Glossary

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Words (or words that have the same definition)	The definition is case sensitive	(Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages]	(Optional) Caption for Image	(Optional) External or Internal Link	(Optional) Source for Definition
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Glossary Entries
Word(s)	Definition	Image	Caption	Link	Source
aa	a lava flow that solidifies with a blocky high-relief surface
ablation	melting of ice in the context of glaciation
ablation till	till that is formed when englacial and supraglacial sediments are deposited because the ice that was supporting them melts
abyssal plain	the flat surface of the deep ocean, typically beyond the limits of the continental slopes
abyssalpelagic zone	the deeper parts of the ocean, between 4000 and 6000 metres.
accretion (plate tectonics)	the process by which continental blocks (terranes) are added to existing continental areas
accretion (planetary)	the process by which solid celestial bodies are added to existing bodies during collisions
acid rock drainage	the production of acid from oxidation of sulphide minerals (especially pyrite) in either naturally or anthropogenically exposed rock
aeolian	processes related to transportation and deposition of sediments by wind
aerobic	processes that take place in the presence of abundant oxygen
aerosol	an aggregate of fine solid particles or a small droplet of liquid suspended in the air
aftershock	an earthquake that can be shown to have been caused by another earthquake
aggregate	unconsolidated materials (typically sediments) that are used in the construction industry
albedo	the reflectivity of a surface of a planet (expressed as the percentage of light that reflects)
albite	sodium-rich plagioclase feldspar
alpine glacier	a glacier formed in a mountainous region and confined to a valley (same as valley glacier)
amphibole	a double-chain ferromagnesian silicate mineral (e.g., hornblende)
amphibolite	a foliated metamorphic rock in which the mineral amphibole is an important component
amplification	in the context of seismic shaking the process by which the amplitude of the seismic waves are enhanced, especially because the
amplitude	for any type of wave, the difference in height between a crest and the adjacent trough
anaerobic	processes that take place without oxygen
andesite	a volcanic rock of intermediate composition
anion	a negatively charged ion
angular unconformity	a geological boundary at the base of a sedimentary layer where the sedimentary rock beneath has been tilted or folded and then eroded
anorthite	calcium-rich plagioclase feldspar
Antarctic Bottom Water	water at abyssal depths in the ocean that forms from the sinking of dense cold water adjacent to Antarctica
anticline	an upward fold where the beds are known not to be overturned
anthracite	a high grade of coal (92 to 98% carbon) that is formed from deep burial and weak metamorphism
anthropogenic	resulting from the influence of humans
antiform	an upward fold where it is not known if the beds have been overturned
aphanitic	an igneous texture characterized by crystals that are too small to see with the naked eye
aquifer	a body of rock or sediment that has sufficient permeability to allow it to be used as a source of groundwater
aquitard	a body of rock or sediment that has insufficient permeability to allow it to be used as a source of groundwater
arch	a rock weathering remnant in the form of an arch (typically along a coast and resulting from wave erosion)
arenite	a sandstone with less than 15% silt and clay
arete	a sharp ridge that separates adjacent glacially carved valleys
arkose	a sandstone with more than 10% feldspar and more feldspar than lithic fragments
arkosic arenite	an arkose with less than 15% clay/silt matrix
artesian well	a well that is completed in a confined aquifer and in which the water level in the well rises above the top of the aquifer
asteroid	a rocky body orbiting the Sun
asteroid belt	the region between the orbits of Mars and Jupiter that is populated with many asteroids
asthenosphere	the part of the mantle, from about 100 to 200 kilometres below surface, within which the mantle material is close to its melting point, and therefore relatively weak
asymmetrical	in the context of folds, where the two sides of the fold make significantly different angles with respect to the axial plane
atoll	a ring-shaped carbonate (or coral) reef or series of islands
atomic mass	the total number of neutrons plus protons in an atom
atomic number	the total number of protons in an atom
attitude	the orientation of a sloping geological feature, such as a bedding plane or fracture
aureole	a zone of metamorphism around a source of heat such as a magma body
axial plane	a plane that can be traced through all of the hinge lines of a fold
back reef	the zone of shallow water on the shore-side of a reef
background	the typical level of an element in average rocks or sediments
backwash	the wash of wave water down the slope of a beach
banded iron formation	an iron-bearing sedimentary rock that is rich in minerals such as hematite and magnetite, which may be interbedded with chert
bank-full stage	the water level of stream when it is in flood and just about to flow over its banks
barrier reef	a carbonate (or coral) reef that forms a barrier to waves along a coast
basal sliding	the motion of glacial ice along the base of a glacier that is warm enough to have liquid water
basalt	a volcanic rock of mafic composition
base level	in the context of a stream the base level is the lowest level that it can erode down to, as defined by the ocean, a lake or another stream that it flows into
batholith	an irregular body of intrusive igneous rock that has an exposed surface of at least 100 km²
bathypelagic zone	the moderately deep parts of the ocean, between 1000 and 4000 metres.
