Earth Science Exam Review – Flashcards
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seismic waves
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Vibrations that travel through Earth carrying the energy released during an earthquake.
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crust
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the outer layer of the Earth
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mantle
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the layer of hot, solid material between Earth's crust and core
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lithosphere
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the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle
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asthenosphere
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the soft layer of the mantle on which the lithosphere floats
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basalt
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a rock that makes up much of the ocean floor
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granite
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a usually light-colored rock that is found in continental crust
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outer core
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a layer of molten iron and nickel that surrounds the inner core of Earth
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inner core
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a dense sphere of solid iron and nickel at the center of Earth
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radiation
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the transfer of energy through space
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conduction
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the direct transfer of heat from one substance to another substance that it is touching
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convection
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the transfer of heat by the movement of a fluid
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density
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the amount of matter in a given space
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convection current
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the movement of a fluid, caused by differences in temperature, that transfers heat from one part of the fluid to another
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continental drift
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the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations
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Pangaea
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large, ancient landmass that was composed of all the continents joined together
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fossil
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the remains (or an impression) of a plant or animal that existed in a past geological age and that has been excavated from the soil
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mid-ocean ridge
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An underwater moutain chain where new ocean floor is formed
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sonar
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a device that determines the distance of an object under water by recording echoes of sound waves
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sea-floor spreading
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the process by which molten material adds new oceanic crust to the ocean floor
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deep-ocean trench
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a deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle
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subduction
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the process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary
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plate
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a section of the lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust
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plate tectonics
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the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle
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fault
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a crack in the earth's crust
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divergent plate boundary
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a boundary where plates are spreading apart
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rift valley
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a deep valley that forms where two plates move apart
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convergent boundary
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a plate boundary where two plates move tward each other
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transform boundary
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boundary where two plates slide past each other
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stress
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a force that acts on rock to change its shape or volume
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tension
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stress that stretches rock so that it becomes thinner in the middle
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compression
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the type of stress that occurs when an object is squeezed
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shearing
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stress that pushes a mass of rock in opposite directions
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normal fault
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a type of fault where the hanging wall slides downward; caused by tension in the crust
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reverse fault
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a type of fault where the hanging wall slides upward; caused by compression in the crust
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hanging wall
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The block of rock that forms the upper half of a fault.
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footwall
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the block of rock that forms the lower half of a fault
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strike-slip fault
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a type of fault where rocks on either side move past each other sideways with little up or down motion
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anticline
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an upward fold in rock formed by compression of Earth's crust
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syncline
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a downward fold in rock formed by compression in earth's crust
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plateau
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a large area of flat land elevated high above sea level
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earthquake
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The shaking that results from the movement of rock beneath Earth's surface
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focus
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The point beneath Earth's surface where rock breaks under stress and causes an earthquake
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epicenter
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the point on the Earth's surface directly above the focus of an earthquake
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P wave
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A type of seismic wave that compresses and expands the ground.
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S wave
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a type of seismic wave that moves the ground up and down or side to side
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surface wave
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a type of seismic wave that forms when P waves and S waves reach Earth's surface
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magnitude
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measure of the energy released during an earthquake
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seismograph
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a device that records ground movements caused by seismic waves as they move through Earth
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liquefaction
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The process by which an earthquake's violent movement suddenly turns loose soil into liquid mud
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aftershock
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an earthquake that occurs after a larger earthquake in the same area
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tsunami
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a giant wave caused by an earthquake on the ocean floor
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volcano
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a weak spot in the crust where magma has come to the surface
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magma
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molten rock beneath the earth's surface
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lava
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magma that reaches Earth's surface.
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hot spot
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an area where magma from deep within the mantle melts through the crust above it
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viscosity
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the resistance of a gas or liquid to flow
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silica
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a material found in magma that is formed from the elements oxygen and silicon
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pahoehoe
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a hot, fast-moving type of lava that hardens to form smooth, ropelike coils
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aa
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a slow-moving type of lava that hardens to form rough chunks; cooler that pahoehoe
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magma chamber
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the pocket beneath a volcano where magma collects
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pipe
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a long tube through which magma moves from the magma chamber to Earth's surface
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crater (volcano)
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a bowl-shaped opening at the top of a volcano
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dormant
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describes a volcano that is not currently active, but that may become active in the future
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extinct
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A volcano that is no longer active and is unlikely to erupt again.
