Glossary

Every key word

661 terms from all 28 chapters.

A'a CH 15
rough, jagged lava.
Abrasion CH 8
rock being scraped and worn down by other particles.
Absolute dating CH 23
finding the actual age of a rock in years.
Absolute magnitude CH 28
how bright a star actually is.
Abyssal plain CH 18
a flat, sediment-covered area of the deep sea floor.
Accretion CH 24
small objects clumping together to form larger ones.
Acid rain CH 8
rain made more acidic by pollution.
Adaptation CH 22
preparing for and adjusting to climate changes.
Aerosol CH 19
tiny solid or liquid particles in air, like dust or smoke.
Air mass CH 20
a huge body of air with similar temperature and humidity.
Air pollution CH 26
harmful substances in the air.
Air pressure CH 19
the weight of air pressing down.
Air Quality Index (AQI) CH 26
a daily rating of how clean the air is.
Albedo CH 19
how much light a surface reflects.
Alfred Wegener CH 13
the scientist who proposed continental drift in 1912.
Altitude CH 19
height above sea level.
Amber CH 23
hardened tree sap that can trap organisms.
Analyze CH 1
to study data to find patterns.
Anemometer CH 20
an instrument that measures wind speed.
Anthropocene CH 26
a proposed name for the age when humans strongly shape Earth.
Anthropogenic CH 22
caused by humans.
Anticline CH 16
an upward, arch-shaped fold.
Anticyclone CH 20
a high-pressure system with sinking air.
Apparent magnitude CH 28
how bright a star looks from Earth.
Aquifer CH 11
an underground layer of rock or sediment that holds and moves water.
Aquitard CH 11
a layer that blocks the flow of groundwater.
Arid CH 22
very dry; a desert climate.
Artesian well CH 11
a well where pressure pushes water up on its own.
Asteroid CH 28
a rocky or metal chunk orbiting the Sun.
Asteroid belt CH 28
the region of asteroids between Mars and Jupiter.
Asthenosphere CH 12
the soft, flowing layer of mantle under the lithosphere.
Astronomical unit (AU) CH 27
Earth's average distance from the Sun, about 150 million km.
Astronomy CH 1
the study of the Moon, Sun, stars, and space.
Atmosphere CH 3
the layer of air around Earth.
Atmosphere CH 19
the layer of gases surrounding Earth.
Atom CH 3
the tiny basic building block of matter.
Aurora CH 12
glowing lights in the sky near the poles caused by solar particles.
Avalanche CH 21
a mass of snow sliding down a mountain.
Axis CH 27
the imaginary line Earth spins around.
Axis tilt CH 22
Earth's 23.5° tilt, which causes seasons.
Banded iron formation CH 24
striped rock formed as oxygen rusted iron in the oceans.
Barometer CH 19
an instrument that measures air pressure.
Barrier island CH 18
a long sandy island parallel to the coast.
Basalt CH 5
a dark, fine-grained extrusive rock; covers the Snake River Plain.
Basin and Range CH 16
a region of alternating mountains and valleys formed by stretching crust.
Batholith CH 16
a huge mass of intrusive igneous rock, like the Idaho Batholith.
Bathymetry CH 18
the measurement of ocean depth.
Bedrock CH 8
the solid rock beneath soil.
Big Bang theory CH 28
the theory that the universe began hot and dense about 13.8 billion years ago and has expanded since.
Biodiversity CH 26
the variety of life in an area.
Biomass CH 25
energy from plant and animal material.
Biosphere CH 3
all living things on Earth.
Black hole CH 28
an object with gravity so strong not even light escapes.
Blizzard CH 21
a storm with heavy blowing snow and strong winds.
Breaker CH 18
a wave that tips over in shallow water.
Caldera CH 15
a huge crater formed when a volcano collapses.
California Current CH 17
a cold current flowing down the U.S. West Coast.
Cambrian Explosion CH 24
the rapid appearance of many new life forms about 541 million years ago.
Carbon dioxide CH 19
a greenhouse gas, about 0.04% of air.
Carbon film CH 23
a thin carbon outline of an organism.
Carbon isotope CH 22
a form of carbon whose mix reveals where carbon came from.
Carbon-14 CH 23
an isotope used to date once-living things up to about 50,000 years old.
Carbonate CH 4
a mineral containing carbon and oxygen, like calcite.
Cast CH 23
a copy formed when minerals fill a mold.
Cave CH 11
an underground hollow, often dissolved in limestone.
Cementation CH 6
minerals gluing sediment together.
Cementation CH 7
gluing sediment into rock.
Cenozoic CH 23
the era of mammals, 66 million years ago to now.
CFCs CH 19
chemicals that destroyed ozone, now banned.
Chemical bond CH 3
the force that holds atoms together in a compound.
Chemical rock CH 6
sedimentary rock formed from minerals coming out of water.
Chemical weathering CH 8
changing the minerals in a rock into new substances.
Chicxulub crater CH 24
the impact crater in Mexico linked to the K-Pg extinction.
Cinder cone CH 15
a small, steep volcano made of lava chunks.
Cirque CH 9
a bowl-shaped hollow carved at the head of a glacier.
Cirrus CH 20
thin, wispy, high clouds of ice crystals.
Clastic rock CH 6
sedimentary rock made of broken rock pieces.
Clean Air Act CH 26
a 1970 U.S. law limiting air pollution.
Clean Water Act CH 26
a 1972 U.S. law protecting water quality.