baymouth bar	a spit that extends across the mouth of a bay
beach face	the part of the beach that is relatively steep and lies between the high and low tide levels
bed	a sedimentary layer
bed load	the fraction of a stream’s sediment load that typically rests on the bottom and is moved by saltation and traction
bedding	repeated layering in a sedimentary rock
bentonite	a type of smectite clay that has strong swelling properties and is effective at absorbing dissolved ions
berm	a flat area of a beach in the backshore area (above the high tide level)
big-bang theory	the theory that the universe started with a giant explosion approximately 13.77 billion years ago
biotite	a sheet silicate mineral (mica) that includes iron and or magnesium, and is therefore a ferromagnesian silicate
biozone	a stratigraphic interval that can be defined on the basis of a specific fossil
bituminous	a medium-grade type of coal with 70 to 92% carbon
blueschist	a metamorphic facies characterized by relatively low temperatures and high pressures, such as can exist within a subduction zone
body wave	a seismic wave that travels through rock (e.g., a P-wave or an S-wave)
boulder	a sediment clast with a diameter of at least 256 millimetres
Bowen reaction series	the scheme that defines the typical order of crystallization of minerals from magma
braided	a stream pattern which is characterized by abundant sediment and numerous intertwining channels around bars
breakwater	a structure built offshore in order to deflect the energy of waves
breccia	a sedimentary- or volcanic-rock texture characterized by angular clasts
brunisol	a relatively immature forest soil, lacking in well-defined horizons
caldera	a volcanic depression that is many times larger than the volcanic vents within it
caliche	a white calcium-carbonate rich layer within soils in arid regions
calving	the loss of ice from the front of a glacier by collapse into water
Canadian Shield	the exposed part of the continent Laurentia
carbonate	a mineral in which the anion is CO₃-2
carbonate compensation depth	the depth in the ocean (typically around 4000 metres) below which carbonate minerals are soluble
cation	a positively charged ion
cementation	the process by which minerals are precipitated between grains in sediments
Cenozoic	the most recent of the eras, representing the past 65.5 Ma of geological time
chemical sedimentary rock	a sedimentary rock comprised of material that was transported as ions in solution
chernozem	a black soil typical of grasslands in cold climates such as the Canadian Prairies
chert	a very fine grained sedimentary rock formed almost entirely of silica
chlorite	a ferromagnesian sheet silicate mineral, typically present as fine crystals and forming from the low-temperature metamorphism of mafic rock
cinder cone	a steep-sided volcano comprised almost entirely of loose rock fragments and typically formed during a single eruptive event
cirque	a steep-sided semi-circular basin eroded by a glacier at the head of its valley
clast	a sedimentary fragment of mineral or rock
clastic sedimentary rock	a sedimentary rock comprised of material that was transported as clasts or fragments
clay	sediment particle that is less than 1/256 millimetres in diameter
clay mineral	a hydrous sheet silicate mineral that typically exists as clay-sized grains
claystone	a sedimentary rock comprised mostly of clay-sized grains
cleavage	the tendency for a mineral to break along smooth planes that are predetermined by its lattice structure
climate feedback	a process by which the physical effects of a climate forcing can have other effects (either negative or positive) on the climate
climate forcing	a mechanism, such as a change in greenhouse gas levels, that forces the climate to change
coal-bed methane	methane that is trapped within the porosity of coal
coastal straightening	the tendency for an irregular coast to be straightened over time by coastal erosion processes
cobble	sediment particle that is between 64 and 256 millimetres in diameter
col	the low point or pass along a ridge between two glacial valleys
columnar jointing	the fracturing of rock or sediment (but typically volcanic rock) into columns that are typically six-sided
composite volcano (or stratovolcano)	a volcano that is constructed of alternating layers of pyroclastic debris and lava flows
concentrate	a product of ore processing that includes a specific ore mineral, separated from the rest of the rock
concordant	parallel to pre-existing layering or foliation within a rock
cone of depression	the depression of the water table around a well that is heavily pumped
confined aquifer	an aquifer that lies below a confining layer
confining layer	an aquitard that overlies an aquifer and restricts the flow of water down from the surface
conglomerate	a sedimentary rock that is comprised predominantly of rounded grains that are larger than 2 mm
contact metamorphism	metamorphism that takes place adjacent to a source of heat, such as a body of magma
continental drift	the concept that tectonic plates can move across the surface of the Earth
continental glacier	a glacier that covers a significant part of a continent and has an area of at least 50,000 km²
continental shelf	the shallow (typically less than 200 metres) and flat sub-marine extension of a continent
continental slope	the steeper part of a continental margin, that slopes down from a continental shelf towards the abyssal plain
contractionism	the now discredited theory that mountain ranges formed as a result of the contraction of the Earth
convergent boundary	a plate boundary at which the two plates are moving towards each other
Cordilleran Ice Sheet	the continental glacier that covered part of western North America, including almost all of British Columbia, part of the Yukon, and part of northern Washington, during the Pleistocene glaciations
core	the metallic interior part of the Earth, extending from a depth of 2900 kilometres to the centre
core-mantle boundary	the boundary, at a 2900 kilometre depth, between the mantle and the core
Coriolis effect	the tendency for moving bodies (e.g., ocean currents) to rotate on the surface of the Earth, clockwise in the northern hemisphere and counter-clockwise in the southern hemisphere
cosmic microwave background	radiation left over from the an early stage in the development of the universe at the time when protons and neutrons were recombining to form atoms
country rock	the original rock of a region, into which younger rock (typically igneous) rock has been intruded
covalent bond	a bond between two atoms in which electrons are shared
crater	a volcanic depression that is related to a specific volcanic vent
craton	a region of ancient (typically Precambrian) crystalline rock (equivalent to a shield)
creep	the very slow (a millimetre to centimetre per year) flow of unconsolidated material on a gentle slope
crest	the highest point on a wave
crevasse	an open fissure on the surface of a glacier
cross bedding	small-scale inclined bedding within larger horizontal beds
crust	the uppermost layer of the Earth, ranging in thickness from about 5 kilometres (in the oceans) to over 50 kilometres (on the continents)
cyanobacteria	photosynthetic bacteria that evolved in the early Archean
“D” layer	(d-double-prime layer) a low seismic velocity zone within the basal 200 km of the mantle
debris flow	a gravity-driven flow of water and sediment that includes a significant proportion of coarse (cobble to boulder) material
decline	in mining a decline is a sloped tunnel used to access lower parts of a mine with wheeled equipment
decompression melting	melting (or partial melting) of rock resulting from a reduction in pressure without a significant reduction in temperature
dendritic	a pattern of drainage channels that resembles the branches in a tree
