Book Glossary Flashcards - Essentials of Geo P1
A type of lava flow that has a
jagged, blocky surface.
aa
A general term for the
loss of ice and snow from a glacier.
Ablation
The grinding and
scraping of a rock surface by the
friction and impact of rock particles
carried by water, wind, or ice.
Abrasion
Very level area of
the deep-ocean floor, usually lying
at the foot of the continental rise
Abyssal plain
A large
wedge-shaped mass of sediment
that accumulates in subduction
zones. Here sediment is scraped
from the subducting oceanic plate
and accreted to the overriding
crustal block.
Accretionary wedge
Usually narrow and consisting of
highly deformed sediments, they
occur where oceanic lithosphere is
being subducted beneath the
margin of a continent.
Active continental margin
The zone above the
permafrost that thaws in summer
and refreezes in winter.
Active layer
Tiny solid and liquid
particles suspended in the
atmosphere.
Aerosols
A smaller earthquake
that follows the main earthquake.
Aftershock
A stream
channel in which the bed and
banks are composed largely of
unconsolidated sediment (alluvium)
that was previously deposited in the
valley
Alluvial channel
A fan-shaped deposit
of sediment formed when a stream’s
slope is abruptly reduced.
Alluvial fan
Unconsolidated
sediment deposited by a stream
Alluvium
A type of convergent boundary in
which a slab of oceanic crust is
subducting beneath a continental
margin.
Andean-type plate margin
Igneous rocks having a
mineral makeup between that of
granite and basalt, after the common
volcanic rock andesite.
Andesitic
The steepest
angle at which loose material
remains stationary without sliding
downslope.
Angle of repose
An unconformity in which the older
strata dip at an angle different from
that of the younger beds.
Angular unconformity
A hard, metamorphic
form of coal that burns clean and
hot
Anthracite
A fold in sedimentary
strata that resembles an arch.
Anticline
A texture of
igneous rocks in which the crystals
are too small for individual minerals
to be distinguished with the
unaided eye.
Aphanitic texture
Rock or sediment
through which groundwater moves
easily.
Aquifer
An impermeable bed
that hinders or prevents
groundwater movement.
Aquitard
The first eon of
Precambrian time; the eon
preceding the Proterozoic. It
extends between 4.5 and 2.5 billion
years ago.
Archean eon
A narrow, knifelike ridge
separating two adjacent glaciated
valleys
Arête
A feldspar-rich sandstone.
Arkose
A well in which the
water rises above the level where it
was initially encountered
Artesian well
A subdivision of
the mantle situated below the
lithosphere. This zone of weak
material exists below a depth of
about 100 kilometers and in some
regions extends as deep as 700
kilometers. The rock within this
zone is easily deformed.
Asthenosphere
The gaseous portion
of a planet; the planet’s envelope of
air. One of the traditional
subdivisions of Earth’s physical
environment
Atmosphere
A continuous or broken ring
of coral reef surrounding a central
lagoon.
Atoll
The smallest particle that
exists as an element.
Atom
A mass unit
equal to exactly one-twelfth the
mass of a carbon-12 atom
Atomic mass unit
The number of
protons in the nucleus of an atom
Atomic number
The average of the
atomic masses of isotopes of a given
element.
Atomic weight
A zone or halo of contact
metamorphism found in the host
rock surrounding an igneous
intrusion
Aureole
A poorly drained
area on a floodplain, resulting when
natural levees are present.
Back swamp
The inner portion of
the shore, lying landward of the
high-tide shoreline. It is usually dry,
being affected by waves only during
storms.
Backshore
An apron of sediment
along a mountain front created by
the coalescence of alluvial fans
Bajada
Finely
layered iron- and silica-rich (chert)
layers deposited mainly during the
Precambrian
Banded iron formations
Common term for sand and
gravel deposits in a stream channel.
Bar
A solitary sand
dune shaped like a crescent with its
tips pointed downwind
Barchan dune
Dunes forming scalloped rows of sand
oriented at right angles to the wind.
This form is intermediate between
isolated barchans and extensive
waves of transverse dunes.
