Glossary
Nahgeib Miller
- 0.6 rule
-
A system for approximating the velocity of flow of a river
- A strike-slip fault
-
A fault in which movement occurs along the strike of the fault plane and the crust is conserved
- ablation
-
For glaciers, the amount of snow and ice lost in one year
- abrasion
-
The wearing away of rock by sediments moving with the water
- accumulation
-
For glaciers, the amount of snow and ice added in one year
- alluvial fan
-
A fan-shaped depositing of sediments create by an abrupt change, from steep to shallow, in a river’s profile
- amphibole group
-
Silicates in which two oxygens in a tetrahedron bond with the silicon of an adjacent tetrahedron
- anions
-
Ions that have resulted from an atom gaining an electron or electrons and that are thus negatively charged
- Antecedent streams
-
Streams that develop on beds that are then deformed and folded
- anticline
-
The upward fold in a rock layer
- arêtes
-
Ridges where adjacent glacial valleys meet
- arid
-
Describing conditions in which insufficient rainfall leads to extremely dry conditions
- asteroids
-
In a planetary system, chunks of rock larger than meteoroids but smaller than a planet
- asthenosphere
-
The plates that float on Earth’s upper mantle
- atmosphere
-
The gaseous “ocean” that surrounds Earth
- atom
-
The smallest part of an element that retains its physical and chemical properties
- aurora borealis
-
Arches of light in the upper atmosphere near the poles. Aurora Borealis at the north pole and aurora Australis at the south pole.
- avalanche
-
(n.) The rapid fall of material down a mountainside or cliff face; (v.) to tumble as an avalanche
- axial precession
-
Cyclic “wobble” in Earth’s axis of rotation
- azimuth
-
An angle less than 90° as defined within a quadrant with cardinal directions
- banding
-
In rock, a thick striped pattern of different mineral compositions
- basal slip
-
For glaciers, glacial motion as a block over lubricated bedrock
- basins
-
A depression in the Earth crust
- batholith
-
The largest size of discordant intrusion
- bearing
-
An angle between 0° and 360°
- bedding sequence
-
An outcrop consisting of multiple layers of sediments deposited in different environments
- Big Gap
-
An unconformity created by a period of erosion followed by non-deposition 350 million to 2 million years ago
- Biological sedimentary rock
-
Rock derived from shell and skeleton fragments of biological organisms
- biosphere
-
All living organisms on Earth
- bioturbation
-
The creating of hollow tubes in substrate by burrowing benthic animals
- bombs
-
The largest particles of pyroclastic igneous rock
- braided
-
Of a stream, flowing in many channels simultaneously
- Brunisolic soils
-
Residual soils with a brownish B horizon
- Burial
-
The covering of sediments by later sediment layers
- Burial metamorphism
-
Transformation of rock by pressure from rock layers deposited above
- Canadian Shield
-
The basement rocks of the Precambrian age in Eastern Canada and the northeastern United States characterized by granitic igneous rocks and gneisses of igneous origin
- capacity
-
For streams, the total amount of sediments a stream can carry*combine with previous definition in same location
- cations
-
Ions that have resulted from an atom giving up an electron or electrons and that are thus positively charged
- cementation
-
The binding together of sediments by minerals to form rock
- channel
-
The bottom of a valley in which a stream flows
- chemical reaction
-
The interaction of two or more atoms of elements in a certain fixed ratio or proportion
- Chemical sedimentary rock
-
Rock derived from mineral precipitate
- Chemical weathering
-
Chemical reactions that break down rock when minerals come in contact with air and water
- Chernozemic soils
-
Soils with high carbonate concentration and a dark A horizon
- cirque
-
A roughly circular basin with cone-shaped sides
- Cleavage
-
The tendency for a mineral to break along planar surfaces
- cohesion
-
A property of sticking together due to electrostatic forces
- compaction
-
The creation of rock of through removal of water by pressure
- competence
-
