Earth and Space Science 2025

hard test :((

Inner Core

The solid, dense, and hottest part of Earth's structure, composed primarily of iron and nickel. The pressure here is so intense that the metals can't move around like a liquid and are forced to vibrate like a solid.

Outer Core

The liquid layer surrounding the inner core, made of molten iron and nickel, responsible for generating Earth's magnetic field.

Mantle

A thick layer of semi-solid rock beneath the crust, divided into the upper and lower mantle, where convection currents occur.

Lithosphere

The rigid outer layer of the Earth, consisting of the crust and the uppermost part of the mantle.

Asthenosphere

The semi-fluid (plastic) layer of the mantle beneath the lithosphere, which allows tectonic plates to move.

Continental Crust

The thick, less dense portion of Earth's crust, composed mostly of granite.

Oceanic Crust

The thinner, denser portion of Earth's crust, composed mainly of basalt.

Plate Tectonic Theory

The theory describing large-scale movement of the Earth's lithospheric plates. The Earth's lithosphere is divided into rigid sections called tectonic plates that float and move around on top of the asthenosphere.

Evidence for continental drift

Continents fit together like a jigsaw puzzle, fossils are found on the edges of continents separated by oceans, shape of the ocean floor and age/polarity of ocean sediments, glaciers and glacial deposits.

Planetesimal Accretion Theory

The Earth was formed 4.56 billion years ago from a distant supernova. Small planetesimals grouped together by gravity to form the spherical shape of the Earth.

Plate movement

The lithosphere (made up of the crust and upper mantle) is less dense than the asthenosphere, so it floats on top.

Oceanic Trench

When an oceanic plate collides with another, the more dense of the two plates slides under the less dense plate creating a deep trench where they first meet.

Oceanic-Continental Trench

As the oceanic plate subducts it 'pulls on' the edge of the continental plate down to form a crease.

Volcanic Mountain

The heat from the friction between the plates melts the crust, the newly formed magma rises and forms volcanoes.

Island Arc

The heat from friction causes the subducting plate to melt. Magma rises and forms volcanoes under the ocean. When they penetrate the ocean surface, they form island arcs.

Thrust Mountain

The collision pushes up the crust to form mountains.

Young

Refers to geological features that are relatively new in terms of formation.

Older

Refers to geological features that have been formed for a longer period of time.

Dense

Having a high mass per unit volume, often referring to materials like oceanic crust.

Buoyant

Having the ability to float, often referring to materials like continental crust.

Thin

Refers to a measurement of about 7km in thickness, typically describing oceanic crust.

Thick

Refers to a measurement ranging from 10-70km in thickness, typically describing continental crust.

Mid-Ocean Ridge

Magma flows out faster than in seafloor spreading and water cools it quickly, forming raised new oceanic crust (ridge underwater).

Seafloor Spreading

As oceanic plates diverge, magma slowly rises to fill the gap, creating new, flat oceanic crust.

Rift Valley

Plates diverge on land, but there is no magma to fill the gap creating a gap in the crust.

Fissure Volcano

As plates diverge on land, magma slowly rises to fill the gap, creating new crust. There is no eruption and sometimes a ridge can be formed.

Fault

Meeting point between two plates.

Faults

Breaks or series of breaks in the Earth's Crust. Occurs when too much stress is applied to the crust.

Stress

Force acting on a material.

Strain

The deformation of a material in response to stress.

Fold

When stress is applied to both ends of a section of rock, it folds.

Anticline

Upward curves.

Syncline

Downward curve.

Earthquakes

When a lot of pressure builds up at the fault line as plates try to move but friction prevents it.

Focus

Location deep within the Earth where the rupture occurs.

Epicentre

The geographic point on the Earth's surface exactly above the focus.

P waves

Shakes the Earth in the same direction as the wave (compression and expansion).

S waves

Shakes the Earth perpendicular to the wave (up and down).

Surface waves

Circular movement of rocks that travel along the surface.

Divergent Boundary

A boundary where plate tectonics move apart, creating new crust.

Convergent Boundary

A boundary where plate tectonics push closer together, causing subduction or thrusting.

