Geology 101
radiation
(physics) Electromagnetic energy traveling away from a source through a medium or space.
delamination
(plate tectonics) the process by which dense ithospheric mantle separates from the base of a plate and sinks into the mantle.
resonance
(seismology) a situation that arises when earthquake waves of a particular frequency cause particularly large amplitude movements because energy input happens at just the right time.
Hydrocarbon reserve
A known supply of oil and gas held underground
Iceberg
A large block of ice that calves off the front of a glacier and drops into the sea.
Ice stream
A portion of a glacier that travels much more quickly than adjacent portions of the glacier.
Hydro fracturing (fracking)
A process by which drillers generate new fractures or open preexisting ones underground, by pumping a high pressure fluid into a portion of the drill hole, in order to increase the permeability of surrounding hydrocarbon- bearing rocks.
Hydrocarbon generation
A process in which oil shale warms to temperatures of greater than about 90c so kerogen molecules transform into oil and natural gas molecules.
volcano
(1) A vent from which melt from inside the Earth spews out onto the planet's surface; (2) a mountain formed by the accumulation of extrusive volcanic rock.
crater
(1) a circular depression at the top of a volcanic mound; 2. a depression formed by the impact of a meteorite.
chimney
(1) a conduit in a magma chamber in the shape of a long vertical pipe through which magma rises and erupts at the surface; 2. an isolated column of strata in an arid region.
head
(1) the elevation of the water table above a reference horizon; (2) the edge of ice at the origin of a glacier.
zone of accumulation
(1) the layer of regolith in which new minerals precipitate out of water passing through, thus leaving behind a load of fine clay; (2) the area of a glacier in which snowfall adds to the glacier.
sorting
(1) the range of clast sizes in a collection of sediment; (2) the degree to which sediment has been separated by flowing currents into different sized fractions.
cleavage
(1) the tendency of a mineral to break along preferred planes; 2. a type of foliation in low-grade metamorphic rock.
Fahrenheit scale
An English-system measure of temperature in which the differenc between the freezing point 32F and the boiling point 212F is divided into 180 units.
Hydrothermal deposit
An accumulation of ore minerals precipitated from hot water solutions circulating through a magma or through the rocks surrounding an igneous intrusion.
Hydraulic conductivity
The coefficient k in Darcy's law; ___________________ takes into account the permeability of the sediment or rock as well as the fluid's viscosity.
Hydrologic cycle
The continual passage of water from reservoir to reservoir in the earth system.
Earth System
The global interconnecting web of physical and biological phenomena involving the solid Earth, the hydrosphere, and the atmosphere.
Horst
The high block between two grabens
Ma
Millions of years ago (abbreviation)
silica
SIO2
P-waves
Compressional seismic waves that move through the body of the Earth
banded-iron formation
Iron-rich sedimentary layers consisting of alternating gray beds of iron oxide and red beds of iron-rich chert.
parallax method
a trigonometric method used to determine the distance from the Earth to a nearby star.
tropical depression
a tropical storm with winds reaching up to 61 km per hour, such storms develop from tropical disturbances, and may grow to become hurricanes.
channel
a trough dug into the ground surface by flowing water.
canyon
a trough or valley with steeply sloping walls, cut into the land by a stream.
valley
a trough with sloping walls, cut into the land by a stream.
syncline
a trough-shaped fold whose limbs dip toward the hinge.
avalanche
a turbulent cloud of debris mixed with air that rushes down a steep hill slope at high velocity; the debirs can be rock and/ or snow.
columnar jointing
a type of fracturing that yields roughly hexagonal columns of basalt; _______________ form when a dike, sill, or lava flow cools.
compositional banding
a type of metamorphic foliation, found in gneiss, defined by alternating bands of light and dark minerals.
fusion
a type of nuclear reaction during which nuclei collide and bond; ______ occurs in stars and hydrogen bombs.
loam
a type of soil consisting of roughly equal parts of sand, silt, and clay; it tends to be good for growht of crops.
bacteria
a type of tiny prokaryotic single-celled organism
nonconformity
a type of unconformity at which sedimentary rocks overlie basement (older intrusive igneous rocks and or metamorphic rocks.)
atm
a unit of air pressure that approximates the pressure exerted by the atmosphere at sea level.
calorie
a unit of energy approximately equal to 4.2 joules; 1 calorie can raise the temperature of 1 gm of water by 1 C.
V-shaped valley
a valley whose cross-sectional shape resembles the shape of a V; the valley probably has a river running down the point of the v.
alluvium-filled valley
a valley whose floor fills with sediment
batholith
a vast composite, intrusive, igneous rock body up to serveral hundred km long and 100 km wide, formed by the intrusion of numerous plutons in the same region.
continental glacier
a vast sheet of ice that spreads over thousands of square km of continental crust.
reg
a vast stony plain in the desert.
oasis
a verdant region surrounded by desert, occurring ata place where natural springs provide water at the surface.
ion
a version of an atom that has lost or gained electrons, relative to an electrically neutal version, so that it has a net electrical charge.
distillation column
a vertical pipe in which crude oil is separated into several components
soil profile.
a vertical sequence of distinct zones of soil.
earthquake
a vibration caused by the sudden breaking or frictional sliding of rock in the Earth.
mud pot
a viscous slurry that forms in a geothermal region when hot water or stream rises into soils rich in volcanic ash and clay.
tidal bore
a visible wall of water that moves toward shore with the rising tide in quiet waters.
plate-boundary volcano
a volcanic arc or mid-ocean ridge volcano, formed as a conseqauence of movement along a plate boundary.
supervolcano
a volcano that erupts a vast amount (more than 1,000 cubic km) of volcanic material during a single event; none have erupted during recorded human history)
active volcano
a volcano that has erupted within the past few centuries and will likely erupt again.
dormant volcano
a volcano that has not erupted for hundrs to thousands of years but does have the potential to erupt again in the future.
extinct volcano
a volcano that was active in the past but has now shut off entirely and will not erupt in the future.
seawall
a wall of riprap built on the landwad side of a backshore zone
breaker
a water wave in which water at the top of the wave cruves over the base of the wave.
standing water
a wave whose crest and trough remain in place as water moves through the wave.
failure surface
a weak surface that forms the base of a landslide.
delta
a wedge of sediment formed at a river mouth when the running water of the stream enters standing water, the current slows, the stream loses competence, and sediment settles out.
submarine fan
a wedge-shaped accumulation of sediment at the base of a submarine slope; fans usually accumulate at the mouth of a submarine canyon
half-graben
a wedge-shaped basin in cross section that develops as the hanging-wall block above a normal fault slides down and rotates; the basin develops between the fault surface and the top surface of the rotated block.
accretionary prism
a wedge-shaped mass of sediment and rock scraped off the top of a downgoing plate and accreted onto the overriding plate at a convergent plate margin
injection well
a well in which a liquid is pumped down into the ground under pressure so that it passes from the well back into the pore space of the rock or regolith.
artesian well
a well in which water rises on its own.
dry well
a well that does not supply water because the well has been drilled into an aquitard or into rock that lies above the water table; 2. a well that does not yield oil, even though it has been drilled into an anticipated reservoir.
seasonal well
a well that provides water only during the rainy season when the water table rises below the base of the well.
ordinary well
a well whose base penetrates below the water table andcan thus provide water.
current
a well-defined stream of ocean water; 2. the moving flow of water in a stream.
marsh
a wetland dominated by grasses
bog
a wetland dominated by moss and shrubs.
swamp
a wetland dominated by trees.
cirrus cloud
a wispy cloud that tapers into delicate, feather-like curls.
negative anomaly
an area where the magnetic field strength is less than expected
drainage network (basin)
an array of interconnecting streams that together drain an area.
nonflowing artesian well
an artesian well in which water rises on its own up to a level that lies below the ground surface.
fold-thrust belt
an assemblage of folds and related thrust faults that develop above a detachment fault.
cuesta
an asymmetric ridge formed by tilted layers of rock, with a steep cliff on one side cutting across the layers and gentle slope on the other side; the gentle slope is parallel to the layering.
magnetism
an attractive or repulsive field force generated by permanent magnets or y an electrical current.
volcanic agglomerate
an accumulation consisting dominantly of volcanic bombs and other relatively large chunks of igneous materials.
scoria cone
an accumulation of lapilli-sized or larger fragments formed from a volcanic eruption that spatters clots of basaltic lava. (also called cinder cone.)
volcaniclastic deposit
an accumulation of large quantities of fragmental igneous material (including both pyroclsatic debris, and water-transported debris).
sediment
an accumulation of loose mineral grains, such as boulders, pebbles, sand, silt, or mud, that are not cemented together.
felsic
an adjective used in reference to igneous rocks that are rich in elements forming felspar and quartz.
geocentric Universe concept
an ancient Greek idea suggesting that the Earth sat motionless in the center of the Universe while stars and other planets and the Sun orbited around it .
hail streak
an approximately 2-by-10 km stretch of ground, elongate in the direction fo a strom, onto which hail has fallen.
unconfined aquifer
an aquifer that intersects the surface of the Earth.
confined aquifer
an aquifer that is separated from the Earth's surface by an overlying aquitard.
sea arch
an arch of land protruding into the sea and connected to the mainland by a narrow bridge.
debris avalanche
an avalanche in which the falling debris consists of rock fragments and dust.
ash flow
an avalanche of ash that tumbles down the side of an explosively erupting volcano.
modified mercalli scale
an earthquake characterization scale based on the amount of damage that the earthquake cases.
natural arch
an arch that forms when erosion along joints leaves narrow walls of rock; when the lower part of the wall erodes while the upper part remains, an arch results
rocky coast
an area of coast where bedrock rises directly from the sea, so beaches are absent.
ozone hole
an area of the atmosphere, over polar regions, from which ozone has been depleted.
sandspit
an area where the beach stretches out into open water across the mouth of a bay or estuary.
deep-focus earthquake
an earthquake that occurs at a depth between 300 and 670 km; below 670 km, earthquakes do not happen.
ore deposit
an economically significant accumulation of ore
electromagnet
an electrical device that produces a magnetic field.
pause
an elevation in the atmosphere where temperature stops decreasing and starts increasing, or vice versa.
bajada
an elongate wedge of sediment formed by the overlap of several alluvial fans emerging from adjacent valleys.
fossil fuel
an energy resource such as oil or coal that comes from organisms that lived long ago and thus stores solar energy that reached the Earth then.
ecosystem
an environment and its inhabitants.
storm
an episode of severe weather in which winds, precipitation, and in some cases lightening become strong enough to be bothersome and even dangerous.
summit eruption
an eruption that occurs in the summit crater of a volcano.
flank eruption
an eruption that occurs when a secondary chimney, or fissure, breaks through the flank of a volcano.
effusive eruption
an eruption that yields mostly lava, not ash.
spring tide
an especially high tide that occurs when the Sun is on the same side of the Earth as the Moon.
neap tide
an especially low tide that occurs when the angle between the direction of the Moon and the direction of the Sun is 90.
flood
an event during which the volume of water in a stream becomes so great that it overs areas outside the stream's normal channel.
dust storm
an event in which strong winds hit unvegetated land, strip off the topsoil, and send it skyward to formrolling dark clouds that block out the Sun.
epeirogeny
an event of epeirogenic movement; the term is usually used in reference to the formation of braod mid-continent domes and basins.
phreatomagmatic eruption
an explosive eruption that occurs when water enters the magma chamber and turns into steam.
outcrop
an exposure of bedrock
Laurentide ice sheet
an ice sheet that spread over northeastern Canada during the Pleistocene age.
stalactite
an icicle-like cone that grows from the ceiling of a cave as dripping water precipitates limestone.
heliocentric Universe concept
an idea propsoed by Greek philosphers around 250 BCE suggesting that all heavenly objects including the Earth orbited the Sun.
obsidian
an igneous rock consisting of a solid mass of volcanic glass
axis
an imaginary line around which an object spins.
fold axis
an imaginary line that , when moved parallel to itself, can trace out the shape of a folded surface.
galaxy
an immense system of hundreds of billions of stars.
gene
an individual component of the DNA code that guides the growth and development of an organism.
graywacke
an informal term used for sedimentary rock consisting of sand-sized up to small-pebble-sized grains of quartz and rock fragments all mixed together in a muddy matrix; typically, graywacke occurs at the base of a graded bed.
continental-interior desert
an inland desert that develops because by the time air masses reach the continental interior, they have lost all of their moisture.
estuary
an inlet in which seawater and river water mix; created when a coastal valley is flooded because of either rising sea level or land subsidence.
bornhardt
an inselberg with a loaf gemoetry, like that of Uluru (Ayers Rock) in central Australia.
seismometer (seismograph(
an instrument that can recorfd the ground motion from an earthquake.
magnetometer
an instrument that measures the strength of the Earth's magnetic field.
dimension stone
an intact block of granite or marble to be used for architectural purposes.
core-mantle boundary
an interface 2900 km below the Earth's surface separating the mantle and core.
Younger Dryas
an interval of cooler temperatures that took place 4500 years ago during a general warming/glacier-retreat period.
period
an interval of geologic time representing a subdivision of a geologic era.
epoch
an interval of geologic time representing the largest subdivision of a period
era
an interval of geologic time representing the largest subdivision of the Phanerozoic eon.
stratigraphic sequence
an interval of strata deposited during periods of relatively high sea level, and bounded above and below by regional unconformities.
inselberg
an isolated mountain or hill in a desert landscape created by progressive cliff retreat, so that the hill is surounded by a pediment or an alluvial fan.
seamount
an isolated submarine mountain.
sea stack
an isolated tower of land just offshore, disconnected from the mainland by the collapse of a sea arch.
eddy
an isolated, ring-shaped current of water.
star
an object in the Universe in which fusion reactions occur pervasively, producing vast amounts of energy; our Sun is a _____.
planet
an object that orbits a star, is roughly spherical and has cleared its neighborhood of other objects.
deep current
an ocean current at a depth greater than 100m.
barrier island
an offshore sand bar that rises above the mean high-water level, forming an island.
breakwater
an offshore wall, built parallel or at an angle to the beach, that prevents the full force of waves from reaching a harbor.
shield
an older, interior region of a continent.
water gap
an opening in a resistant ridge where a trunk river has cut through the ridge.
wind gap
an opening through a high ridge that developed earlier in geologic history by steam erosion, but that is now dry.
magmatic deposit
an ore deposit formed when sulfide ore minderals accumulate at the bottom ofa magma chamber.
mid-ocean ridge
a 2-km high submarine mountain belt that forms along a divergent oceanic plate boundary
thin section
a 3/100-mm-thick slice of rock that can be examined with a petrographic microscope.
extraordinary fossil
a arare fossilized relict, or trace, of the soft part of an organism.
comet
a ball of ice and dust, probably remaining from the formation of the solar system, that orbits the sun.
P-wave shadow zone
a band between 103 and 143 degrees from an earthquake epicenter, as measured along the circumference of the Earth, inside which P-waves do not arrive at seismograph stations.
S-wave shadow zone
a band between 103 and 180 degrees fom the epicenter of an earthquake inside of which S-waves do not arrive at seismograph stations
channeled scablands
a barren, soil-free landscape in eastern Washington, scoured clean by a flood unleashed when a large glacial lake drained.
local base level
a base level upstream from a drainage network's mouth.
foreland sedimentary basin
a basin located under the plains adjacent to a mountain front, which develops as the weight of the mountains pushes the crust down, creating a depression that traps sediment.
interior basin
a basin with no outlet to the sea.
subtropical high (subtropical divergence zone)
a belt of high pressure in the atmosphere at 30 degrees latitude formed where the Hadley cell converges with the Ferrel cell, causing cool, dense air to sink.
doldrums
a belt with very slow winds along the equator.
fold
a bend or wrinkle of rock layers or foliation; ____ form as a consequence of ductile deformation.
coal
a black, organica rock consisting of greater than 50% carbon; it forms from the buried and altered remains of plant material.
laccolith
a blister-haped igneous intrusion that forms when magma injects between layers undergorund in a manner that pushes overlying layers upward to form a dome.