Barchanoid dunes
A low, elongated
ridge of sand that parallels the coast.
Barrier island
A mechanism of glacial
movement in which the ice mass
slides over the surface below
Basal slip
An aphanitic igneous rock
of mafic composition.
Basalt
Term used to describe
igneous rocks that contain abundant
dark (ferromagnesian) minerals and
about 50 percent silica.
Basaltic
The level below which
a stream cannot erode
Base level
A circular downfolded
structure.
Basin
A large mass of igneous
rock that formed when magma was
emplaced at depth, crystallized, and
was subsequently exposed by
erosion.
Batholith
A sandbar that
completely crosses a bay, sealing it
off from the main body of water
Baymouth bar
An accumulation of
sediment found along the landward
margin of the ocean or a lake
Beach
The transport of
sediment in a zigzag pattern along a
beach. It is caused by the uprush of water from obliquely breaking
waves.
Beach drift
The wet, sloping
surface that extends from the berm
to the shoreline
Beach face
Large quantities of sand are added to the
beach system to offset losses caused
by wave erosion. By building
beaches seaward, beach quality and
storm protection are both improved.
Beach nourishment
Sediment rolled along
the bottom of a stream by moving
water, or particles rubbed along the
ground surface by wind.
Bed load
A nearly flat
surface separating two beds of
sedimentary rock. Each bedding
plane marks the end of one deposit
and the beginning of another having
different characteristics.
Bedding plane
A general term for the
rock that underlies soil or other
unconsolidated surface materials.
Bedrock
A zone in
which water is held as a film on the
surface of soil particles and may be
used by plants or withdrawn by
evaporation. The uppermost
subdivision of the zone of aeration
Belt of soil moisture
The dry, gently sloping zone
on the backshore of a beach at the
foot of the coastal cliffs or dunes
Berm
Describing a type of
chemical sediment that forms when
material dissolved in water is
precipitated by water-dwelling
organisms. Shells are common
examples.
Biochemical
Seafloor
sediments consisting of material of
marine-organic origin.
Biogenous sediment
The most
common form of coal, often called
soft, black coal.
Bituminous coal
Lava having a surface
of angular blocks associated with
material having andesitic and
rhyolitic compositions.
Block lava
A depression excavated by wind in
easily eroded materials.
Blowout (deflation hollow)
A seismic wave that
travels through Earth’s interior
Body wave
A layer of fine sediment deposited beyond the
advancing edge of a delta and then
buried by continuous delta growth.
Bottomset bed
A concept proposed by N. L. Bowen
that illustrates the relationship
between magma and the minerals
crystallizing from it during the
formation of igneous rock.
Bowen’s reaction series
A stream consisting of numerous intertwining
channels.
Braided stream
A structure protecting a nearshore area from
breaking waves.
Breakwater
A sedimentary rock
composed of angular fragments that
were lithified.
Breccia
Deformation
that involves the fracturing of rock.
Associated with rocks near the
surface.
Brittle deformation
Lowgrade metamorphism that occurs in the lowest layers of very thick accumulations of sedimentary strata.
Burial metamorphism
A large depression
typically caused by collapse of the
summit area of a volcano following
a violent eruption.
Caldera
A hard layer, rich in
calcium carbonate, that forms
beneath the B horizon in soils of arid
regions.
Caliche
Wastage of a glacier that
occurs when large pieces of ice
break off into water.
Calving
A necessary part of
an oil trap, the _____ is
impermeable and hence keeps
upwardly mobile oil and gas from
escaping at the surface.
Cap rock
The total amount of
sediment a stream is able to
transport
Capacity
A relatively
narrow zone at the base of the zone
of aeration. Here water rises from
the water table in tiny threadlike
openings between grains of soil or
sediment
Capillary fringe
The concept that
Earth was shaped by catastrophic
events of a short-term nature.
Catastrophism
A naturally formed
underground chamber or series of
chambers most commonly
produced by solution activity in
limestone.
Cavern
One way in which
sedimentary rocks are lithified. As
material precipitates from water that
percolates through the sediment,
open spaces are filled and particles
are joined into a solid mass.