Cleavage CH 4
when a mineral breaks along flat, smooth surfaces.
Climate CH 22
the average weather of a place over 30 years or more.
Climate change CH 22
long-term changes in climate patterns.
Coal CH 6
organic rock made from ancient swamp plants.
Coal CH 25
a fossil fuel from ancient swamp plants.
Coarse-grained CH 5
having crystals big enough to see.
Coevolution CH 24
life and Earth's systems changing each other over time.
Cold front CH 20
cold air pushing under warm air; quick storms.
Coma CH 28
the glowing cloud around a comet's head.
Comet CH 28
an icy body that grows a glowing tail near the Sun.
Compaction CH 6
squeezing sediment together under weight.
Compaction CH 7
pressing sediment together.
Compass rose CH 2
the symbol showing north, south, east, and west.
Composite volcano (stratovolcano) CH 15
a tall volcano built of lava and ash layers.
Compound CH 3
a substance made of two or more elements bonded together.
Compression CH 16
stress that squeezes rock together.
Conclusion CH 1
what the data tells you about your hypothesis.
Condensation CH 3
a gas turning into a liquid.
Condensation CH 10
water vapor cooling into liquid droplets.
Condensation CH 20
water vapor turning into liquid.
Condensation nuclei CH 20
tiny particles water condenses onto.
Conduction CH 19
heat moving by direct contact.
Conduit CH 15
the pipe from the magma chamber to the vent.
Conglomerate CH 6
sedimentary rock of rounded pebbles cemented together.
Conservation CH 25
using resources carefully so they last.
Contact metamorphism CH 6
rock baked by nearby magma.
Continental CH 20
an air mass formed over land; dry.
Continental climate CH 22
an inland climate with big temperature swings.
Continental crust CH 12
thicker, lighter crust made mostly of granite.
Continental Divide CH 10
the divide separating water flowing to the Pacific from water flowing to the Atlantic.
Continental drift CH 13
Wegener's idea that continents slowly move.
Continental glacier CH 9
a huge ice sheet covering a large area of land.
Continental margin CH 18
the underwater edge of a continent.
Continental rise CH 18
the gentle pile of sediment at the base of the slope.
Continental shelf CH 18
the shallow, gently sloping edge of a continent underwater.
Continental slope CH 18
the steep drop from the shelf to the deep ocean.
Contour interval CH 2
the height difference between contour lines.
Contour line CH 2
a line on a topo map connecting points of equal elevation.
Control CH 1
what you keep the same so the test is fair.
Convection CH 12
heat transfer by hot material rising and cool material sinking.
Convection CH 19
heat moving by rising and sinking currents.
Convection current CH 12
a circular flow caused by convection, like in the mantle.
Convergent boundary CH 13
where plates move toward each other.
Coordinates CH 2
the latitude and longitude that give a place's exact address.
Coprolite CH 23
fossilized poop.
Coriolis effect CH 17
Earth's spin bending moving air and water to the side.
Correlation CH 23
matching rock layers from different places.
Cosmic microwave background (CMB) CH 28
leftover radiation from the early universe.
Crater CH 15
the bowl-shaped pit at a volcano's top.
Crater CH 27
a bowl-shaped pit made by an impact.
Creep CH 9
very slow downhill movement of soil.
Crescent CH 27
a phase showing a thin sliver of the Moon.
Crest CH 18
the top of a wave.
Critical minerals CH 25
minerals needed for modern tech, like lithium and cobalt.
Crosscutting relationships CH 23
anything cutting across rock is younger than the rock.
Crust CH 12
Earth's thin, rocky outer layer.
Crystal CH 4
a solid whose atoms line up in a repeating pattern.
Crystallization CH 7
magma or lava cooling into crystals.
Cumulonimbus CH 20
a towering thunderstorm cloud.
Cumulus CH 20
puffy clouds with flat bottoms.
Cyanobacteria CH 24
bacteria that make food and oxygen by photosynthesis.
Cycle CH 3
a process that repeats over and over.
Cyclone CH 20
a low-pressure system with rising air.
Cyclone (tropical) CH 21
a hurricane in the Indian Ocean.
Dark energy CH 28
a mysterious force speeding up the universe's expansion.
Dark matter CH 28
unseen matter detected by its gravity.
Data CH 1
the facts and measurements you collect.
Daughter isotope CH 23
what a parent isotope decays into.
Deep current CH 17
a slow current along the ocean floor driven by density.
Deflation CH 9
wind blowing away loose sand and dust.
Deforestation CH 26
clearing forests.
Deformation CH 16
a change in rock's shape caused by stress.
Degree CH 2
the unit for measuring latitude and longitude.
Degrees Celsius CH 1
the metric temperature scale; water freezes at 0 and boils at 100.
Delta CH 10
a fan of sediment where a river enters a lake or ocean.
Density CH 4
how much mass is packed into a certain space.
Density CH 17
how much mass is packed into a space; cold, salty water is denser.
Dependent variable CH 1
the thing you measure in an experiment.
Deposition CH 7
dropping sediment in a new place.
Deposition CH 8
dropping sediment when the mover slows down.
Desertification CH 26
dry land turning into desert.
Dew point CH 20
the temperature at which air becomes saturated.
Differentiation CH 24
Earth separating into layers by density.
Divergent boundary CH 13
where plates move apart.
Divide CH 10
high ground that separates watersheds.
Dome mountain CH 16
a mountain formed when magma pushes rock layers up.