Waccreted terrane
a block of crust that collided with a continent at a convergent margin and stayed attached to the continent.
exotic terrane
a block of land that collided with a continent along a convergent margin and attached to the continent; the term exotic implies that the land was not originally part of the continent to which it is now attached.
air mass
a body of air, about 1500 km across, that has recognizable physical caracteristics.
lagoon
a body of shallow seawater separted from the open ocean by a barrier island
protoplanet
a body that grows by the accumulation of planetesimals but has not yet become big enough to be called a planet
erratic
a boulder or cobble that was picked up by a glacier and deposited hundreds of kilometers away from the outcrop from which it detached.
transform plate boundary
a boundary at which one lithosphere plate slips laterally past another.
divergent plate boundary
a boundary at which two litosphere plates move apart from each other; they are marked by mid-ocean ridges.
convergent plate boundary
a boundary at which two plates move toward each other so that one plate sinks (subducts) beneath the otehr; only oceanic lithosphere can subduct.
thermocline
a boundary between layers of water with differing temperatures.
unconformity
a boundary between two different rock sequences representing an interval of time during which new strata were not deposited and or were eroded.
seismic-velocity discontinuity
a boundary in the Earth at which seismic velocity changes abruptly.
cirque
a bowl-shaped depression carved by a glacier on the side of a mountain.
outwash plain
a broad area of gravel and sandbars deposited by a braided stream network, fed by the melt water of a glacier.
basin and range province
a broad, cenozoic continental rift that has affected a protion of the western united states in nevada, utah, and Arizona; in this province, tilted fault blocks form ranges, and alluvium-filled valleys are basins.
Canadian Shield
a broad, low-lying region of exposed precambrian rock in the canadian interior.
tidal flat
a broad, nearly horizontal plain of mud and silt, exposed or nearly exposed at low tide but totally submerged at high tide.
abyssal plain
a broad, relatively flat region of the ocean that lies at least 4.5 km below sea level.
continental shelf
a broad, shallowly submerged fringe of a continent; ocean-water depth over the continental shelf is generally less than 200 meters; the widest continental shelves occur over passive margins.
heliosphere
a bubble-like region in space in which solar wind has blown away most interstellar atoms.
organic chemical
a carbon-containing compound that occurs in living organisms, or that resembles such compounds; it consists of carbon atoms bonded to hydrogen atoms along with varyig amounts of oxygen, nitrogen, and other chemicals.
mold
a cavity in sedimentary rock left behind when a shell that once filled the space weathers out.
geode
a cavity in which euhedral crystals precipitate out of water solutions passing through a rock.
eukaryotic cell
a cell with a complex internal structure, capable of building multicellular organisms.
elastic strain
a change in shape of a material; the change disappears instantly when stress is removed.
shear strain
a change in shape of an object that involves the movement of one part of a rock body sideways past another part so that angular relationships within the body change.
deformation
a change in the shape, position, or orientation of a material, by bending, breaking, or flowing.
phylogenetic tree
a chart representing the ideas of paleontologists showing which groups of organisms radiated from which ancestors.
metallic bond
a chemical bond in which the outer atoms are atached to each other in such a way that electrons flow easily atom to atom.
kettle hole
a circular depression in the ground made when a block of ice calves off the toe of a glacier, becomes buried by till, and later melts.
sinkhole
a circular depression in the land that forms when an underground cavern collapses.
Chicxulub crater
a circular excavation buried beneath younger sediment on the Yucatan Peninsula; geologists suggest that a meteorite landed there 65 Ma.
anticyclonic flow
a circulation of air around a high-pressure region in the atmosphere; it rotates clockwise in the northern hemisphere
cyclonic flow
a circulation of air around a low-pressure region in the atmosphere; it rotates counterclockwise in the nortern hemisphere.
arkose
a clastic sedimentary rock containing both quartz and feldspar grains
contaminant plume
a cloud of contaminated groundwater that moves away from the source of the contamination
nebula
a cloud of gas or dust in space.
Oort Cloud
a cloud of icy objects, left over from Solar System formation, that orbit the sun in a region outside of the heliosphere.
fog
a cloud that forms at ground level.
pegmatite
a coarse-grained igneous rock containing crystals of up to tens of centimeters across and occurring in dike-shaped intrusions.
gabbro
a coarse-grained, intrusive, mafic igneous rock.
granite
a coarse-grained, intrusive, silicic igneous rock.
peridotite
a coarsegrained ultramafic rock.
organic coast
a coast along which living organisms control landforms along the shore.
submergent coast
a coast at which the land is sinking relative to sea level.
emergent coast
a coast where the land is rising relative to sea level or sea level is falling relative to the land.
accretionary coast
a coastline that receives more sediment than erodes away
erosional coast
a coastline where sediment is not accumulating and wave action grinds away at the shore.
rock
a coherent, naturally occuring solid, consisting of an aggregate of minerals or a mass of glass.
tundra
a cold, treeless region of land at high latitudes, supporting only species of shrubs, moss, and lichen capable of living on permafrost.
mantle plume
a column of very hot rock rising up throug hthe mantle
earthquake warning system
a communications network that provides an alert within microseconds after the first earthquake waves arrive at a seismograph near the epicenter, but before damaging vibrations reach population centers.
geologic column
a composite stratigraphic chart that represents the entirety of the Earth's history.
gneiss
a compositionally banded metamorphic rock typically composed of alternating dark and light colored layers.
climate-change model
a computer-generated model designed to provide insight into how climate changed in the past and may change in the future, and what the consequences of cimate change may be.
digital elevation map (DEM)
a computer-produced portrayal of elevation differences commonly using shading to simulate shadows; the data used to produce the map assigns elevations to each point on the map.
groin
a concrete or stone wall built perpendicular to a shoreline in order to prevent beach drift from removing sand.
differential stress
a condition causing a material to experience a push or pull in one direction of a greater magnitude than the push or pull in another direction; in some cases, ___________________ can result in shearing.
feedback mechanism
a condition that arises when the consequence of a phenomenon influences the phenomenon itself.
leader
a conductive path stretching from a cloud toward the ground, along which electrons leak from the base of the cloud, and which provides the start for a lightning flash to the ground.
fissure
a conduit in a magma chamber in the shape of a long cack throug hwhich magma rises and erupts at the surface.
star dune
a constantly changing dune formed by frequent shifts in wind direction, it consists of overlapping crescent dunes pointing in many different directions.
Laurentia
a continent in the early Paleozoic Era composed of today's North America and Greenland.
continental margin
a continent's coastline.
passive margin
a continental margin that is not a plate boundary
active continental margin
a continentla margin that coincides witha plate boundary
acadian orgeny
a convergent mountain-building event that occurred around 400 million years ago, during which continental slivers accreted to the eastern edge of the North American continent.
taconic orogeny
a convergent mountain-building event that took place around 400 million years ago, in which a volcanic island arc collided with eastern North America.
nevadan orogeny
a convergent-margin mountain building event that took place in western North america during the Late Jurassic Period
Sonoma orogeny
a convergent-margin mountain building event that took place on the western coast of North America in the Late Permian and Early Triassic periods.
atoll
a coral reef that develops around a circular reef surrounding a lagoon.
barrier reef
a coral reef that develops offshore, separated from the coast by a lagoon.
fringing reef
a coral reef that forms directly along the coast.
lithologic correlation
a correlation based on similarites in rock type.
barchan dune
a crescent-shaped dune whose tips point downwind.
bathymetric profile
a cross section showing ocean depth plotted against location.
stratifigraphic column
a cross-section diagram of a sequence of strata summarizing information about the sequence.
seismic-reflection profile
a cross-sectional view of the crust made by measuring the reflection of artificial seismic waves off boundaries between different layers of rock in the crust.
euhedral crystal
a crystal whose faces are well formed and whose shape reflects crystal form.
volcanic arc
a curving chain of active volcanoes formed adjacent to a convergent plate boundary.
desert varnish
a dark, rusty-brown coating of iron oxide and magnesium oxide that accumulates on the surface of the rock.
solstice
a day on which the polar ends of the terminator (the boundary between the day hemisphere and the night hemisphere) lie 23.5 degrees away from the associated geographic poles.
blowout
a deep, bowl-like depression scoured out of desert terrain by a turbulent vortex of wind.
trench
a deep, elongate trough bordering a volcanic arc, a ______ defines the trace of a convergent plate boundary.
fjord
a deep, glacially, carved, U-shaped valley flooded by rising sea level.
protostar
a dense body of gas that is collapsing inward because of gravitational forces and that may eventually become a star.
sedimentary basin
a depression, created as a consequence of subsidence, that fills with sediment.
ventifact (faceted rock)
a desert rock whose surface has been faceted by the wind.
fossil correlation
a determination of the stratigraphic relation between two sedimentary rock units, reached by studying fossils.
cross section
a diagram depicting the gemoetry of materials underground as they would appear on an imaginary vertical slice through the Earth.
acid mine runoff
a dilute solution of sulfuric acid, produced when sulfur-bearing minerals in mines react with rainwater, that flows out of a mine
convective cell
a distinct flow configuration for a volume of material that is moving during convective heat transport, simplistically, the material rises when warm and sinks when cool, and thus follows a loop-like path.
metamorphic texture
a distinctive arrangement of mineral grains produced by metamorphism
thin-skinned deformation
a distinctive style of deformation characterized by displacement on faults that terminate at depth along a subhorizontal detachment fault.
wave
a disturbance that transmits energy from one point to another in the form of periodic motions.
lava dome
a dome-like mass of rhyolitic lava that accumulates above the eruption vent.
graben
a down-dropped crustal block bounded on either side by a normal fault dipping toward the basin.
avalanche chute
a downslope hillside pathway along which avalanches repeatedly fall, consequently clearing the pathway of mature trees.
debris flow
a downslope movement of mud mixed with larger rock fragments.
mudflow
a downslope movement of mudat slow to moderate speed.
radial network
a drainage network in which the streams flow outward from a cone-shaped mountain and define a pattern resembling spokes on a wheel.
rectangular network
a drainage network in which the streams join each other at right angles because of a rectangular grid of fractures that breaks up the ground and localizes channels.
dendritic network
a drainage network whose interconnecting streams resemble the pattern of branches connecting to a deciduous tree.
trellis network
a drainage system that develops across a landscape of parallel valleys and ridges so that major tributaries flow down the valleys and join a trunk stream that cuts through the ridge; the resulting map pattern resembles a garden trelli.
longitudinal dune
a dune formed when there is a abundant sand and a strong, steady wind, and whose axis lies parallel to the wind direction
metamorphic foliation
a fabric defined by parallel surfaces or layers that develop in a rock as a result of metamorphism; schistocity and gneissic layering are examples.
global cooling
a fall in the average atmospheric temperature
piedmont glacier
a fan or lobe of ice that forms where a valley glacier emerges from a valley and spreads out into the adjacent plain.
pyroclastic flow
a fast-moving avalanche that occurs when hot volcanic ash and debris mix with air and flow down the side of a volcano.
jet stream
a fast-moving current of air that flows at high elevations.
shear zone
a fault in which movement has occurred ductilely.
strike-slip fault
a fault in which one block slides horizontally past another (and therefore parallel to the strike line), so there is no relative vertical motion.
oblique-slip fault
a fault in which sliding occurs diagonally along the fault plane.
dip-slip fault
a fault in which sliding occurs up or down the slope of the fault.
normal fault
a fault in which the hanging wall wblock moves down the slope of the fault.
transform fault
a fault marking a transform plate boundary; along mid-ocean ridges _______________ are the actively slipping segment of a fracture zone between two ridge segments.
blind fault
a fault that does not intersect the ground surface.
active fault
a fault that has moved recently or is likely to move in the future.
sheetwash
a film of water less than a few mm thick that covers the ground surface during heavy rains.
phyllite
a fine-grained metamorphic rock with a foliation caused by the preferred orientation of very fine-grained mica.
basalt
a fine-grained, mafic, igneous rock.
gem
a finished cut and polished gemstone ready to be set in jewelry.
lodgment till
a flat layer oftill smearted out over the ground when a glacier ovverides an end moraine as it advances
coastal wetland
a flat-lying coastal area that floods during high tide and drains during low tide, and hosts salt resistant plants.
floodplain flood
a flood during which a floodplain is submerged
delta-plain flood
a flood in which water submerges a delta plain
flash flood
a flood that occurs during unusally intense rainfall or as the result of a dam collapse, during which the floodwaters rise very fast.
flank flood
a flood that occurs during unusually intense rainfall or as the result of a dam collapse, during which the floodwaters rise very fast.
angiosperm
a flowering plant.
monocline
a fold in the land surface whose shape resemebles that of a carpet draped over a stair step.
basin
a fold or depression shaped like a right-side-up bowl.
drag fold
a fold that develops in layers of rock adjacent to a fault during or just before slip.
flow fold
a fold that forms when the rock is so soft that it behaves like weak plastic.
nonplunging fold
a fold with a horizontal hingee
anticline
a fold with an arch-like shape in which the limbs dip away from the hinge.
speleothem
a formation that grows in a limestone cave by the accumulation of travertine precipitated from water solutions dripped in a cave or flowing down the wall of a cave.
macrofossil
a fossil large enough to be seen with the naked eye.
microfossil
a fossil that can be seen only with a microscope or an electron microscope.
gusher
a fountain of oil formed when underground pressure causes the oil to rise on its own out of a drilled hole..
geyser
a fountain of stream and hot water that erupts periodically from a vent in the ground in a geothermal region.
fault
a fracture on which one body of rock slides past another.
grain
a fragment of a mineral crystal or of a rock.
clast
a fragment or grain produced by the physical or chemical weathering of a pre-existing rock.
warm front
a front in which warm air rises slowly over cooler air in the atmosphere.
occluded front
a front that no longer intersects the ground surface.
substrate
a general term for material just below the ground surface.
thrust fault
a gently dipping reverse fault; the hanging-wall block moves up the slope of the fault.
alluvial fan
a gently sloping apron of sediment dropped by an ephemeral stream at the base of a mountain in arid or semiarid regions.
beach
a gently sloping fringe of sediment along the shore.
oil trap
a geologic configuration that keeps oil underground in the reservoir rock and prevents it from rising to the surface.
external process
a geomorphologic process-such as downslope movement, erosion, or deposition-- that is the consequence of gravity or of the interaction between the solid Earth and its fluid envelope (air and water). Energy for these processes comes from gravity and sunlight.
mineralogist
a geoscientist specializing in the study of minerals
mineral resources
a geoscientist specializing in the study of minerals.
aurora borealis
a ghostly curtain of varicolored light that appears across the night sky in the northern hemisphere when charged particles from the Sun interact with the ions in the ionospere.
lightning bolt
a giant spark or pulse of current that jumps across a gap of charge separation
hanging valley
a glacially carved tributary valley whose floor lies ata higher elevation than the floor of the trunk valley.
roche moutonnee
a glacially eroded hill that becomes elongate in the direction of flow and asymmetric; glacial rasping smoothes the upstream part of the hill into a gentle slope, while glacial
dry-bottom polar glacier
a glacier so cold that its base remains frozen to the substrate.
mountain alpine glacier
a glacier that exists in or adjacent to a mountainous region.
tidewater glacier
a glacier that has entered the sea alog a coast.
wet-bottom (temperate) glacier
a glacier with a thin layer of water at its base, over which the glacier slides.
pumice
a glassy igneous rock that forms from felsic frothy lava and contains abundant, over 50%, pore space.
scoria
a glassy, mafic, igneous rock containing abundant air-filled holes.
eustatic sea-level change
a global rising or falling of the ocean surface.
turbidite
a graded bed of sediment built up at the base of a submarine slope and deposited by turbidity currents
travel-time curve
a graph that plots the time since an earthquake began on the vertical axis and the distance to the epicenter on the horizontal axis.
velocity-versus-depth curve
a graph that shows the variation in the velocity of seismic waves with increasing depth in the Earth.
fossil assemblage
a group of fossil species found in a specific sequence of sedimentary rock
metamorphic mineral assemblage
a group of minerals that form in a rock as a result of metamorphism.
joint set
a group of systematic joints.
fault system
a grouping of numerous related faults.
sedimentary sequence
a grouping of sedimentary units bounded on top and bottom by regional unconformities
laterite soil
a hard, brick red, soil formed from iron-rich rock in a tropical environment; it consists primarily of insoluble iron and aluminum oxide and hydroxide and forms due to extreme leaching.
drainage divide
a highland or ridge that separates one watershed from another.
continental divide
a highland separating drainage that flows into one ocean from drainage that flows into another.
dip slope
a hill slope underlain by bedding parallel to the slope.
well
a hole in the ground dug or drilled in order to obtain wtaer.
soda straw
a hollow stalactite in which calcite precipitates around the outside of a drip.
mineral
a homogenous, naturally occurring, solid inorganic substance with a definable chmical composition and an internal structure characterized by an orderly arrangement of atoms, ions, or molecules in a lattice. Most minerals are inorganic.
berm
a horizontal or landward-sloping terrace in the backshore zone of a beach that receives sediment during a storm.
superplume
a huge mantle plume
red giant
a huge red star that forms when Sun-sized stars start to die and expand.
cornice
a huge, overhanging drift of snow built up by strong winds at the crest of a mountain ridge.
vein deposit
a hydrothermal deposit in which the ore minerals occur in veins that fill cracks in preexisting rocks.
disseminated deposit
a hydrothermal ore deposit in which ore minerals are dispersed throughout a body of rock.
tower karst
a karst landscape in which steep-sided residual bedrock towards remain between sinkholes.
archaea
a kingdom of "old bacteria" now commonly found in extreme environments like hot springs.
electron microprobe
a laboratory instrument that can focus a beam of electrons on a small part of a mineral grain in order to create a signal that defines its chemical composition.
meltwater lake
a lake fed by glacial meltwater
tarn
a lake that forms at the base of a cirque on a glacially eroded mountain.
knob-and-kettle topography
a land surface with many kettle holes separated by round hills of glacial till.
depositional landform
a landform resulting from the deposition of sediment where the medium carrying the sediment evaporates, slows down, or melts.
orographic barrier
a landform that diverts air flow upward or laterally.
erosional landform
a landform that results from the breakdown and removal of rock or sediment.
caldera
a large circular depression with steep walls and a fairly flat floor, formed after an eruption as the center of the volcano collapses into the drained magma chamber below.