Cementation
A time span on the
geologic time scale beginning about
65.5 million years ago following the
Mesozoic era.
Cenozoic era
A strong attractive force that exists between
atoms in a substance. It involves the
transfer or sharing of electrons that
allows each atom to attain a full
valence shell.
Chemical bond
Sedimentary rock consisting of
material that was precipitated from
water by either inorganic or organic
means.
Chemical sedimentary rock
The processes by which the internal
structure of a mineral is altered by
the removal and/or addition of
elements.
Chemical weathering
A rather small
volcano built primarily of pyroclastics
ejected from a single vent.
Cinder cone
An amphitheater-shaped
basin at the head of a glaciated
valley produced by frost wedging
and plucking.
Cirque
A sedimentary rock
texture consisting of broken
fragments of preexisting rock.
Clastic
The tendency of a
mineral to break along planes of
weak bonding.
Cleavage
Because the atmosphere is a
complex interactive physical system,
several different outcomes may
result when one of the system’s
elements is altered. These various
possibilities are called _________
Climate feedback mechanism
The exchanges of
energy and moisture occurring
among the atmosphere,
hydrosphere, geosphere, biosphere,
and cryosphere.
Climate system
A strip of land that
extends inland from the coastline
as far as ocean-related features can
be found.
Coast
The coast’s seaward
edge; the landward limit of the effect
of the highest storm waves on the
shore.
Coastline
A pass between mountain
valleys where the headwalls of two
cirques intersect.
Col
A phenomenon of light by
which otherwise identical objects
may be differentiated.
Color
A feature found in caves
that is formed when a stalactite and
stalagmite join.
Column
A pattern of
cracks that forms during cooling of
molten rock to generate columns
Columnar joints
A type of
lithification in which the weight of
overlying material compresses more
deeply buried sediment. It is most
important in fine-grained
sedimentary rocks such as shale
Compaction
A measure of the
largest particle a stream can transport;
a factor dependent on velocity.
Competence
A volcano
composed of both lava flows and
pyroclastic material.
Composite Cone
Mountains in which great horizontal
forces have shortened and
thickened the crust. Most major
mountain belts are of this type.
Compressional Mountains
A term used to
describe intrusive igneous masses
that form parallel to the bedding of
the surrounding rock.
Concordant
A pipelike opening
through which magma moves
toward Earth’s surface. It terminates
at a surface opening called a vent.
Conduit
An aquifer that
has impermeable layers (aquitards)
both above and below.
An aquifer that
has impermeable layers (aquitards)
both above and below.
A coneshaped
depression immediately
surrounding a well.
Cone of depression
Rock layers
that were deposited without
interruption.
Conformable layers
A sedimentary
rock consisting of rounded,
gravel-size particles.
Conglomerate
Changes in rock caused by the heat
of a nearby magma body.
Contact Metamorphism
A hypothesis,credited largely to Alfred Wegener,
that suggested all present continents
once existed as a single
supercontinent.
Continental Drift
A linear zone
along which continental lithosphere
stretches and pulls apart. Its creation
may mark the beginning of a new
ocean basin.
Continental rift
The gently
sloping surface at the base of the
continental slope.
Continental Rise
The gently
sloping submerged portion of the
continental margin, extending from
the shoreline to the continental
slope
Continental shelf
The steep
gradient that leads to the deepocean
floor and marks the seaward
edge of the continental shelf.
Continental slope
Mountains formed in part by
igneous activity associated with the
subduction of oceanic lithosphere
beneath a continent. Examples
include the Andes and the
Cascades.
Continental volcanic arc
A boundary in which two plates move
together, resulting in oceanic
lithosphere being thrust beneath an
overriding plate, eventually to be
reabsorbed into the mantle.
Convergent plate boundary
Located beneath the mantle,
it is Earth’s innermost layer. The
core is divided into an outer core
and an inner core.
Core
Establishing the
equivalence of rocks of similar age
in different areas.
Correlation
A chemical bond produced by the sharing of
electrons.