Doppler effect CH 28
the change in wave frequency when a source moves toward or away from you.
Doppler radar CH 20
radar that detects precipitation and wind in storms.
Downdraft CH 21
sinking air in a storm.
Drought CH 21
a long period of below-normal precipitation.
Dry lightning CH 21
lightning with little or no rain reaching the ground.
Dust Bowl CH 8
1930s disaster when drought and poor farming blew away Great Plains topsoil.
Dwarf planet CH 28
a round body orbiting the Sun that hasn't cleared its orbit, like Pluto.
Early atmosphere CH 24
Earth's first air, made of volcanic gases with almost no oxygen.
Earth science CH 1
the study of Earth and its neighbors in space.
Earthquake CH 14
shaking caused by rocks suddenly slipping along a fault.
Ecological footprint CH 26
the land and resources needed to support a person's lifestyle.
Effusive eruption CH 15
a gentle eruption with flowing lava.
El Niño CH 17
a periodic warming of the eastern Pacific that changes world weather.
Elastic rebound CH 14
rocks bending under stress, then snapping back.
Electron CH 3
a negative particle that moves around an atom's nucleus.
Element CH 3
a substance made of only one kind of atom.
Elevation CH 2
height above sea level.
Ellipse CH 27
an oval shape; the shape of planetary orbits.
Elliptical galaxy CH 28
an oval-shaped galaxy.
Endangered species CH 26
a species at risk of going extinct.
Energy CH 3
the ability to cause change or do work.
Energy efficiency CH 25
using less energy to get the same result.
Enhanced Fujita scale CH 21
rates tornadoes from EF0 to EF5 by damage.
Eon CH 23
the largest division of geologic time.
Epicenter CH 14
the point on the surface directly above the focus.
Epoch CH 23
a division of a period.
Equal-area projection CH 2
a map that keeps sizes correct but bends shapes.
Equator CH 2
the 0° latitude line around Earth's middle.
Equinox CH 27
a day when day and night are about equal.
Era CH 23
a division of an eon.
Erosion CH 7
moving weathered rock away.
Erosion CH 8
moving weathered material to a new place.
Eutrophication CH 26
excess nutrients causing algae blooms that use up oxygen in water.
Evaporation CH 3
a liquid turning into a gas.
Evaporation CH 10
liquid water turning into water vapor.
Evidence CH 1
facts and data that support or reject an idea.
Exosphere CH 19
the outermost layer, fading into space.
Experiment CH 1
a fair test of a hypothesis.
Explosive eruption CH 15
a violent eruption caused by trapped gas.
Extrusive CH 5
igneous rock that cooled quickly at the surface; small or no crystals.
Eye CH 21
the calm center of a hurricane.
Eye wall CH 21
the ring of strongest winds around the eye.
Fault CH 14
a break in the crust where rocks have moved.
Fault scarp CH 14
a step in the ground formed by fault movement.
Fault-block mountain CH 16
a mountain formed when blocks of crust are lifted along faults.
Feedback CH 3
when one change causes other changes in a system.
Feedback loop CH 22
a process where a change causes effects that speed up or slow down the change.
Felsic CH 5
light-colored igneous rock rich in silica.
Fine-grained CH 5
having crystals too small to see easily.
Flash flood CH 21
a sudden flood within hours of heavy rain.
Floodplain CH 10
flat land beside a river that floods.
Focus CH 14
the point underground where an earthquake starts.
Fog CH 20
a cloud at ground level.
Fold CH 16
a bend in rock layers.
Folded mountain CH 16
a mountain formed by rock crumpled into folds.
Foliated CH 6
metamorphic rock with flat layers or bands.
Fossil CH 6
preserved remains or traces of ancient life.
Fossil CH 23
preserved remains or traces of ancient life.
Fossil fuel CH 22
coal, oil, or natural gas formed from ancient life.
Fracture CH 4
when a mineral breaks unevenly or in curves.
Freezing rain CH 20
rain that freezes when it hits cold surfaces.
Front CH 20
the boundary between two air masses.
Frost wedging CH 8
water freezing and expanding in cracks, splitting rock.
Full moon CH 27
the phase showing the whole face lit.
Funnel cloud CH 21
a rotating cloud that hasn't touched the ground.
Galaxy CH 28
a huge system of stars, gas, and dust held by gravity.
Gas CH 3
matter that spreads out to fill any space.
Gas giant CH 28
a huge planet made mostly of gas, like Jupiter and Saturn.
Gem CH 4
a rare, hard, beautiful mineral cut and polished for jewelry.
Geologic time scale CH 23
the calendar of Earth's history.
Geology CH 1
the study of rocks, minerals, and the solid Earth.
Geosphere CH 3
the solid Earth: rocks, mountains, and the core.
Geothermal energy CH 15
energy from Earth's internal heat.
Geyser CH 11
a hot spring that erupts water and steam.
Giant impact hypothesis CH 24
the idea that a collision with a Mars-sized object formed the Moon.
Gibbous CH 27
a phase showing more than half lit.
GIS CH 2
Geographic Information Systems; computer maps that stack layers of data.
Glacier CH 9
a large mass of moving ice on land.
Glassy CH 5
having no crystals because it cooled extremely fast.
Global conveyor belt CH 17
the worldwide loop of deep and surface currents.
Global warming CH 22
the rise in Earth's average surface temperature.
Globe CH 2
a round model of Earth; the only fully accurate map.
Gneiss CH 6
a foliated rock with striped bands.
