Textbook Key Terms
Carrying Capacity: The maximum population size that can be supported under a given
set of environmental conditions.
CE: Common era (same thing as AD).
Drought: A prolonged interval of dryness causing damage to plants and animals.
Earthquake: The shaking of the Earth by seismic waves radiating away from a
disturbance, most commonly a fault movement.
Flood: Overflowing of a body of water onto normally dry land when discharge exceeds
the capacity to contain the flow or when there is an obstruction to flow.
Energy: Capacity for performing work
Frequency: The number of events in a given time interval.
For waves, it is the number of cycles that pass in a second.
Great Natural Disaster: A natural disaster so overwhelming that outside assistance is
needed to handle the response and recovery for the region.
Magnitude: An assessment of the amount of energy released during an event.
Magnitude scales exist for earthquakes, volcanic eruptions, hurricanes, and tornadoes. In
seismology, different magnitudes are calculated for the same earthquake when different
types of seismic waves are used.
Mitigation: Actions taken to minimize the risk associated with a natural hazard.
Natural Disaster: An extreme even triggered by destructive forces occurring in nature
that causes significant disruption to society.
Natural Hazard: A source of danger to life, property, and the environment, from
atmospheric and geological phenomena.
Preparedness: Actions taken in advance to ensure people are ready when disaster
Recovery: Actions taken in the long term to restore the pre-disaster conditions of a
Response: Actions taken in the short term to provide assistance after an emergency has
occurred. Return Period: The amount of time between similar events.
Risk: The possibility of being harmed or damaged, often expressed as the product of
vulnerability and hazard.
Seismograph: An instrument that records Earth motions.
Storm: A violent weather event featuring strong winds and heavy precipitation (rain,
snow, or hail).
Tsunami: Long-period sea waves caused by oceanic disturbances, such as fault
movements, volcanic eruptions, meteorite impacts, and landslides.
Volcano: An opening of the Earth’s surface where magma has poured or blown forth,
typically creating hills or mountains.
Vulnerability: Exposure to being harmed or damaged.
Wildfire: An unplanned fire occurring in a forested area, or thick brush.
Actualism: The concept of using the processes operating on Earth today to interpret the
Albedo: The reflectivity of a body
In terms of the Earth, how much solar radiation is reflected back to space
Asteroid: A small, rocky body that orbits the Sun.
Asthenosphere: The layer of the Earth below the lithosphere in which isostatic
adjustments take place. The rocks here deform readily and flow slowly.
Atmosphere: The gaseous envelope around the Earth, composed chiefly of nitrogen and
oxygen. The average atmospheric pressure at sea level is 101.3 kPA
BCE: Before the common era (Same thing as BC)
Brittle: Behaviour of material where stress causes abrupt fracture.
Chondrule: A small, glassy sphere crystallized in space from semi-molten or molten
droplets of rock.
Comet: An icy body moving through outer space.
Compression: A state of stress that causes a pushing together or contraction. Conduction: A process of heat transfer through collisions between particles. Hot, rapidly
vibrating particles transfer kinetic energy to neighbouring colder, slow-moving particles.
Continent: Lower-density masses of rock, exposed as about 40% of the Earth’s surface
(29% land, 11% floor of shallow seas).
Convection: A process of heat transfer through movement of a fluid
Core: The central zone of the Earth about 2900 kilometres below the surface. The core is
made mostly of iron and nickel, and exists as a solid inner zone surrounded by a liquid
outer shell. The Earth’s magnetic field originates within the core.
Coriolis Effect: The tendency of moving objects on the surface of the Earth to be
deflected due to the Earth’s rotation.
Crust: The outermost layer of the lithosphere, composed of relatively low-density
materials. Continental crust has a lower density than oceanic crust.
Dielectric Constant: A constant measure of a material’s ability to store electrical charge.
Ductile: Behaviour of material where stress causes permanent flow or strain.
Elastic: Behaviour of material where stress causes deformation that is recoverable. When
stress stops, the material returns to its original state.
Element: Distinct varieties of matter. An atom is the smallest particle of an element.
Erosion: The processes that loosen, dissolve, and wear away earth materials. Active
agents include gravity, streams, glaciers, winds, and ocean waves.
Force: Mass times acceleration
Friction: The resistance to motion of two bodies in contact
Glacier: A large mass of ice that flows downslope or outward due to the internal stresses
caused by its own weight.
Gravity: The attraction between bodies of matter
Greenhouse Effect: The build-up of heat beneath substances such as glass, water vapour,
and carbon dioxide that allow incoming, short-wavelength solar radiation to pass through
but block the return of long-wavelength reradiation.
Half-Life: The length of time needed for half of a radioactive sample to lose its
radioactivity via decay. Heat: The capacity to raise the temperature of a mass, expressed in joules.
Heat Capacity: The amount of energy required to raise the temperature of a body by one
Humidity: A measure of the amount of water vapour in an air mass.
Hydrologic Cycle: The solar-powered cycle where water is evaporated from the oceans,
dropped on the land as rain and snow, and puled by gravity back to the oceans as glaciers,
streams, and groundwater.
Igneous Rock: Rock formed by the solidification of magma.
Ion: An electrically charged atom or group of atoms.
Isostasy: The condition of equilibrium wherein the Earth’s crust floats upward or
downward as loads are removed or added.