Sierran arc
a large continental volcanic arc along western North America that was initiated at the end of the Jurassic Period and lasted until about 80 million years ago.
crevasse
a large crack that develops by brittle deformation in the top 60 m of a glacier
phenocryst
a large crystal surrounded by a finer-grained matrix in an igneous rok.
anvil cloud
a large cumulonimbus cloud that spreads laterally at the tropopause to form a broad, flat top.
volcanic bomb
a large piece of pyroclastic debris thrown into the atmosphere during a volcanic eruption.
lava lake
a large pool of lava produce around a vent when lava fountains spew forth large amounts of lava in a short period of time.
oversized stream valley
a large valley with a small stream running through it; the valley formed earlier when the flow was greater.
tsunami
a large wave along the sea surface triggered by an earthquake or large submarine slump
gyre
a large, circular flow pattern of ocean surface currents.
stratovolcano
a large, cone-shaped subaerial volcano consisting of alternating layers of lava and tephra.
mesa
a large, flat-topped hill (with a surface area of several square km) in an arid region
nor'easter
a large, midlatitude North American cyle; when it reaches the east coast, it produces strong winds that come out of the northeast.
extratropical cyclone
a large, rotating storm system, in mid-latitudes, associated with a regional-scale low-pressure zone.
olistotrome
a large, submarine, slump block, buried and preserved.
a'a
a lava flow with a rubbly surface
pahoehoe
a lava flow with a surface texture of smooth, glassy, ropelike ridges.
atmosphere
a layer of gases that surrounds a planet.
saprolite
a layer of rotten rock created by chemical weathering in warm, wet climates.
graded bed
a layer of sediment, deposited by a turbidity current, in which grain size varies from corase at the bottom to fine at the top.
fission track
a line of damage formed in the crystal lattice of a mineral by the impact of an atomic particle ejected during the decay of a radioactive isotope.
isobar
a line on a map along which the air has a specifed pressure
isograd
a line on a pressure-temperature graph along which all points are taken to be at the same metamorphic grade; (2) a line on a map making the first appearance of a metamorphic index mineral.
continental rift
a linear belt along which continental lithosphere stretches and pulls apart.
orogen (orogenic belt)
a linear range of mountains
oil
a liquid hydrocarbon that can be burned as a fuel
Mohs hardness scale
a list of ten minerals in a sequence of relative hardness, with which other minerals can be compared.
downgoing plate
a lithosphere plate that has been subducted at a covergent margin.
discharge area
a location where groundwater flows back up to the surface and may emerge at springs.
artesian spring
a location where the ground surface intersects a natural fracture (joint) that taps a confined aquifer in whcih the pressure can drive the water to the surface.
recharge area
a location where water enters the ground and infiltrates down to the water table.
snotite
a long gob of bacteria that slowly drips from the ceiling of a cave.
continental volcanic arc
a long, curving chain of subaerial volcanoes on the margin of a continent adjacent to a convergent plate boundary
craton
a long-lived block of durable continentla crust commonly found in the stable interior of a continent.
embayment
a low area of coastal land.
end moraine
a low, sinuous ridge of till that develops when the terminus (toe) of a glacier stalls in one position for a while.
greenstone
a low-grade metamorphic rock formed from basalt; if foliated, the rock is called greenschist.
dipole
a magnetic field with a north and south pole, like that of a bar magnet.
artificial levee
a man-made retaining wall to hold back a river from flooding
jetty
a man-made wall that protects the entrance to a harbor
volcanic danger-assessment map
a map delineating areas that lie in the path of potential lava flows, lahars, debris flows, or pyroclastic flows of an active volcano.
bathymetric map
a map illustrating the shape of the ocean floor.
landslide-potential map
a map on which regions are ranked according to the likelihood that a mass movement will occur.
geologic map
a map showing the distribution of rock units and structures across a region.
topographical map
a map that uses contour lines to represent variations in elevation
floodway
a mapped region likely to be flooded, in whcih people avoid constructing buildings.
maritime tropical air mass
a mass of air that originates over tropical or subtropical oceanic regions.
rockfall
a mass of rock that separates from a cliff, typically along a joint, and then ree-falls downslope.
volcaniclastic rock
a material composed of cemented-together grains of volcanic material; it includes both pyroclastic rocks and rocks formed from accumulations of water-transported volcanic debris.
compound
a material composed of two or more elements that cannot be separated mechanically; the smallest piece is a molecule.
element
a material consisting entirely of one kind of atom; elements cannot be subdivided or changed by chemical reactions.
chemical
a material consisting of a distinct element or compound.
mixture
a material consisting of two or more substances that can be separated mechanically (without chemical reactions.
solution
a material containing dissolved ions.
Darcy's law
a mathematical equations stating that a volume of water, passing through a specified area of material at a given time, depends on the material's permeability and hydraulic gradient.
abandoned meander
a meander that dries out after it was cut off
oxbow lake
a meander that has been cut off yet remains filled with water.
incised meander
a meander that lies at the bottom of a steep=walled canyon.
Kelvin (K) scale
a measure of temperature in which 0 K is absolute zero and the freezing point of water is 273.15 K; divisions in the _______________ have the same value as those in the Celsius scale.
heat capacity
a measure of the amount of heat that must be added to a material to change its temperature.
temperature
a measure of the hotness or coldness of a material.
hardness of a mineral
a measure of the relative ability of a mineral to resist scratching; it represents the resistance of bonds in the crystal structure from being broken.
intensity
a measure of the relative size of an earthquake (the severity of ground shaking) at a location, as determined by examining the aount of damage caused.
coal rank
a measurement of the carbon content of coal; higher-rank coal forms at higher temperatures.
butte
a medium-sized, flat-topped hill in an arid region.
schist
a medium-to-coarse grained metamorphic rock that possesses schistosity.
alloy
a metal containing more than one type of metal atom.
fuel rod
a metal tube that holds the nuclear fuel in a nuclear reactor.
marble
a metamorphic rock composed of calcite and transformed from a protolith of limestone.
quartzite
a metamorphic rock composed of quartz and transformed from a protolith of quartz sandstone
metaconglomerate
a metamorphic rock produced by metamorphism of a conglomerate; typically, it contains flattened pebbles and cobbles.
celsius scale
a metric-system measure of temperature in which the difference between the freezing point (0 C) and boiling point (100 C) of water is divided into 100 units; equivalent to centigrade scale.
gemstone
a mineral that has special value because it is rare and people consider it beautiful.
cloud
a mist of tiny water droplets in the sky.
till
a mixture of unsorted mud, sand, pebbles, and larger rocks deposited by glaciers.
volcanic debris flow
a mixture of water and pyroclastic debris that moves like wet concrete.
snowball Earth
a model proposing that, at times during Earth history, glaciers covered all land, and the entire ocean surface froze.
desert pavement
a mosaic-like stone surface forming the ground in a desert.
coral reef
a mound of coral and coral debris forming a region of shallow water.
mountain ice cap
a mound of ice that suberges peaks and ridges at the crest of a mountain range.
orogeny
a mountain building event
Sevier orogeny
a mountain-building event that affected western Norht America between about 150 MA and 80 Ma, a result of convergent margin tectonism; a fold-thrust belt formed during this event.
yardang
a mushroom-like column with a resistant rock perched on an eroding column of softer rock; created by wind abrasion in deserts where a resistant rock overlies softer layers of rock.
fracture zone
a narrow band of vertical fractures in the ocean floor, ____________ lie roughly at right angles to a mid-ocean ridge, and the actively slipping part of a ___________ is a transform fault.
axial trough
a narrow depression that runs along a mid-ocean ridge axis.
meander neck
a narrow isthmus of land separating two adjacent meanders.
tombolo
a narrow ridge of sand that links a sea stack to the mainland.
offshore bar
a narrow ridge of snad that forms of fthe shore of a beach; some _____________ rise above sea level, and separate a lagoon on one side from the open ocean on the other.
submarine canyon
a narrow, steep canyon that dissects a continental shelf and slope
submarine canyon
a narrow, steep canyon that dissects a continental shelf and slope.
native metal
a natrually occurrin pure mass of a single metal in an ore deposit
natural hazard
a natural feature of the environment that can cause injury to living organisms and or damage to buildings and the landscape.
spring
a natural outlet from which groundwater flows up onto the ground surface.
tornado
a near-vertical, funnel-shaped cloud in which air rotates etremely rapidly around the axis of the funnel.
peneplain
a nearly flat surface that lies at an elevation close to sea level; thought to be the product of long-term erosion.
detachment fault
a nearly horizontal fault at the base of a fault system.
sill
a nearly horizontal tabletop-shaped tabular intrusion that occurs between the layers of country rock.
anion
a negatively charged ion.
electron
a negatively charges subatomic particale that orbits the nucleus of an atom; _________ are about .0005x the size of a proton.
Western Interior Seaway
a north-south-trending seawaythat ran down the middle of North America during the Late Cretaceous Period.
wave-cut notch
a notch in a coastal cliff cut out by wave erosion.
fission
a nuclear reaction during which the nucleus of a large atom splits to form two nuclei of smaller atoms; the process also releases neutrons and energy.
breeder ractor
a nuclear reactor that produces its own fuel.
specific gravity
a number representing the density of a mineral, as specified by the ratio between the weight of a volume of the mineral and the weight of an equal volume of water.
general circulation model
a numerical caculation that simulates the flow of the atomosphere and resulting phenomena, due to changes in atmospheric temperature and other parameters.
varve
a pair of thin layers of glacial lake-bed sediment, one consisting of silt brought in during the spring floods and the other of clay deposited during the winter when the lake's surface freezes over and the water is still.
baltica
a paleozoic continent that included crust that is now part of today's Europe.
natural levees
a pari of low ridges that appear on either side of a stream and develop as a result of the accumulation of sediment deposited naturally during flooding
marker bed
a particular unique layer that provides a definitive basis for correlation.
apparent polar-wander path
a path on the globe along which a magnetic pole appears to have wandered over time; in fact, the continents drift, while the magnetic pole stays fairly fixed.
little ice age
a period of cooler temperatues, between 1500 and 1800 c.e. during which many glaciers advanced.
Medieval Warm Period
a period of high temperatures in the Middle Ages.
interglacial
a period of time between two glaciations.
meteorite
a piece of rock or metal alloy that fell from space and landed on Earth.
dune
a pile of sand generally formed by deposition from the wind.
tailings pile
a pile of waste rock from a mine.
headland
a place where a hill or cliff protudes into the sea.
upwelling zone
a place where deep water rises in the ocean, or where hot magma rises in the asthenosphere.
downwelling zone
a place where near-surface water sinks
seep
a place where oil-filled reservoir rock intersects the ground surface, or where fractures connect a reservoir to the ground surface, so that oil flows out onto the ground on its own.
divergence zone
a place where sinking air separates into two flows that move in opposite directions
convergence zone
a place where two surface air flows meet so that air has to rise.
waterfall
a place where water drops over an escarpment.
tectonic foliation
a planar fabric, such as cleavage, schistocity, or gneissic banding, that develops in rocks; caused by compression or shearing during deformation (e.g., during mountain building).
gymnosperm
a plant whose seeds are "naked," not surrounded by a fruit.
vascular plant
a plant with woody tissue and seeds and veins for transporting water and food.
wave-cut bench
a platform of rock, cut by wave erosion, at the lowtide line that was left behind a retreating cliff.
triple junction
a point where three lithosphere plate boundaries intersect.
horn
a pointed mountain peak surrounded by atleast three circques.
patterned ground
a polar landscape in which the ground splits into pentagonal or hexagonal shapes.
glacially polished surface
a polished rock surface created by the glacial abrasion of the underlying substrate.
glaciation (glacial period(
a portion of an ice age during which huge glaciers grew and covered substantial areas of the continents.
cation
a positively charged ion
proton
a positively charged subatomic particle in the nucleus of an atom.
dynamo
a power plant generator in which water or wind power spins an electrical conductor around a permanent magnet
stoping
a process by which magma intrudes; blocks of wall rock break off and then sink into the magma.
scouring
a process by which running water removes loose fragments of sediment from a streambed.
dissolution
a process during which materials dissolve in water.
differentiation of a planet
a process early in a planet's history during which dense iron alloy melted and sank downward to form the core, leaving less-dense mantle behind.
internal process
a process in the Earth System such as plate motion, mountain building, or volcanis, ultimately caused by Earth's internal heat.
ridge-push force
a process in which gravity causes the elevated lithosphere at a mid-ocean ridge axis to push on the lithosphere that lies farther from the axis, making it move away.
advection
a process of heat transfer in which heat is carried into a solid by a liquid or gas moving through fractures or pores in the solid.
conduction
a process of heat transfer involving progressive migration of thermal energy from cooler to warmer regions in a merterial, without the physical flow of the material itself.
gravitational spreading
a process of lateral spreading that occurs in a material because of the weakness of the material; _________________________ causes continental glaciers to grow and mountain belts to undergo orogenic collapse.
stream piracy
a process that happens when headward erosion by one stream causes the stream to intersect the course of the base level.
nuclear reaction
a process that results in changing the nucleus of an atom by breakig or forming nuclear bonds
secondary recovery technique
a process used to extract the quantites of oil that will not come out of a reservoir rock with just simple pumping.
