NCEA Level 3 Earth and Space Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Subduction zone

Convergent boundary where denser oceanic lithosphere sinks beneath another plate, producing deep earthquakes, volcanic arcs, and ocean trenches.

Divergent boundary

Plate boundary where lithosphere pulls apart, magma rises to form new crust; produces mid-ocean ridges, rift valleys, and shallow earthquakes.

Transform boundary

Plate boundary where two plates slide past each other horizontally, generating shallow earthquakes but little or no volcanism.

Superposition principle

In undisturbed sedimentary sequences, older layers lie below younger layers, allowing relative ages to be determined.

Half-life

Time for half the radioactive atoms in a sample to decay; the decay constant lambda relates by t1/2 = ln2 divided by lambda.

Radiometric dating

Method using known decay rates of isotopes such as carbon-14, potassium-40, or uranium-238 to estimate the absolute age of rocks or materials.

Igneous rock

Rock formed from cooling magma or lava; intrusive types have coarse crystals, extrusive types have fine crystals or glassy texture.

Sedimentary rock

Rock formed from compaction and cementation of sediments, or from precipitation; often layered and may contain fossils.

Metamorphic rock

Rock altered by heat and pressure without melting; may show foliation or recrystallisation of minerals such as mica and quartz.

P waves

Primary seismic waves that are compressional, travel fastest, and pass through solids, liquids, and gases.

S waves

Secondary seismic waves that are shear waves, travel slower than P waves, and cannot pass through liquids.

Epicentre

Point on Earth's surface directly above the earthquake focus, where shaking is usually strongest.

Troposphere

Lowest atmospheric layer where most weather occurs; temperature decreases with altitude and contains most water vapour.

Ozone layer

Region in the stratosphere rich in ozone that absorbs much of the Sun's ultraviolet radiation, protecting life at the surface.

Coriolis effect

Apparent deflection of moving air or water due to Earth's rotation; deflects to the right in the Northern Hemisphere and left in the Southern.

Thermohaline circulation

Deep ocean circulation driven by differences in temperature and salinity that change water density, moving heat around the globe.

Albedo

Fraction of incoming solar radiation reflected by a surface; ice has high albedo, oceans and forests have low albedo.

Main sequence star

Star fusing hydrogen into helium in its core; stable balance between gravitational collapse and outward radiation pressure.

Red giant

Late stage of a low- or medium-mass star when core hydrogen is exhausted and outer layers expand and cool.

White dwarf

Dense remnant of a low-mass star after it sheds its outer layers; supported by electron degeneracy pressure, slowly cooling.

Supernova

Explosive death of a massive star (or accreting white dwarf), briefly outshining a galaxy and dispersing heavy elements.

Neutron star

Extremely dense remnant of a massive supernova, composed mainly of neutrons; may emit pulses as a pulsar.

Black hole

Region where gravity is so strong that not even light escapes; forms when a massive star's core collapses beyond the event horizon.

Hertzsprung-Russell diagram

Graph of stellar luminosity against temperature or spectral class, showing main sequence, giants, supergiants, and white dwarfs.

Kepler's third law

The square of a planet's orbital period is proportional to the cube of its semi-major axis (T squared proportional to a cubed).

Newton's law of gravitation

Every mass attracts every other with force F = G*m1*m2/r squared, explaining orbits, weight, and tides.

Redshift

Increase in observed wavelength of light from receding objects; evidence for the expansion of the universe.

Hubble's law

Recession velocity of a galaxy is proportional to its distance (v = H0*d), consistent with an expanding universe.

Solar nebula theory

Model in which a collapsing cloud of gas and dust forms a rotating disc, then accretes into the Sun, planets, and other bodies.

Terrestrial planet

Small, dense, rocky planet with a solid surface, such as Mercury, Venus, Earth, or Mars.

Gas giant

Large, low-density planet composed mainly of hydrogen and helium, such as Jupiter or Saturn, often with rings and many moons.

Lunar eclipse

Event when Earth passes between the Sun and Moon, casting its shadow on the Moon; occurs only at full moon.