Geology terms

Crust

20-500C; Made of rocks and minerals; 5-70km → Thinnest

Mantle

500-2000C; Solid rock that flows; 2900km → Thickest

Outer Core

3000C; Liquid Iron and Nickel; 2300km

Inner Core

4000C; Solid Iron and Nickel; 1200km

Hardness

Measures rocks ability to scratch other materials, measured using Mohs

Lustre

Shininess of a material, how it reflects light. E.g. Earthy, Brilliant, Pearly, etc.

Streak

The colour of the rock in its powdered form.

Cleavage

How a mineral breaks into pieces.

Mineral

Chemicals (elements or compounds) that occur in the Earth's crust and are the basic building blocks of rocks.

Igneous Rock

Rocks that form from the cooling of magma below the earth's crust.

Intrusive Igneous Rock

Formed from magma that is cooled slowly beneath the Earth.

Extrusive Igneous Rock

Cooled quickly when magma/lava reaches the Earth's surface.

Lava

Molten rock at/above Earth's surface.

Magma

Molten rock below the Earth's surface.

Crystal Size

Large, visible crystals suggest slow cooling.

Sedimentary Rocks

Form when sediments compact over time.

Examples of Sedimentary rocks

Sandstone, Mudstone, siltstone, conglomerate, shale, limestone.

Weathering

The breaking down of rock.

Erosion

The moving of rock/sediment.

Metamorphic Rock

Formed when other types of rocks are changed by heat & pressure by the Earth.

Parent Rock

The original rock before it evolves into the metamorphic rock.

Limestone

A sedimentary rock that can be transformed into marble, which is used in building and benchtops.

Shale

A sedimentary rock that can be transformed into slate, which is used for roofing, flooring, and electrical pathways.

Foliated

A characteristic of metamorphic rocks that shows layered or banded appearance.

Rock Cycle

The continuous process by which rocks are transformed from one type to another through various geological processes.

Deposition

The process of depositing sediment after weathering and erosion.

Heat and Pressure

Processes that transform existing rocks without melting them.

Fossils

Remains and traces of organisms preserved in rocks.

Body Fossils

Fossils of bones, teeth, and shells.

Trace Fossils

Preserved evidence of biological activity, such as footprints and leaves.

Cast Fossil

A solid copy of the shape of an organism.

Mould Fossil

A hollow area in sediment in the shape of an organism or part of an organism.

Relative Dating

A method to determine the relative age of fossils based on their position in sediment layers.

Type of rock where fossils are commonly found due to the process of their formation involving burial by sediment

Sedimentary Rock

Tectonic Plates

Large sections of the Earth's crust that move and interact with each other.

Convergent Boundaries

Where tectonic plates move towards each other.

Divergent Boundaries

Where tectonic plates move away from each other.

Transform Boundaries

Where tectonic plates slide past each other.

Convection Currents

Currents in the mantle caused by heat energy from the Earth's core that drive the movement of tectonic plates.

Seafloor Spreading

The process by which the seafloor spreads as tectonic plates move apart at mid-ocean ridges.