Covalent bond
The depression at the
summit of a volcano, or that which
is produced by a meteorite impact
Crater
That part of the continental
crust that has attained stability; that
is, it has not been affected by
significant tectonic activity during the
Phanerozoic eon. It consists of the
shield and stable platform.
Craton
The slow downhill
movement of soil and regolith.
Creep
A deep crack in the
brittle surface of a glacier.
Crevasse
Structure in which
relatively thin layers are inclined at
an angle to the main bedding.
Formed by currents of wind or water.
Cross-bedding
A principle of
relative dating. A rock or fault is
younger than any rock (or fault)
through which it cuts.
Cross-cutting
The very thin, outermost
layer of Earth
Crust
An orderly arrangement
of atoms
Crystal
The formation
and growth of a crystalline solid
from a liquid or gas
Crystallization
The temperature
above which a material loses its
magnetization.
Curie point
The area of active
erosion on the outside of a meander.
Cut bank
A short channel segment
created when a river erodes through
the narrow neck of land between
meanders.
Cutoff
Silicate minerals
containing ions of iron and/or
magnesium in their structure. They
are dark in color and have a higher
specific gravity than
nonferromagnesian silicates.
Dark silicate
An isotope resulting from radioactive decay.
Daughter product
A relatively rapid
type of mass wasting that involves a
flow of soil and regolith containing a
large amount of water; also called
mudflows.
Debris flow
Melting that occurs as rock ascends due to a
drop in confining pressure
Decompression melting
An earthquake focus at a depth of more
than 300 kilometers.
Deep-focus earthquake
The portion of
seafloor that lies between the
continental margin and the oceanic
ridge system. This region comprises
almost 30 percent of Earth’s surface.
Deep-ocean basin
The lifting and removal
of loose material by wind.
Deflation
General term for
the processes of folding, faulting,
shearing, compression, or extension
of rocks as the result of various
natural forces
Deformation
An accumulation of
sediment formed where a stream
enters a lake or ocean
Delta
A stream system that resembles the
pattern of a branching tree.
Dendritic drainage pattern
The weight per unit
volume of a particular material.
Density
One of the two types of
dry climate; the drier of the dry
climates.
Desert
A layer of coarse pebbles and gravel created when wind removes the finer
material.
Desert pavement
A low-angle
fault that represents a major
boundary between unfaulted rocks
below that exhibit ductile
deformation and rocks above that
exhibit brittle deformation via
faulting.
Detachment fault
Rocks that form from the accumulation of
materials that originate and are
transported as solid particles derived
from both mechanical and chemical
weathering.
Detrital sedimentary rocks
A collective term for
all the chemical, physical, and
biological changes that take place
after sediments are deposited and
during and after lithification.
Diagenesis
A tabular-shaped intrusive
igneous feature that cuts through
the surrounding rock.
Dike
The angle at which a rock
layer is inclined from the horizontal.
The direction of dip is at a right
angle to the strike.
Dip
A fault in which
the movement is parallel to the dip
of the fault.
Dip-slip fault
The quantity of water in a stream that passes a given point
in a given period of time.
Discharge
A type of unconformity in which the beds
above and below are parallel
Disconformity
A sudden change
with depth in one or more of the
physical properties of the material
making up Earth’s interior
Discontinuity
The boundary between two dissimilar
materials in Earth’s interior as
determined by the behavior of
seismic waves.
A term used to
describe plutons that cut across
existing rock structures, such as
bedding planes.
Discordant
Any economic mineral deposit in which
the desired mineral occurs as
scattered particles in the rock but in
sufficient quantity to make the
deposit an ore.
Disseminated deposit
The portion of a
stream’s load carried in solution.
Dissolved load
A section of a stream
that leaves the main flow.
Distributary
A tide characterized
by a single high and low water
height each tidal day.
Diurnal tide
A boundary in which two plates move
apart, resulting in upwelling of
material from the mantle to create
new seafloor.
Divergent plate boundary
An imaginary line that
separates the drainage of two
streams; often found along a ridge.
Divide
A roughly circular,
upfolded structure.