GPS CH 2
Global Positioning System; uses satellites to find your exact location.
Graben CH 16
a dropped-down block between faults.
Gram CH 1
a metric unit of mass.
Granite CH 5
a light, coarse-grained intrusive rock.
Gravity CH 27
the force of attraction between objects with mass.
Great Oxygenation Event CH 24
oxygen building up in the air about 2.4 billion years ago.
Greenhouse effect CH 19
gases trapping heat and keeping Earth warm.
Greenhouse gas CH 19
a gas that absorbs heat, like CO₂, methane, or water vapor.
Ground-level ozone CH 26
ozone near the ground that harms lungs.
Groundwater CH 11
water stored underground in spaces in soil and rock.
Gulf Stream CH 17
a warm current flowing up the U.S. East Coast to Europe.
Guyot CH 18
a flat-topped seamount.
Gyre CH 17
a huge circular system of ocean currents.
H-R diagram CH 28
a graph of stars' brightness vs. temperature.
Habitat loss CH 26
the destruction of places where organisms live.
Hail CH 20
balls of ice formed in thunderstorms.
Half-life CH 23
the time for half of a radioactive sample to decay.
Hardness CH 4
how easily a mineral can be scratched.
Hazard map CH 26
a map showing areas at risk from natural hazards.
High pressure CH 19
an area of sinking air and usually clear weather.
Highlands CH 27
bright, mountainous areas of the Moon.
Horizon CH 8
a layer of soil.
Horn CH 9
a sharp peak carved by glaciers on several sides.
Horst CH 16
a raised block between faults.
Hot spring CH 11
a spring of groundwater heated by hot rock.
Hotspot CH 13
a plume of hot mantle that melts through a plate, like Yellowstone.
Humidity CH 20
the amount of water vapor in the air.
Humus CH 8
dark, rotting plant and animal material in soil.
Hurricane CH 21
a huge rotating tropical storm with winds of 74 mph or more.
Hydraulic fracturing (fracking) CH 25
cracking rock with high-pressure fluid to release oil and gas.
Hydroelectric power CH 25
electricity from flowing water; Idaho's biggest source.
Hydrosphere CH 3
all of Earth's water.
Hydrothermal vent CH 18
a hot spring on the sea floor.
Hygrometer CH 20
an instrument that measures humidity.
Hypothesis CH 1
a smart guess that can be tested.
Ice age CH 9
a long cold period when glaciers covered large areas.
Ice age CH 22
a long cold period with widespread glaciers.
Ice core CH 22
a long tube of ice drilled to study ancient air and climate.
Ice giant CH 28
a giant planet with lots of ices, like Uranus and Neptune.
Ice storm CH 21
freezing rain that coats everything in ice.
Ice-albedo feedback CH 22
melting ice exposing darker surfaces that absorb more heat.
Igneous rock CH 5
rock formed when melted rock cools and hardens.
Inclusion CH 23
a piece of rock inside another rock; it's older than the rock around it.
Independent variable CH 1
the thing you change on purpose in an experiment.
Index fossil CH 23
a widespread, short-lived species used to date rock layers.
Inertia CH 27
an object's tendency to keep moving in a straight line.
Infiltration CH 10
water soaking into the ground.
Inner core CH 12
the solid iron and nickel center of Earth.
Inorganic CH 4
not made by living things.
Intensity CH 14
how strongly shaking is felt in a certain place.
Internal heat CH 3
heat inside Earth left over from its formation and from radioactive elements.
International Date Line CH 2
the line near 180° where the calendar date changes.
Intrusive CH 5
igneous rock that cooled slowly underground; big crystals.
Invasive species CH 26
a species introduced to a new place where it spreads and causes harm.
Iridium CH 24
an element rare on Earth but common in asteroids.
Irregular galaxy CH 28
a galaxy with no clear shape.
Isobar CH 20
a line on a map connecting places with equal air pressure.
Isostasy CH 16
the balance of crust floating on the mantle.
Isotope CH 23
a form of an element with a different number of neutrons.
Jet stream CH 19
a fast, high-altitude river of wind that steers storms.
Jetty CH 18
a wall built into the sea to protect a harbor or trap sand.
K-Pg extinction CH 24
the asteroid-caused extinction of the dinosaurs, 66 million years ago.
Keeling Curve CH 22
the graph of CO₂ measured at Mauna Loa since 1958.
Kepler's laws CH 27
three rules describing how planets orbit the Sun.
Kilogram CH 1
1,000 grams.
Köppen system CH 22
a way of classifying climates by temperature and precipitation.
Kuiper Belt CH 28
a region of icy bodies beyond Neptune.
La Niña CH 17
a periodic cooling of the eastern Pacific.
Lab safety CH 1
rules that keep you from getting hurt during experiments.
Lahar CH 15
a volcanic mudflow.
Landfill CH 26
a place where trash is buried.
Landslide CH 9
a large mass of rock and soil suddenly sliding downhill.
Lapilli CH 15
pebble-sized tephra.
Latitude CH 2
distance north or south of the equator, in degrees.
Lava CH 5
melted rock at the surface.
Law of superposition CH 23
in undisturbed layers, the oldest is on the bottom.
Law of universal gravitation CH 27
Newton's law explaining gravity between all objects.
Leap year CH 27
a year with an extra day, every four years.
Legend (key) CH 2
the box that explains a map's symbols.
Levee CH 10
a raised wall along a river to prevent flooding.
Light-year CH 28
the distance light travels in one year, about 9.5 trillion km.