Rodinia
a proposed Precambrain supercontinent that existed around 1 billion years ago.
cratonic platform
a province in the interior of a continent in which Phanerozoic strata bury most of the underlying Precambrian rock.
cumulus cloud
a puffy, cotton-ball-shaped cloud.
surge (glacial)
a pulse of rapid flow in a glacier.
field force
a push or pull that applies across a distance (i.e., without contact objects); exmples are gravity and magnetism.
compression
a push or squeezing felt by a body
mechancial force
a push, pull, or shear applied by one object on another, it can be applied only if the objects are in contact.
tuff
a pyroclastic igneous rock composed of volcanic ash and fragmented pumice, formed when accumulations of the debris cement together.
volcanic breccia
a pyroclastic igneous rock that consists of fragments of volcanic debris, which either fall through the air and accumulate, or form when solidifying lava breaks up during flow.
perched water table
a quantity of groundwater that lies above the regional water tale because an underlying lens of impermable rock or sediment prevents the water from sinking down to the regional water table.
carbon 14
a radioactive isotope of the element carbon, the ratio of C14 to C12 can provide an isotopic date or organic carbon.
parent isotope
a radioactive isotope that undergoes decay
carbon 14 dating
a radiometric dating process that can tell us the age of organic material containing carbon orgianlly exracted from atmosphere.
cumulonimbus cloud
a rain-producing, puffy cloud
reflected ray
a ray that bounces off a boundary between two different materials.
rapids
a reach of a stream in which water becomes particularly turbulent; as a consequence, waves develop on the surface of the stream.
meandering stream
a reach of stream containing many meanders (snake-like curves)
oxidation reaction
a reaction in which an element loses electrons; an exmple is the reaction of iron with air to form rust.
stratigraphic formation
a recognizable layer of a specific sedimentary rock type or set of rock types, deposited during a certain time interval, that can be traced over a broad region.
plate interior
a region away from the plate boundaries that consequently expereienes few earthquakes.
oil field
a region containing a significant amount of accessible oil underground
large igneous province (LIP)
a region in which huge volumes of lava and or ash erupted over a relatively short interval of geologic time
geothermal region
a region of current or recent volcanism in which magma or very hot rock heats up groundwater, which may discharge at the surface in the form of hot springs and or geysers.
subkah
a region of formerly flooded coastal desert in which stranded seawater has left a salt crust over a mire of mud that is rich in organic material.
oceanic plateau
a region of oceanic floor that is higher than surrounding areas; such regions have particularly thick oceanic crust and are relicts of submarine large igneous provinces.
surf zone
a region of the shore in which breakers crash onto the shore.
desert
a region so arid that it contains no permanent streams, except for those that bring water in from elsewhere, and has very sparse vegetation cover.
karst landscape
a region underlain by caves in limestone bedrock; the collapse of the caves creates a landscape of sinkholes separated by low areas.
periglacial environment
a region with widespread permafrost but without a blanket of snow or ice.
seal
a relatively impermeable rock, such as shale, salt, or unfractured limestone, that lies above a reservoir rock and stops the oil from rising further.
sand dune
a relatively large ridge of sand built up by a current of wind (or water); cross bedding typically occurs within the dune.
earthquake belt
a relatively narrow, distinct belt of earthquakes that defines the position of a plate boundary.
body fossil
a relict of an organism's body, preserved in rock.
xenolith
a relict of wall rock surrounded by intrusive rock when the intrusive rock freezes.
cyclothem
a repated interval within a sedimentary sequence that contains a specific succession of sedimentary beds.
flood-hazard map
a representation of a portion of the Earth's surface that is designed to show how the danger of flooding varies with location.
metamorphic grade
a representation of the intensity of metamorphism, meaning the amount or degree of metamorphic change.
arete
a residual knife-edge ridge of rock that separates two adjacent cirques.
bauxite
a residual mineral deposit rich in alluminum.
renewable resource
a resource that can be replaced by nature within a short time span relative to a human life span.
nonrenewable resource
a resource that nature will take a long time (hundreds to millions of years) to replenish or may never replenish.
growth ring
a rhythmic layering that develops in trees, travertine deposits, and shelly organisms as a consequence of seasonal changes.
stream
a ribbon of water that flows in a channel.
esker
a ridge of sorted sand and gravel that snakes across a ground moraine, the sediment of an _____ was deposited in subglacial meltwater tunnels.
protoplanetary nebula
a ring of gas and dust that surrounded the newborn Sun, from which the planets were formed.
salt dome
a rising bulbous dome of salt that bends up the adjacent layers of sedimentary rock.
valley glacier
a river of ice that flows down a mountain valley.
glacier
a river or sheet of ice that slowly flows across the land surface and lasts all year long.
source rock
a rock (organic rich shale) containing the raw materials from which hydrocarbons eventually form.
travertine
a rock composed of crystalline calcium carbonate (CaCO3) formed by chemical precipitation from groundwater that has seeped out at the ground surface.
fragmental igneous rock.
a rock consisting of igneous chunks and/ or shards that are packed together, welded together, or cemented together after having solidified.
migmatite
a rock formed when gneiss is heated high enough so tat it begins to partially melt, creating layers, or lenses, of new igneous rock that mix with layers of the relict gneiss
crystalline igneous rock
a rock that consists of minerals that grew when a melt solidified, and eventually interlock like pieces of a jigsaw puzzle.
dropstone
a rock that drops to the sea floor once the iceberg that was carrying the rock melts.
eye wall
a rotating vertical cylinder of clouds surrounding the eye of a hurricane.
baymouth bar
a sandspit that grows across the opening of a bay.
seismic-moment magnitude scale
a scale that defines earthquake size on the basis of calculations involving the amount of slip, length of rupture, depth of rupture, and rock strength=.
Richter magnitude scale
a scale that defines earthquakes on the basis of the amplitude of the largest ground motion recorded on a seismogram.
geologic time scale
a scale that describes the intervals of geologic time.
Fujita scale
a scale that distinguishes among tornadoes on the basis of wind speeed, path dimensions, and possible damage.
theory
a scientific idea supported by an abundance of evidence that has passed many tests and failed none.
dendrochronologist
a scientist who analyzes tree rings to determine the geologic age of features.
vein
a seam of minerals that forms when dissolved ions carried by water solutions precipitate in cracks.
guyot
a seamount that had a coral reef growing on top of it, so that it is now flat-crested.
monsoon
a seasonal reversal in wind direction that causes a shift from a very dry season to a very rainy season in some regions of the world.
moraine
a sediment pile composed of till deposited by a glacier.
braided stream
a sediment-choked stream consisting of entwined subchannels.
seam
a sedimentary bed of coal interlayered with other sedimentary rocks.
chert
a sedimentary rock composed of very fine-grained silica (cryptocrystalline quartz).
chain reaction
a self-perpetuating process in a nuclear reaction, whereby neutrons eleased during the fission trigger more fission.
scientific method
a sequence of steps for systematically analyzing scientific problems in a way that leads to verifiable results.
cycle
a series of interrelated events or steps that occur in succession and can be repeated, perhaps indefinitely.
cleavage planes
a series of surfaces on a crystal that form parallel to the weakest bonds holding the atoms of the crystal together.
greenschist facies
a set of metamorphic minderal assemblages formed under relatively low pressures and temperatures.
granulite facies
a set of metamorphic mineral assemblages formed at very high pressures and temperatures
amphibolite facies
a set of metamorphic mineral assemblages formed under intemediate pressures and temperatures
metamorphic facies
a set of metamorphic minerals assemblages indicative of metamorphism under a specific range of pressures and temperatures.
depositional environment
a setting in which sediments accumulate; its character (fluvial, deltaic, reef, glacial, ect.) reflects local conditions.
epicontinental sea
a shallow sea overlying a continent
flowstone
a sheet of limestone that forms along the wall of a cave when groundwater flows along the surface of the wall.
supernova
a short-lived, very bright object in space that results from the cataclysmic explosion marking the death
phyllitic luster
a silk-like sheen characteristic of phyllite, a result of the rock's fine-grained mica.
transverse dune
a simple, wave-like dune that appears when enough sand accumulates fro the ground surface to be completely buried, but only moderate winds blow.
crystal
a single, continuous piece of a mineral bounded by flat surfaces that formed naturally as the mineral grew.
mine
a site at which ore is extracted from the ground
quarry
a site at which stone is extracted from the ground.
moon
a sizable solid body locked in orbit around a planet.
ophiolite
a slice of oceanic crust that has been thrust onto continental crust.
stable slope
a slope on which downward sliding is unlikely
unstable slope
a slope on which sliding will likely happen.
talus
a sloping apron of fallen rock along the base of a cliff.
Wandati-Benioff zone
a sloping band of seismicity defined by intermediate and deep-focus earthquakes that occur in the downgoing slab of a covergent plate boundary.
rock glacier
a slow-moving mixture of rock fragements and ice.
drilling mud
a slurry of water mixed with clay that oil driillers use to cool a drill bit and flush rock cuttings up and out of the hole.
sand volcano (sand blow)
a small mound of sand produce when sand layers below the ground surface liquify as a result of seismic shaking, cuasing the sand to erupt onto the Earth's surface through cracks or holes in overlying clay layers.
marginal sea
a small ocean basin created when sea-floor spreading occurs behind an island arc.
fault scarp
a small step on the ground sruface where one side of a fault has moved vertically with respect to the other.
yazoo stream
a small tributary that runs parallel to the main river in a floodplain because the tributary is blocked from entering the main river by levees.
tributary
a smaller stream that flows into a larger stream
meander
a snake-like curve along a stream's course.
metal
a solid composed almost entirely of atoms of metallic elements; it is generally opaque, shiny, smooth, malleable, and can conduct electricity.
bolide
a solid extraterrestrial object such as a meteorite, comet, or asteroid that explodes in the atmosphere.
glass
a solid in which atoms are not arranged in an orderly pattern.
caliche
a solid mass created where calcite cements the soil together.
oversaturated solution
a solution that contains so much solute (dissolved ions) that precipitation begins.
semipermanent pressure cell
a somewhat ellipticalzone of high or low atmospheric pressure that lasts much of the year; it forms because high-pressure zones tend to be narrower over land than over sea.
magma chamber
a space below ground filled with magma.
.permanent magnet
a special material that behaves magnetically for a long time all b itself
weather system
a specific set of weather conditions, reflecting the configuration of air movement in the atmosphere, that affects a region for a period of time.
volatility
a specification of the ease with which evaporates.
reach
a specified segment of a stream's path
rain band
a spiraling arm of a hurricane radiating outward from the eye.
truncated spur
a spur (elongate ridge between two valleys) whose end was eroded off by a glacier)
hogback
a steep-sided ridge of steeply dipping strata
U-shaped valley
a steep-walled valley shaped by glacial erosion into the form of a U.
beach face
a steeply concave part of the foreshore zone formed where the swash of the waves actively scours the sand.
reverse fault
a steeply dipping fault on which the hanging wall block slides up.
storm-center velocity
a storm's (hurricane's) velocity along its track.
cutoff
a straight reach in a stream that develops when erosion eats through a meander neck.
kame
a stratifed sequence of lateral-moraine sediment that's sorted by water flowing along the edge of a glacier.
meteor
a streak of bright, glowing gas created as a meteoroid vaporizes in the atmosphere due to friction.
solar wind
a stream of particles with enough energy to escape from the Sun's gravity and flow outward into space.
antecedent stream
a stream that cuts across an uplifted mountain range; the stream must have existed before the range uplifted and must then have been able to downcut as fast as the land was rising.
permanent stream
a stream that flows year-round because its bed lies below the water table, or because more water is supplied from upstream than can infiltratre the ground.
graded stream
a stream that has attained an equilibrium longitudinal profile in which the sediment input into an area equals sediment removal.
disappearing stream
a stream that intersects a crack or sinkhole leading to an underground cavern, so that the water disappears into the subsurface and becomes an underground stream.
ephemeral intermittent stream
a stream whose bed lies above the water table, so that the stream flows only when the rate at which water enters the stream from rainfalll or meltwater exceeds the rate at which water infiltrates the ground below.
superposed stream
a stream whose geometry has been laid down on a rock structure and is not controlled by the structure
drumlin
a streamlined, elongate hill formed when a glacier overrides glacial till.
shear stress
a stress that moves one part of a material sideways past another part.
tension
a stress that pulls on a material and could lead to stretching.
right-lateral strike-slip fault
a strike-slip fault in which the block on the opposite fault plane from a fixed spot moves to the right of that spot.
lateral mroaine
a strip of debris along the side margins of a glacier.
medial moraine
a strip of sediment in the interior of a glacier, parallel to the flow direction of the glacier, formed by the lateral moraines of two merging glaciers.
rip current
a stron, localized seaward flow of water perpendicular to a beach.
cinder cone
a subaerial volcano consisting of a cone-shaped pile of tephra whose slope approaches the angle of repose for tephra.
shield volcano
a subaerial volcano with a broad, gentle dome, formed either from low-viscosity basaltic lava or from large pyroclastic sheets.
neutron
a subatomic particle, in the nucleus of an atom, that has a neutral charge.
turbidity current
a submarine avalanche of sediment and water that speeds down a submarine slope.
trap
a subsurface configuration of seal rocks and structrues that keep oil and or gas underground, so it doesn't seep out at the surface.
strata
a succession of several layers of beds together.
group
a sucession of stratigraphic formations that have been lumped together, making a single, thicker stratigrpahic entity.
quenching
a sudden cooling of molten material to form a solid.
debris slide
a sudden downslope movement of material consisting only of regolith.
rockslide
a sudden downslope movement of rock.
rock burst
a sudden explosion of rock of fthe ceiling or wall of an underground mine.
landslide
a sudden movement of rock and debris down a nonvertical slope.
critical mass
a sufficiently dense and large mass of radioactive atoms in which a chain reaction happens so quickly that the mass explodes
Pangaea
a supercontinent that assembled at the end of the Paleozoic Era.
Gondwana
a supercontinent that consisted of today's South America, Africa, Antarctica, India, and ustralia. (Also called Gondwanaland.)
pannotia
a supercontinent that may have existed sometime between 800 Ma and 600 Ma
coal swamp
a swamp whose oxygen-poor water flows thick piles of woody debris to accumulate; this debris transforms into coal upon deep burial.
dike
a tabular (wall-shaped) intrusion of rock that cuts across the layering of country rock.
pedalfer soil
a temperate-climate soil characterized by well-defined soil horizons and an organic A-horizon.
equant
a term for a grain that has the same dimensions in all directions
inequant
a term for a mineral grain whose length and width are not the same..
heterosphere
a term for the upper portion of the atmosphere, in which gases separate into distinct layers on the basis of composition.
petrified
a term used by geologists to describe plant material that has transformed into rock by permineralization
mafic
a term used in reference to magamas or igneous rocks taht are relatively poor in silica and rich in iron and magneisum.
undersaturated
a term used to describe a solution capable of holding more dissolved ions.
ultramafic
a term used to describe igneous rocks or magmas that are rich in iron and magnesium and very poor in silica.
jovian
a term used to describe the outer gassy, Jupiter-like planets (gas-giant planets).
aphanitic
a textural term for fine-grained igneous rock.
phaneritic
a textural term used to describe coarse=grained igneous rock.
fine-grained
a texturla term for rock consisitng of many fine grains or clasts.
passive-margin basin
a thick accumulation of sediment along a tectonically inactive coast, formed over crust that stretched and thinned when the margin first began.
lahar
a thick slurry formed when volcanic ash and debris mix with water, either in rivers or from rain or melting snow and ice on the flank of a volcano.
ground moraine
a thin, hummocky layer of till left behind on the land surface during a rapid glacial recession.
stratus cloud
a thin, sheet-like, stable cloud.
mass-extinction event
a time when vast number of species abruptly vanish.
Mississippi Valley-type ore
an ore deposit, typically in dolostone, containing lead and zinc bearing minerals that precipitated from groundwater that had moved up from seeral km depth in the upper crust, such deposits occur in the the upper Mississippi Valley
eukaryote
an organism whose cells contain a nucleus; all plants and animals consist of eukaryotic cells.
accretionary orogen
an orogen formed by the attachment of numerous buoyant slivers of crust to an older, larger continentla block.
fault-block mountains
an outdated term for a narrow, elongate range of mountains that develops in a continental-rift setting as normal faulting drops down blocks of crust or tilts blocks.
angular unconformity
an unconformity in which the strata below were tilted or folded before the unconformity developed; strata below the unconformity therefore have a different tilt than strata above.
disconformity
an unconformity parallel to the two sedimentary sequences it separates.
radioactive isotope
an unstable isotope of a given element.
return stroke
an upward-flowing electric current from the ground that carries positive charges up to a cloud during a lightning flash.
stalagmite
an upward-pointing cone of limestone that grows when drips of water hit the floor of a cave.
seismic tomography
analysis by sophisticated computers of global seismic data in order to create a three-dimensional image of variations in seismic-wave velocities within the Earth.