Isotope: Any two or more forms of the same element. The number of protons is fixed for
any element, but the number of neutrons in the nucleus can vary, thus producing isotopes.
Kinetic Energy: Energy due to motion. (See potential energy)
Latent Heat: The energy absorbed or released during a change of state.
Lithosphere: The outer rigid shell of the Earth that lies above the asthenosphere, and
below the atmosphere and hydrosphere.
Magma: Molten rock material. It solidifies on the Earth’s surface as volcanic rock and at
depth as plutonic rock.
Mantle: The largest zone of the Earth comprising 83% by volume and 67% by mass.
Mesosphere: The mantle from the base of the asthenosphere to the top of the core.
Meteorite: A stony or iron-rich body from space that passed through the atmosphere and
landed on the surface of the Earth.
Nuclear Fission: Splitting the nucleus of an atom with resultant release of energy.
Nuclear Fusion: Combining of smaller atoms to make larger atoms with a resultant
release of energy.
Plastic: The behaviour of a material that flows as a fluid (liquid) over time, but is strong
(solid) at a moment in time.
Potential Energy: The energy a body possesses because of its position Example: A large rock sitting high on a steep slope (See kinetic energy)
Power: The rate of work, expressed in watts.
Processes of Construction: The land building processes of volcanism, seafloor
formation, and mountain building fuelled by Earth’s internal energy.
Processes of Destruction: The land destroying processes such as erosion and land
sliding fuelled by Earth’s external energy sources of Sun and gravity.
Radiation: A process of heat transfer where energy is emitted as electromagnetic waves.
Radioactive Elements: Unstable elements containing excess subatomic particles that are
emitted to achieve smaller, more stable atoms.
Sediment: Fragments of material of either inorganic or organic origin. Sizes are gravel
(over 2mm diameter), sand (2-0.0625mm diameter), silt (0.0625-0.0039mm diameter),
and clay (less than 0.0039mm diameter).
A mixture of silt and clay forms mud.
Shear Stress: A state of stress that causes internal planes within a body to move parallel
to each other.
Solar Radiation: The energy emitted from the Sun mostly in the infrared, visible light,
and ultraviolet wavelengths.
Strain: A change in form or size of a body due to external forces.
Stress: Force per area.
Includes shear, tension, and compression
Surface Tension: The attractive force between molecules at the surface of a liquid.
Tension: A state of stress that tends to pill the body apart.
Uniformitarianism: The concept that the same laws and processes operating on and
within the Earth throughout geological time are the same laws and processes operating
Viscous: The more viscous a substance, the less readily it flows.
Work: Distance times force
Chapter 3 Bathymetry: The mapping of depths of water in oceans, rivers, and lakes.
The underwater equivalent of topography
Continental Drift: The movement of continents across the face of the Earth, including
their splitting apart and recombination into new continents.
Convergent Zone: A linear area where plates collide and move closer together. This is a
zone of earthquakes, volcanoes, mountain ranges, and deep-ocean trenches.
Curie Point: The temperature above which a mineral will not be magnetic.
Divergent Zone: A linear zone formed where plates pull apart as at a spreading centre.
Epicentre: The point on the surface of the Earth directly above the fault that moved to
generate an earthquake.
Aka the point directly above the hypocentre
Failed Rift: The site of a spreading centre that did not open wide enough to create an
Fault: A fracture in rock where the two sides move relative to each other.
Gondwanaland: A southern supercontinent that included South America, Africa,
Antarctica, Australia, New Zealand, and India from about 180 to 75 million years ago.
Hot Spot: A place on Earth where a plume of magma has risen upward from deep in the
mantle and through a plate to reach the surface.
Hypocentre: The initial portion of a fault that moved to generate an earthquake.
Hypocentres are below the ground surface.
Epicentres are projected above them on the surface
Island Arc: A curved linear belt of volcanoes above an oceanic-oceanic subduction
Laurasia: A northern supercontinent that included most of North America, Greenland,
Europe, and Asia (excluding India) from about 180-75 million years ago.
Lava: Magma that flows on the Earth’s surface.
Magnetic Field: A region where magnetic forces affect any magnetized bodies or
electric currents. Earth is surrounded by a magnetic field. Magnetic Pole: Either of two regions (the north and south poles) where the lines of force
of the magnetic field are perpendicular to the Earth’s surface. Magnetic poles do not
coincide with geographic poles but are in their vicinity.
Pangaea: A supercontinent that existed during Late Palaeozoic time when all the
continents were unified into a single landmass.
Plate: A piece of lithosphere that moves atop the asthenosphere. There are a dozen
large plates, and many smaller ones.
Plate Tectonics: The description of the movements of plates and the effects caused by
plate formation, collision, subduction, and slide past.
Plume: An upwelling of magma rising from deep in the mantle.
Ridge: A long and narrow volcanic mountain range.
Rift: The valley created at a pull-apart zone.
Seafloor Spreading: The movement of two oceanic plates away from each other,
resulting in magma welling up and solidifying to create new ocean floor.
Spreading Centre: The site where plates pull apart and magma flows upward to fill the
gap and then solidifies as new ocean floor.
Subduction: The process of one lithospheric plate descending beneath another.
Tectonic Cycle: Describes how new lithosphere forms at oceanic volcanic ridges, the
lithospheric plates spread apar