Lightning CH 21
a giant electrical spark in a storm.
Limestone CH 6
sedimentary rock made mostly of calcite, often from shells.
Liquefaction CH 14
wet soil acting like liquid during shaking.
Liquid CH 3
matter that takes the shape of its container.
Liter CH 1
the basic metric unit of volume.
Lithosphere CH 12
the rigid outer layer made of crust and upper mantle.
Loess CH 9
fine, fertile, wind-blown dust deposits.
Longitude CH 2
distance east or west of the prime meridian, in degrees.
Longshore current CH 18
a current moving sand along the shore.
Low pressure CH 19
an area of rising air and usually stormy weather.
Lunar eclipse CH 27
Earth's shadow falling on the Moon.
Luster CH 4
how a mineral shines: metallic or nonmetallic.
Mafic CH 5
dark-colored igneous rock rich in iron and magnesium.
Magma CH 5
melted rock underground.
Magma chamber CH 15
an underground pool of magma.
Magnetic field CH 12
the invisible force field around Earth created by its outer core.
Magnetic reversal CH 13
a flip of Earth's magnetic poles, recorded in rock.
Magnitude CH 14
a measure of the energy an earthquake releases.
Main sequence CH 28
the band on the H-R diagram where most stars spend their lives.
Mantle CH 12
the thick, hot, slowly flowing layer under the crust.
Map CH 2
a flat drawing of an area.
Map projection CH 2
a way to show round Earth on flat paper; always distorts something.
Marble CH 6
a non-foliated rock formed from limestone.
Maria CH 27
dark, flat lava plains on the Moon.
Maritime CH 20
an air mass formed over water; humid.
Mass CH 3
the amount of matter in an object.
Mass extinction CH 23
the dying out of a huge share of species in a short time.
Mass movement CH 9
rock and soil moving downhill because of gravity.
Matter CH 3
anything that has mass and takes up space.
Meander CH 10
a loop or bend in a slow river.
Mechanical weathering CH 8
breaking rock without changing what it's made of.
Melting CH 3
a solid turning into a liquid.
Melting CH 7
heat turning rock into magma.
Mercator projection CH 2
a map good for navigation that makes land near the poles look too big.
Mesocyclone CH 21
a rotating updraft in a supercell.
Mesosphere CH 19
the coldest layer, where meteors burn up.
Mesozoic CH 23
the era of reptiles and dinosaurs, 252–66 million years ago.
Metamorphic rock CH 6
rock changed by heat, pressure, or fluids without melting.
Meteor CH 28
a meteoroid burning up in the atmosphere; a shooting star.
Meteorite CH 24
a space rock that lands on Earth.
Meteoroid CH 28
a small piece of space rock.
Meteorologist CH 20
a scientist who studies and forecasts weather.
Meteorology CH 1
the study of weather and the atmosphere.
Meter CH 1
the basic metric unit of length.
Metric system (SI) CH 1
the measuring system scientists use, based on tens.
Microclimate CH 22
the climate of a small area that differs from its surroundings.
Microplastics CH 26
tiny pieces of broken-down plastic.
Mid-ocean ridge CH 13
an underwater mountain chain where new ocean crust forms.
Milankovitch cycles CH 22
long-term changes in Earth's orbit and tilt that affect climate.
Milky Way CH 28
our home galaxy, a spiral.
Mineral CH 4
a natural, inorganic solid with a set chemical makeup and a crystal structure.
Minute CH 2
one-sixtieth of a degree.
Mitigation CH 22
reducing greenhouse gas emissions.
Model CH 1
a map, diagram, globe, or computer program that represents something real.
Modified Mercalli scale CH 14
a scale rating earthquake intensity by damage.
Mohs scale CH 4
ranks mineral hardness from 1 (talc) to 10 (diamond).
Mold CH 23
an empty print of an organism left in rock.
Moment magnitude scale CH 14
the modern scale for earthquake magnitude.
Monocline CH 16
a step-like bend in flat rock layers.
Moraine CH 9
a ridge of rock and dirt dumped by a glacier.
Mudflow CH 9
a fast flow of water-soaked soil.
Native element CH 4
a mineral made of one pure element, like gold or copper.
Natural gas CH 25
a gas fossil fuel, mostly methane.
Natural resource CH 25
anything from nature that people use.
Neap tide CH 18
a smaller tide at quarter moons.
Nebula CH 24
a giant cloud of gas and dust in space.
Neutron CH 3
a particle with no charge in an atom's nucleus.
Neutron star CH 28
a super-dense remnant of a supernova.
New moon CH 27
the phase when the Moon's lit side faces away from Earth.
Nimbostratus CH 20
a thick gray cloud bringing steady rain or snow.
Nitrogen CH 19
the most common gas in air, about 78%.
Non-foliated CH 6
metamorphic rock without layers.
Nonpoint-source pollution CH 26
pollution from many spread-out sources, like farm runoff.
Nonrenewable resource CH 25
a resource that takes millions of years to form.
Normal fault CH 14
a fault where rocks pull apart and one side drops down.
Nuclear energy CH 25
energy released from atoms.
Nuclear fission CH 25
splitting atoms to release energy.
Nuclear fusion CH 27
combining atoms to release energy; powers the Sun.
Nucleus CH 3
the center of an atom.
Observation CH 1
noticing something using your senses or tools.
Obsidian CH 5
natural volcanic glass.
Occluded front CH 20
a cold front catching up to a warm front.