The measure of the largest size of rock particle a stream or glacier can carry
- Composition
-
The relative proportions of the different types of minerals in a rock
- Concordant intrusions
-
Magmatic intrusions that follow cracks and natural zones of weakness in the surrounding country rock
- Contact metamorphism
-
Transformation of rock by the heat from adjacent magma
- Continental crust
-
The less dense portion of Earth’s crust, with higher silicate content than oceanic crust
- continental drift
-
The movement of continents carried with plates of Earth’s crust
- Continental glaciers
-
Slow-moving, thick sheets of ice covering a large part of a continent
- convection
-
An upward and downward cycle of movement caused by the flow of heat energy in a system
- convergence zone
-
A region in which plates meet
- convergent boundaries
-
A meeting of plates where plates move toward each other
- country rock
-
The unmelted rock into which magma is intruded
- covalent bonding
-
The sharing of electrons between atoms
- creep
-
The very slow movement of unconsolidated material down a slope
- cross-bedding
-
A sedimentary structure created by migrating ripples or dunes
- crust
-
The thin outer portion of Earth consisting of solid rock
- Crysolic soils
-
Permafrost soils
- crystal habit
-
The geometric description of the overall shape of a completely developed mineral
- cut-off meander
-
A stream path across adjacent cutbanks
- cutbanks
-
The banks on the outside curves of a meander
- deductive reasoning
-
A logical process that goes from the general to the specific
- deep time
-
Time in the order of millions to billions of years
- deform
-
A change in dimension of a solid material
- Dendritic drainage
-
A branching waterflow pattern
- Deposition
-
The coming to rest of sediments in their environments
- diagenesis
-
The physical and chemical changes in sediment resulting in lithification
- differentiation
-
The separation of one material into separate constituent materials, as in the division of Earth into separate layers
- dike
-
A concordant intrusion created when magma solidifies in a crack that cuts across the layers in the host rock
- dip
-
A measurement of the tilt to the horizontal of bedding planes, fault planes, and fold axes of rock
- Dip-slip faults
-
Faults in which movement occurs along the dip of the planar crack
- Discordant intrusions
-
Magmatic intrusions that do not follow the prevailing geology of the country rock
- divergent boundaries
-
Margins at which plates move away from each other on either side
- dome
-
A shaping of the Earth crust like an inverted bowl
- Double-chain tetrahedra
-
Silicates in which two oxygens in a tetrahedron bond with the silicon of an adjacent tetrahedron
- drift
-
Material of glacial origin
- drumlins
-
Large, streamlined hills of till and bedrock
- dunes
-
Wide structures formed by sediments transported at the base of flowing water or wind
- electrons
-
Negatively charged particles that orbit an atom’s nucleus and that take part in atomic reactions
- end moraine
-
Prominent glacial deposit at the ice front
- Erosion
-
The process that removes newly created sediments
- Erosional landforms
-
Landforms created by the scarping and plucking action of glacial ice as it is created and moves downslope
- erratics
-
Large boulders deposited by glaciers
- eskers
-
A ridge of sand and gravel in a ground moraine
- exfoliation
-
The exposure of rock by the removal of other strips from its surface
- Extrusive igneous rocks
-
Those that form from magma that erupts at the surface as lava
- fault breccia
-
Rock created from fragments along a fault
- faults
-
Planar cracks in deformed rock along which movement occurs
- faunal and floral succession
-
The pattern by which species of animals (fauna) and plants (flora) come after each other in evolutionary history
- feldspar group
-
Silicates with few cation bonds
- felsic
-
Of igneous rock, that are rich in feldspars and quartz
- Felsic igneous rocks
-
Rocks rich in feldspars and quartz minerals
- firn
-
Granular ice with low air content
- fjords
-
Flooded post-glacial steep U-shaped valleys
- floodplain
-