density	weight per volume of a substance (e.g., g/cm³) used widely in the context of minerals or rocks
deranged	a pattern of drainage channels that is chaotic
detrital	referring to fragments of rocks or minerals
diatom	photosynthetic algae that make their tests (shells) from silica
differentiation	the un-mixing of a magma, typically by the physical separation of minerals that crystallize early and settle towards the bottom
diorite	an intermediate intrusive igneous rock
dip	the angle below horizontal at which a sedimentary bed or other feature slopes
discharge	the volume of water flow in a stream expressed in terms of volume per unit time (e.g., m³/s)
discharge area	the part of an aquifer where groundwater discharge takes place
disconformity	a boundary between parallel sedimentary layers where some erosion of the lower layer has taken place
discordant	a geological feature that is not parallel to any existing layering in the country rock
divalent	an ion with a charge or +2 or -2
divergent	a plate boundary at which the two plates are moving towards away from each other
dodecahedron	an object with twelve surfaces, such as a garnet crystal
dolomite	a calcium-magnesium carbonate mineral (Ca,Mg)CO₃
dolomitization	the addition of magnesium to limestone during which some or all of the calcium carbonate is converted to dolomite
dolostone	a carbonate rock made up primarily of the mineral dolomite
drainage basin	the catchment area of a stream, including the area where all surface water drains into the stream
drop stone	a fragment of rock within otherwise fine-grained sediment that has been dropped from floating ice on a body of water
drumlin	a streamlined glacial erosional feature comprised of sediments and/or bedrock
dyke	a tabular intrusive igneous body that is discordant to any existing layering in the country rock
eccentricity	in the context of Milankovitch Cycles, the degree to which the Sun is offset from the geometric centre of the Earth’s orbit
eclogite	a garnet-pyroxene-glaucophane bearing rock that is the product of high-pressure metamorphism of oceanic crustal rock, typically within a subduction zone
effusive	a volcanic eruption dominated by the relatively gentle flow of lava
El Niño	a periodic climatic situation in which warm water extends all or most of the way to the eastern edge of the equatorial Pacific
elastic deformation	the deformation of material (including rock) from which it can fully recover if the stress is removed
electron	a sub-atomic particle of essentially no mass and a single negative charge
end moraine	a deposit of sediment that accumulates at the front of a glacier
englacial	within a glacier, referring especially to sediment carried within the glacial ice
epicentre	the location on the surface vertically above the location (i.e., “hypocentre” or “focus”) where an earthquake takes place
epipelagic zone	the upper layer of water (0 to 200 metres) in areas of the open ocean
epithermal deposit	a mineral deposit formed near to surface in an area of hydrothermal activity, typically associated with a body of magma
equilibrium line	on a glacier, the line between the zone of accumulation and the zone of ablation (in late summer the equilibrium line is the boundary between snow-covered ice and bare ice)
equipotential lines	in the context of groundwater an equipotential line connects locations with equal hydraulic head or water pressure
esker	a ridge of sediment deposited by a sub-glacial stream
eustatic sea level change	sea level change related to a change in the volume of the oceans, typically because of an increase or decrease in the amount of glacial ice on land
exfoliation	the fracturing of rock that results from a reduction in the pressure when overlying rock is eroded away
exoplanet	a planet that orbits a star other than the Sun
extrusive	igneous rock that cooled at surface
fall	in mass wasting, the vertical or near-vertical fall of rock
fault	a boundary in rock or sediment along which displacement has taken place
feedback	a process by which the physical effects of a climate forcing can have other effects (either negative or positive) on the climate
feldspar	a very common framework silicate mineral
felsic	silica rich (>65% SiO₂) in the context of magma or igneous rock
ferric	the oxidized form of an ion of iron (Fe3+)
ferromagnesian	referring to a silicate mineral that contains iron and or magnesium
ferrous	the reduced (non-oxidized) form of an ion of iron (Fe2+)
fetch	the distance over which wind blows to form waves
finger lake	a lake that occupies a glacial valley
firn	the granular transitional state between snow and ice within a glacier
flood plain	the area that is occupied by water when a stream floods and overtops its banks
flow	the fluid-like motion of material during mass-wasting
flow path	the path that groundwater flows along between a recharge area and a discharge area
flowing artesian well	an artesian well in which the water level naturally rises above the surface of the ground
flux melting	melting of rock that is facilitated by the addition of a flux (typically water) which lowers the rocks melting point
focus	the actual point below surface at which an earthquake takes place (equivalent to hypocentre)
foliated	the existence of foliation in a metamorphic rock
foliation	the alignment of mineralogical or structural features of a rock – especially a metamorphic rock
footwall	the lower surface of a non-vertical fault
foraminifera	a single-celled protist with a shell that is typically made of CaCO₃
fore-reef	the zone on the ocean side of a reef
formation	a unit of sedimentary rock that is lithologically consistent and sufficiently thick and extensive to be shown on a geological map at the scale that is typically used in the area in question
fracking	fracturing rock by injecting water and chemicals down a well at very high pressure (equivalent to hydraulic fracturing)
fractional crystallization	the sequential crystallization of minerals from magma, and the physical separation of early-forming crystals from the magma in the area where they crystallized
fracture	a break within a body of rock in which the rock on either side is not displaced
fringing reef	a reef adjacent to a shoreline where there is either a very narrow back reef area or none at all (in which case the reef is effectively attached to the shore)
frost line	in the context of planetary systems the boundary beyond which volatile components (e.g., water, carbon dioxide, methane, ammonia etc.) are frozen
frost wedging	the situation where the expansion of freezing water pries rock apart
Ga	(giga annum) billions of years before the present
gabbro	a mafic intrusive igneous rock
Gaia hypothesis	the hypothesis advanced by James Lovelock that the organisms have affected the atmosphere and oceans such that conditions on Earth have been kept habitable, in spite of significantly changing energy received from the Sun
galaxy	a gravitationally-bound system of stars and interstellar matter
gas giant	a large planet composed mostly of hydrogen and helium (e.g. Jupiter)
geosyncline	a kilometre thick deposit of sediments that has accumulated along the edge of a continent and is sufficient mass to depress the crust beneath it
geothermal gradient	the rate of increase of temperature with depth in the Earth (typically around 30˚ C/km within the crust)
giant impact hypothesis	the theory that the Moon formed when a Mars-sized planet (Theia) collided with the Earth at 4.5 Ga
glacial period	a period of Earth’s history during which glacial ice was present over a sufficient extent to have left recognizable evidence
glacial groove	a straight line created on a rock surface by erosion by a rock fragment embedded in the base of glacial ice (larger and deeper than a glacial striation)
glacial striation	a straight line created on a rock surface by erosion by a rock fragment embedded in the base of glacial ice (finer than a glacial groove – typically less than 1 centimetre wide)