Dome
The land area
that contributes water to a stream.
Drainage basin
The difference in
height between the bottom of a cone
of depression and the original height
of the water table.
Drawdown
A streamlined
asymmetrical hill composed of
glacial till. The steep side of the hill
faces the direction from which the
ice advanced.
Drumlin
A climate in which
the yearly precipitation is less than
the potential loss of water by
evaporation.
Dry Climate
A type of
solid-state flow that produces a
change in the size and shape of a
rock body without fracturing.
Occurs at depths where temperatures and confining
pressures are high.
Ductile deformation
A hill or ridge of
wind-deposited sand.
Dune
The downslope
movement of water-saturated,
clay-rich sediment, most
characteristic of humid regions
Earthflow
The vibration of
Earth produced by the rapid release
of energy.
Earthquake
An instrument
used to determine the depth of
water by measuring the time
interval between emission of a
sound signal and the return of its
echo from the bottom.
Echo sounder
Nonpermanent deformation in
which rock returns to its original
shape when the stress is released.
Elastic deformation
The sudden
release of stored strain in rocks that
results in movement along a fault
Elastic rebound
The washing out of
fine soil components from the A
horizon by downward-percolating
water.
Eluviation
A coast where
land formerly below the sea level
has been exposed by either crustal
uplift or a drop in sea level or both.
Emergent coast
A ridge of till
marking a former position of the
front of the glacier.
End moraine
Spherically shaped
negatively charged zones that
surround the nucleus of an atom
Energy levels
The largest time unit on the
geologic time scale, next in order of
magnitude above era.
Eon
The location on Earth’s
surface that lies directly above the
focus of an earthquake.
Epicenter
A unit of the geological
time scale that is a subdivision of a
period.
Epoch
A major division on the
geologic time scale; are divided
into shorter units called periods.
Eras
The incorporation and
transportation of material by a
mobile agent, such as water, wind,
or ice.
Erosion
Buoyant plumes of hot ash-laden gases that
can extend thousands of meters into
the atmosphere
Eruption column
Sinuous ridge composed
largely of sand gravel deposited
by a stream flowing in a tunnel
beneath a glacier near its
terminus.
Esker
A partially enclosed
coastal water body that is connected
to the ocean. Salinity here is
measurably reduced by the
freshwater flow of rivers.
Estuary
Organisms whose
genetic material is enclosed in a
nucleus. Plants, animals, and fungi
are eukaryotes.
Eukaryotes
A sedimentary rock
formed of material deposited from
solution by evaporation of water
Evaporite
The combined effect of evaporation and
transpiration.
Evapotranspiration
Large, dome-shaped structure, usually
composed of granite, formed by
sheeting.
Exfoliation dome
A permanent stream that traverses a desert and
has its source in well-watered areas
outside the desert.
Exotic stream
Process such as weathering, mass wasting, or
erosion that is powered by the Sun
and transforms solid rock into
sediment.
External process
Igneous activity that
occurs at Earth’s surface.
Extrusive
A zone of scattered clouds
and calm averaging about 20
kilometers in diameter at the center
of a hurricane.
Eye
A doughnut-shaped area
of intense cumulonimbus
(thunderstorm) development and
very strong winds that surrounds
the eye of a hurricane.
Eye wall
A type of movement
common to mass-wasting processes
that refers to the free falling of
detached individual pieces of any
size.
Fall
A break in a rock mass
along which movement has
occurred.
Fault
Slow, gradual
displacement along a fault that
occurs relatively smoothly and with
little noticeable seismic activity.
Fault creep
A cliff created by
movement along a fault. It
represents the exposed surface of
the fault prior to modification by
weathering and erosion.
Fault scarp
A mountain formed by the
displacement of rock along a fault.
Fault-block mountain
A term derived from
feldspar and silica (quartz). It is a
term used to describe granitic
igneous rocks.
Felsic
The distance that the wind
has traveled across the open water.
Fetch
A steep-sided inlet of the
sea formed when a glacial trough
was partially submerged.
Fiord
A crack in rock along
which there is a distinct separation.
Fissure