The flat part of the valley immediately adjacent to the channel
- Flow
-
The fluid movement of matter
- folds
-
A shaping of rock layers with an axis between limbs
- foliation
-
The realignment of platy minerals such that their long axes is perpendicular to the direction of compressive force
- footwall
-
Layers of split rock beneath the plane in a fault
- fossil assemblages
-
Grouping of fossils in the rock record
- fracture
-
The tendency for a mineral to break along irregular surfaces
- Framework tetrahedra
-
Silicates with few cation bonds
- frost wedging
-
The process by which water entering zones of weakness in rock freezes, opening up a larger crack
- galloping glacier
-
A glacier that moves at up to 50 metres per day
- geologic time scale
-
A diagram that shows the rock succession (rock record) as if we were indeed able to cut a slice through the crust
- glaciers
-
Large masses of ice on land that are in motion or that show evidence of once having moved
- glass
-
A three-dimensional array of elements with a chaotic pattern
- Gleysolic soils
-
Soils with greyish or mottled A, B, or C horizons due to prolonged or intermittent lack of aeration
- gorge
-
A canyon or steep-walled valley cut by a stream through a mountainous region
- graben
-
A depression caused by a series of normal faults resulting in a rift valley
- graded bedding sequence
-
An order of layering of sedimentary rocked associated with a fluvial environment
- granoblastic textures
-
Fine to coarse grains of interlocking crystals with little or no foliation
- Great Unconformity
-
The result of a period of erosion then non-deposition ~800 million to ~600 million years ago
- ground moraine
-
Unsorted sediment deposited at the base of the glacier
- groundmass
-
In porphyritic igneous rock, minerals surrounding phenocrysts
- Gullies
-
The beginnings of stream channels in a rock indentation
- half-life
-
The time taken for half the parent atoms to decay into daughter atoms
- hanging valley
-
A tributary valley with a floor above that of the valley its waters empty into
- hanging wall
-
Layers of split rock above the plane in a fault
- Hardness
-
A measure of how resistant a mineral is to being scratched
- headward erosion
-
Erosion of rock creating gullies that seem to migrate upstream in the headwaters
- Horizon A
-
The top zone of a soil profile, consisting of the humus layer, quartz, and clays
- Horizon B
-
The middle zone of a soil profile where soluble minerals are oxidized and deposited
- Horizon C
-
The zone in a soil profile dominated by bedrock altered by weathering
- Horizon D
-
Is the zone in a soil profile dominated by unaltered/unweathered bedrock
- horizons
-
The zones of a soil profile, defined by their contents
- horn
-
A pointed peak of a mountain created by adjacent cirques
- horst
-
A raised section of rock between normal faults
- hotspot volcanism
-
The rising of superheated magma from the mantle–core boundary as a jet or plume
- humus layer (O-horizon)
-
An organic rich soil layer
- Hydrolysis
-
A chemical reaction of a substance with water
- hydrosphere
-
The water of Earth, in all its phases: solid (ice), liquid (water), and gas (water vapour)
- hypothesis
-
A tentative explanation based inductive reasoning from empirical evidence
- Ice caps
-
Polar ice masses
- Ice-laid deposits
-
Deposits of till left directly by retreating glaciers
- Igneous rocks
-
Rocks formed by the crystallization or solidification of magma or lava
- inductive reasoning
-
A logical process that uses a specific observation to make a generalization
- inner core
-
The portion of Earth’s core 5150–6370 km deep
- intermediate
-
Of igneous rock, with equal amounts of felsic and mafic minerals
- Intrusive igneous rocks
-
Those that form from magma that cools and solidifies within Earth’s crust
- ionic bonding
-
A transfer of electrons from one atom to another
- ions
-
An atom or molecule that has gained or lost an electron or electrons
- Isolated tetrahedra
-
A silicate structure in which a silicate anion is separated from an adjacent anion by a cation
- isotopes
-
Atoms of an element with the same number of protons but a different number of neutrons
