Precipitation
Pressure release
Primary production
A long, gently sloping area either of bare rock or of rock
covered in a thin layer of debris found on the foot of highland
areas.
Slower, constant downward movement of water through
deeper soils and underlying rock layers which leads to the
creation of groundwater storage systems.
A stream that is permanent (e.g. perennial streams in the case
of rivers).
Refers to where frost and snow have a major impact on
landscape or including any area that has a cold climate.
Tens of millions of years in length (subdivided into epochs).
The rate at which water may be stored within a rock or is able
to pass through it.
Refers to the division of the lithosphere into seven large and
several smaller plates which are rigid and float on the
underlying semi‐molten mantle.
Found in desert locations these are shallow, seasonal saline
lakes which form after rainstorms. As the rain water
evaporates flat layers of silt or clay or salt are left behind.
Occurs at the bottom of a waterfall where collapsed rock may
be swirled around by turbulence to form a deep (plunge) pool.
A curved feature formed on the inside of a meander bend
where most material is deposited and where river velocity and
discharge are at a minimum.
The rate at which water is able to be stored within rocks or
transported through it and is dependent upon the texture off
the rock and the size, shape and arrangement of its mineral
particles.
The amount of water loss that would occur if sufficient
moisture was always available to the existing vegetation cover.
Particles of liquid or ice that fall from the atmosphere and
reach the surface including rain, snow, sleet, hail, frost and
fog.
Many rocks develop under intense confined pressure and if
exposed to atmospheric conditions later on, a large release of
pressure can occur, weakening the rock and allowing agents to
enter it and processes to develop.
Referring to farming, fishing, mining and forestry.
Proportional
Fastest travelling seismic waves produced by earthquakes.
These waves can travel through any gas, liquid or solid.
Corresponding in size or amount to something else.
Pyroclastic material
Material ejected by volcanoes in a fragmented form.
Primary waves
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R
Radial
Radiometric dating
Rain shadow
Rapid
Refraction
Regolith
A river drainage pattern where rivers radiate from a central
point, likened to the spokes of a wheel.
Method of determining the geological age of a rock or
mineral by measuring the proportions of certain of its
elements in their different isotopic form.
A dry rain‐scarce area found on the leeward side of a
mountain range. Air is forced down the side of the mountain
and is compressed and warmed which leaves it much
warmer and with less moisture meaning little precipitation
will fall.
Develops where the gradient of a river bed increases
without a sudden break in slope or where the stream flows
over dipping bands of harder rock. Rapids increase the
turbulence and erosive ability of a river.
As waves enter shallow water the wave crests become
increasingly parallel with the coastline. When a wave
encounters shallow water it allows the crests in deeper
water to move ahead and causes the shallow crests to follow
it causing the waves to bend.
Weathered material such as soil, loose stones and rocks.
Resilience
Ability of an individual/group to cope with or adapt to a
hazard and reflects the degree of planned preparation taken
in relation to a potential hazard event.
Resistance
In relation to erosion, resistance refers to the abilities of
different rock type to withstand or become susceptible to
erosion.
Riffle
Areas of shallow water found in the sequence of a meander
where erosive capacity and energy built in the river is lost,
allowing material to be deposited.
Risk
It is the potential for physical, social, economic,
environmental, cultural or institutional consequences or
losses, in a given area and over a period of time.
River capture
This occurs when large rivers attempt to adjust their
structure and capture the headwaters of nearby smaller
rivers. Larger rivers tend to have a higher discharge and
erosive capacity that allows it to expand its drainage area at
the expense of surrounding smaller rivers.
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S
Salt crystallisation
Salt marsh
Saltation
Saturation
Scree slope
Sea floor spreading
Sea waves
A form of mechanical weathering where saline water entering
rock spaces evaporates forming salt crystals. As the crystals
enlarge, they exert stresses on the rock and cause the rock to
disintegrate.
These form in river estuaries and behind spits where silt and
mud are deposited by gently rising or falling tides, or by the
river as it runs into the ocean.
Transportation of pebbles, sand and gravel in a river where the
material is temporarily lifted up by the current and bounced
along the river bed in a hopping motion.
After a heavy period of rain or snowmelt all the pore spaces
within the soil will be filled with water and become saturated.
Also known as a ‘talus slope’ and refers to the accumulation of
angular broken off rock fragments found at the bottom of
steep slopes.
Associated with constructive plate margins where two plates
diverge allowing magma to rise and fill any gaps creating a new
oceanic crust.
Waves that result from local winds and travel short distances.
Seismic waves
Where water reaches the ground during a persistent rainfall
event through the undergrowth.
The second fastest travelling seismic waves and can travel
through solids but not through liquids or gas.
A major type of rock formed from layers of mineral particles
found in other rocks that have been weathered and
accumulated over time.
Weathered rock material that is transported through air, water
or glacial ice.
Shock waves experienced during an earthquake.
Shale
A sedimentary rock formed out of mainly silt and clay.
Silica
Silicate rocks are rich in iron and magnesium and are one of
the main components of the mantle of the earth.
A horizontal intrusion of magma that has cooled and
contracted leaving vertical cracks or joints within the bedding
planes of two existing rock layers.
Small, smooth/silky sediment particles between 0.06mm and
0.002mm in size and usually referred to when discussing soil
texture and the deposition of material transported in rivers.