Transform Boundary

A boundary where plates slide past each other.

Australian Continent

Australia's great minerals and energy resources from the Pre-Cambrian era have been preserved despite global supercontinent cycles because of its isolation and location in the centre of a tectonic plate.

Igneous Rocks

Formed when magma cools and solidifies.

Plutonic Intrusive Igneous Rock

Igneous rock that cools under the crust, characterized by larger crystals and a coarse-grained texture.

Volcanic Extrusive Igneous Rock

Igneous rock that cools above the crust, characterized by smaller or no crystals due to faster cooling and gas holes, resulting in a fine-grained texture.

Granite

An example of an intrusive igneous rock.

Gabbro

An example of an intrusive igneous rock.

Pumice

An example of an extrusive igneous rock.

Basalt

An example of an extrusive igneous rock.

Obsidian

An example of an extrusive igneous rock.

Sedimentary Rocks

Rocks formed when other types of rock are weathered, carried into bodies of water, and compacted with the crystallisation of dissolved chemicals.

Weathering

The breakdown of rocks into smaller pieces through physical, chemical, and biological processes.

Erosion

The displacement of rock caused by wind, water, ice, or gravity.

Metamorphic Rocks

Rocks formed when extreme heat and pressure act on other rock types, causing them to recrystallise.

Regional Metamorphism

Metamorphism that occurs over a large area where plates meet or rocks are buried.

Contact Metamorphism

Metamorphism that occurs in smaller areas due to hot magma intruding into rock.

Dynamic Metamorphism

Metamorphism that occurs in smaller areas where rocks are scraping past one another.

Foliation

The movement of minerals into bands or layers which can then become folded.

Rock Processing

The methods used to extract and refine rocks, including crushing, magnetic separation, enrichment, and extraction.

Minerals

A naturally occurring inorganic solid with a specific chemical composition and crystalline structure.

Crystal

A solid substance where atoms are arranged in an orderly repeating pattern.

Cleavage

The tendency of a mineral to break along flat surfaces.

Lustre

The way a mineral reflects light (e.g., metallic, glassy).

Streak

The colour of a mineral's powder when rubbed on a streak plate.

Hardness

The resistance of a mineral to being scratched, measured by Moh's hardness scale.

Ore

A rock containing valuable minerals that can be mined for profit.

MYA (Million Years Ago)

A time measurement unit used in geology to represent events in Earth's history.

Geological Event

A significant occurrence, such as volcanic eruptions or mountain formation, that shapes Earth's surface.

Geological Time Scale

A system of chronological measurement that relates stratigraphy to time, dividing Earth's history into eras, periods, and epochs.

Eon

A major division of geological time.

Era

A subdivision of an eon.

Period

A subdivision of an era.

Epoch

A subdivision of a period.

Age

A subdivision of an epoch.

5 BYA

Earth is formed.

3.7 BYA

Crust solidifies.

3.5 BYA

First life in oceans.

3.25 BYA

Photosynthesis begins in oceans.

1.9 BYA

First cells with nuclei in oceans.

0.65 BYA

First multi-cellular organisms.

0.5 BYA

Supercontinent Pannotia split into 3.

250 MYA

Mass extinction of 99% of all life.

245 MYA

Age of Dinosaurs begin.

150 MYA

Supercontinent breaks up, continents drift apart.

65 MYA

Mass extinction of 70% of all life.

3.5 MYA

First proto humans in Africa.

100,000 YA

First homo sapiens.

10,000 YA

Recorded human history begins.

0 YA

Present day.

Open Cut Mining

Extracts rocks and minerals close to the surface; involves drilling, blasting, and loading.

Underground Mining

Extracts ore deposits that are deeper underground through tunnels.

Dredging

Underwater excavation of deposits using floating equipment.

Leach Mining

A solution dissolves the ore and pumps it back up to the surface.

Economic Viability Factors

Includes grade, size of the deposit, access to infrastructure, current price, and demand.

Satellite Imaging

Remote sensing that uses spectral signatures to identify materials.

Infra-red

Uses differences in mineral properties to separate them.

Seismic Sensing

Uses S-waves to create models of Earth's internal structures.