GEOL225 Exam 3
volatiles
gaseous components of magma dissolved in the melt; readily vaporize (from a gas) at surface pressures
lava
magma that reaches Earth's surface
continental volcanic arc
mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent; examples include the Andes and the Cascades
lahar
mudflows on the slopes of volcanoes that result when unstable layers of ash and debris become saturated and flow downslope, usually following stream channels
gypsum
nonsilicate mineral commonly found in sedimentary rocks used to manufacture and similar building materials
fragmental texture
pyroclastic texture
metaphoric rock
rock formed by the alteration of preexisting rock deep within Earth (but still in the solid state) by heat, pressure, and/or chemically active fluids
detrital sedimentary rock
rock formed from the accumulation of material that originated and was transported in the form of solid particles derived from both mechanical and chemical weathering
fissure
a crack in rock along which there is a distinct separation
Modified Mercalli Intensity Scale
a 12-point scale developed to evaluate earthquake intensity based on the amount of damage to various structures
augite
a black, opaque silicate mineral of the pyroxene group that is a dominate component of basalt
magma
a body of molten rock found at depth, including any dissolved gasses and crystals
convergent plate boundaries
a boundary in which two plates move together, causing one of the slabs of lithosphere to be consumed into the mantle as it descends beneath an overriding plate
transform plate boundary
a boundary in which two plates slide past one another without creating or destroying lithosphere; also called a transform fault or transform boundary
fault
a break in a rock mass along which movement has occurred
shield volcano
a broad, gently sloping volcano built from fluid basaltic lavas
eruption column
a buoyant plume of hot, ash-laden gases that, can extend thousands of meters into the atmosphere
island arc
a chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another
volcanic island arc
a chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another; also known simply as an island arc
hot-spot track
a chain of volcanic structures produced as a lithospheric plate moves over a mantle plume
magnetic reversal
a change in the polarity of Earth's magnetic field that occurs over time intervals of roughly 200,000 years
ionic bond
a chemical bond between two oppositely charged ions formed by the transfer of valence electrons from one atom to the other
covalent bond
a chemical bond produced by the sharing of electrons
metallic bonds
a chemical bond that is present in all metals that may be characterized as an extreme type of electron sharing in which the electrons move freely from atom to atom
limestone
a chemical sedimentary rock composed chiefly of calcite; can form by inorganic means or from biochemical processes
coquina
a coarse rock composed of loosely cemented shells and shell fragments
granite
a coarse-grained, igneous rock of approximately 10-20 percent quartz and 50 percent potassium feldspar that forms where large masses of magma solidify at depth; used as a building material
diorite
a coarse-grained, intrusive igneous rock primarily composed of plagioclase feldspar and amphibole minerals
lithospheric plates
a coherent unit of Earth's rigid outer layer that includes the crust and uppermost mantle; also known as a tectonic plate
muscovite
a common member of the mica family of minerals, with excellent cleavage
basaltic composition
a compositional group of igneous rocks in which the rock contains substantial dark silicate minerals and calcium-rich plagioclase feldspar
granitic composition
a compositional group of igneous rocks in which the rock is made up almost entirely of light-colored silicates
andesitic composition
a compositional group of igneous rocks, in which the rock contains at least 25 percent dark silicate minerals; the other dominate mineral is plagioclase feldspar
hot spot
a concentration of heat in the mantle that is capable of producing magma, which in turn extrudes onto Earth's surface; the intraplate volcanism that produced the Hawaiian islands is one example
Bowen's reaction series
a concept proposed by N.L. Bowen that illustrates the relationships between magma and the minerals crystallizing from it during the formation of igneous rocks
vent
a conduit that connects a magma chamber to a volcanic crater
volcanic cone
a cone-shaped structure built by successive eruptions of lava and/or pyroclastic materials
rock
a consolidated mixture of minerals
phenocrysts
a conspicuously large crystal embedded in a matrix of finer-grained crystals
oceanic ridge system
a continuous elevated zone on the floor of all the major ocean basins and varying in width from 500 to 5000 kilometers (300-3000 miles); the rifts at the crests of ridges represent divergent plate boundaries
hornblende
a dark green to black mineral of the amphibole group, often found in igneous rocks