Milankovic cycles
climate cycles that occur over tens to hundreds of thousands of years because of changes in Earth's orbit and tilt.
glacial outwash
coarse sediment deposited on a glacial outwash plain by meltwater streams.
breccia
coarse sedimentary rock consisting of angular fragments; or rock broken into angular fragments by faulting.
sandstone
coarse-grained sedimentary rock consisting almost entirely of quartz.
peat
compacted and partially decayed vegetation accumulating beneath a swampe
firn
compacted granular ice (derived from snow) that forms where snow is deeply buried; if buried more deepy, ____ turns into glacial ice.
placer deposit
concentrations of metal grains in stream sediment that develop when rocks containing native metals erode and create a mixture of sand grains and metal fragments; the moving water of te stream carries away lighter mineral grains.
unconsolidated
consisting of unattached grains.
crystalline
containing a crystal lattice.
anhedral grains
crystalline mineral grains without well0formed crystal faces.
volatiles (volatile materials)
elements or compounds such as H2O and CO2 that evaporate at relatively low temperatures and can exist in gaseous forms at the Earth's surface.
volcanic gas
elements or compounds that bubble out of magma or lava in gaseous form.
tidal power
energy produced by the daily rise and fall of the tides; people can utilize this energy, for example, by damming a by or estuary, so that water passes through turbines when the tide changes.
undercutting
excavation at the base of a slope that results in the formation of an overhang.
storm surge
excess seawater driven landward by wind during a storm; the low atmospheric pressure beneath the storm allows sea level to rise locally, increasing the surge.
insolation
exposure to the sun's rays.
hail
falling ice balls from the sky, formed when ice crystallizes in turbulent storm clouds.
negative feedback
feedback that slows a precess down or reverses it.
rock flour
fine-grained sediment produced by glaciel abrasion of the substrate over which a glacier flows.
siltstone
fine-grained sedimentary rock gnerally composed of very small quartz grains
slate
fine-grained, low-grade metamorphic rock, formed by the metamorphism of shale.
matrix
finer-grained material surrounding larger grains in a rock.
seasonal floods
floods that appear almost every year during seasons when rainfall is heavy or when winter snows start to melt.
dome
folded or arched layers with the shape of an orverturned bowl.
accretionary lapilli
hailstone-like clumps of wet ash that fall from a volcanic eruptive cloud.
amber
hardened (fossilized) ancient sap or resin.
geothermal energy
heat and electricity produced by using the internal heat of the Earth.
convection
heat transfer that results when warmer, less dense material rises while cooler, denser material sinks.
tar
hydrocarbons that exist in solid form at room temperature.
sea ice
ice formed by the freezing of the surface of the sea.
glassy igneous rock
igneous rock consisting entirely of glass, or of tiny crystals surrounded by a glass matrix.
chemical reaction
interactions among atoms and or molecules involving breaking or forming chemical bonds.
cross bed
internal laminations in a bed, inclined at an angle to the main bedding; __________ are a relict of the slip face of dunes or ripples.
dissolved load
ions dissolved in a stream's water.
unstable ground
land capable of slumping or slipping downslope in the near future.
bed load
large particles, such as sand, pebbles, or cobbles, that bounce or roll along a streambed.
block
large, angular pyroclastic fragments consisting of volcanic rock, broken up during the eruption.
blocky lava
lava that is so viscous that it breaks into boulder-like blocks as it moves; typically, such lavas are andesitic or rhyolitic.
stromatolite
layered mounds of sediment formed by cyanobacteria; cyanobacteria secrete a mucous-like substance to which sediment sticks, and as each layer of cyanobacteria gets buried by sediment it colonizes the surface of the new sediment, building a mound upward.
foliation
layering formed as a consequence of the alignment of mineral grains, or of compositional banding in a metamorphic rock.
bedding
layering or stratification in sedimentary rocks.
loess
layers of fine-grained sediments deposited from the wind; large deposits of _____ formed from fine-grained glacial sediment blown off outwash plains.
dripstone
limestone (travertine in a cave) fromed by the prcipitation of calcium carbonate out of groundwater,
fossiliferous limestone
limestone consisting of abundant fossil shells and shell fragements
micrite
limestone consisting of lime mud. (very fine-grained limestone.)
slip lineations
linear marks on a fault surface created during movement on the fault; some slip lineations are defined by grooves, some by aligned mineral fibers.
striations
linear scratches in rock.
contour lines
lines on a map along which a parameter has a constant value; for example, all points along a ___________ on a topographic map are at the same elevation.
isoterm
lines on a map or cross section along which the temperature is constant.
surface water
liquid or seasonally frozen water that resides at the surface of the Earth in oceans, lakes, streams, and marshes.
organic shale
lithified, muddy, organic-rich ooze that contains the raw materials from which hydrocarbons eventually form.
continental lithosphere
lithosphere topped by continental crust; this lithosphere reaches a thickness of 150 km.
oceanic lithosphere
lithosphere topped by oceanic crust; it reaches a thickness of 100 km.
weather
local-scale conditions as defined by temperature, air pressure, relative humidity, and wind speed.
systematic joints
long planar cracks that occur fairly regularly throughout a rock body.
riprap
loose boulders or concrete piled together along a beach to absorb wave energy before it strikes a cliff face.
dehydration
loss of water.
lignite
low rank coal that consist of 50% carbon.
crustal root
low-density crustal rock that protrudes downward beneath a mountain range.
coastal plain
low-relief regions of land adjacent to the coast.
manganese nodules
lumpy accumulations of manganese-oxide minerals precipitated onto the sea floor.
black lung disease
lung disease contracted by miners from the inhalation of too much coal dust.
brittle-ductile transition (brittle-plastic transition)
the depth above which aterials behave brittely which materials behave ductilely (plastically); this transition typically lies between a depth of 10 and 15km in continental crustal rock, and 60 m deep in glacial ice.
lava
molten rock that has flowed out onto the Earth's surface.
stick-slip behavior
stop-start movement along a fault plane caused by friction, which prevents movement until stress builds up sufficiently.
formation
stratigraphic formation
catabatic winds
strong winds that form at the margin of a glacier where the warmer air above ice-free land rises and the cold, denser air from above the glaciers rushes in to take its place.
refractory materials
substances that have a relatively high melting point and tend to exist in solid form.
biogenic minerals
substances that meet the definition of a mineral and are produced naturally by organisms (e.g., calcite in sheels)
L-waves
surface seismic waves that cause the ground to ripple back and forth, creating a snake-like movement.
R-waves (Rayleigh waves)
surface seismic waves that cause the ground to ripple up and down, like water waves in a pond.
northeast tradewinds
surface winds that come out of the northeaast and occur in the rgio between the equator and 30 N.
wave base
the depth, approximately equal in distance to half a wavelength in a body of water, beneath which there is no wave movement.
earthquake engineering
the design of buildings that can withstand shaking.
zone of ablation
the area of a glacier in which ablation (melting, sublimation, calving) subtracts from the glacier.
intertidal zone
the area of coastal land across which the tide rises and falls.
equatorial low
the area of low pressure that develops over the equator because of the intertropical convergence zone.
crystal structure
the arrangement of atoms in a crystal.
low-velocity zone
the asthenosphere underlying oceanic lithosphere in which seismic waves travel more slowly, probably because rock has partially melted.
covalent bonding
the attachment of one atom to another that develops when the atoms share electrons; one type of chemical bond.
diversification
the development of many different species.
ionic bond
the attachment of one atom to another that happens when one atom transfers electrons to anotehr; one type of chemical bond.
gravity
the attractive force that one mass exerts on another; the magnitude depends on the size of the objects and the distance between them.
residence time
the average length of time that a substane stays in a particular reservoir
mean sea level
the average level beetween the high and low tide over a year ata given point.
magnetic anomaly
the difference between the expected strength of the Earth's magnetic field at a certain locatio nand the actual measured strength of the field at that location.
marine magnetic anomaly
the difference between the expected strength of the Earth's main dipole field ata certain location on the sea floor and the actual measured strength of the magnetic field at that location.
relief
the difference in elevation between adjacent high and low regions on the land surface.
tidal reach
the difference in sea level between high tide and low tide at a given point.
scattering
the dispersal of energy that occurs when light interacts with particles in the atmosphere.
fetch
the distance across a body of water along which a wind blows to build waves.
head scarp
the distinct step along the upslope edge of a slump where the regolith detached.
slope failure
the downslope movement of material on an ubstable slope.
cone of depression
the downward-pointing, cone-shaped surface of the water table in a location where the water table is experiencing drawdown because of pumping at a well.
plate boundary earthquakes
the earthquakes that occur along and define plate boundaries
amplitude
the eight of a wave from crest to trough
terrace
the elevated surface of an older floodplain into which a younger floodplain had cut down.
lava tube.
the empty space left when a lava tunnel drains; this happens when the surface of a lava flow solidifies while the inner part of the flow continues to stream downslope.
terminal moraine
the end moraine at the farthest limit of glaciation.
recessional moraine
the end moraine that forms when a glacier stalls for a while as it recedes.
magnetic poles
the ends of a magnetic dipole; all magnetic dipoles have a north pole and south pole`
intertropical convergence zone
the equatorial convergence zone in boundaries
typhoon
the equivalent of a hurricane in the western pacific ocean
sublimation
the evaporation of ice directly into vapor without first forming a liquid
biogeochemical cycle
the exchange of chemicals between living and nonliving reservoirs in the Earth System.
ebb tide
the falling tide.
distributaries
the fan of small streams formed where a river spreads out over its delta
superrotation
the faster rotation of the core; relative to the rest of the Earth.
floodplain
the flat land on either side of a stream that becomes covered with water during a flood.
crystal face
the flat surfaces of a crystal, formed during the crystal's growth.
playa
the flat, typically salty lake bed that reminas when all the water evaporates in drier times; forms in desert regions.
streambed
the floor of a stream
El Nino
the flow of warm water eastward from the Pacific Ocean that reverses the upwelling of cold water along the western coast of South America and causes significant global changes in weather patterns.
longshore current
the flow of water parallel to the shore just off a coast, because of the diagonal movement of waves toward the shore.
slaty cleavage
the foliation typical of slate, and reflective of the preferred orientation of slate's clay minerals, that allows slate to be split into thin sheets.
nuclear bond
the force that attaches subatomic particles to each other within the nucleus of an atom.
slab-pull force
the force that downgoing plates (or slabs) apply to oceanic lithosphere ata covergent margin.
permafrost
permanently frozen ground
subaerial
pertaining to land regions above sea level (under air)
mechanical weathering
physical weathering
terrestrial planets
planets that are of comparable size and character to the Earth and consist of a metallic core surrounded by a rock mantle.
normal polarity
polarity in which the paleomagnetic dipole has the same orientation as it does today.
reversed polarity
polarity in which the paleomagnetic dipole points north.
acid rain
precipitation in which air pollutants react with water to makea weak acid that then falls from the sky.
Bergeron process
precipitation involving the growth of ice crystals in a cloud at the expense of water droplets.
condensation nuclei
preexisting solid or liquid particles, such as aerosols, onto which water condenses during cloud formation
fault gouge
pulverized rock consisting of fine powder that lies along fault surfaces; gouge forms by crushing and grinding.
nuee ardente
pyroclastic flow
extrusive igneous rock
rock that forms by the freezing of lava above ground, after it flows or expoldes out (extrudes( onto the surface and comes into contact wit hthe atmosphere or ocean.
sedimentary rock
rock that forms either by the cementing together of fragments broken off preexisting rock or by the precipitation of mineral crystals out of water solutions at or near the Earth's surface.
metamorphic rock
rock that forms when preexisting rock changes into new rock as a result of an increase in pressure
weathered rock
rock that has reacted with air and or water at or near the Earth's surface.
hornfels
rock that undergoes metamorphism simply because of a change in temperatures, without being subjected to differential stress.
fresh rock
rock whose mineral grains have their original composition and shape.
reservoir rock
rock with high porosity and permability, so it can contain an abundant amount of easily accessible oil.
ore
rockcontaining native metals or a concetrated accumulation of ore minerals
carbonate rocks
rocks containing calcite and or dolomite.
high-grade metamorphic rocks
rocks that metamorphose under relatively high temperatures.
low-grade metamorphic rocks
rocks that underwent metamorphism at relatively low temperatures.
control rod
rods that absorb neutrons in a nuclear reactor and thus decrease the number of collisions between neutrons and radioactive atoms.
erg
sand seas formed by the accumulation of dunes in a desert.
tar sand
sandstone reservoir rock in which less viscous oil and gas molecules have either escaped or been eaten by microbes, so that only tar remains.
ultimate base level
sea level; the level below which a trunk stream cannot cut.
glacial marine
sediment consisting of ice-rafted clasts mixed with marine sediment.
glacial drift
sediment deposited in glacial environments.
fluvial deposit
sediment deposited in stream channel, along a stream bank, or on a flood plain.
aquitard
sediment or rock that does not transmit water easily and therefore retards the motion of the water.
aquiclude
sediment or rock that transmits no water.
aquifer
sediment or rock that transmits water easily.
soil
sediment that has undergone changes at the surface of the Earth, including reaction with rainwater and the addition of organic material.
cast
sediment that preserves the shape of a shell it once filled before the shell dissolved or mechanically weathered away.
surface load (bed load)
sediment that rolls and bounce along the ground (under the air) or along a stream bed (under water).
glacial till
sediment trasported by flowing ice and deposited beneath a glacier or at its toe.
organic sedimentary rock
sedimentary rock (such as coal) formed from carbon-rich relicts of organisms)
limestone
sedimentary rock composed of calcite
clastic (detrital) sedimentary rock
sedimentary rock consisting of cemented-together detritus derived from the weathering of preexisting rock.
biochemical sedimentary rock
sedimentary rock formed from material (such as shells) produced by living organisms.
argillaceous sedimentary rock
sedimentary rock that contains abundant clay.
siliceous sedimentary rock
sedimentary rock that contains abundant quartz.
chemical sedimentary rocks
sedimentary rocks made up of minerals that precipitate directly from water solution.
infiltrate
seep deep into
induced seismicity
seismic events caused by the actions of people (e.g., filling a reservoir that lies over a fault with water.)
S-waves
seismic shear waves that pass through the body of the Earth.
shear waves
seismic waves in which particles of material move back and forth perpendicular to the direction in which the wave itself moves.
body waves
seismic waves that pass through the interior of the Earth.
surface waves
seismic waves that travel along the Earth's surface.
stratigraphic group
several adjacent stratigraphic formations in a succession
oil shale
shale containing kerogen
tabular intrusions
sheet intrusions that are planar and of roughly uniform thickness.
lava flows
sheets or mounds of lava that flow onto the ground surface or sea floor in olten form and then solidify.
anthracite coal
shiny black coal formed at temperatures between 200 C and 300 C. A high-rank coal.
nonsystematic joints
short cracks in rocks that occur in a range of orientations and are randomly placed and oriented.
land subsidence
sinking elevation of the ground surface; the process may occur over an aquifer that is slowly draining and decreasing in volume because of pore collapse.
faulting
slip events along a fault.
shatter cones
small, cone-shaped fractures formed by the shock of a meteorite impact.
conchoidal fractures
smoothly curving, clamshell-shaped surfaces along which materials with no cleavage planes tend to break.
residual mineral deposit
soils in which the residuum left behind after leaching by rainwater is so concentrated in metals that the soil itself becomes an ore deposit.
energy resource
something that can be used to produce work; in a geologic context, a material (such as oil, coal, wind, flowing water) that can be used to produce energy.
alluvium
sorted sediment deposited by a stream
vacuum
space that contains very little matter in a given volume (e.g., a region in which air has been removed).
recurrence interval
the average time between sucessive geologic events.
climate
the average weather conditions, along with the range of conditions, of a region over a year.
second
the basic unit of time measurement, now defined as the time it takes for the magnetic field of a cesium atop to flip polarity 8,9192,631,770 times, as measured by an atomic clock.
headwaters
the beginning point of a stream
coast
the belt of land bordering the sea
ductile (plastic) deformation
the bending and flowing of a material (without cracking and breaking) subjected to stress.
wave refraction (ocean)
the bending of waves as they approach a shore so that their crests make no more than a 5 degree angle with the shoreline.
plate boundary
the border between two adjacent lithosphere plates.
snow line
the boundary above which snow remains all year.
cold front
the boundary at which a cold air mass pushes underneath a warm air mass.
mountain front
the boundary between a mountain range and adjacent plains
intrusive contact
the boundary between country rock and an intrusive igneous rock.
pycnocline
the boundary between layers of water of different densities
terminator
the boundary between the half of the Earth that has daylight an the half experiencing night.
wave front
the boundary between the region through which a wave has passed and the region through which it has not yet passed.
equilibrium line (of a glacier)
the boundary between the zone of accumulation and the zone of ablation.
front
the boundary between two air masses.
shoreline
the boundary between water and land.
halocline
the boundary in the ocean between surface-water and deep-water salinities.
contact
the boundary surface between two rock bodies (as between two stratigraphic formations, between an igneous intrusion and adjacent rock, between two igneous rock bodies, or between rocks juxtaposed by a fault.)
mesopause
the boundary that marks the top of the mesophere of Earth's atmosphere.
water table
the boundary, approximately parallel to the Earth's surface, that separates substrate in which groundwater fills the pores from substrate in which air fills the pores.
calving
the breaking off of chunks of ice at the edge of a glacier
mare
the broad darker areas on the Moon's surface; they consist of flood basalts that erupted over 3 billion years ago and spread out across the Moon's lowlands.
pediment
the broad, nearly horizontal bedrock surface at the base of a retreating desert cliff.
energy
the capacity to do work.
Sargasso Sea
the center of North Atlantic Gyre, named for the tropical seaweed sargassum, which accumulates in its relatively noncirculating waters.
nucleus
the central ball of an atom that consists of protons and neutrons (except for hydrongen, whose nuclei contains only a proton).