- joints
-
Planar cracks with similar and/or related orientations
- Kames
-
Small hills of sand and gravel deposited at or near the edge of a glacier
- kettle lakes
-
Kettles occupied by water
- Kettles
-
Depressions formed when ice left by glaciers melts beneath sediments
- lamellar flow
-
The following of smooth and generally parallel paths by fluid particles
- lateral moraine
-
Glacial sedimentary deposits parallel to glacier flow
- lee side
-
The steep concave side of a bedload sediment formation
- leeward slope or lee slope
-
The concave, downstream-facing profile of ripples and dunes
- left lateral strike-slip fault
-
A fault characterized by movement of the layers on one side of the plane to the left
- levees
-
Raised lines of deposited sediment constraining a stream to a channel
- lithification
-
Transformation of sediments into rock
- lithosphere
-
The crust of Earth
- Lustre
-
A description of how the surface of a mineral reflects light
- Luvisolic soils
-
Clay-dominant soils with a light A horizon and dark B horizons
- mafic
-
Of igneous rock, that are rich in magnesium and iron cations
- Mafic igneous rock
-
Rock rich in metallic cations of magnesium and iron
- mantle
-
That portion of Earth between the core and crust that consists of semi-molten rock
- mass wasting
-
Processes that cause the movement of soil and rock downslope
- meanders
-
Alternating bends in a stream channel
- medial moraine
-
Merged lateral moraines from adjacent glaciers
- metamorphic facies
-
Categories of rock that correspond to particular environments during which they were transformed into their current state
- Metamorphic rocks
-
Rocks formed from existing rocks in Earth’s crust
- Metasomatism
-
Transformation of rock by the exchange of superheated water between the rock and magmatic intrusions
- meteorites
-
Meteoroids that reach the surface of Earth
- meteoroids
-
Particles of rock in a solar system that are not accreted into larger bodies
- meteors
-
Meteoroids that burn up in Earth’s atmosphere
- mica group
-
Silicates in which three oxygens bond with the silicon of an adjacent tetrahedron
- minerals
-
A naturally occurring solid, inorganic, three-dimensional array of specific chemical composition with an ordered crystalline structure
- Moh’s Scale of Hardness
-
A range from 1 to 10 defining the relative degree to which a mineral resists being scratched
- Moraines
-
Accumulations of coarse rock, sand, and clay material carried by ice or deposited as till
- morphology
-
The physical shape of a rock or landform due to large-scale processes that were incident on it
- moulins
-
A near-vertical tube that forms in a glacier
- mylonite
-
A texture of rock in which minerals are almost pulverized
- nebula
-
A loose, slowly rotating amalgam of cosmic dust and gas
- neutrons
-
Noncharged particles in an atom’s nucleus
- normal fault
-
A fault in which the crust is extended
- nucleus
-
The central, high-density portion of an atom consisting of protons and neutrons
- Oblique slip faults
-
A fault characterized by movement of rock layers on opposite sides of the fault plan diagonal to each other
- oceanic crust
-
The denser, more metallic portion of Earth’s crust with lower silicate content than continental crust
- olivine group
-
Silicates in which oxygens of adjacent tetrahedra bond to a shared cation
- orders
-
Categories of soil taxonomy
- Organic soils
-
Soils of 30% or more organic matter
- orogeny
-
The process of mountain building through plate collisions
- outcrop
-
That portion of rock exposed at the surface of Earth
- outer core
-
The inner portion of Earth, consisting of molten iron alloy
- outwash
-
Drift that has been carried, modified, sorted, and distributed by meltwater streams
- oxbow lake
-
A cut-off meander containing water
- Oxidation
-
The reaction of minerals with oxygen from air or water, altering the mineral structure
- oxides
-
Minerals with an oxygen anion
- phenocryst
-
In porphyritic igneous rock, a relatively larger mineral surrounded by relatively smaller minerals
- planetary accretion
-
The sweeping up of debris in the orbital path of planetesimals