glacier	a long lasting (centuries or more) body of ice on land that moves under its own weight
glaciofluvial	referring to sediments deposited from a stream that is derived from a glacier
glaciolacustrine	referring to sediments deposited within a lake in a glacial environment
glaciomarine	referring to sediments deposited within the ocean in a glacial environment
glaucophane	a blue-coloured sodium-magnesium bearing amphibole mineral that forms during metamorphism at high pressures and relatively low pressures, typically within a subduction zone
gneiss	high-grade metamorphic rock in which the mineral components are separated into bands
graben	a down-dropped fault block, bounded on either side by normal faults
grade	in the context of a mineral deposit, the amount of a specific metal or mineral expressed as a proportion of the whole rock
graded bedding	an individual sedimentary layer that shows a distinctive gradation in grain size (normal graded bedding is finer towards the top, reverse graded bedding is coarser towards the top)
gradient	the slope of a stream bed over a specific distance, typically expressed in m per km
granite	a felsic intrusive igneous rock
granule	a sedimentary particle ranging in size from 2 to 4 millimetres in diameter
greenhouse gas	a gaseous molecule with 3 or more atoms that is able to absorb infrared radiation
greenhouse effect	in the context of climate, the ability of an atmosphere to absorb infrared radiation due to the presence of greenhouse gases
greenschist	a foliated metamorphosed rock (typically derived from basalt) in which the green colouration is derived from either chlorite, epidote or green amphibole
greenstone	a non-foliated metamorphosed rock (typically derived from basalt) in which the green colouration is derived from either chlorite, epidote or green amphibole
greywacke	a sandstone with more than 15% silt and clay, and with a significant proportion of sand-sized rock fragments
groundwater	water that lies beneath the surface of the ground
group	a stratigraphically-continuous series of related formations
groyne	a man-made structure extending from the shore built to deflect the energy of waves
gyre	a closed circular ocean current
habit	a characteristic crustal form or combination of forms of a mineral
habitable zone	the region around a star that is considered to be suitable for a life-bearing planet
Hadean	the first eon of Earth history, extending from 4.57 to 3.80 Ga
halide	a mineral in which the anion is one of the halide elements (e.g., halite – NaCl or fluorite – CaF₂)
halite	NaCl, a halide mineral also known as table salt
halogen	an element in the second-last column of the periodic table that forms anions with a negative-1 charge
hanging valley	a glacial valley created by a tributary glacier which does not erode as deeply as the main-valley glacier that it joins
hanging wall	the upper surface of a non-vertical fault
headland	a point extending out to sea
horn	a peak that has been eroded on at least three sides by glaciers
hornfels	a fine-grained metamorphic rock that is not foliated
horst	an uplifted fault block, bounded on either side by normal faults
hot spot	the surface area of volcanism and high heat flow above a mantle plume
hydrated mineral	a mineral that includes either hydroxyl (OH) or water (H₂O) in its chemical formula (e.g., gypsum CaSO_{4_.2H₂O)}
hydraulic conductivity	an expression of the rate at which a liquid will flow through a porous medium, as determined by the permeability of the medium and the viscosity of the liquid
hydraulic fracturing	fracturing rock by injecting water and chemicals down a well at very high pressure (equivalent to fracking)
hydrolysis	a reaction between a mineral and water in which H+ ions are added to the mineral and a chemically equivalent amount of cations are released into solution
hydroxide	the anion OH- or an mineral that includes that anion
hydrothermal alteration	chemical alteration of minerals by hot water solutions
hypocentre	the actual point below surface at which an earthquake takes place (equivalent to focus)
ice giant	a planet that is comprised mainly of gases heavier than hydrogen and helium, including oxygen, carbon, nitrogen, and sulfur (e.g., Uranus and Neptune)
igneous	a rock formed from the cooling of magma
illite	a clay mineral with a composition similar to that of muscovite mica
imbricate	aligned and overlapping, like the tiles on a roof
index fossil	a fossil with a distinctive appearance and a wide geographic range but from a relatively restricted time range, thus making it useful for dating a correlating rocks from different regions (the most useful index fossils are from organisms that lived for less than a million years)
inert	in chemistry, an element that does not readily react with other elements (e.g., neon)
infiltration	the recharge of groundwater from the downward percolation of surface water
insolation	a measure of the intensity of solar energy at a specific location or time (expressed in W/m2)
intensity	in seismology, a qualitative measure of the amount of shaking at specific location, based on what was felt by observers, or the amount of damage done
Intergovernmental Panel on Climate Change	(IPCC) an international body established in 1988 by the UN’s World Meteorological Organization and the UN Environment Program to prepare periodic reports on the status of global climate change and its mitigation
intrusive	an igneous rock that has cooled slowly beneath the surface
ionic bond	a bond in which electrons are transferred from one atom to another, thus forming ions
ion	an atom that has either gained or lost electrons and has thus become charged (or a group of atoms that also has a charge – e.g., HCO^3-)
isoclinal fold	a tight fold in which the limbs are parallel to each other
isostasy	the equilibrium between a block of crust floating on the underlying plastic mantle
isostatic sea level change	the effect on relative sea level of a vertical adjustment of the crust resulting from a change in the mass of the crust (e.g., from losing or gaining ice)
isotope	an form of an element that differs from other forms because it has a different number of neutrons (e.g., 16O has 8 protons and 8 neutrons while 18O has 8 protons and 10 neutrons)
joint	a fracture in rock
Jovian planet	a gas giant
ka	(kilo annum) thousands of years before the present
kaolinite	a clay mineral that does not have cations other than Al and Si
karst	the solutional erosion of an area with soluble rock (typically limestone) to form depressions and caves
kettle	a depression formed at the front of a large glacier when a stranded ice block that was surrounded by sediment eventually melts
kettle lake	a lake that forms within a kettle
kimberlite	an ultramafic volcanic rock that originates at significant depth (> 200 metres) in the mantle (some kimberlites include diamonds)
Kuiper belt	a region of the Solar System beyond the orbit of Neptune that is populated by small objects and dwarf planets (including Pluto)
laccolith	concordant intrusion in which the central part has formed an upward dome
lahar	a mudflow or debris flow that is either caused by a volcanic eruption, or forms on the flank of a volcano as a result of flooding not related to an eruption
landfill gas	gases produced within a landfill during the microbial breakdown of landfill components (most are dominated by carbon dioxide and methane)
large igneous province	a very large area of mafic volcanic rock produced by a massive eruption typically related to a mantle plume
lateral moraine	a deposit of rocky material that forms along the margin of a valley or alpine glacier, mostly from the freeze-thaw release of material from the steep slopes above
lattice	the regular and repeating three-dimensional structure of a mineral