Elements of the land surface that are inclined from the
horizontal surfaces.
A type of landslide (rotational landslide), this refers to the
rotational movement of weathered material down a slope
where softer rock material such as clay or sand overlies a more
resistant rock.
Secondary interception
Secondary waves
Sedimentary
Sediments
Sill
Silt
Slope
Slump
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Solifluction
Solution load
Spectral line
Spit
Stack
Stemflow
Storage
Strata
Stream order
Subsequent stream
Surface creep
Surface runoff
Suspended
Suspension
Swash
Swell
The movement of soil down a slope at an annual rate between
5cm and 1m, occurs mainly in glacial conditions where
vegetation cover is limited and where bedrock and loose
weathered material freeze in the winter seasons.
Transportation of readily dissolved material in a river.
It is a dark or bright line in an otherwise uniform and
continuous spectrum, resulting from emission or absorption of
light in a narrow frequency range. Used to identify atoms and
molecules.
Long, narrow accumulations of sand/shingle on the coast with
one end joined to the mainland and the other extending out to
sea.
When the sea cuts inland erosion on the cliffs takes place
backwards and creates an isolated portion of the cliff.
When water reaches the ground during a rain event flowing
down plant stems and tree trunks.
Water stored within the pore spaces of rocks and soils.
Layers of sediment separated from one another in the bedding
planes of sedimentary rocks.
Ranking of streams and stream segments in a drainage system.
Tributaries which form through erosion after the main river
has already developed.
Constant gradual movement of small stones and pebbles over
the desert surface as a result of material being dislodged by
sand being transported by saltation.
When soils become saturated after heavy rainfall excess water
will flow over the surface.
Material transported in the turbulence of a river is said to be
suspended.
One of the three river transportation processes where fine
material is dislodged in a river and is carried by the turbulence.
Body of foaming water which moves up the beach as waves
break on the shore.
Waves of low height and gentle steepness formed from distant
storms and that travel across long distances.
T
Terrestrial
Thermal expansion
Throughfall
Living or growing on land.
A process of mechanical weathering where rocks expand in
higher temperatures and contract at lower temperatures
which causes stresses within inner and outer the rock and can
lead to layers of rock peeling off or pieces of the rock
disintegrating.
Occurs during a rainfall event where water reaches the ground
through dropping off leaves.
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Tidal bore
Tombolo
Transverse waves
Trellised
Trough
Turbulent flow
An advancing wall of water moving upriver when estuaries
narrow and the tide rises quickly.
A beach that extends outwards to join with an offshore island.
A moving wave that consists of oscillations occurring
perpendicular to the direction of energy transfer.
A drainage basin pattern that forms in areas of alternating
resistant and less resistant rock where tributaries join the main
river at right angles.
Lowest point of a wave.
A pattern of flow in a river with a series of horizontal and
vertical eddies in a downstream direction.
U
Undercutting
Upwelling
In coastal environments when waves make contact with the
headland, they exert a great erosive force on the cliffs.
Erosion caused by the force of the waves is concentrated on
the base of the cliffs where the rock is undercut causing the
cliff to erode towards the shore.
A process that draws very cold water upwards to the ocean
surface.
V
Velocity
When two continental plates collide they are squeezed
together causing the crust to rumble creating fold belts. The
fold creates alternating upward bends and troughs and when
the folds erode they produce a ridge and valley landscape with
the valleys consisting of less resistant rock.
The rate of flow of a river.
Ventifacts
Individual rocks with sharp edges and smooth sides.
Volcanic
Activity relating to or produced by a volcano.
Volcanic eruption
When molten rock and material is ejected from the vent of a
volcano.
Conditions determined by physical, social, economic and
environmental factors or processes which increase
susceptibility of an individual, community, and livelihoods to
the impacts of hazard events.
Valley
Vulnerability
W
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Waning slope
Waterfall
Watershed
Also known as a concave or accumulation slope and is found
on the bottom of slopes where weathered material is
transported down.
Forms when a river flows over a stretch of more resistant
rock then less resistant rock before falling over a plateau. As
water approaches the falls it has a high velocity unaffected
by friction while the underlying softer rock is worn away as
water falls on it.
The boundary of a drainage basin marked by a ridge or high
land which drains rainfall into adjacent drainage basins.
Wave
Created by the transfer of energy from the wind blowing
over the surface of the sea.
Wave height
The distance between the crest (highest point) and trough
(lowest point) of a wave.
Wave steepness
Wave‐cut platform
Wavelength
Waxing slope
Weathering
The ratio of wave height to the wave length. Steepness of
waves determines whether the waves will build up or
degrade beaches.
Found at the foot of retreating cliffs; it is formed by steep
waves breaking at the foot of a cliff causing it to erode
backwards and leave a gently sloping feature.
The distance between two successive wave crests.
Also known as a convex or denudation slope and is found at
the top of slopes where there is a gentle gradient caused by
a slow movement of weathered material down the slope.
Disintegration and decomposition of earth materials
especially rock in situ (in is original position and location).
Y
Yardang
A product of abrasion (wind erosion), these are extensive
ridges of rock separated by grooves with their alignment
similar to the direction of the prevailing wind.
Z
Zeugen
A product of abrasion (wind erosion), these are tabular
masses of resistant rock separated by trenches where the
wind has cut vertically into the underlying softer rock.
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