garnet
a dark silicate mineral with a glassy luster, lacking cleavage and of varying colors; can be used as a gemstone
biotite
a dark, iron-rich mineral and a member of the mica family with excellent cleavage
gabbro
a dark-green to black intrusive igneous rock composed of dark silicate minerals; makes up a significant percentage of oceanic crust
orderly crystalline structure
a definite chemical composition in which the atoms are arranged in an orderly pattern
solid substance
a family of materials which have a range of compositions and a single crystal structure
basalt
a fine-grained igneous rock of mafic composition
siltstone
a fine-grained sedimentary rock composed of clay-sized sediment mixed with silt-sized grain
seismic wave
a form of elastic energy released during an earthquake that causes vibrations in the materials that transmit them
travertine
a form of limestone (CaCO3) that is deposited by hot springs or as a cave deposit
andesite
a gray, fine-grained igneous rock, primarily of volcanic origin and commonly exhibiting a porphyritic texture
clay minerals
a group of light-colored silicates that typically form as products of chemical weathering of igneous rocks; major components of soil and sedimentary rocks
quartzite
a hard metamorphic rock formed from quartz sandstone
olivine
a high temperature, dark silicate mineral typically found in basalt
nuee ardente
a highly heated mixture, largely of ash and pumice fragments, travelling down the flanks of a volcano or along the surface of the ground
pyroclastic flow
a highly heated mixture, largely of ash and pumice fragments, travelling down the flanks of a volcano or along the surface of the ground
calderas
a large depression typically caused by collapse or ejection of the summit area of a volcano
supercontinent
a large landmass that contains all, or nearly all, of the existing continents
exfoliation dome
a large, dome-shaped structure, usually composed of granite, formed by sheeting
pahoehoe flow
a lava flow with a smooth-to-ropey surface
outer core
a layer beneath the mantle that is about 2200 kilometers (1364 miles) thick and has the properties of a liquid
pumice
a light-colored, glassy vesicular rock that commonly has a granite composition
continental rift
a linear zone along which continental lithosphere stretches and pulls apart; its creation may mark the beginning of a new ocean basin
fracture zone
a linear zone of irregular topography on the deep-ocean floor that follows transform faults and their inactive extensions
subduction zones
a long, narrow zone where one lithosphere plate descends beneath another
reverse polarity
a magnetic field opposite that which exists at present
normal polarity
a magnetic field that is the same as that which exists at present
transform fault
a major strike-slip fault that cuts through the lithosphere and accommodates motion between two plates; also called a transform plate boundary
viscosity
a measure of a fluid's resistance to flow
intensity
a measure of the degree of earthquake shaking at a given locale, based on the amount of damage
sheeting
a mechanical weathering process that is characterized by the splitting off of slab like sheets of rock
slab pull
a mechanism that contributes to plate motion in which cool, dense oceanic crust sinks into the mantle and "pulls" the trailing lithosphere along
ridge push
a mechanism that may contribute to plate motion; it involves the oceanic lithosphere sliding down the oceanic ridge under the pull of gravity
phyllite
a metamorphic rock composed mainly of fine crystals of muscovite, chlorite, or both
nonsilicate
a mineral group that lacks silicas in their mineral structures; accounts for less than 10 percent of Earth's crust
economic minerals
a mineral used extensively in the manufacture of products
rock cycle
a model that illustrates the origin of the three basic rock types and the interrelatedness of Earth materials and processes
moment magnitude
a more precise measure of earthquake magnitude than the Richter scale that is derived from the amount of displacement that occurs along a fault zone
deep-ocean trenches
a narrow, elongated depression on the floor of the ocean
mineral
a naturally occurring, inorganic crystalline material that has a unique chemical composition
electrons
a negatively charged subatomic particle that has a negligible mass and is found outside an atom's nucleus
liquefaction
a phenomenon, sometimes associated with earthquakes, in which soils and other unconsolidated materials containing abundant water are turned into a fluidlike mass that is not capable of supporting buildings
conduit
a pipelike opening through which magma moves toward Earth's surface; it terminates at a surface opening called a vent
protons
a positively charged subatomic particle found in the nucleus of an atom
inertia
a property by which objects at rest tend to remain at rest, and objects in motion tend to stay in motion unless either is acted upon by an outside force
Pangaea