Ocean acidification CH 22
the ocean becoming more acidic as it absorbs CO₂.
Oceanic crust CH 12
thin, dense crust made of basalt under the oceans.
Oceanographer CH 17
a scientist who studies the ocean.
Oceanography CH 1
the study of the oceans.
Ooze CH 18
sea-floor sediment made of tiny shells.
Orbit CH 27
the path of one object around another.
Ore CH 4
a mineral mined for profit, usually for a metal.
Organic rock CH 6
sedimentary rock made from the remains of living things.
Original horizontality CH 23
sediment is first laid down in flat layers.
Orogeny CH 16
the process of mountain building.
Orographic lifting CH 20
air forced upward over mountains.
Outer core CH 12
the liquid iron and nickel layer around the inner core.
Oxbow lake CH 10
a curved lake formed when a meander is cut off.
Oxidation CH 8
oxygen reacting with iron in rock; rusting.
Oxide CH 4
a mineral made of a metal bonded to oxygen, like hematite.
Oxygen CH 3
the most common element in Earth's crust.
Oxygen CH 19
the gas we breathe, about 21% of air.
Ozone layer CH 19
ozone in the stratosphere that absorbs UV radiation.
P wave CH 12
the fastest seismic wave; travels through solids and liquids.
Pahoehoe CH 15
smooth, ropey lava.
Paleontologist CH 23
a scientist who studies fossils.
Paleozoic CH 23
the era of "ancient life," 541–252 million years ago.
Pangaea CH 13
the supercontinent that broke apart about 200 million years ago.
Pangaea CH 24
the supercontinent that formed in the Paleozoic.
Parent isotope CH 23
the original radioactive isotope.
Particulate matter CH 26
tiny particles of soot, dust, and smoke in air.
Parts per million (ppm) CH 22
a unit for measuring small amounts of a gas in air.
Peat CH 25
partly decayed plant material, the first stage of coal.
Penumbra CH 27
the lighter outer part of a shadow.
Period CH 23
a division of an era.
Periodic table CH 3
the chart that organizes all the elements.
Permeability CH 11
how easily water flows through rock or soil.
Permian extinction CH 24
the largest mass extinction, about 252 million years ago.
Petrified fossil CH 23
a fossil where minerals replaced the original material.
Petroleum CH 25
crude oil, a liquid fossil fuel.
Phase CH 27
the shape of the Moon's lit part as seen from Earth.
Photosynthesis CH 24
the process plants and some bacteria use to make food, releasing oxygen.
Photovoltaic cell CH 25
a solar cell that turns sunlight into electricity.
Planetary nebula CH 28
the glowing shell of gas shed by a dying Sun-like star.
Planetesimal CH 24
a small early chunk of rock that grew into planets.
Plankton CH 17
tiny drifting organisms at the base of ocean food webs.
Plasma CH 3
super-hot, electrically charged gas, like lightning and the Sun.
Plate boundary CH 13
where two plates meet.
Plate tectonics CH 13
the theory that Earth's lithosphere is broken into moving plates.
Point-source pollution CH 26
pollution from one clear source, like a pipe.
Polar CH 20
an air mass formed near the poles; cold.
Porosity CH 11
how much open space a rock or soil has.
Porphyritic CH 5
big crystals in a fine-grained background.
Precambrian CH 23
Earth's earliest and longest time span, about 88% of its history.
Precipitation CH 10
water falling from clouds as rain, snow, sleet, or hail.
Precipitation CH 20
water falling from clouds.
Pressure CH 17
the force of water pressing down; increases with depth.
Prevailing westerlies CH 19
global winds that blow west to east over the U.S.
Prime meridian CH 2
the 0° longitude line through Greenwich, England.
Proton CH 3
a positive particle in an atom's nucleus.
Protostar CH 28
a young star still forming.
Proxy data CH 22
natural clues like ice cores and tree rings that record past climate.
Pumice CH 5
a light, holey volcanic rock that can float.
Pyroclastic flow CH 15
a fast, deadly avalanche of hot gas, ash, and rock.
Quarter moon CH 27
a phase showing half of the Moon's face lit.
Quartzite CH 6
a hard non-foliated rock formed from sandstone.
Question CH 1
what you want to find out about an observation.
Radiation CH 19
energy traveling as waves through space.
Radioactive decay CH 23
unstable atoms breaking down into other elements.
Radioactive waste CH 25
dangerous leftover material from nuclear reactors.
Radiometric dating CH 23
using radioactive decay to find a rock's age.
Rain band CH 21
a spiral arm of storms in a hurricane.
Rain shadow CH 20
a dry area on the far side of mountains.
Recharge CH 11
water refilling an aquifer.
Reclamation CH 25
restoring land after mining.
Red giant CH 28
a large, cool star near the end of its life.
Redshift CH 28
light from a receding object stretching toward red.
Regional metamorphism CH 6
large areas of rock changed by heat and pressure during mountain building.
Relative dating CH 23
putting events in order without exact ages.
Relative humidity CH 20
how full the air is with water vapor compared to its maximum.
Remote sensing CH 2
studying Earth from a distance using satellites or planes.
Renewable resource CH 25
a resource replaced naturally as fast as it's used.
Restoration CH 26
returning damaged ecosystems to health.
Reverse fault CH 14
a fault where rocks push together and one side moves up.
Revolution CH 27
Earth's trip around the Sun; one year.
Richter scale CH 14
an older scale for earthquake magnitude.