Laurentide Ice Sheet	the continental glacier that extended across central eastern North America during the Pleistocene, covering most of Canada and a significant part of the United States
lava levée	a ridge that forms along the edge of a lava flow because the magma at the edge cools faster than that in the middle
lava tube	a tube that forms as mafic lava flows along a channel and lava leveés build up on either side, eventually forming a roof (once a lava tube forms it insulates the flowing magma, allowing it to stay hot a liquid for longer and therefore flow much further)
leachate	in the context of landfills, the liquid (rainwater) that passes through the waste and becomes contaminated with soluble components from the waste
levée	on a stream, the ridge that naturally forms along the edge of the channel during flood events
level	in mining, a horizontal mine opening
light year	the distance that light can travel in one year (9.4607 x 1012 km)
lignite	a low-grade type of coal with less than 70% carbon
limbs	the layers of rock on either side of a fold
limestone	a sedimentary rock that is comprised mostly of calcite
liquefaction	the tendency for unconsolidated and water saturated sediments to lose strength during seismic shaking
lithic arenite	an arenite in which there is more than 10% lithic clasts and in which there are more lithic clasts than feldspar clasts
lithic clasts	fragments of rock (e.g., basalt) that are included in the sand-sized grains in sandstone, or in the larger grains in conglomerate
lithification	the conversion of unconsolidated sediments into rock by compaction and cementation
lithosphere	the rigid outer part of the Earth, including the crust and the mantle down to a depth of about 100 kilometres
lodgement till	sediment that accumulates at the base of a glacier and typically has a wide range of grain sizes (including clay) and is well compacted
longshore current	the movement of water along a shoreline produced by the approach of waves at an angle to the shore
longshore drift	the movement of sediment along a shoreline resulting from a longshore current and also from the swash and backwash on a beach face
Love wave	a surface seismic wave, with horizontal motion, that develops in relatively weak (e.g., unconsolidated) materials at surface
luvisol	a cold climate forest soil formed in which clay has been removed from the A horizon and relocated into the B horizon
Ma	(Mega annum) millions of years before the present
mafic	silica poor (<45% SiO₂) in the context of magma or igneous rock
magma	molten rock typically dominated by silica
magnetic chronology	the study of the timing of reversals of the Earth’s magnetic field, and the application of that understanding to dating geological materials
magnitude	a measure of the amount of energy released by an earthquake
mantle	the middle layer of the Earth, dominated by iron and magnesium rich silicate minerals and extending for about 2900 kilometres from the base of the crust to the top of the core
mantle plume	a plume of hot rock (not magma) that rises through the mantle (either from the base or from part way up) and reaches the surface where it spreads out and also leads to hot-spot volcanism
marble	metamorphosed limestone (or dolostone) in which the calcite or dolomite has been recrystallized into larger crystals
mass wasting	the mass failure, by gravity, of rock or unconsolidated material on a slope
meander cutoff	the formation of a shorter stream channel across the narrow boundary between two meanders on a stream
meandering	the sinuous path taken by a stream within a wide flat flood plain
medial moraine	a lateral moraine that has been shifted towards the centre of a valley glacier at a point where two glaciers meet
member	a subdivision of a formation
mesopelagic zone	the upper middle zone of the open ocean extending from a 200 to 1000 metre depth
metallic lustre	the lustre of a mineral into which light does not penetrate but only reflects off of the surface
metallic bond	a type of bond in which abundant electrons are easily shared amongst cations
metamorphism	the transformation of a parent rock into a new rock as a result of heat and pressure that leads to the formation of new minerals, or recrystallization of existing minerals, without melting
metasomatism	metamorphism facilitated by ion transfer through water
meteoroid	a fragment of either stony or metallic debris in space
methane hydrate	a combination of water ice and methane in which the methane is trapped inside “cages” in the ice
mica	a sheet silicate mineral (e.g., biotite)
migmatite	a rock that is a mixture of metamorphic and igneous rock, formed at very high grades of metamorphism when a part of the parent rock starts to melt
Milankovitch cycles	millennial-scale variations in the orbital and rotational parameters of the Earth that have subtle effects on the Earth’s climate
Mohorovičić discontinuity	the boundary between the crust and the mantle
moment magnitude	a way of estimating earthquake magnitude based on the area of the rupture surface and the amount of displacement
monogenetic	a volcano that forms in a single eruptive event
moraine lake	a finger lake that forms within a glacial valley and is dammed by an end moraine
mud crack	a dessication crack formed in mud that has accumulated in a small body of water that later dries up or drains
mudflow	a mass-wasting event involving the flow of mud (sand, silt and clay) within a channel
mudrock	an inclusive term for mudstone, shale and claystone
muscovite	a potassium-bearing non-ferromagnesian mica
native element	(also native element mineral) a mineral that consists of only one element (e.g., native gold)
nebula	a cloud of interstellar dust and gases
negative feedback	a process that results in a decrease in that process (in the context of climate change it is a process that reduces the change in climate, such as the enhanced growth of vegetation in response to an increase in atmospheric carbon dioxide)
neutron	a sub-atomic particle with a mass of 1 and a charge of 0
nonconformity	a geological boundary where non-sedimentary rock is overlain by sedimentary rock
non-ferromagnesian mineral	a silicate mineral that does not contain iron or magnesium (e.g., feldsspar)
non-metallic lustre	the lustre of a mineral into which light does penetrate
normal fault	a non-vertical fault along which the hanging wall (upper surface) has moved down relative to the footwall
normal force	the component of the gravitational force that acts directly into the slope
North Atlantic Deep Water	deep Atlantic Ocean water that has descended in the far north of the basin in the area between Scandinavia and Greenland
nunatuk	a rocky peak that extends above the ice level of a continental glacier
obliquity	in the context of Milankovitch Cycles, the angle of the tilt of the Earth’s rotational axis with respect to the plane of its orbit around the Sun
ocean plain	the extremely flat surface of the deep ocean floor in areas unaffected by plate tectonic processes and volcanism
oil window	the depth range, which is approximately 2000 to 4000 metres, within which the temperature is appropriate for the formation of oil from organic matter in sedimentary rock
ooid	a small (approximately 1 millimetre) sphere of calcite formed in areas of tropical shallow marine water with strong currents
olivine	a silicate mineral made up of isolated silica tetrahedra and with either iron or magnesium (or both) as the cations
Oort cloud	a spherical cloud of icy objects extending from between about 5,000 and 500,000 astronomical units (Sun-Earth distances) from the Sun (thought to be the source area of comets)
open-pit mine	a mine that is open to the surface
outcrop	a surface exposure of rock that is part of the crust (bedrock)
outwash plain	an extensive region of sand and gravel deposited by streams flowing out of a glacier (same as sandur)