a proposed supercontinent that 200 million years ago began to break apart and form the present landmasses
tsunami
a rapidly moving ocean wave generated by earthquake activity that is capable of inflicting heavy damage in coastal regions
cinder cone
a rather small volcano built primarily of pyroclastics ejected from a single vent
scoria cone
a rather small volcano built primarily of pyroclastics ejected from a single vent
seismograms
a record made by a seismograph
rift valley
a region of Earth's crust along which divergence is taking place
divergent plate boundaries
a region where the rigid plates are moving apart, typified by the mid-ocean ridges
spreading center
a region where the rigid plates are moving apart, typified by the mid-ocean ridges
plagioclase feldspar
a relatively hard light silicate mineral containing both sodium and calcium ions that freely substitute for one another depending on the crystallization environment
igneous rock
a rock formed by the crystallization of molten magma
octet rule
a rule which states that atoms combine in order that each may have the electron arrangement of a noble gas--that is, so the outer energy level contains eight neutrons
Richter scale
a scale of earthquake magnitude based on the motion of a seismograph
breccia
a sedimentary rock composed of angular fragments that were lithified
biochemical sedimentary rock
a sedimentary rock composed of material that was extracted from water by organisms to create hard parts such as shells
conglomerate
a sedimentary rock composed of rounded, gravel size particles
coal
a sedimentary rock consisting primarily of organic, matter, formed in stages from accumulations of large quantities of undecayed plant material; used as a fossil fuel
evaporite deposit
a sedimentary rock formed of material deposited from solution by evaporation of the water
S waves
a seismic wave that involves oscillation perpendicular to the direction of propagation
secondary waves
a seismic wave that involves oscillation perpendicular to the direction of propagation
magnetometer
a sensitive instrument used to measure the intensity of Earth's magnetic field
Mohs scale
a series of 10 minerals used as a standard in determining mineral hardness
dark silicate minerals
a silicate mineral that contains ions of iron and/ or magnesium in its structure; it is dark in color and has a higher specific gravity than a light silicate mineral
light silicate minerals
a silicate mineral that lacks iron and/or magnesium; it is generally lighter in color and has a lower specific gravity than a dark silicate mineral
marble
a soft metamorphic rock formed from limestone or dolostone; various colors are used for building stones and monuments
chemical bond
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
silicon-oxygen tetrahedron
a structure composed of four oxygen atoms surrounding a silicon atom that constitutes the basic building block of silicate minerals
neutrons
a subatomic particle found in the nucleus of an atom; is electronically neutral and has a mass approximately that of a proton
asthenosphere
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
chemical compounds
a substance formed by the chemical combination of two or more elements in definite proportions and usually having properties different from those of its constituent elements
vesicular texture
a term applied to fine-grained igneous rocks that contain many small cavities called vesicles, which are openings on the outer portion of a lava flow that were created by escaping gasses
glassy texture
a term used to describe the texture of certain igneous rocks, such as obsidian, that contain no crystals
fine-grained texture
a texture of igneous rocks in which the crystals are too small for individual minerals to be distinguished with the unaided eye
foliation
a texture of metamorphic rocks that gives the rock a linear or layered appearance
continental drift
a theory which originally proposed that the continents are rafted about; it has essentially been replaced by the plate tectonics theory
lava tubes
a tunnel in hardened lava that acts as a horizontal conduit for lava flowing from a volcanic vent; allow fluid lavas to advance great distances
aa flow
a type of lava flow that has a jagged, blocky surface
compaction
a type of lithification in which the weight of overlying material compresses more deeply buried sediment; it is most important in the fine-grained sedimentary rocks such as shale
P waves
a type of seismic wave that involves alternating compression and expansion of the material through which it passes
primary waves
a type of seismic wave that involves alternating compression and expansion of the material through which it passes
fumaroles
a vent in a volcanic area from which fumes or gases escape
slate
a very fine-grained metamorphic rock containing platy minerals and having excellent rock cleavage
parasitic cones
a volcanic cone that forms on the flank of a larger volcano
obsidian
a volcanic glass of felsic composition
composite volcano