Ridge push CH 13
new crust at a ridge pushing plates apart.
Rift valley CH 13
a valley formed where land is pulling apart.
Ring of Fire CH 15
the ring of volcanoes around the Pacific Ocean.
Rock cycle CH 7
the endless process of rocks changing from one type to another.
Rockfall CH 9
rocks falling freely from a cliff.
Rotation CH 27
Earth spinning on its axis; causes day and night.
Runoff CH 10
water flowing over the ground into streams.
S wave CH 12
a slower seismic wave; travels only through solids.
Saffir-Simpson scale CH 21
rates hurricanes from Category 1 to 5.
Salinity CH 17
the amount of dissolved salt in water.
Sand dune CH 9
a hill of wind-blown sand.
Sandstone CH 6
sedimentary rock made of sand grains.
Satellite CH 2
an object that orbits a planet.
Satellite CH 27
an object that orbits a planet.
Saturated CH 20
air holding as much water vapor as it can.
Scale CH 2
shows how distance on a map compares to real distance.
Schist CH 6
a sparkly foliated rock.
Scientific law CH 1
a statement of what always happens, often written as math.
Scientific method CH 1
a step-by-step way scientists answer questions.
Scientific theory CH 1
a well-tested explanation of why something happens, backed by lots of evidence.
Sea breeze CH 19
a cool wind blowing from sea to land during the day.
Sea stack CH 18
a pillar of rock left standing offshore by erosion.
Sea-floor spreading CH 13
new crust forming at ridges and pushing older crust away.
Sea-level rise CH 22
the ocean's surface rising as water warms and ice melts.
Seamount CH 18
an underwater volcano that doesn't reach the surface.
Sediment CH 6
loose bits of rock, sand, mud, and shells.
Sedimentary rock CH 6
rock formed from sediment pressed and glued together.
Seismic wave CH 12
energy from an earthquake traveling through Earth.
Seismograph CH 12
an instrument that records seismic waves.
Semi-arid CH 22
fairly dry, like southern Idaho's high desert.
Shadow zone CH 12
the area on Earth where no S waves are detected, showing the outer core is liquid.
Shale CH 6
sedimentary rock made of fine mud.
Shear CH 16
stress that pushes rock in opposite directions side by side.
Shield volcano CH 15
a wide, gently sloping volcano built by runny lava.
Silica CH 15
a compound of silicon and oxygen that makes magma thicker.
Silicate CH 4
a mineral containing silicon and oxygen; makes up most of the crust.
Silicon CH 3
the second most common element in Earth's crust.
Sinkhole CH 11
a hole formed when ground collapses into an empty space below.
Slab pull CH 13
a sinking plate pulling the rest of the plate along.
Slate CH 6
a foliated rock formed from shale.
Sleet CH 20
rain that freezes into ice pellets before landing.
Slump CH 9
a block of ground sliding down along a curved surface.
Smog CH 26
a brownish haze formed from car exhaust and sunlight.
Snowball Earth CH 24
a time when Earth may have frozen nearly completely.
Soil CH 8
a mix of weathered rock, humus, water, air, and living things.
Solar eclipse CH 27
the Moon blocking the Sun's light from Earth.
Solar energy CH 3
energy from the Sun.
Solar energy CH 25
energy from sunlight.
Solar flare CH 27
a sudden burst of energy from the Sun.
Solar system CH 28
the Sun and everything held by its gravity.
Solar wind CH 27
a stream of charged particles from the Sun.
Solid CH 3
matter with a fixed shape.
Solstice CH 27
the longest or shortest day of the year.
Sonar CH 18
using sound echoes to measure distance underwater.
Spectroscope CH 28
a tool that splits light into a spectrum.
Spectrum CH 28
the band of colors made when light is split.
Spiral galaxy CH 28
a galaxy with pinwheel arms.
Spit CH 18
a sandbar sticking out from shore.
Spring CH 11
a place where groundwater flows out naturally.
Spring tide CH 18
an extra-large tide at new and full moon.
Stalactite CH 11
a mineral formation hanging from a cave ceiling.
Stalagmite CH 11
a mineral formation growing up from a cave floor.
Star CH 28
a huge ball of hot gas powered by nuclear fusion.
States of matter CH 3
the forms matter takes: solid, liquid, gas, plasma.
Stationary front CH 20
a front that stalls.
Stellar nucleosynthesis CH 28
stars making new elements by fusion.
Storm surge CH 21
a wall of seawater pushed ashore by a hurricane.
Strata CH 6
layers of rock.
Stratosphere CH 19
the layer containing the ozone layer.
Stratus CH 20
flat, gray, sheet-like clouds.
Streak CH 4
the color of a mineral's powder.
Stress CH 16
force acting on rock.
Strike-slip fault CH 14
a fault where rocks slide sideways past each other.
Stromatolite CH 24
a layered mound built by bacteria; among the oldest fossils.
Subduction CH 13
one plate sinking beneath another.
Submarine canyon CH 18
a deep canyon cut into the shelf and slope.
Submersible CH 18
a small underwater vehicle for deep-sea exploring.
Subsoil CH 8
the lighter B horizon below topsoil.
Sunspot CH 27
a cooler, darker area on the Sun.
Supercell CH 21
a powerful, long-lasting rotating thunderstorm.
Supergiant CH 28
an extremely large, bright star.
Supernova CH 28
the explosion of a massive star.
Supervolcano CH 15
a volcano capable of an enormous eruption, like Yellowstone.