Ekman spiral
the change in flow direction of water with depth, caused by the Coriolis effect.
strain
the change in shape of an object in response to deformation (i.e. as a result of the application of a stress)
geotherm
the change in temperature with depth in the Earth.
cliff (scarp) retreat
the change in the position of a cliff face caused by erosion.
magnetic reversal
the change of the Earth's magnetic polarity; when a reversal occurs, the field flips from normal to reversed polarity, or vice versa.
shock metamorphism
the changes that occur in a rock due to the passage of a shock wave, generally resulting from a meteorite impact.
seismic ray
the changing position of an imaginary point on a wave front as the front moves through rock.
dry wash
the channel of an ephemeral stream when empty of water.
arroyo
the channel of an ephemeral stream; dry wash; wadi
turbulence
the chaotic twisting, swirling motion in flowing fluid
eruptive style
the character of a particular volcanic eruption; geologists name styles based on typical examples (e.g., Hawaiian Strombolian).
color
the characteristic of a material due to the spectrum of light emitted or reflected by the material due to the spectrum of light emitted or reflected by the material, as perceived by eyes or instruments.
detritus
the chunks and smaller grains of rock broken off outcrops by physical weathering.
anticyclone
the clockwise flow of air around a high-pressure mass.
black smoker
the cloud of suspended minerals formed where water spews out of a vent along a mid-ocean ridge; the dissolved sulfide components of the hot water instantly precipitate when the water mixes with seawater and cools.
flocculation
the clumping together of clay suspended in river water into bunches that are large eonough to settle out.
lag deposit
the coarse sediment left behind in a desert after wind erosion removes the finer sediment.
streak
the color of the powder produced by pulverizing a mineral on an unglazed ceramic plate.
wave erosion
the combined effects of the shattering, wedging, and abrading of a cliff face by waves and the sediment they carry.
magnetostratigraphy
the comparison of the pattern of magnetic reversals in a sequence of strata, with a reference column showing the succession of reversals through time.
DNA
the complex molecule, shaped like a double helix, containing the code that guides the growth and development of an organism.
downslope force
the compoent of the force of gravity acting in the downslope direction.
normal force
the componet of the gravitational force acting perpendicular to a slope.
grade of an ore
the concentration of a useful metal in an ore the higher the concentration, the higher the grade.
elastic-rebound theory
the concept that earthquakes happen because stress builds up, causing rock adjacent to a fault to bend elastically until breaking and slip on a fault occurs; the slip relaxes the elastic bending and decreases stress.
nebular theory of planet formation
the concept that planets grow out of rings of gas, dust, and ice surrounding a newborn star.
structural control
the condition in which geologic structures, such as faults, affect the distribution and drainage of water or the shape of the land surface.
symmetry
the condition in which the shape of one part of an object is a mirror image of the other part.
isostasy (isostatic equilbrium)
the condition that exists when the buoyancy force pushing lithosphere up equals the gravitational force pulling lithosphere down
steady state conditions
the condition when proportions of a chemical in different reservoirs remain fairly constant even though there is a constant flux (flow) of the chemical among the reservoirs.
mesosphere
the cooler layer of atmosphere overlying the stratosphere.
adiabatic cooling
the cooling of a body of air or matter without the addition or subtraction of thermal energy
brittle deformation
the cracking and fracturing of a material subjected to stress.
ridge axis
the crest of a mid-ocean ridge; the ___________ defines the position of a divergent plate boundary.
continental crust
the crust beneath the continents
oceanic crust
the crust beneath the oceans; composed of gabbro and basalt, overlain by sediment.
eccentricity cycle
the cycle of the gradual change of the Earth's orbit from a more circular to a more elliptical shape; the cycle takes around 100,000 years.
sunspot cycle
the cyclic appearance of large numbers of sunspots (black spots thought to be magnetic storms on the Sun's surface) ever 9 to 11.5 years.)
tide
the daily rising or falling of sea level at a given point on the Earth.
reef bleaching
the death and loss of color of a coral reef.
extinction
the death of the last memebrs of a species so that there are no parents to pass on their genetic traits to offspring.
daughter isotope
the decay product of radioactive decay
thalweg
the deepest part of a stream's channel
lower mantle
the deepest section of the mantle, stretching from 670 km down to the core-mantle boundaries.
Coriolis effect
the deflection of objects, winds, and currents on the surface of the Earth owing to the planet's rotation.
plastic deformation
the deformational process in which mineral grains behave like plastic and, when compressed or sheared, become flattened or elongate without cracking or breaking.
salinity
the degree of concentration of salt in water.
permeability
the degree to which a material allows fluids to pass through it via an interconnected network of pores and cracks.
magnetization
the degree to which a material can exert a magnetic force.
compressibility
the degree to which a material's volume changes in response to squashing
sediment maturity
the degree to which a sediment has evolved from a crushed up version of the original rock into a sediment that has lost its easily weatehr minerals and become well sorted and rounded.
angularity
the degree to which grains have sharp or rounded edges or corners.
core
the dense, iron-rich center of the Earth.
tide-generating force
the force, caused in part by the gravitational attraction of the Sun and Moon and in part by the centrifugal force created by the Earth's spin, that generates tides.
glacial advance
the forward movement of a glacier's toe when the supply of snow exceeds the rate of ablation.
permineralization
the fossilization process in which plant material becomes transformed into rock by the precipitation of silica from groundwater.
giant planets
the four outer, or Jovian, planets of our Solar System, which are significantly larger than the rest of the planets and consist largely of gas and or ice.
crystal habit
the general shape of a crystal or cluster of crystals that grew unimpeded.
crystal form
the geometric shape of a crystal, defined by the arrangement of crystal faces.
facet (of a gem(
the gorund and polished surface of a gem, produced by a gem cutter using a grinding lap.
creep
the gradual downslope movement of regolith
beach drift
the gradual migration of sand along a beach.
epeirogenic movement
the gradual uplift or subsidence of a braod region of the Earth's surface.
sea-floor spreading
the gradual widening of an ocean basin as new oceanic crust forms at a mid-ocean ridge axis and then moves away from the axis.
mass movement (mass wasting)
the gravitationally caused downslope transport of rock, regolith, snow, or ice.
backwash
the gravity-driven flow of water back down the slope of a beach.
erosion
the grinding away and removal of Earth's surface materials by moving water, air, or ice.
wind abrasion
the grinding away at surfaces in a desert by windblown sand and dust.
neocrystallization
the growht of new crystals, not in the protolith, during metamorphism.
latent heat of condensation
the heat relased during condensation which comes only fom a change in state.
smelting
the heating of a metal-containing rock to high temperatures in a fire so that the rock will decompose to yield metal plus a non-metallic residue.
solidus
the highest temperature at which all the components of a material are solid, at the solidus temperature, the material begins to melt.
magnetic-reversal chronology
the history of magnetic reversal through geologic time
wavelength
the horizontal difference between two adjacent wave troughs or two adjacent crests.
punctuated equilibrium
the hypothesis that evolution takes place in fits and starts; evolution occurs very slowly for quite a while and then, during a relatively short period, takes place very rapidly.
continental drift hypothesis
the idea that continents have moved and are still moving slowly across the Earth's surface.
light year
the idstance that light travels in one Earth year (about 6 trillion miles or 9.5 trillion km).
rotational axis
the imaginary line through the center of the Earth around which the Earth spins.
axial plane
the imaginary surface that encompasses the hinges of successive layers of a fold.
bioremediation
the injection of oxygen and nutrients into a contaminated aquifer to foster the growht of bacteria that will ingest or break down contaminants.
transgression
the inland migration of shoreline resulting from a rise in sea level.
rain shadow
the inland side of a mountain range, which is arid because the mountains block rain clouds from reaching the area.
inner core
the inner section of the core, extending from 5195 km deep to the Earth's center at 6371 km and consisting of solid into alloy.
fault trace (fault line)
the intersection between a fault and the ground surface.
ionosphere
the interval of Earth's atmosphere, at an elevation between 50 and 400 km, containing abundant positive ions.
range (for fossils)
the interval of a sequence of strata in which a specific fossil species appears.
hiatus
the interval of time between deposition of the youngest rock below an unconformity and deposition of the oldest rock above the unconformity.
chemical bond
the invisible link that holds together atoms in a molecule and or in a crystal.
decompression melting
the kind of melting that occurs when hot mantle rock rises to shallower depths in the Earth so that pressure decreases while the temperature remains unchanged.
Eubacteria
the kingdom of "true bacteria/"
oil reserve
the known supply of oil held underground
Alpine-Himalayan chain
the largest orgenic belt on Earth today, formed by collisions of the former Gondwana continents with the southern margins of Europe and Asia.
eon
the largest subdivision of geologic time.
Hercynian orogen
the late Paleozoic orogen that affected parts of Europe; a continuation of the Alleghenian orogen.
Antler orogeny
the late devonian mountain-building event in which slices of deep-marine strata were pushed eastward, up and over the shallow-water strata on the western coast of North America.
ancestral rockies
the late paleozoic uplifts of the rocky mountain region; they eroded away long before the present Rocky Mountains formed.
bioturbation
the mixing of sediment by burrowing anials such as clams and worms.
air
the mixture of gases that make up the Earth's atmosphere.
tephra
unconsolidated accumulations of pyroclastic grains.
soil moisture
underground water that wets the surface of the mineral grains and organic material making up soil, but lies above the water table.
basement uplift
uplift of basement rock by faults that penetrate deep into the continental crust.
updraft
upward-moving air.
bathymetry
variation in depth.
topography
variations in elevation
flood basalt
vast sheets of basalt that spread from a volcanic vent over an extensive surface of land; they may form where a rift develops above a continental hot spot, and where lava is particularly hot and has low viscosity.
conglomerate
very coarse-grained sedimentary rock consisting of rounded clasts.
chalk
very fine-grained limestone consisting of weakly cemented plankton shells.
shale
very fine-grained sedimentary rock that breaks into thin sheets.
mudstone
very fine-grained sedimentyar rock that will not easily split into sheers.
explosive eruptions
violent volcanic eruptions that produce clouds and avalanches of pyroclastic debris.
ash
volcanic ash
saturated solution
water that carries as many dissolved ions as possible under given environmental conditions.
meteoric water
water that falls to Earth from the atmosphere as either rain or snow
running water
water that flows down the surface of sloping land in response to the pull of gravity.
brine
water that is not fresh but is less salty than seawater; _____ may be found in estuaries.
groundwater
water that resides under the surface of the Earth, mostly in pores or cracks of rock or sediment.
compressional waves
waves in which particles of material move back and forth parallel to the direction in which the wave itself moves.
seismic (earthquake ) waves
waves of energy emitted at the focus of an earthquake.
rogue wave
waves that are two to five time the size of most of the large waves passing a locality in a given time interval.
chatter marks
wedge-shaped indentations left on rock surfaces by glacial plucking.
high-altitude westerlies
westerly winds at the top of the troposphere.
differential weathering
what happens when different rocks in an outcrop undergo weathering at different rates.
plate tectonics
what the theory of plate tectonics is about.
stream terrace
when a stream downcuts through the alluvium of a floodplain so that a new, lower floodplain develops and the original floodplain becomes a step-like platform.
shear
when one part of a material moves sideways, relative to another.
sediment liquifaction
when pressure in the water in the pores push sediment grains apart so that they become surrounded by water and sediment grains apart so that they become surrounded by water and no longer rest against each other, and the sediment becomes able to no longer rest against each other, and the sediment becomes able to flow like a liquid.
drainage reversal
when the overall direction of flow in a drainage network becomes the opposite of what it once had been.
Laramide orogeny
the mountain-building event that lasted from about 80 Ma to 40 Ma, in western North America; in the United States, it formed the Rock Mountains as a result of basement uplift and the warping of the younger overlying strata into large monoclines.
global circulation
the movement f volumes of air in paths that ultimately take it around the planet.
glacial retreat
the movement of a glacier's toe back toward the glacier's origin; ________________ occurs if the rate of ablation exceeds the rate of supply.
absolute plate velocity
the movement of a plate relative to a fixed point in the mantle
saltation
the movement of a sediment in which grains bounce along their substrate, knocking other grains into the water column (or air)in the process.
southern oscillation
the movement of atmospheric pressure cells back and forth across the Pacific Ocean, in association with El Nino.
relative plate velocity
the movement of one lithosphere plate with respect to another.
longshore drift
the movement of sediment laterally along a beach; it occurs when waves wash up a beach diagonally.
Hadley cells
the name given to the low-latitude convection cells in the atmosphere
Ferrel cells
the name given to the middle-latitude convection cells in the atmosphere.
oil window
the narrow range of temperatures under which oil can form in a source rock.
resurgent dome
the new mound, or cone, of igneous rock that grows within a caldera as an eruption begins anew.
atomic number
the number of protons in the nucleus of a given element.
atomic weight
the number of protons plus the number of neutrons in the nucleus of a given element.
frequency
the number of waves that pass a point in a given time interval.
magnitude (of an earthquake)
the number that represents the maximum amplitude of ground motion that would be measured by a seismometer placed at a specified distance from the epicenter.
paleozoic era
the oldest era of the phanerozoic eon.
Hadean Eon
the oldest of the precambrian eons; the time between Earth's orgin and the formation of the first rocks that have been preserved.
crystal lattice
the orderly framework within which the atoms or ions of a mineral are fixed.
alleghenian orgeny
the orgenic event that occured about 270 miollion years ago when Africa collided with North america.
protolith
the original rock from which a metamorphic rock formed
Grenville orogeny
the orogeny that occurred about 1 billion years ago and yielded the belt of deformed and metamorphosed rocks that underlie the eastern fifth of the North American continent.
cut bank
the ouside bank of the channel wall of a menader, which is continually undergoing erosion.
thermosphere
the outermost layer of the atmosphere, containing very little gas.
mouth
the outlet of a stream where it discharges into another stream, a lake, or a sea.
Ekman transport
the overall movement of a mass of water, resulting from the Eckman spiral, in a direction 90 degrees to the wind direction.
nuclear reactor
the part of a nuclear power plant where the fission reactions occur.
dipole field for Earth
the part of the Earth's magnetic field, caused by the flow f liquid iron alloy in the outer core, that can be be represented by an imaginary bar magnet with a north and south pole.
paleoclimate
the past climate of the Earth.
Holocene climatic maximum
the period from 5,0000 to 6,000 years ago, when Holocene temperatures reached a peak.
Holocene
the period of geologic time since the last glaciation.
Oil Age
the period of human history, including our own, so named becaue hte conomy depends on oil.
pleistocene epoch
the period of time from about 2 ma to 14000 years ago, during which the earth experienced an ice age.
cementation
the phase of lithification in which cement, consisting of minerals that precipitate from groundwater, partially or completely fills the spaces between clasts and attaches each grain to its neighbor.
compaction
the phase of lithification in which the pressure of the overburden on the buried rock squeezes out water and air that was trapped between clasts, and the clasts press tightly together.
