ILTS Earth and Space Science (241) flashcards

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

Scientific theory

A well-substantiated explanation of natural phenomena supported by multiple independent lines of evidence and repeatedly tested predictions; it is not an untested guess.

Independent variable

The factor deliberately manipulated or changed by the investigator in an experiment so that its effect on the measured outcome can be observed.

Correlation versus causation

A statistical association between two variables does not prove that one causes the other; confounding variables may explain the observed relationship.

Accuracy versus precision

Accuracy describes closeness to the true value; precision describes how closely repeated measurements agree with one another.

Mohs hardness scale

A relative scale from 1 (talc) to 10 (diamond) ranking minerals by their resistance to scratching, with each standard mineral scratching those below it.

Bowen's reaction series

The sequence in which minerals crystallize from cooling magma, from high-temperature mafic minerals such as olivine to low-temperature felsic minerals such as quartz.

Foliated metamorphic rock

Metamorphic rock whose minerals align in layers or bands under directed pressure, producing slate, schist, or gneiss with increasing metamorphic grade.

Convergent plate boundary

A boundary where plates move toward each other, producing subduction zones, volcanic arcs, deep-ocean trenches, and fold mountain belts.

Seafloor spreading evidence

Symmetric magnetic stripes on either side of mid-ocean ridges and sediment thickness increasing away from ridges support new crust forming at ridges.

Stream competence

The maximum particle size a stream can transport, which increases as flow velocity increases with steeper gradient or greater discharge.

Glacial till

Unsorted, unstratified sediment deposited directly by melting glacial ice, in contrast to sorted outwash deposited by meltwater streams.

Karst topography

A landscape formed by dissolution of soluble bedrock such as limestone, characterized by caves, sinkholes, disappearing streams, and solution valleys.

Mass wasting

Downslope movement of earth materials under gravity, classified by material type and motion as creep, slump, debris flow, or rockfall.

Angular unconformity

An erosional surface where tilted or folded older strata are overlain by younger, roughly horizontal layers, indicating deformation followed by erosion and deposition.

Radiometric half-life

The time required for half the parent atoms in a sample to decay to daughter products; after n half-lives, the parent fraction is one-half raised to n.

Index fossil

A fossil of an organism that was geographically widespread and short-lived stratigraphically, making it useful for correlating rock layers of the same age.

End-Permian extinction

The largest mass extinction in Earth history, about 252 million years ago, eliminating most marine species and marking the Paleozoic-Mesozoic boundary.

Principle of superposition

In an undisturbed sequence of sedimentary rocks, each layer is younger than the one below it and older than the one above it.

Thermohaline circulation

Deep-ocean circulation driven by density differences caused by temperature and salinity, with cold, salty water sinking in high-latitude regions.

Coriolis effect

The apparent deflection of moving air or water caused by Earth's rotation, to the right in the Northern Hemisphere and left in the Southern.

Spring tide

A tide of maximum range occurring at new and full moons, when solar and lunar tidal forces align and reinforce each other.

Upwelling

The rise of cold, nutrient-rich deep water to the ocean surface, typically along western continental margins, supporting high biological productivity.

Adiabatic lapse rate

The rate at which a rising air parcel cools by expansion without exchanging heat with its surroundings, about 10 degrees Celsius per kilometer when dry.

Relative humidity

The ratio of the actual water vapor content of air to the maximum it could hold at that temperature, expressed as a percentage.

Cold front

The leading edge of advancing cold air that pushes warm air upward, often producing a narrow band of intense precipitation and a temperature drop.

Dew point

The temperature to which air must be cooled at constant pressure for it to reach saturation and begin forming condensation or dew.

Kepler's third law

The square of an orbiting body's period is proportional to the cube of its semimajor axis, expressed as P squared equals a cubed in AU and years.

Cause of seasons

Earth's approximately 23.5-degree axial tilt changes the angle and duration of sunlight through the year, producing seasons, not distance from the Sun.

Terrestrial versus Jovian planets

Terrestrial planets are small, dense, and rocky with solid surfaces; Jovian planets are large, low-density, hydrogen-rich, and lack solid surfaces.

Main sequence star

A star in the stable stage of core hydrogen fusion, plotted along the diagonal band of the Hertzsprung-Russell diagram by luminosity and temperature.

5E instructional model

A lesson cycle of Engage, Explore, Explain, Elaborate, and Evaluate in which students investigate phenomena before the teacher formalizes the explanation.

Formative assessment

Ongoing evidence gathered during instruction, such as probes, exit tickets, or questioning, used to adjust teaching while learning is still in progress.