HSC Earth and Environmental Science flashcards

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

Geosphere

The solid Earth component, including the crust, mantle, and core, together with rocks, minerals, and sediments. It interacts with the atmosphere, hydrosphere, and biosphere through processes such as weathering and volcanism.

Negative feedback

A process in which a change triggers a response that counteracts the original change, stabilising the system. For example, increased evaporation may produce more cloud that reflects sunlight and cools the surface.

Radiometric dating

A method of absolute dating that measures the ratio of a radioactive parent isotope to its decay product in a sample. Knowing the half-life allows the age of the rock or mineral to be calculated.

Latent heat transfer

Energy absorbed when water evaporates and released when vapour condenses. This transfer moves heat from Earth's surface into the atmosphere and powers storms and global circulation.

Seafloor magnetic stripes

Symmetrical bands of alternately magnetised rock on either side of mid-ocean ridges. They record reversals of Earth's magnetic field as new crust formed, providing evidence for seafloor spreading.

Subduction zone

A convergent boundary where denser oceanic crust sinks beneath another plate. It produces deep ocean trenches, earthquakes, volcanic arcs, and magma generated by melting of the descending plate.

Intrusive igneous rock

Rock that crystallises from magma beneath the surface, where slow cooling allows large crystals to grow. Granite and gabbro are examples and typically show a coarse-grained texture.

Ore grade

The concentration of a valuable mineral within a deposit. Higher grade generally makes extraction more economic, but viability also depends on depth, accessibility, and market price.

Greenhouse effect

Warming of Earth's surface because gases such as carbon dioxide, water vapour, and methane absorb outgoing longwave radiation and re-emit some back towards the surface.

Coriolis effect

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

El Nino

A phase of the Southern Oscillation in which weakened trade winds allow warm water to spread east across the Pacific. It typically brings drought to eastern Australia and heavy rain to the eastern Pacific.

Dew point

The temperature to which air must cool, at constant pressure and moisture content, for it to become saturated. Further cooling below the dew point causes condensation into cloud or dew.

Trophic level

A feeding position within a food chain, such as producer, primary consumer, or secondary consumer. Only about ten percent of energy transfers to the next level, limiting chain length.

Carrying capacity

The maximum population size of a species that an environment can sustain indefinitely given available food, water, shelter, and other resources. It can change as conditions alter.

Mutualism

A symbiotic relationship in which both participating species benefit. For example, some ants protect acacia trees while receiving food and shelter from the tree's structures.

Biodiversity

The variety of life at genetic, species, and ecosystem levels. Higher biodiversity generally improves ecosystem resilience, because more species can maintain functions if conditions change.

Eutrophication

Nutrient enrichment of water, often from fertiliser runoff, that triggers algal blooms. Decomposition of the algae then depletes dissolved oxygen, harming fish and other aquatic organisms.

Environmental impact assessment

A formal process that identifies, predicts, and evaluates the likely environmental effects of a proposed project before approval. It usually includes scoping, baseline studies, mitigation planning, and monitoring.

Dryland salinity

Soil and water salinisation caused by rising water tables that bring dissolved salts to the surface. Clearing deep-rooted vegetation and excessive irrigation are common contributing causes.

Waste hierarchy

A ranked order of waste management options from most to least preferred: avoid, reduce, reuse, recycle, recover energy, and dispose. Earlier options generally produce greater environmental benefit.

Controlled variable

A factor held constant across experimental trials so that it cannot influence the dependent variable. Controlling such factors helps ensure that observed changes result from the independent variable.

Reliability

The extent to which repeated measurements or trials produce consistent results. Reliability is improved by increasing sample size, repeating measurements, and standardising procedures.

Percentage error

A measure of accuracy calculated as the measured value minus the accepted value, divided by the accepted value, then multiplied by 100. A large value indicates low accuracy.

Capture-recapture estimate

A population estimate calculated as the number first marked multiplied by the number caught in a second sample, divided by the number of marked individuals recaptured.

Quadrat sampling

A fieldwork technique using a square frame placed randomly to sample a small area. Counts or percentage cover are scaled up to estimate density or abundance across a larger area.

Contour lines

Lines on a topographic map joining points of equal elevation. Closely spaced contours indicate steep terrain, and rivers flow downhill crossing contours perpendicularly.

Climograph

A graph showing monthly average temperature as a line and monthly rainfall as bars for a location. It allows climate classification and comparison between different sites.

Systematic error

A consistent error that shifts all measurements in the same direction, often from faulty calibration or faulty technique. It reduces accuracy and cannot be removed by averaging.

Nitrogen fixation

Conversion of atmospheric nitrogen gas into compounds usable by living things, carried out by certain bacteria and by lightning. It is the main entry point of nitrogen into ecosystems.

Foliated metamorphic rock

Metamorphic rock in which mineral grains are aligned in parallel bands by directed pressure. Schist and gneiss are examples, and the alignment records the direction of stress.

Upwelling

The rise of cold, nutrient-rich water from depth to the ocean surface, often driven by winds moving surface water offshore. It supports highly productive fisheries and plankton blooms.

Habitat fragmentation

The division of a continuous habitat into smaller, isolated patches, usually by land clearing or development. It reduces gene flow and increases extinction risk for vulnerable species.