overturned	a geological feature that has been tilted to the point where it is upside down
oxbow	a part of a stream meander that has become isolated from the rest of the stream as the result of a meander cutoff
oxidation	the reaction between a mineral and oxygen
oxide	a mineral in which the anion is oxygen (e.g., hematite Fe₂O₃)
pahoehoe	a lava flow with a ropy surface texture formed when the surface cools and hardens while the lava beneath is still flowing
paleomagnetic	past variations in the intensity and polarity of the Earth’s magnetic field
Pangea	the supercontinent that existed between approximately 300 and 180 Ma
paraconformity	an interruption representing a period of non-deposition, without tilting or erosion, in a sequence of sedimentary rocks
parasitic fold	a fold within a fold
parent rock	the rock that was already in existence when a process of metamorphism started
partial melting	the process during which a only specific mineral components of a rock melt in response to changing conditions
parting	a narrow gap between individual sedimentary layers
passive margin	a boundary between a continent and an ocean at which there is no tectonic activity (e.g., the eastern edge of North America)
paternoster lake	one of a series of rock basin lakes
pebble	a sedimentary particle ranging in size from 2 to 64 millimetres (includes granule)
pelagic	the part of a lake or the ocean that is not close to shore
permafrost	ground that remains frozen for two or more years
permanentism	the now discredited theory that the features on the Earth have not changed significantly over geological time
permeability	an expression of the ease with which liquid will flow through a porous medium
phaneritic	a rock texture in which the individual crystals or grains are visible to the naked eye
Phanerozoic	the most resent eon of geological time, encompassing the Paleozoic, Mesozoic and Cenozoic
phenocryst	a relatively large crystal within an igneous rock
phyllosilicate	a silicate mineral in which the silica tetrahedra are made up of sheets
phosphate	a mineral in which the anion is PO43-
photic zone	the upper 200 metres of the ocean or a lake, where, depending on the turbidity of the water, light can penetrate
phreatic eruption	a steam-drive volcanic eruption that takes place when surface or near-surface water is heated by volcanic activity
phyllite	a metamorphic rock with slaty cleavage and a sheen on the surface produced by aligned micas
pillow	a pillow-shaped mass of volcanic rock (typically basalt) formed when magma erupts beneath the surface
pillow lava	a volcanic rock (typically basalt) that is made up primarily of pillows
pipe	a cylindrical body of igneous rock, typically resulting from a feeder conduit to a volcano
plate	a region of the lithosphere that is considered to be moving across the surface of the Earth as a single unit
plate tectonics	the concept that the Earth’s crust and upper mantle (lithosphere) is divided into a number of plates that move independently on the surface and interact with each other at their boundaries
plinian eruption	a large volcanic eruption in which a column of hot tephra and gases rises many kilometres into the atmosphere
pluton	a body of intrusive igneous rock
podsol	a soil with well-developed horizons formed in temperate forested regions
podsolization	the process of the formation of podsol
polar wandering path	a path of varying magnetic pole positions defined by paleomagnetic data (in fact it is now understood that the continents have wandered, not the poles, so a more appropriate terms is “apparent polar wandering path”)
polymerize	the formation of molecular chains within a fluid (e.g., a magma) that lead to an increase in the fluid’s viscosity
polymorphs	two or more minerals with the same chemical formula but different crystal structures
porosity	the percentage of open pore space within a body of rock or sediment
porphyritic	an igneous texture in which some of the crystals are distinctively larger than the rest
porphyry deposit	a mineral deposit (of copper or molybdenum especially) in which part of the host rock is a porphyritic stock
positive feedback	a process that results in an increase in that process (in the context of climate change it is a process that enhances the change in climate, such as the reduced reflectivity of the Earth’s surface when ice melts)
potassium feldspar	feldspar with the formula KAlSi₃O₈
potentiometric surface	the imaginary surface defined by the levels to which water would rise in a series of wells drilled into a confined aquifer
precession	in the context of Milankovitch Cycles, the variation in the direction at which the Earth’s rotational axis is pointing
principle of cross-cutting relationships	the principle that a body of rock that cuts across or through another body of rock is younger than that other body
principle of faunal succession	the principle that life on Earth has evolved in an orderly way, and that we can expect to always find fossils of a specific type in rocks of a specific age
principle of inclusions	the principle that inclusions within a body of rock must be older than the rock
principle of original horizontality	the principle that sedimentary beds are originally deposited in horizontal layers
principle of superposition	the principle that in a sequence of layered rocks that is not overturned or interrupted by faulting, the oldest will be at the bottom and the youngest at the top
proglacial	referring to the area in front of a glacier
proton	a sub-atomic particle with a mass of 1 and a charge of 1
protoplanetary disk	a rotating cloud of gas and dust surrounding a young star
pumice	a highly vesicular felsic volcanic rock (typically composed mostly of glass)
p-wave	a seismic body wave that is characterized by deformation of the rock in the same direction that the wave is propagating (compressional vibration)
pyroclastic	volcanic material formed during an explosive eruption
pyroclastic density current	a body of hot pyroclastic rock and gases that is flowing rapidly down the flank of a volcano
pyroxene	a single chain silicate mineral
quartz	a silicate mineral with the formula SiO2
quartz sandstone	a sandstone in which more than 90% of the grains are quartz
quartzite	a metamorphic rock formed from the contact or regional metamorphism of sandstone
radial	a pattern of streams radiating out from a central point, typically an isolated mountain
radioactivity	the natural transformation of unstable isotopes into new elements
radiolaria	microscopic (0.1 to 0.2 millimetres) marine protozoa that produce silica shells
Rayleigh wave	a surface seismic wave, with vertical motion
recharge	the transfer of surface water into the ground to become groundwater
recharge area	an area of an aquifer where recharge is predominant over discharge
rectangular	a drainage pattern in which tributaries typically flow at right angles to each other and meet at right angles
recumbent fold	a fold that is overturned such that its limbs are close to horizontal
redshift	the increase in wavelength of light resulting from the fact that the source of the light is moving away from the observer
reef	a mound of carbonate formed in shallow tropical marine environments by corals, algae and a wide range of other organisms
regional metamorphism	metamorphism caused by burial of the parent rock to depths greater than 5 kilometres (typically takes place beneath mountain ranges, and extends over areas of hundreds of km²)
remnant magnetism	magnetism of a body of rock that formed at the time the rock formed and is consistent with the magnetic field orientation that existed at that time and place
reservoir rock	rock into which petroleum has migrated and is now trapped
residual soil	soil formed by weathering of the underlying rock or sediment
retrograde metamorphism	metamorphism that takes place at a lower temperature than that at which the rock originally formed or was previously metamorphosed