a volcano composed of both lava flows and pyroclastic material
stratovolcano
a volcano composed of both lava flows and pyroclastic material
carbonic acid
a weak acid formed when carbon dioxide is dissolved in water; it plays an important role in chemical weathering
sandstone
an abundant, durable sedimentary rock primarily composed of sand-size grains
potassium felspar
an abundant, relatively hard light silicate mineral containing potassium ions in its structure
periodic table
an arrangement of the elements in which atomic number increases from the left to right and elements with similar properties appear in columns called families or groups
ions
an atom or molecule that possesses an electrical charge
peridotite
an igneous rock of ultramafic composition thought to be abundant in the upper mantle
coarse-grained texture
an igneous rock texture in which the crystals are roughly equal in size and large enough that individual minerals can be identified with the unaided eye
pyroclastic texture
an igneous rock texture resulting from the consolidation of individual rock fragments that are ejected during a violent eruption
porphyritic texture
an igneous texture consisting of large crystals embedded in a matrix of much smaller crystals
seismographs
an instrument that records earthquake waves
seismometers
an instrument that records earthquake waves
seamount
an isolated volcanic peak that rises at least 1000 meters (3000 feet) above the deep-ocean floor
color
an obvious mineral characteristic that is often unreliable as a diagnostic property
intermediate composition
andesitic composition
fracture
any break or rupture in rock along which no appreciable movement has taken place
silicates
any one of numerous minerals that have the silicon-oxygen tetrahedron as their basic structure
mafic
basaltic composition
pillow lavas
basaltic lava that solidifies in an underwater environment and develops a structure that resembles a pile of pillows
calcite
calcium carbonate (CaCO3), one of the two most common carbonate minerals
dolomite
calcium/magnesium carbonate, CaMg(CO3)2, one of the two most common carbonate minerals
contact metamorphism
changes in rock caused by the heat from a nearby magma body; also known as thermal metamorphism
tenacity
describes a mineral's toughness or resistance to breaking or deforming
nonfoliated
descriptive term for metamorphic rocks that do not exhibit foliation
volcanic rock
extrusive rocks
differential stress
forces that are unequal in different directions
fault creep
gradual displacement along a fault; such activity occurs relatively smoothly and with little noticeable seismic activity
felsic
granite composition
extrusive rock
igneous rock formed when magma solidifies at Earth's surface
intrusive rock
igneous rock that formed below Earth's surface
magnitude
in seismology, the total amount of energy released during an earthquake
plutonic rock
intrusive rocks
generally inorganic
involving neither organic life nor the products created from or by organic life
longer wavelengths have _________ pressure than shorter wavelengths
less
humid air is ________ than dry air
less dense
As one ascends through the atmosphere what is happening to pressure
less pressure (decreases)
gneiss
medium- to coarse-grained banded metamorphic rocks in which granular and elongated minerals dominate
schists
medium- to coarse-grained metamorphic rocks having a foliated texture, in which platy minerals dominateme
regional metamorphism
metamorphism associated with large-scale mountain-building processes
definite chemical composition that allows for some variation
mineral
halite
mineral name for common table salt (NaCl); a nonsilicate mineral commonly found in sedimentary rocks
naturally occurring
minerals are found and made in nature, not laboratories
plates
one of numerous rigid sections of the lithosphere that move as a unit over the material of the asthenosphere; also called lithosphere plate, tectonic plate
rock-forming minerals
one of the few dozen most abundant minerals that make up most common rocks; minerals rich in oxygen and silicon (silicate minerals) dominate this group
cementation
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
strata
parallel layers of sedimentary rock
sedimentary rock
rock formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified
chemical sedimentary rock
sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means
surface waves
seismic waves that travel along the outer layer of Earth
body waves
seismic waves that travel through Earth's interior
beds
strata
confining pressure
stress that is applied uniformly in all directions
mantle plume
structures that originate at great depth and, upon reaching the crust, spread laterally, creating a localized volcanic zone called a hot spot; a source of some intraplate basaltic magma
ultramafic
term for igneous rocks that consist mostly of olivine and pyroxene
theory of plate tectonics
tested theory proposing that Earth's outer shell consists of individual plates that interact in various ways and thereby produce earthquakes, volcanoes, mountains and the crust itself
