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Yr 10 Geology
all definitions
Term | Definition |
---|---|
Andesite magma | Magma containing more silica than basalt, is viscous and forms cone shaped volcanoes such as Ruapehu and Taranaki |
Ash eruption | Very small fragments of magma erupted from a volcano |
Active volcano | A volcano that is ‘ejecting’ or erupting |
Basalt | Igneous rock with small crystals |
Basalt magma | Contains about 50% silica, flows like honey is least explosive and forms shield volcanoes like Dunedin and Christchurch |
Caldera | Large bowl shaped volcanic depression formed from the collapse of the top of a volcanic cone |
Collision zone | Where tectonic plates collide at their boundaries |
Continental | Type of crust that carries land |
Core | Central part of the Earth (about one third of the Earth’s mass, mainly iron and nickel) |
Crater | a bowl-shaped geological formation at the top of a volcano |
Crust | Outer layer of the Earth made up of rocks |
Continental crust | Crust underlying the continents |
Convection currents | Currents formed by the rising of hot, less dense material being replaced by cooler, denser material. |
Dormant volcano | Volcano not recently active but is not extinct |
Earthquake | Vibration of Earth caused by sudden release of energy |
Epicentre | Point on Earth’s surface above the focus of an earthquake |
Erosion | Transport of rock fragments and other materials |
Extinct volcano | A volcano that has not erupted for millions of years |
Extrusive | Cools rapidly on the surface of the Earth, contains small crystals e.g. basalt |
Fault / transform | Break in the rocks of the Earth’s crust |
Focus | Point where an earthquake starts |
Fossil | Remains of plants and animals that are preserved in rock / found in sedimentary rock |
Geological | To do with the structures of the Earth’s crust |
Geothermal | Where hot rock within the Earth’s crust heats water, which finds its way to the surface as hot springs, geysers and mud pools |
Granite | An example of an intrusive igneous rock |
Igneous rock | Rock formed by the cooling and solidifying of magma |
Intrusive | Cools slowly inside the crust contains large crystals, e.g. granite |
Inner core | The solid part of the core, hottest part of the Earth. Is made up of iron and nickel. |
Lahar | Mudflow on a volcano consisting largely of volcanic fragments |
Lava | Molten rock which has solidified on the surface of the Earth |
Limestone | An example of sedimentary rock made from the remains of tiny shellfish. |
Magma | Molten rock formed when rocks of the mantle or crust melt / hot liquid rock inside the Earth |
Mantle | Thickest section of the Earth, sits underneath the crust. It is made up of semi-molten rock called magma. |
Marble | Metamorphic rock made from chalk |
Mercalli scale | Used for measuring earthquake intensity |
Metamorphic rock | Formed when rocks are subjected to long periods of high pressure or heat without melting |
Molten | Liquid (melted) |
Obsidian | A shiny black igneous rock |
Oceanic | Type of crust that carries water |
Outer core | The liquid part of the core (molten iron and nickel) |
Pumice | An example of an extrusive igneous rock (A light volcanic rock with gas holes) |
Rhyolite | Magma that contains about 70% silica flows like tar is very viscous and most explosive, forms dome and caldera volcanoes such as Mt Tarawera or Taupo. |
Richter scale | Scale for measuring magnitude of an earthquake. |
Sandstone | An example of a sedimentary rock |
Sedimentary rock | Rocks formed from layers of deposition and cementation of rock fragments e.g. sandstone |
Seismic waves | Waves which travel out from the focus of an earthquake |
Seismograph | Instrument which records earthquake waves |
Shale | Compressed mud, an example of a sedimentary rock |
Slate | Metamorphic rock formed from shale |
Spreading zone | Where plates move apart at mid-ocean ridges |
Subduction | When one tectonic plate is pushed down under another at a collision boundary |
Tectonic plates | The crust is made up of 12 major plates that are moving at different speeds and directions |
Tsunami | Tidal wave |
Volcano | A hole or vent in the Earth’s surface where molten rock, gas and ash are erupted. |
Weathering | Breaking down of rocks on Earth’s surface |