reverse fault	a non-vertical fault along which the hanging wall (upper surface) has moved up relative to the footwall
rhyolite	a felsic volcanic rock
ridge push	the concept that at least part of the mechanism of plate motion is the push of oceanic lithosphere down from a ridge area
rip current	a strong flow of water outward from a beach
ripple	on a series of small parallel ridges formed within sediment that has accumulated in moving water or wind
rip-rap	angular rock fragments, typically boulder sized, used to armour slopes and shorelines against erosion
roche moutonée	a product of glaciation in which a bedrock protrusion is eroded into a streamlined shape that has a broken or jagged leading (down-ice) edge
rock avalanche	a rapid turbulent flow of broken bedrock fragments down a steep slope
rock basin lake	a lake situated in a rock basin carved at the upper end of an alpine glacier
rock cycle	the series of processes through which rocks are transformed from one type to another
rock fall	the near-vertical fall or bouncing of rock released from a steep slope
rock slide	the translational motion of an essentially intact body of rock down a slope (rock slides are typically slow, because once they start to move fast the rock body becomes fragmented and then flows as a rock avalanche)
runoff	flow of water down a slope, either across the ground surface, or within a series of channels
rupture	breaking of rock subject to stress, typically resulting in an earthquake
rupture surface	the area over which rock rupture takes place during an earthquake
sackung	an escarpment or trough at the top of a slow-moving rock slide (sackungen)
saltation	the bouncing of particles along a stream bottom or desert floor
sand	a mineral or rock fragment ranging in size from 1/16th to 2 millimetres
sandstone	a rock that is primarily comprised of sand-sized particles
sandur	an extensive region of sand and gravel deposited by streams flowing out of a glacier (same as outwash plain)
saturated zone	the part of an aquifer, or any body of rock, that is saturated with water
schist	a metamorphic rock with visible aligned mica crystals
sea cave	a shallow cave formed on a rocky shore by wave erosion
sea cliff	a coastal escarpment that is typically eroding inland as a result of wave action
sea-floor spreading	the formation of new oceanic crust by volcanism at a divergent plate boundary
sector collapse	the sudden collapse of a significant part of the flank of a volcano
sedimentary rock	rock that has formed by the lithification of sediments
sediments	unconsolidated particles of mineral or rock
seismic	pertaining to earthquakes
seismic moment	a measurement of an earthquake’s energy based on longwave vibrations, or on the product of the fault area and displacement
seismic reflection sounding	measurement of the properties of sediments based on detection of sounds generated at surface and reflected from layers beneath the surface
septae	calcareous partitions between the successive living chambers in a cephalopod
septic system	a system constructed to facilitate the dispersion and detoxification of sewage (typically includes a septic tank and a drainage field)
shaft	a vertical opening at a mine
shale	a silt- and clay-rich rock that has evidence of layering
shear force	the component of the gravitational force in the direction parallel to a slope
shear strength	the strength of a body of rock or sediment that counteracts the shear force
shear stress	the stress placed on a body of rock or sediment adjacent to a fault
sheeted dykes	a series of near-vertical dykes formed in the vicinity of a spreading ridge when magma from depth flows into fractures formed by extensional forces
sheet silicate	a silicate mineral in which the silica tetrahedra are combined within sheets
sheetwash	overland flow of water, typically related to a heavy precipitation event
shield	a region of ancient (typically Precambrian) crystalline rock (equivalent to a craton)
shield volcano	a low-profile volcano formed primarily from eruptions of low-viscosity mafic magma
SIAL	referring to rock or magma in which silica and aluminum are the predominant components (generally equivalent to felsic)
silica	a form of the mineral quartz (SiO₂)
silica tetrahedron	a combination of 1 silicon atom and 4 oxygen atoms that form a tetrahedron
silicate	a mineral that includes silica tetrahedra
silicon	the 14th element
silicone	resin or caulking made from silicon-oxygen chains and various organic molecules
sill	an igneous intrusion that is parallel to existing layering in the country rock
silt	sedimentary particles ranging is size from 1/256th to 1/16th of a millimetres
SIMA (simatic)	referring to rock or magma in which silica, magnesium and iron are the predominant components (generally equivalent to mafic)
skarn	the contact metamorphism (and metasomatism) of limestone
slab pull	the concept that at least part of the mechanism of plate motion is the pull of oceanic lithosphere down into the mantle
slate	a fine-grained metamorphic rock that splits easily into sheets
slaty cleavage	the tendency for slate or phyllite to split into sheets (note that this is the only situation in this textbook where the term “cleavage” is applied to a rock as opposed to a mineral)
slide	the downward movement of rock or sediment on a slope as an intact mass
slump	a slide in which the nature of the motion is rotational (typically only develops in unconsolidated sediments)
smectite	a fine-grained sheet silicate mineral that can accept water molecules into interlayer spaces, resulting is swelling
smelter	a refinery at which minerals are processed to produce pure metals
snowline	in astronomy the radius around a star at which represents the boundary between gases (or liquids) and solids
soil horizon	a layer, within a well-developed soil, that is physically or chemically different from layers above or below
solar system	a star and the planets surrounding it
solar wind	a stream of ionized (charged) particles away from the Sun
solid solution	the substitution of one element for another in a mineral (e.g., iron can be substituted for magnesium in the mineral olivine)
solifluction	the flow of water saturated sediment or soil over a stronger and less permeable substrate
source rock	the sedimentary rock from which petroleum originates prior to its migration into a reservoir rock
speleothem	a solutionally-formed feature within a limestone cave (e.g., a stalactite)
spit	a sand or coarser deposit extending from shore out into open water
spring	the flow of groundwater onto the surface
stack	a prominent rocky island that is a remnant of the erosion of a headland
stage	the level of water in a stream
stalactite	a cone-shaped speleothem that is suspended from the roof of a cave
stalagmite	a cone-shaped speleothem that forms on the floor of a cave
step-pool	a characteristic of stream flow in which water flows from one pool to another, typically on a stream with a steep gradient
stock	an irregular pluton with n exposed area less than 100 km²
stoping	the fracturing and incorporation of fragments of country rock as a magma body moves upward through the crust
strain	the deformation of rock that is subjected to stress
streak	the mark left on a porcelain plate when a mineral sample is ground to a powder by being rubbed across the plate (typically considered to provide a more reliable depiction of the colour than the whole sample)
stream	any body of flowing water
stress	a force applied to a rock
stress transfer	the change in the pattern of stress on a region of rock as a result of an earthquake (typically stress is reduced in the area of a rupture zone, but is increased elsewhere in the vicinity)
strike	the compass direction of a horizontal line on a sloped surface (e.g., bedding plane, fracture etc.)