Doppler effect
the phenomenon in whcih the frequency of wave energy appears to change when a moving source of wave energy passes an observer.
red shift
the phenomenon in which a source of light moving away from you very rapidly shift to a lower frequency; that is, toward the red end of the spectrum.
blue shift
the phenomenon in which a source of light moving toward you appears to have a higher frequency.
basal sliding
the phenomenon in which meltwater accumulates at the base of a glacier, so that the mass of the glacier slides on a layer of water or on a slurry of water and sediment.
drawdown
the phenomenon in which the water table around a well drops because the users are pumping water out of the well faster than it flows infrom the surrounding aquifer.
ecliptic
the plane defined by a planet's orbit.
overriding plate (slab)
the plate ata subduction zone that overrides the downgoing plate.
epicenter
the point on the surface of the Earth directly above the focus of an earthquake
slickensides
the polished surface of a fault caused by slip on the fault; lineated _____________ also have grooves that indicate the direction of fault movement.
hinge
the portion of a fold where curvature is greatest
country rock (wall rock)
the preexisting rock into which magma intrudes.
surface westerlies
the prevailing surface winds in North America and Europe, which come out of the west or southwest.
exhumation
the process (involving uplift and erosion) that returns deeply buried rocks to the surface.
continental rifting
the process by which a continent stretches and splits along a belt; if it is successful, rifting separates a larger continent into two smaller continents separated by a divergent boundary.
glacial plucking glacial quarrying
the process by which a glacier breaks off and carries away fragments of bedrocks.
fractional crystallization
the process by which a magma becomes progressively more silicic as it cools, because early-formed crystals settle out.
secondary enrichment
the process by which a new ore deposit forms from metals that were dissolved and carried away from preexisting ore minerals.
metasomatism
the process by which a rock's overall chemicall composition changes during metamorphism because of reactions with hot water that bring in or remove elements.
headward erosion
the process by which a stream channel lengthens up its slope as the flow of water increases.
exfoliation
the process by which an outcrop of rock splits apart into onion-like sheets along joints that lie parallel to the ground surface.
glacial abrasion
the process by which clasts embedded in the base of a glacier grind away as the substrate as the glacier flows.
glacial incorporation
the process by which flowing ice surrounds and incorpoates debris
percolation
the process by which groundwater meanders through tiny- crooked channels in the surrounding aterial
subduction
the process by which one oceanic plate bends and sinks down into the asthenosphere beneath another plate.
metamorphism
the process by which onekind of rock transforms into a different kind of rock.
grain rotation
the process by which rigid, inequant mineral grains distributed through a soft matrix may rotate into parallelism as the rock changes shape owing to differential stress.
liquifaction
the process by which saturated, unconsilidated sediments are transformed into a substance that acts like a liquid as a result of ground shaking.
deposition
the process by which sediment settles out of a transporting medium.
crustal thickening
the process by which the continental crust increases in thickness, becoming up to 70 km thick (vs. normal thickness of about 35-40 km); it can occur during continental collision.
natural selection
the process by which the fittest organisms survive to pass on their characteristis to the next generation
glacial rebound
the process by which the surface of a continent rises back up after an overlying continental ice sheet melts away and the weight of the ice is removed.
liquification
the process by which wet sediment becomes a slurry; ____________ may be triggered by earthquake vibrations.
shortening
the process during which a body of rock or a region of crust becomes shorter.
stretching
the process during which a layer of rock or a region of crust becomes longer.
photosynthesis
the process during which chlorophyll-containing plants remove carbon dioxide from the atmosphere, form tissues, and expel oxygen back to the atmosphere.
salt wedging
the process in arid climates by whcih dissolved salt in groundwater crystallizes and grows in open pore spaces in rock and pushes apart the surrounding grains.
frost wedging
the process in whcih water trapped in a joint freezes, forces the joint open, and may cause the joint to grow.
change of state
the process in which a material changes from one phase (liquid, gas, or solid) to another.
avulsion
the process in which a river overflows a natural levee and begins to flow in a new direction.
chemical weathering
the process in which chemical reactions alter or destroy minerals when rock comes in contact with water solutions and or air.
magma contamination
the process in which flowing magma incorporates components of the country rock through which it passes.
physical weathering
the process in which intact rock breaks into smaller grains or chunks.
recrystallization
the process in which ions or atoms in minerals rearrange to form new minerals.
orogenic collapse
the process in which mountains begin to collapse under their own weight and spread out laterally.
abrasion
the process in which one material (such as sand-laden) water) grinds away at another (such as a stream channel's floor and walls).
isostatic compensation
the process in which the surface of the crust slowly rises or falls to reestablish isostatic equilibrium after a geologic event changes the density or thickness of the litosphere.
downcutting
the process in which water flowing through a channel cuts into the substrate and deepens the channel relative to its surroundings.
supercontinent cycle
the process of change during which supercontients develop and later break apart, forming pieces that may merge once again in geologic time to make yet another supercontinent.
directional drilling
the process of controlling the trajectory of a drill bit to make sure that the drill hole goes exactly where desired.
correlation
the process of defining the age relations between the strata at one locality and the strata at another.
carbon sequestration
the process of extracting carbon dioxide from sources (e.g., power plants) and sending it back underground to keep it out of the atmosphere and diminish the greenhouse effect.
flexing
the process of folding in which a succession of rock layers bends and slip occurs between the layers.
flexing
the process of folding in which a sucession of rock layers bends and slip occurs between the layers.
fossilization
the process of forming a fossil
condensation
the process of gas molecules linking together to form a liquid.
deflation
the process of lowering the land surface by wind abrasion.
assimilation
the process of magma contamination in which blocks of wall rock fall into a magma chamber and dissolve.
coal gasification
the process of producing relatively clean-burning gases from solid coal.
desertification
the process of transforming nondesert areas into desert.
collision
the process of two buoyant pieces of lithosphere converging and squashing together.
weathering
the processes that break up and corrode solid rock, eventually transforming it into sediment.
stellar nucleosynthesis
the production of new, larger atoms by fusion reactions in stars; the process generates more massive elements that were not produced by the Big Bang.
concentration
the proportion of one substance (the solute) dissolved within another (the solvent)
sediment budget
the proportion of sand supplied to sand removed from a depositional setting.
iron catastrophe
the proposed event very early in Earth history when the Earth partly melted and molten iron sank to the center to form the core.
magnetic force
the push or pull exerted by a magnet.
normal stress
the push or pull that is perpendicular to a surface.
air pressure
the push that air exerts on its surroundings
stress
the push, pull, or shear that a material feels when subjected to a force; formally, the force applied per unit area over which the force acts.
coal reserve
the quantities of discovered, but not yet mined, coal in sedimentary rock of the continents.
nuclear waste
the radioactive material produced as a byproduct in a nuclear plant that must be disposed of carefully due to its dangerous radioactivity.
heat flow
the rate at which heat rises from the Earth's interior up to the surface.
spreading rate
the rate at which sea floor moves away from a mid-ocean ridge axis, as measured with respect to the sea floor on the opposite side of the axis.
geothermal gradient
the rate of change in temperature with depth.
relative humidity
the ratio between the measured water content of air and the maximum possible amount of water the air can hold at a given condition.
seismogram
the record of an earthquake produced by a seismograph.
paleomagnetism
the record of ancient magnetism preserved in rock.
albedo
the reflectivity of a surface
magnetic field
the region affected by the fore emanating from a magnet.
subduction zone
the region along a convergent boundary where one plate sinks beneath another.
metamorphic aureole
the region around a pluton, stretching tens to hundreds of meters out, in which heat transferred into the country rock and metamorphosed the country rock.
metamorphic zone
the region between two metamorphic isograds, typically named after an index mineral found within the region.
habitable zone
the region in the solar system where the intensity of radiation is sufficient to allow water to exist in liquid form on the surface of a planet .
biosphere
the region of the Earth and atmosphere inhabited by life; this region stretches from a few km below the Earth's surface to a few km above.
unsaturated zone
the region of the subsurface above the water table.
horse latitudes
the region of the subtropical high in which winds are weak.
watershed
the region that collects water that feeds into a given drainage network.
eye
the relative calm in the center of a hurricane.
seismic belts (seismic zones)
the relatively narrow strips of crust on Earth under which most earquakes occur.
lithosphere
the relatively rigid, nonflowable, outer 100_ to 150-km_ thick layer of the Earth, constituting the crust and the top part of the mantle.
van der Waals bonding
the relatively weak attachment of two elements or molecules due to their polarity and not due to covalent or ionic bonding
transpiration
the release of moisture as a metabolic by-product.
Cambrian explosion of life
the remarkable diversification of life, indicated by the fossil record, that occurred at the beginning of the Cambrain Period.
fossil
the remnant, or trace, of an ancient living organism that has been preserved in rock or sediment.
beach erosion
the removal of beach sand caused by wave action and longshore currents.
denudation
the removal of rock and regolith from the Earth's surface.
soil erosion
the removal of soil by wind and runoff.
viscosity
the resistance of material to flow.
stream rejuvenation
the revewed downcutting of a stream into a floodplain or peneplain, caused by a relative drop of the base level.
subpolar low
the rise of air where the surface flow of a polar cell converges with the surface flow of a ferrel cell, creating a low-pressure zone in the atmosphere.
thermohaline circulation
the rising and sinking of water driven by contrasts i water density, which is due in turn to differences in temperature and salinity; this circulation involves both surface and deep-water currents in the ocean.
flood tide
the rising tide.
hanging wall
the rock or sediment above an inclined fault plane.
crust
the rock that makes up the outermost layer of the Earth.
aurora australis
the same phenomenon as the aurora borealis, but in the southern hemisphere.
Inactive sand
the sand along a coast that is buried beneath a layer of active sand and oves only during sever storms or not at all.
radiometric dating
the science of dating geologic events in years by measuring the ratio of parent radioactive atoms to daughter product atoms.
geochronology
the science of dating geologic events in years.
strip mining
the scraping off of all soil and sedimentary rock above a coal seam in order to gain access to the seam.
regression
the seaward migration of shoreline caused by a lowering of sea level.
outer core
the section of the core, between 2900 and 5150 km deep, that consists of liquid iron alloy.
sediment sorting
the segregation of sediment by size.
Moho
the seismic-velocity discontinuity that defines the boundary between the Eart's crust and mantle. Named for Andrija Mohorovicic.
Bowen's reaction series
the sequence in which different silicate minerals crystallize during the progressive cooling of a melt.
aftershocks
the series of smaller earthquakes that follow a major earthquake.
foreshocks
the series of smaller earthquakes that precede a major earthquake
limb
the side of a fold showing less curvature than at the hinge.
trunk stream
the single larger stream into which an array of tributaries flow.
glacial subsidence
the sinking of the surface of a continent caused by the weight of an overlying glacial ice sheet.
stream capture (stream piracy)
the situation in which headward erosion causes one stream to intersect the course of another, previously independent stream, so that the intersected stream starts to flow down the channel of the first stream.
continental slope
the slope at the edge of a continental shelf, leading down to the deep sea floor.
stream gradient
the slope of a stream's channel in the downstream direction
continental rise
the sloping sea floor that extends from the lower part of the continental slope to the abyssal plain.
solid-state diffusion
the slow movement of atoms or ions through a solid
atom
the smallest peice of an element that has the properties of the element; it consists of a nucleus surrounded by an electron cloud.
molecule
the smallest piece of a compound that has the properties of the compound; it consists of two ro more atoms attached by chemical bonds.
geologic time
the span of time since the formation of the Earth.
seismic velocity
the speed at which seismic waves travel.
diffraction
the splitting of light into many tiny beams that interfere with one another.
stratosphere
the stable, stratiphied layer of atmosphere directly above the troposphere.
flood stage
the stage when water reaches the top of a stream channel.
reactact
the starting materials of a chemical reaction.
stellar wind
the stream of atoms emitted from a star into space.
seismic retrofitting
the strengthening of an already existing structure (building, bridge, etc.) so that it can withstand earthquake vibrations.
taxonomy
the study and classification of the relationships among different forms of life.
genetics
the study of genes and how they transmit information.
geology
the study of the Earth, including our planet's composition, behavior and history.
cosmology
the study of the overall structure of the Universe.
rock cycle
the sucession of events that results in the transformation of Earth materials from one rock type to another, then another, and so on.
evapotranspiration
the sum of evaporation from bodies of water and the ground surface and transpiration from plants and animals.
palepole
the supposed position of the Earth's magnetic pole in the past, with respect to a particular continent.
glide horizon
the surface along which a slump slips
dewpoint temperature
the temperature at which air becomes saturated so that dew can form.
melting temperature
the temperature at which the thermal vibration of the atoms or ions in the lattice of a mineral is sufficent to break the chemical bonds holding them to the lattice, so a material transforms into a liquid.
blocking temperature
the temperature below which isotopes in a mineral are no longer free to move, so that radiometric clock starts.
tropopause
the temperature pause marking the top of the troposphere
stratopause
the temperature pause that marks the top of the stratosphere
inertia
the tendency of an object at rest to remain at rest.
Gaia
the term used for the Earth System, with the implication that it resembles a complex living entity.
interlocking texture
the texture of crystalline rocks in which mineral grains fit together like pieces of a jigsaw puzzle.
gradualism
the theory that evolution happens at a constant, slow rate.
theory of plate tectonics
the theory that the outer layer of the Earth (the lithosphere) consists of separate plates that move with respect to one another.
expanding universe theory
the theory that the whole univrse must be expanding because galaxies in every directio nseem to be moving away from us.
mantle
the thick layer of rock below the Earth's crust abd above the core.
capillary fringe
the thin subsurface layer in which water molecules seep up from the water table by capillary action to fill pores.
Greenwich mean time (GMT)
the time at the astronomical observatory in Greenwich, England; time in all other time zones is set in relation to GMT.
great oxygenation event
the time in Earth's history, about 2.4 Ga, when the concentration of oxygen in the atmosphere increased dramatically.
chron
the time interval between successive magnetic reversals.
half-life
the time it takes for half of a group of a radioactivie element's isotopes to decay.
day
the time it takes for the Earth to spin once on its axis.
active sand
the top layer of beach sand, which moves daily because of wave action
topsoil
the top soil horizons, which are typically dark and nutrient-rich.
thermal energy
the total kinetic energy in a material due to the vibration and movement of atoms in the material.
capacity of a stream
the total quantity of sediment a stream can carry.
stream capacity
the total quantity of sediment a stream carries
sediment load
the total volume of sediment carried by a stream.
magnetic field lines
the trajectories along which magnetic particles would align, or charged particles would flow, if placed in a magnetic field.
flux melting
the transformation of hot solid to liquid that occurs when a volatile material injects into the solid.
lithification
the transformation of loose sediment into solid rock through compaction and cementation
global change
the transformations or modifications of both physical and biological components of the Earth System through time.
greenhouse effect
the trapping of heat in the Earth's atmosphere by carbon dioxide and other greenhouse gases, which absorb infrared radiation; somewhat analogous to the effect of glass in a greenhouse.
planetesimal
tiny, solid pieces of rock and metal that collect in a planetary nebula and eventually accumulate to form a planet.
evaporate
to change from liquid to vapor
leach
to dissolve and carry away.
southeast tradewinds
tradewinds in the southern hemisphere, which start flowing northward, deflect to the west, and end up flowing from southeast to northwest.
global climate change
transformations or modifications in Earth's climate over time.
welded tuff
tuff formed by the welding together of hot volcanic glass shards at the base of pyroclastic flows.
air-fall tuff
tuff formed when ash settles gently from the air.
Ice sheet
A vast glacier that covers the landscape
shell
(biology) a relatively hard, protective structure formed of minerals and surrounding the soft part of an invertebrate organism.
bar
1. a sheet or elongate lends or mound of alluvium; 2. a unit of air-pressure measurement approximately equal to 1 atm.
facies
1. sedimentary: a group of rocks and primary structures indicative of a given depositional environment; 2. metamorphic: a set of metamorphic mineral assemblages formed under a given range of pressures and temperatures.
cyclone
1. the counterclockwise flow of air around a low-pressure mass; 2. the equivalent of a hurricane in the Indian Ocean.
Ice shelf
A broad, flat region of ice along the edge of a continent formed where a continental glacier flowed into the sea.
Big Bang
A cataclysmic explosion that scientists suggest represents the formation of the Universe; before this event, all matter and all energy were packed into one volumeless point.
Hydrocarbon
A chain-like or ring-like molecule made of hydrogen and carbon atoms; petroleum and natural gas are hydrocarbon.
Kuiper Belt
A diffuse ring of icy objects, remnants of Solar System formation, that orbit our sun outside the orbit of Neptune.
Inactive fault
A fault that last moved in the distant past and probably won't move again in the near future yet is still recognizable because of displacement across the fault plane.
Hyposmetric curve
A graph that plots surface elevation on the vertical axis and the percentage of the earth's surface on the horizontal axis.
Hurricane
A huge rotating storm, resembling a giant spiral in map view, in which sustained winds blow over 119 km per hour.
Hot spot
A location at the base of the lithosphere, at the top of a mantle plume, where temperatures can cause melting
Ice-margin lake
A meltwater lake formed along the edge of a glacier.
Icehouse period
A period of time when the earth's temperature was cooler than usual and ice ages could occur.
Hyloclastite
A rubbly extrusive rock consisting of glassy debris formed in a submarine or sub-ice eruption.
Hot spring
A spring that emits water ranging in temperature from about 30c to 104 c.
Ice age
An interval of time in which the climate was colder than it is today, glaciers occasionally advanced to cover large areas of the continents, and mountain glaciers grew; an _______ can include many glacials and interglacials.
Hummocky surface
An irregular and lumpy ground surface.
Hot spot volcano
An isolated volcano not caused by movement at a plate boundary but rather by the melting of a mantle plume.
surface current
An ocean current in the top 100 m of water.
Ga
Billions of years ago
Ediacaran fauna
Multicellular invertebrate organisms that lived perhaps as early as 620 Ma and certainly by 565 Ma. They were named for a region in southern Australia.
ozone
O3, an atmospheric gas that absorbs harmful ultraviolet radiation from the sun.
Ignimbrite
Rock formed when deposits of pyroclastic flows solidify
Igneous rock
Rock that forms when hot molten rock (magma or lava) cools and freezes solid.
Ice rafted sediment
Sediment carried out to sea by icebergs
Hydration
The absorption of water into the crystal structure of minerals; a type of chemical weathering.
Hydrocarbon system
The association of source rock, migration pathway, reservoir rock, seal, and trap geometry that leads to the occurrence of a hydrocarbon of a hydrocarbon reserve.
Hydrogen bond
The attraction of a hydrogen atom to a negatively charged atom or molecule (e.g., ___________s attach water molecules to each other.
earthquake zoning
The determination of where land is relatively stable and where it might collapse because of seismicity.
Hydrosphere
The earth's water, including surface water (lakes, rivers, and oceans.) groundwater, and liquid water in the atmosphere.
Mesozoic Era
The middle of the three Phanerozoic eras; it lasted from 245 Ma to 65 Ma.
Phanerozoic Eon
The most recent eon, an interval of time from 54 Ma to the present.