Surface current CH 17
a wind-driven current in the ocean's top layer.
Surface mining CH 25
removing soil and rock to reach shallow deposits.
Surface wave CH 14
the slowest, most damaging seismic wave.
Sustainability CH 25
meeting today's needs without harming future generations.
Synchronous rotation CH 27
when an object rotates and orbits in the same time, always showing one side.
Syncline CH 16
a downward, U-shaped fold.
System CH 3
a group of parts that work together and affect each other.
Temperate CH 22
mild, with distinct seasons.
Temperature inversion CH 20
warm air trapping cold air near the ground.
Tension CH 16
stress that pulls rock apart.
Tephra CH 15
rock fragments blasted from a volcano.
Terrestrial planet CH 28
a small, rocky inner planet.
Texture CH 5
the size, shape, and arrangement of a rock's grains.
Thermocline CH 17
an ocean layer where temperature drops quickly with depth.
Thermohaline circulation CH 17
deep ocean circulation driven by temperature and salinity.
Thermosphere CH 19
a very thin, hot layer where auroras occur.
Thunder CH 21
the sound of air expanding from lightning's heat.
Thunderstorm CH 21
a storm with lightning and thunder.
Tide CH 18
the daily rise and fall of sea level, caused mostly by the Moon.
Time zone CH 2
a region that uses the same clock time, about 15° wide.
Topographic map CH 2
a map that shows the shape and height of the land.
Topsoil CH 8
the dark, rich A horizon where plants grow.
Tornado CH 21
a violently spinning column of air touching the ground.
Tornado Alley CH 21
the region of the Great Plains with the most tornadoes.
Trace fossil CH 23
evidence of activity, like footprints or burrows.
Trade winds CH 19
steady global winds near the equator.
Transform boundary CH 13
where plates slide past each other.
Transpiration CH 10
plants releasing water vapor through their leaves.
Tree rings CH 22
yearly growth rings that record growing conditions.
Trench CH 13
a deep ocean valley formed at a subduction zone.
Trench CH 18
a deep, narrow valley where one plate subducts.
Triangulation CH 14
using three stations to locate an epicenter.
Tributary CH 10
a smaller stream that flows into a larger river.
Trilobite CH 24
an extinct ocean animal common in the Paleozoic.
Tropical CH 20
an air mass formed near the equator; warm.
Tropopause CH 19
the boundary between the troposphere and stratosphere.
Troposphere CH 19
the lowest layer, where weather happens.
Trough CH 18
the bottom of a wave.
Tsunami CH 14
a giant ocean wave caused by an undersea earthquake.
Tundra CH 22
a cold, treeless polar region.
Typhoon CH 21
a hurricane in the western Pacific.
U-shaped valley CH 9
a valley widened and carved by a glacier.
Ultraviolet (UV) radiation CH 19
harmful high-energy sunlight.
Umbra CH 27
the darkest part of a shadow.
Unconformity CH 23
a gap in the rock record.
Underground mining CH 25
digging tunnels to reach deep deposits.
Unstable air CH 21
warm air near the ground with cold air above, which rises easily.
Updraft CH 21
rising air in a storm.
Uplift CH 7
forces pushing buried rock up to the surface.
Uplift CH 16
the raising of Earth's crust.
Upwelling CH 17
cold, nutrient-rich deep water rising to the surface.
Urban heat island CH 22
a city that stays warmer than the countryside around it.
Urbanization CH 26
the growth of cities.
Valley glacier CH 9
a glacier that flows down a mountain valley.
Vent CH 15
the opening where magma comes out.
Vesicular CH 5
full of holes from gas bubbles.
Viscosity CH 15
how thick and sticky a liquid is.
Volcanic ash CH 15
tiny bits of rock and glass from an eruption.
Volcanic bomb CH 15
a large blob of lava thrown from a volcano.
Volcanic mountain CH 16
a mountain built by eruptions.
Volcano CH 15
an opening in the crust where magma, gas, and ash escape.
Waning CH 27
the lit part shrinking.
Warm front CH 20
warm air sliding over cold air; steady rain.
Warning CH 21
a hazard is happening or about to; take action.
Watch CH 21
conditions are right for a hazard; be ready.
Water cycle CH 10
the continuous movement of water between Earth's surface and the air.
Water table CH 11
the top of the zone of saturation.
Water vapor CH 19
water in gas form in the air.
Watershed CH 10
all the land that drains into one river.
Wave CH 18
energy moving through water.
Wave height CH 18
the distance from trough to crest.
Wavelength CH 18
the distance from one crest to the next.
Waxing CH 27
the lit part growing.
Weather CH 20
the condition of the atmosphere at a certain time and place.
Weathering CH 7
breaking rock into smaller pieces.
Weathering CH 8
breaking rock into smaller pieces where it sits.
Well CH 11
a hole dug or drilled to reach groundwater.
Wetland CH 10
land soaked with water, like a marsh or swamp.
White dwarf CH 28
the small, hot core left after a Sun-like star dies.
Wildland-urban interface CH 26
where homes meet forests or wild land; high wildfire risk.
Wind CH 19
air moving from high to low pressure.
Wind energy CH 25
energy from moving air.
Wind shear CH 21
winds changing speed or direction with height.
World ocean CH 17
the single connected body of salt water covering about 71% of Earth.
Zone of aeration CH 11
the upper underground zone where spaces hold air and some water.
Zone of saturation CH 11
the underground zone where all spaces are filled with water.