mantle
the 2900-kilometer- (1800-mile-) thick layer of Earth located below the crust
luster
the appearance or quality of light reflected from the surface of a mineral
metamorphism
the changes in mineral composition and texture of a rock subjected to high temperatures and pressures within Earth
streak
the color of a mineral in powdered form
habit
the common or characteristic shape of a crystal or aggregate of crystals; also known as crystal shape
crystal shape
the common or characteristic shape of a crystal or aggregate of crystals; also known as habit
crater
the depression at the summit of a volcano, or a depression that is produced by a meteorite impact
crystal settling
the downward movement of minerals during the crystallization of magma; the earlier-formed minerals are denser than the liquid portion and settle to the bottom of the magma chamber
valence electrons
the electrons involved in the bonding process; the electrons occupying the highest principal energy level of an atom
rhyolite
the fine-grained equivalent of the igneous rock granite, composed primarily of the light-colored silicates
magnetic time scale
the history of magnetic reversals through geologic time
core
the innermost layer of Earth, based on composition; it is thought to be largely an iron-nickel alloy, with minor amounts of oxygen, silicon, and sulfur
epicenter
the location on Earth's surface that lies directly above the forces of an earthquake
groundmass
the matrix of smaller crystals within an igneous rock that has porphyritic texture
frost wedging
the mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices
shale
the most common sedimentary rock, consisting of silt- and clay-size particles
Epicycles were used to explain what
the movement of planets (around Earth)
fossil magnetism
the natural remnant magnetism in rock bodies; the permanent magnetization acquired by rock that can be used to determine the location of the magnetic poles and the latitude of the rock at the time it became magnetized
paleomagnetism
the natural remnant magnetism in rock bodies; the permanent magnetization acquired by rock that can be used to determine the location of the magnetic poles and the latitude of the rock at the time it became magnetized
atomic number
the number of protons in the nucleus of an atom
mechanical weathering
the physical disintegration of rock, resulting in smaller fragments
megathrust fault
the plate boundary separating a subducting slab of oceanic lithosphere and the overlying plate
partial melting
the process by which most igneous rocks melt; since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees; if the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results
chemical weathering
the process by which the internal structure of a mineral is altered by the removal and/or addition of elements
magmatic differentiation
the process of generating more than one rock type from a single magma
seafloor spreading
the process of producing new seafloor between two divergent plates
lithification
the process, generally concentration and/or compaction, of converting sediments to solid rock
specific gravity
the ratio of a substance's weight to the weight of an equal volume of water
fossil
the remains or traces of an organism preserved from the geologic past
lithosphere
the rigid outer layer of Earth, including the crust and upper mantle
texture
the size, shape, and distribution of the particles that collectively constitute a rock
atoms
the smallest particle that exists as an element
inner core
the solid innermost layer of Earth, about 1300 kilometers (800 miles) in radius
seismology
the study of earthquakes and seismic waves
mineralogy
the study of minerals
elastic rebound
the sudden release of stored strain in rocks that results in movement along a fault
curie point
the temperature above which a material loses its magnetization
cleavage
the tendency of a mineral to break along planes of weak bonding
convection
the transfer of heat by the movement of a mass or substance; it can take place only in fluids
crust
the very thin outermost layer of Earth
pyroclastic material
the volcanic rock ejected during an eruption, including ash, bombs, and blocks; also called tephra
density
the weight per unit volume of a particular material
circum-pacific belt
the zone of intense seismic activity the encompasses the coastal regions of Chile, Central America, Indonesia, Japan, and Alaska, including the Aleutian islands
hypocenter
the zone within Earth where rock displacement produces an earthquake
focus
the zone within Earth where rock displacement produces and earthquake
sediment
unconsolidated particles created by the weathering and erosion of rock, by chemical precipitation from solution in water, or from the secretions of organisms and transported by water, wind, or glaciers
scoria
vesicular ejecta that is the product of basaltic magma
earthquake
vibration of Earth produced by the rapid release of energy