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law of superposition
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The geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it.
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mold
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a fossil formed when an organism buried in sediment dissolves, leaving a hollow area
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cast
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a type of body fossil that forms when crystals fill a mold or sediments wash into a mold and harden into rock
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relative age
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the age of a rock compared to the ages of rock layers
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absolute age
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the age of a rock given as the number of years since the rock formed
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geologic time scale
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A record of the life forms and geologic events in Earth's history.
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period
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unit of time into which eras are subdivided
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era
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a unit of geologic time that includes two or more periods
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salinity
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the amount of salt in water
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current
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a large stream of moving water that flows through the ocean
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coriolis effect
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The way Earth's rotation makes winds in the Northern Hemisphere curve to the right and winds in the Southern Hemisphere curve to the left.
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climate
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average, year-after-year conditions of temperature and precipitation in a particular region
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El Nino
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An abnormal climate event that occurs every two to seven years in the Pacific Ocean; causing changes in winds; currents; and weather patterns for one to two years.
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upwelling
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the movement of deep, cold, and nutrient-rich water to the surface
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tropical zone
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near the equator between 23.5 North and 23.5 South latitudes; receive direct sunlight year round, almost always warm
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temperate zone
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the area between the tropical and polar zones, from about 23.5 degrees to 66.5 degrees north and 23.5 degrees to 66.5 degrees south latitudes
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heliocentric
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A model of the solar system in which Earth and the other planets revolve around the sun.
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corona
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The outermost region of the sun's atmosphere.
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spectrograph
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An instrument that separates light into colors and makes an image of the resulting spectrum.
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nuclear fusion
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The process by which hydrogen atoms join together in the sun's core to form helium.
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apparent brightness
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the brightness of a star as seen from Earth
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absolute brightness
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The brightness a star would have if it were at a standard distance from Earth.
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main sequence
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A diagonal area on an H-R diagram that includes more than 90 percent of all stars.
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prominence
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A loop of gas that protrudes from the sun's surface, linking parts of sunspot regions.
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photosphere
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The inner layer of the sun's atmosphere
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chromosphere
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The middle layer of the sun's atmosphere
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axis
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An imaginary line that passes through Earth's center and its North and South Poles.
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orbit
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The path of an object as it revolves around another object in space.
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geocentric
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Models of the universe based on the assumption that the sun, moon, and planets all orbit Earth.
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sunspot
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A dark area of gas on the sun that is cooler than surrounding gases.
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super nova
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The explosive death of a massive star
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nebula
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A large cloud of dust and gas in space
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protostar
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A contracting cloud of gas and dust with enough mass to form a star
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black hole
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An object whose gravity is so strong that nothing, not even light, can escape
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supergiant
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Life cycle stage of a massive star where the core reaches extremely high temperatures, heavy elements form by fusion, and the star expands.
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binary star
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a star system with two stars
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eclipsing binary
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A system in which one star periodically blocks out light from another star.
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open cluster
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Groups of up to a few thousand stars loosely held together by gravity
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globular cluster
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a tight group of stars that looks like a ball and contains up to 1 million stars
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galaxy
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A huge group of single stars, star systems, star clusters, dust, and gas bound together by gravity
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spiral galaxy
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A galaxy with a bulge in the center and very distinctive spiral arms. Our Milky Way is a spiral galaxy.
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elliptical galaxy
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A galaxy shaped like a round or flattened ball, generally containing only old stars.
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irregular galaxy
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A galaxy that does not have a regular shape.
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quasar
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An enormously bright, distant galaxy with a giant black hole at its center.
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universe
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All of space and everything in it.
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Cosmic background radiation
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The electromagnetic radiation left over from the big bang
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Big bang
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The initial explosion that resulted in the formation and expansion of the universe
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Hubble's law
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states that the farther away a galaxy is, the faster it is moving away from us
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Solar nebula
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A large cloud of gas and dust such as the one that formed our solar system
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Planetesimal
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One of the small asteroid-like bodies that formed the building blocks of the planets.
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Dark matter
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Matter that does not give off electromagnetic radiation
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Dark energy
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a mysterious force that appears to be causing the expansion of the universe to accelerate