strike-slip fault	a fault that is characterized by motion that is close to horizontal and parallel to the strike direction of the fault
subaerial eruption	a volcanic eruption that takes place on land
subaqueous eruption	a volcanic eruption that takes place under water
subducted	when part of a plate is forced beneath another plate along a subduction zone
subduction zone	the sloping region along which a tectonic plate descends into the mantle beneath another plate
subglacial	beneath a glacier
sulphate	a mineral in which the anion is SO42-
sulphide	a mineral in which the anion is S2-
supergroup	a stratigraphically-continuous series of related groups
superterrane	a number of terranes that are contiguous
supraglacial	on the surface of a glacier
surf zone	the near-shore zone where waves are breaking into surf
suture	the line on the surface of a cephalopod that marks the boundary between a septum and the outer shell
swash	the upward motion of a wave on a beach (typically takes place at the same angle that the waves are approaching the shore)
s-wave	a seismic body wave that is characterized by deformation of the rock transverse to the direction that the wave is propagating
symmetrical	a fold in which the limbs are at the same angle to the hinge
syncline	a downward fold where the beds are known not to be overturned
synform	a downward fold where it is not known if the beds are overturned
tailings	the fine-grained waste rock from a plant used to concentrate ore minerals
talus slope	a sloped deposit of angular rock fragments at the base of a rocky escarpment
tarn	a lake within a rock basin
tectonic plate	a region of the lithosphere that is considered to be moving across the surface of the Earth as a single unit
tectonic sea level change	relative sea level change related to the vertical motion of a crustal block caused by tectonic processes
tephra	fragments of volcanic rock (including volcanic ash) ejected during an explosive eruption
terminal moraine	and end moraine that marks the farthest forward advance of a glacier
terrane	a block of crust that has geological features that are distinctive from neighbouring regions, and is assumed to have been moved from elsewhere by tectonic processes
terrestrial planet	a planet with a rocky mantle and crust and metallic core (e.g., Earth)
terrigenous	referring to sedimentary particles that originated on a continent
test	the shell-like hard parts (either silica or carbonate) of small organisms such as radiolarian and foraminifera
thrust fault	a low angle reverse fault
till	unsorted sediment transported and deposited by glacial ice
tiltmeter	a sensitive instrument used to monitor subtle changes in the tilt of the land, particularly in studies of active volcanoes
tombolo	a sand or coarser deposit connecting an island or rocky prominence to a larger body of land
traction	a force that contributes to the movement of particles situated on a stream bed or desert floor
transform fault	a boundary between two plates that are moving horizontally with respect to each other
travertine	a deposit of calcium carbonate that forms at springs, hot springs or within limestone caves
trellis	a drainage pattern in which tributaries typically flow parallel to one other but meet at right angles
trigger	an event, such as an earthquake or a heavy rainfall, that triggers the onset of a mass wasting event
trough	the lowest point of a wave
truncated spur	the steep end of a ridge or arête that has been eroded by a main-valley glacier
tsunami	a long-wavelength wave produced by the vertical motion of the floor of the ocean or a large lake, typically related either to an earthquake or a sub-marine mass wasting event
tufa	a form of travertine that is especially porous as it forms around existing vegetative material.
tuya	a flat-topped volcanic hill or mountain that formed when an eruption took place beneath a glacier and the melting led to the formation of a lake that then resulted in the wave-erosion of the top of the volcano
unconfined aquifer	an aquifer that is not overlain by a confining layer
unconformity	a geological boundary at the base of a sedimentary layer
unconformity-type uranium deposit	a uranium deposit that has formed at a nonconformity between sandstone and older rock
uncompressed density	the density of planetary material that it would have it was not compressed by the planets gravitational force
underground storage tank	(UST) an underground tank for storing liquids, most commonly for liquid fuel
unsaturated zone	the rock or sediment above the water table
U-shaped valley	a relatively straight valley with a flat bottom and steep sides that has been carved by a valley glacier
valley glacier	a glacier formed in a mountainous region and confined to a valley (same as alpine glacier)
varve	a recognizable layer within sediments that represents a single year of deposition
vesicular	an igneous texture characterized by holes left by gas bubbles
volcanic glass	magma that has cooled within minutes, not allowing time for the formation of crystals
volcanic-hosted massive sulphide	a mineral deposit hosted by volcanic rocks and including zones where most of the rock is made up of sulphide minerals (including ore minerals and pyrite)
wacke	a sandstone with more than 15% clay and silt
water table	the upper surface of the saturated zone in an unconfined aquifer
wave base	the depth of water that is affected by the sub-surface orbital motion of wave action (approximately one-half of the wavelength)
wave-cut platform	a nearly-horizontal bench of rock eroded by waves within the surf zone (equivalent to wave-cut terrace)
wavelength	the distance between the crests of two waves
weathering	a range of processes taking place in the surface environment, through which solid rock is transformed into sediment and ions in solution
Western Canada Sedimentary Basin	a large basin in the western interior of Canada, east of the Rocky Mountains, extending from the northern United States to the Northwest Territories
Wisconsin Glaciation	the most recent advance of the Pleistocene glaciations, extending from 85 to 11 ka
xenolith	a fragment of country incorporated into igneous rock, commonly as a result of stoping
youthful stream	a stream that is actively down-cutting its valley in an area that has recently been uplifted
zone of ablation	the part of a glacier, below the equilibrium line, where there is net loss of ice mass due to melting and calving
zone of accumulation	the part of a glacier, above the equilibrium line, where there is net gain of ice mass because not all of the snow that falls each winter is able to melt during the following summer

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