- planetesimals
-
Small spherical astronomical bodies of accreted rock
- plastic deformation
-
For glaciers, glacial motion by of individual ice crystals’ passing each other
- plate tectonics
-
The process of movement of segments of Earth’s crust on the mantle resulting in several geologic phenomena
- plunge
-
The dip of a fold axis in the Earth crust along the axial plan
- plutonic rocks
-
Intrusive igneous rocks
- plutons
-
Formations of intrusive igneous rock
- Podzolic soils
-
Soils with a grey layer near the top and with humus containing iron and aluminum oxide
- point bars
-
The banks on the inside curves of a meander
- pore spaces
-
The hollow spaces in between grains that are occupied by water, air, or a combination of both
- porosity
-
A measurement of the hollow spaces in between grains that are occupied by water, air, or a combination of both
- porphyry
-
A course-grained texture with different mineral sizes in intrusive igneous rock
- principle of cross-cutting relationships
-
Lyell’s concept that abrupt interruptions in lateral continuity reflect events that occur after sediments were deposited and lithified
- principle of lateral continuity
-
Steno’s concept that sediment layers become thinner the farther the sediments have been carried and that changes in topography can stop the formation of a sediment layer
- principle of original horizontality
-
Steno’s concept that sediments, with few exceptions, are laid horizontally, such that most nonhorizontal layers have moved after deposition
- principle of superposition
-
Steno’s concept that each rock layer in a formation is older than the layer above it
- protons
-
Positively charged particles in an atom’s nucleus
- pyroclastic igneous rocks
-
Rock solidified from airborne lava
- pyroxene group
-
Silicates in which one oxygen in a tetrahedron bonds with the silicon of an adjacent tetrahedron
- quartz
-
Solid silica with no cation bonds
- Radial drainage
-
A radial waterflow pattern away from the peak of a dome or volcano
- Rectangular drainage
-
A rectangular waterflow pattern on jointed bedrock
- regional metamorphism
-
The transformation of rock over a large area in the crust, usually under mountain belts
- Regosolic soils
-
Soils with poorly developed profiles featuring slightly altered parent rock
- Residual soils
-
Soils that evolve in one place
- rift valley
-
A depression in Earth’s crust created by the separation of continental plates
- right lateral strike-slip fault
-
Faults characterized by movement of the layers on one side of the plane to the right
- Ripples
-
Narrow structures formed by sediments transported at the base of flowing water or wind
- river
-
The major branch of a stream system
- roches moutonées
-
Small glacier-created bedrock hills; also called “sheep rocks”
- rock
-
Naturally occurring aggregate of minerals
- Rock assemblages
-
Rocks that were laid down in a specific sequence, indicating a specific sequence of geologic processes acting in specific depositional environments
- rock cycle
-
The creation and breaking down of rock in Earth’s crust and their interrelation
- rock flour
-
Finely powdered rock material produced by weathering that occurs during glacial erosion
- rock record
-
Currently existing rock, considered as reflecting the processes that originated it and the environments in which it formed
- rounding
-
The smoothing of rock particles
- saltation
-
The repeated carrying and deposition of sediments by a stream
- schistosity
-
In rock, coarse layering of different mineral compositions
- scientific method
-
The system of employing critical thought to investigate natural phenomena
- Sedimentary rocks
-
Rocks formed from sediments
- Sediments
-
Smaller pieces of rock created by the weathering of existing rock
- sequence
-
The order of layering in sedimentary rock
- Sheet tetrahedra
-
Silicates in which three oxygens bond with the silicon of an adjacent tetrahedron
- Shock metamorphism
-
Transformation of rock by meteorite impact
- sidereal day
-
The 23-hour, 56-minute, 4.091-second Earth day
- silica
-
SiO2
- silicates
-
Minerals with a silicate anion
- siliciclastic
-