Cenozoic Era
The most recent era of the Phanerozoic Eon, lasting from 65 MA up until the present.
wadi
The name used in the Middle East and North africa for a dry wash.
Hurricane track
The path a hurricane follows.
Hypocenter focus
The place within the earth where earthquake energy originates; commonly the hypocenter is the place on a fault where slip took place.
Ice tongue
The portions of a valley glacier that has flowed out into the sea.
Hydraulic head
The potential energy available to drive the flow of a given volume of groundwater at a location; it can be measured as an elevation above a reference.
Hydrolysis
The process in which water chemically reacts with minerals and breaks them down.
geologic history
The sequence of geologic events that has taken place in a region.
Hydraulic gradient
The slope of the water table.
Hydrothermal metamorphism
When very hot water passes through the crust and causes metamorphism of rock.
La Niña
Years in which the El Ñińo event is not strong.
catastrophic change
change that takes place either instantaneously or rapidly in geologic time.
groundwater contamination
addition of chemicals or microbes (e.g., from agricultrual and industrial activities, and landfills or septic tanks.) to the groundwater supply.
stable air
air that does not have a tendency to rise rapidly.
unstable air
air that is significantly warmer than air above and has a tendency to rise quickly.
diagenesis
all of the physical, chemical, and biological process that transform sediment into sedimentary rock and that alter the rock after the rock has formed.
Universe
all ofspace and all the matter and energy within it.
paleosol
ancient soil preserved in the stratigraphic record.
regolith
any kind of uncosolidated debris that covers bedrock.
lapili
any pyroclastic particle that can consist of frozen lava clots, pumice fragments, or ash clumps
short-term climate change
climate change that takes place over hundreds to thousands of years.
intraplate earthquakes
earthquakes that occur away from plate boundaries
swelling clay
clay possessing a mineral structure that allows it to absorb water between its layers and thus swell to several times its original size.
ash fall
ash that falls to the ground out of an ash cloud.
quick clay
clay that behaves like a solid when still (because of surface tension holding the water-coated clay flakes together) but that flows like a liquid when shaken.
greenhouse gases
atmospheric gases, such as carbon dioxide and methane, that regulate the earth's atmospheric temperature by absorbing infrared radiation.
backscattered light
atmospheric scattered sunlight that returns to space
rhythmic layering
banding in sediments, shells, trees, corals, or ice that repeats periodically; it may be correlated to annual cycles.
hamada
barren, rocky highlands in a desert.
Van Allen radiation belts
belts of solar wind particles and cosmic rays that surround the Earth, trapped by Earth's magnetic field.
cyanobacteria
blue-green algae; a type of archaea.
photochemical smog
brown haze that blankets a city when exhaust from cars and trucks reacts in the presence of sunlight.
organic carbon
carbon that has been incorporated in an organism.
tropical disturbances
cyclonic winds that develop in the tropics.
subtropics
desert climate regions that lie on either side of the equatorial tropics between the lines of 20 degrees and 30 degrees north or south of the equator.
isotopes
different versions of a given element that have the same atomic number but different atomic weights.
soil horizon
distinct zones within a soil, distinguished from each other by factors such as chemical composition and organic content.
chemical fossil
distinctive molecules or molecular fragments, formed from the remains of living organisms, that can be preserved in rock.
spreading boundary
divergent plate boundary
slumping
downslope movement in which a mass of regolith detaches from its substrate along a spoon-shaped, sliding surface and slips downward semicoherently.
downdraft
downward-moving air.
tornado swarm
dozens of tornadoes produced by the same storm
catchment
drainage network
petroglyph
drawings formed by chipping into the desert varnish of rocks to reveal the lighter rock beneath.
peles hair
droplets of basaltic lava that mold into long glassy strands as they fall.
peles tears
droplets of basaltic lava that mold into tear-shaped, glassy beads as they fall.
bituminous coal
dull, black intermediate-rank coal formed at temperatures between 100 C and 200 C.
parabolic dunes
dunes formed when strong winds break through transverse dunes to make new dunes whose ends point upwind.
regional metamorphism
dynamothermal metamorphis; metamorphism of a broad region, usually the result of deep burial during an orogeny.
seismicity
earthquake activity
magma
molten rock beneath the Earth's surface.
trace fossil
fossilized imprints or debris that an organism leaves behind while moving on or through sediment; examples include footprints, burrows, and fecal matter.
pyroclastic debris
fragmented material that sprayed out of a volcano and landed on the ground or sea floor in solid form.
fault breccia
fragmented rock in which angular fragments were formed by brittle fault movement; ______________ occurs along a fault.
cinders
fragments of glassy rock ejected from a volcano.
biofuel
gas or liquid fuel made from plant material (biomass). Examples of ______ include alcohol ( from fermented sugar), biodiesel from vegetable oil, and wood.
shale gas
gas that comes directly from a source rock (organic shale.)
stratified drift
glacial sediment that has been redistributed and stratified by flowing water
pillow basalt
glass-encrusted basalt blobs that form when magma extrudes on the sea floor and cools very quickly.
fault creep
gradual movement along a fault that occurs in the absence of an earthquake.
shocked quartz
grains of quartz that have been subjected to intense pressure such as occurs during a meteorite impact.
glacial striation
grooves or scratches cut into bedrock when clasts embedded in the moving glacier act like the teeth of a giant rasp.
hard water
groundwater that contains dissolved calcium and magnesium, usually after passing through limestone or dolomite.
mineral classes
groups of minerals distinguished from each other on the bass of chemical composition.
pumice lapilli
marble-sized chunks consisting of frothy, siliceous igneous rock that fall from a volcanic eruptive cloud.
density
mass per unit volume
heat-transfer melting
melting that results from the transfer of heat from a hotter magma to a cooler rock.
base metals
metals that are mined but not considered precious. Examples include copper, lead, zinc, and tin.
thermal metamorphism
metamorphism caused by heat conducted into country rock from an igneous intrusion.
burial metamorphism
metamorphism due only to the consequences of very deep burial.
dynamothermal metamorphism
metamorphism that involves heat, pressure, and shearing
dynamic metamorphism
metamorphism that occurs as a consequence of shearing alone, with no change in temperature or pressure.
retrograde metamorphism
metamorphism that occurs as pressures and temperatures are decreasing; for retrograde metamorphism to occur, water must be added.
pelagic sediment
microscopic plankton shells and fine flakes of clay that settle out and accumulate on the deep-ocean floor
pelagic sediment
microscopic plankton shells and fine flakes of up to tens of centimeters across and ocurring in dike-shaped intrusion.
foraminifera
microscopic plankton with calcitic shells, components of some limestones
cement
mineral material that precipitates from water and fills the spaces between grains, holding the grains together.
nonmetallic mineral resources
mineral resoures that do not contain metals; examples include building stone, gravel, sand, gypsum, phosphate, and salt.
silicates (silicate minerals)
minerals built from silicon-oxygen tetrahedra arranged in chains, sheets, or 3D networks; tehy make up most of the Earth's crust and mantle.
ore minerals
minerals that have metal in high concentrations and in a form that can be easily extracted.
index minerals
minerals that serve as good indicators of metamorphic grade.
industrial minerals
minerals that serve as the raw materials for manufacturing chemicals, concrete, and wallboard, among other products.
metl
molten liquid rock
coalbed methane
natural gas created during the formation of coal, that gets trapped within the coal.
joints
naturally formed cracks in rocks
metamorphic mineral
new minerals that grow in place within a solid rock under metamorphic teperatures and pressures.
secondary porosity
new pore space in rocks, created some time after a rock first forms.
high-level waste
nuclear waste containing greater than 1 million times the safe level of radioactivity.
cosmic rays
nuclei of hydrogen and other elements that bombard the Earth from deep space.
absolute age
numerical age (the age specified in years).
parallax
the apparent movement of an object seen from two different points on not on a straight line from the object.
crude oil
oil extracted directly from the ground.
basement
older igneous and metamorphic rocks making up the Earth's crust beneath sedimentary cover.
rare earth element
one of a group of 17 elements including the lathanides, scandium, yttrium; they are essential in the production of high-tech devices.
plate
one of about 20 distinct pieces of the relatively rigid lithosphere
lithosphere plate
one of many distinct pieces of the lithosphere (Earth's relatively rigid shell) that are sepearted from one another by breaks (plate boundaries)
asteroid
one of the fragments of solid material, left over from planet formation or produced by collision of planetisimals, that resides between the orbits of Mars and Jupiter.
equinox
one of two days out of the year (September 22 and March 21 in which the Sun is directly overhead at noon at the equator.
vesicles
open holes in igneous rock formed by the preservation of bubbles in magma as the magma cools into solid rock.
solar system
our sun and all the materials that orbit it (including planets, moons, asteroids, kuiper belt objects, and oort cloud objects).
nuclear fuel
pellets of concentrated uranium oxide or a comparable radioactive material that can provide energy in a nuclear reactor.
ripple mark
relatively small elongated ridges that form on a sedimentary bed surface at right angles to the direction of current flow.
greenhouse conditions (greenhouse period)
relatively warm global climate leading to the rising of sea level for an interval of geologic time.
friction
resistance to sliding on a surface.
silicic
rich in silica with relatively little iron and magnesium.
stone rings
ridges of cobbles between adjacent bulges of permafrost ground
silicate rock
rock composed of silicate minerals
nonfoliated metamorphic rock
rock containing minerals that recrystallized during metamorphism but has no foliation.
waste rock
rock dislodged by mining activity yet containing nor ore minerals
intrusive igneous rock
rock formed by the freezing of magma underground
mylonite
rock formed during dynamic metamorphism and caracterized by foliation that lies roughyl parallel to the fault (shear zone) involved in the searing process; mylonites have very fine grains formed by the nonbrittle subdivision of larger grains.
tillite
rock formed from hardened ancient glacial deposits and consisting of larger clasts distributed through a matrix of sandstone and mudstone.
pyroclastic rock
rock made from fragments that were blown out of a volcano during an explosion and were then packed or welded together.
bedrock
rock still attached to the Earth's crust.
wetted perimeter
the area in which water touches a stream channel's walls.
convergent margin
synonymous to convergent margin
consuming boundary
synonymous to convergent plate boundary
composite volcano
synonymous to stratovolcano
contact metamorphism
synonymous to thermal metamorphism.
flux
synonymous with flow
petroleum
synonymous with oil
zone of aeration
synonymous with unsaturated zone.
nuclear fusion
th process by which the nuclei of atoms fuse together, thereby creating new, larger atoms
chemical formula
the 'recipe' that specifies the elements and their proportions in a compound.
silicon-oxygen tetrahedron
the SIO(4)4- anionic group, in which four oxygen atoms surround a single silicon atom, thereby defining the corners of a tetrahedron.
sustainable growth
the ability of society to prosper without depleting the supply of natural resources, and without destroying the environment.
numerical age
the age of a geologic feature given in years
relative age
the age of one geologic feature with respect to anotehr.
atomic mass
the amount of matter in an atom; roughly, it is the sum of the number of protons plus the number of neutrons in the nucleus.
mass
the amount of matter in an object; mass differs from weight in that its value does not depend on the strength of gravity.
displacement offset
the amount of movement or slip across a fault plane.
biomass
the amount of organic material in a specified volume.
magnetic inclination
the angle between a magnetic needle free to pivot on a horizontal axis and a horizontal plane parallel to the Earth's surface.
magnetic declination
the angle between the direction a compass needle points at a given location and the direction of true north.
dip
the angle of a plane's slope as measured in a vertical plane perpendicular to the strike
angle of repose
the angle of the steepest slope that a pile of uncemented material can attain without collapsing from the pull of gravity.
faint young Sun paradox
the apparent contradiction implied by the fact that much of the Earth's surface temperature has remained above the melting point of water during the past 4 Ga, even though calculations indicate that hte sun produced much less energy when young.
zone of leaching
the layer of regolith in which water dissolves ions and picks up very fine clay; these materials are then carried downward by infiltrating water.
asthenosphere
the layer of the mantle that lies between 100-150 km and 350 km deep; the asthenosphere is relatively soft and can flow when acted on by force.
toe(terminus)
the leading edge or margin of a glacier
slip face
the leeward slope of a dune; sand that builds up at the crest of the dune slides down this face; ___________ are preserved as cross beds within sandstone layers.
annual probability
the likelihood that a flood of a given size or larger will happen ata specified locality during an given year.
melting curve
the line defining the range of temperatures and pressures at which a rock melts.
hoodoo
the local nae for the brightly colored shale and sandstone chimneys found in Bryce Canyon National Park in Utah.
focus
the location where a fault slips during an earthquake (hypocenter).
geographical pole
the locations (north and south( where the Earth's rotational axis intersects the planet's surface.
backswamp
the low marshy region between the bluffs and the natural levees of a floodplain.
delta plain
the low, swampy land on the surface of a delta.
homosphere
the lower part of the atmosphere, in which the gases have stirred into a homogenous mixture.
base level
the lowest elevation a stream channel's floor can reach at a given locality.
troposphere
the lowest layer of the atmosphere, where air undergoes convection and where most wind and clouds develop
liquidus
the lowest temperature at which all the compoents of a material have melted and transformed into liquid.
absolute zero
the lowest temperature possible (-273.15 C) at _____________, vibrations and movements of atoms in a material cease.
K-T boundary event
the mass extinction that happened at the end of the Cretaceous Period, 65 millon years ago, possibly due to the collision of an asteroid with the Earth.
antarctic bottom water mass
the mass of cold, dense water that sinks along the coast of Antarctica.
North Atlantic deep-water mass
the mass of cold, dense water that sinks in the north polar regions.
archimedes principle
the mass of the water displaced by a block of material equals the mass of the whole block of material.
matter
the material substance of the universe; it consists of atoms and has mass.
competence (of a stream)
the maximum particle size a stream can carry.
stream competence
the maximum particle size that a stream can carry.
sphericity
the measure of the degree to which a clast approaches the shape of a sphere.
partial melting
the melting in a rock of the minerals with the lowest melting temperatures, while other minerals remain solid.
meltdown
the melting of the fuel rods in a nuclear reactor that occurs if the rate of fission becomes too fast and the fuel rods become too hot.
zeolite facies
the metamorphic facies just above diagenetic conditions, under which zeolite minerals form.
triangulation
the method for determining the map location of a point from knowing the distance between that point and three other points; this method is used to locate earthquake epicenters.
transition zone
the middle portion of the mantle, from 400 to 670 km deep, in which there are several jumps in seismic velocity.
archean eon
the middle precambrian eon.
mineral resources
the minerals extractted from te Earth's upper crust for practical purposes.
aerosols
tiny solid particles or liquid droplets that remain suspended in the atmosphere for a long time.
downslope movement
the tumbling or sliding of rock and sediment from higher elevations to lower ones.
solifluction
the type of creep characteristic of tundra regions; during the summer, the uppermost layer of permafrost melts, and the soggy, weak layer of ground then flows slowly downslope in overlapping sheets.
biodiversity
the umber of different species that exist at a given time.
submarine slump
the underwater downslope movement of a semicoherent block of sediment along a weak mud detachment
upper mantle
the uppermost section of the mantle, reaching down to a depth of 400 km.
buoyancy
the upward force activing on an object immersed or floating in fluid; the tendency of an object to float when placed in a fluid.
swash
the upward surge of water that flows up a beach slope when breakers crash onto the shore.
subsidence
the vertical sinking of the Earth's surface in a region, relative to a reference plane.
volcanic island arc
the volcanic island chain that forms on the edge of the ovverriding plate where one oceanic plate subducts beneath another oceanic plate.
discharge
the volume of water in a conduit or channel passing a point in 1 second.
adiabatic heating
the warming of a body of air or matter without the addition or subtraction of heat.
kerogen
the waxy molecules into which the organic material in shale transforms on reaching about 100C. At higher temperatures, _______ transforms into oil.
luster
the way a mineral surface scatters light.
overburden
the weight of overylying rock on rock buried deeper in the Earth's crust.
foreshore zone
the zone of beach regularly covered and uncovered by rising and falling tides.
backshore zone
the zone of beach that extends from a small step cut by high-tide swash to the front of the dunes or cliffs that lie farther inshore.
heat
thermal energy resulting from the movement of molecules
evaporite
thick salt deposits that form as a consequence of precipitation from saline water.
pedocal soil
thin soil, formed in arid climates. It contains very little organic matter, but significant precipitated calcite.
volcanic ash
tiny glass shards formed when a fine spray of exploded lava freezes instantly upon contact with the atmosphere.
plankton
tiny plants and animals that float in sea or lake water.
suspended load
tiny solid grains carried along by a stream without settling to the floor of the channel