Of sediments, consisting mainly of silicates of igneous origin
- Siliciclastic sedimentary rock
-
Rock derived from weathered igneous rock
- sill
-
A concordant intrusion created when magma solidifies along bedding directions
- Single-chain tetrahedra
-
Silicates in which one oxygen in a tetrahedron bonds with the silicon of an adjacent tetrahedron
- slaty cleavage
-
Weak foliation produced by low compressive forces
- slide
-
Movement of matter along a shear plane parallel to a slope
- solar day
-
The 24-hour Earth day
- Solonetzic soils
-
Soils with significant salt accumulations
- spreading centre
-
The large-scale fissure in the Earth’s crust separating divergent plates
- stock
-
The smallest size of discordant intrusion
- stoss side
-
The shallowly sloped convex side of a bedload sediment formation
- Stratification
-
Layering in sedimentary rock
- stratum
-
A rock layer; pl., strata
- Streak
-
The colour of the powdered form of a mineral
- Stream discharge
-
The amount of water that passes through a particular cross-sectional area of a stream per unit of time
- Streams
-
Flowing bodies of water
- striations
-
Grooves in rock created by glaciers dragging rock over it
- strike
-
A measurement of the compass orientation of bedding planes, fault planes, and fold axes of rock
- subduction
-
The riding up of a less dense plate over a denser plate, which is then pushed into the mantle and eventually recycled
- supercontinents
-
Continents consisting of all land on Earth connected, leaving one massive ocean
- Superposed streams
-
Streams that develop on beds over folded rock
- syncline
-
The downward fold in a rock layer
- terminal moraine
-
Glacial deposit at the farthest point reached by an ice front
- terraces
-
Flat elevated plains on either side of the stream’s channel and floodplain
- Texture
-
A visual description of the size of the minerals in the rock
- theory
-
A hypothesis that has become widely accepted
- thrust fault
-
A reverse fault in which the fault plane has a dip of less than 45°
- till
-
Unstratified, poorly sorted glacial deposit]
- transform boundaries
-
A meeting of plates that move parallel to each other
- transform plate boundary
-
A meeting of plates at which the plates slide past each other
- transformations
-
For soils, processes changing materials from one form to another
- translocations
-
For soils, processes causing materials to move from one zone to another within the soil.
- transport capacity
-
For ice, the quantity of particles of rock that it can carry
- Transportation
-
Movement of sediments, especially by wind, water, or ice
- Transported soils
-
Soils that are eroded from slopes and carried downhill
- Trellis drainage
-
A waterflow pattern of parallel trunks and tributaries
- turbulent flow
-
The following of irregular and overlapping paths by fluid particles
- U-shaped valley
-
A glacier-formed valley with steep sides and a wide base
- ultramafic
-
Of igneous rock, consisting of very little feldspars, no quartz, and considerable magnesium and iron
- unconformities
-
Erosive surfaces with younger rocks deposited on top
- uniformitarianism
-
The principle stating that Earth processes unfolding today unfolded in the same way and at the same rate in the past
- valley
-
The sloping areas around a stream
- valley glaciers
-
River-like glaciers formed in mountain ranges
- varve
-
A pair of sediment layers formed by one year’s seasonal lake-surface freezing and thawing
- vein
-
A concordant intrusion created when magma solidifies in cracks that are irregular and localized
- Vertisolic soils
-
Clay-rich soils with high shrink potential when dry and high swell potential when wet
- volcanic ash
-
The smallest particles of pyroclastic igneous rock
- volcanic island
-
A volcano formed in water that is visible above sea level
- volcanic island arc
-
A series of volcanic islands parallel to a convergence boundary
- volcanic rocks
-
Extrusive igneous rocks
- Water-laid deposits
-
Glacial meltwater outwash deposits
- Weathering
-
The process that breaks down rock at the surface of Earth
- windward slope or stoss slope
-
The convex, upstream-facing profile of ripples and dunes