Earth Science

epicentre

the point on Earth's surface directly above the focus of an earthquake

erosion

the gradual wearing away and removal of rock at the surface of Earth 

igneous rock

a type of rock formed by the cooling and solidification of magma or lava 

lava

molten rock above Earth's surface

lithification

the process in which sediments come together to form sedimentary rock

lithosphere

a layer of earth consisting of the crust and the lithospheric mantle

magma

molten rock located below Earth's surface

metamorphic rock

a type of rock formed by heat and pressure

mineral

a naturally-occurring, inorganic solid substance

protolith

The original rock that has undergone metamorphism.

rock cycle

an idealised series of processes undergone by rocks in Earth's crust that change rocks from one type to another

sedimentary rock

type of rock formed by the accumulation and lithification of sediment

subduction

a geological process at convergent boundaries where one tectonic plate sinks beneath another plate

tsunami

a large ocean wave (or series of waves) caused by the displacement of large amounts of water, typically due to an earthquake or large landslide

weathering

the gradual breakdown of rock while it remains in the same place; weathering can be caused by many things, including heating, cooling, wind, rain, chemical reactions, plant roots and human activity

describe the geosphere

earth’s metallic core, solid rock, molten rock, sediments

describe the hydrosphere

water in all its forms: ice, water vapour, liquid water in the atmosphere, oceans, lakes, rivers, streams, soils, groundwater

describe the atmosphere

mixture of gases surrounding the planet

describe the biosphere

living things

recall the 4 steps in the carbon cycle

1. photosynthesis

2. consumption and assimilation

3. respiration and decomposition

4. combustion

describe the process of photosynthesis

carbon is removed from air and enters food chains via photosynthesis in producers

describe the process of consumption and assimilation

carbon is transferred between organisms in organic matter (food) via feeding and assimilation into biomass

describe the process of respiration and decomposition

carbon leaves organisms and is added to the air as a result of cellular respiration (excreted as CO₂) and also during decomposition (CO₂ and CH₄)

describe the process of combustion

burning wood and fossil fuels adds carbon to the air (CO₂, CO and CH₄)

recall the 4 steps of the nitrogen cycle

1. ammonification

2. nitrogen fixation

3. nitrification

4. denitrification

describe ammonification

the production of ammonia (NH₃) from proteins in dead organisms and urea in urine

describe nitrogen fixation

conversion of nitrogen gas (N₂) into nitrogen compounds eg. ammonia (NH₃) and nitrate (NO₃^-)

describe nitrification

conversion of ammonia (NH₃) into nitrites (NO₂^-) and then into nitrates (NO₃^-)

describe denitrification

conversion of soil nitrates into nitrogen gas

recall the bacteria involved in the nitrogen cycle

1. decomposer bacteria

2. nitrogen fixing bacteria

3. nitrifying bacteria

4. denitrifying bacteria

describe decomposer bacteria

breaks down dead material and waste

describe nitrogen fixing bacteria

converts atmospheric nitrogen into ammonia or nitrates, located in soil or root nodules, eg of mutualism

describe nitrifying bacteria

converts ammonia (NH₃) and nitrites (NO₂^-) into nitrates (NO₃^-)

describe denitrifying bacteria

converts nitrates (NO₃^-) and nitrites (NO₂^-) back into atmospheric nitrogen (N₂)

recall the layers of the earth in order of increasing depth

1. crust

2. mantle

3. outer core

4. inner core

describe the inner core

solid mixture of iron and nickel, depth: 5972km, temp: 5968 degrees celsius, pressure: 563 GPa

describe the outer core

liquid mixture of iron and nickel, flow generates earth’s magnetic field, depth: 3243km, temp: 4056 degrees celsius, pressure: 166 GPa

describe the mantle

thickest of 4 layers, made of solid + partially melted rocks, mostly silicon and oxygen, depth: 1184km, temp: 1706 degrees celsius, pressure: 56GPa

describe the general crust

layer of solid rock (5km-70km thick)- thickest under continents

describe the oceanic crust

not as thick, main rock type is basalt, young rocks, higher density

describe continental crust

thicker, mostly made of granite, old rocks, lower density

recall the three types of rock

igneous, sedimentary and metamorphic 

recall the types of weathering

mechanical and chemical

what is continental drift?

all continents were joined together and broke up to form smaller continents over millions of years- and are still moving

recall the 3 pieces of evidence used to support continental drift

1. the shapes of the continents showed they could fit together like a jigsaw puzzle

2. mountain chains and similar rock types line up on different continents

3. similar plants and animal fossils of the same age were found on land masses separated by oceans

recall the relative plate movement at convergent boundaries

2 neighbouring plates move towards each other → ←

recall the relative plate movement at divergent boundaries

2 neighbouring plates move away from each other ←→

recall the relative plate movement at transform boundaries

2 plates slide past each other → ←

recall the 3 possible explanations for the movement of tectonic plates

1. convection currents

2. ridge push

3. slab pull

describe convergent boundaries (crust + features) for ocean and ocean

crust is destroyed, volcano + oceanic trench

describe convergent boundaries (crust + features) for ocean and continental

crust is destroyed, volcano, oceanic trench

describe convergent boundaries (crust + features) for continental and continental

crust is not created or destroyed, mountain ranges

describe divergent boundaries (crust + features) for continental and continental

crust is created, volcano, rift valleys

describe divergent boundaries (crust + features) for ocean and ocean

crust is created, volcano, mid ocean ridge

describe transform boundaries (crust + features)

crust is not created or destroyed, fault

explain the formation of plutonic igneous rocks

magma cools slowly underground and produces igneous rock with large crystals

explain the formation of volcanic igneous rocks

lava cools quickly on the surface and produces and igneous rock with small/no crystals

how are biological sedimentary rocks formed?

formed from the remains of organisms eg. coal from plants is hardened

how are chemical sedimentary rocks formed?

water travels through rock, carries dissolved minerals away and deposits them elsewhere

how are clastic sedimentary rocks formed?

formed from sediments of other rocks

describe mechanical weathering

breaks rock into smaller pieces but does not change chemical composition

what causes mechanical weathering?

temperature change: makes things expand + contract

frost action: water seeps into cracks + expands

root action: roots grow into existing rocks

animal activity: makes holes/ cracks that let in water and air

describe chemical weathering

breaks rock into smaller pieces by changing the chemical composition of minerals in the rock

what causes chemical weathering?

oxygen: reacts with elements in the rock

rain water: dissolves some minerals

carbon dioxide: dissolves air + forms acid rain

how are contact metamorphic rocks formed?

rocks are exposed to high temperatures next to magma - magma intrudes into rock and changes mineral composition and crystal size

how are regional metamorphic rocks formed?

extensive area of existing rock is exposed to high temperature and high pressure, deep in earth’s crust, have different minerals + increased grain size from protoliths, foliation- has layers of flaky minerals, often occur at subduction zones

Label the parts of the volcano

ash cloud, side cone, side vent, earth’s crust, lava flow, main vent, magma chamber

recall where volcanoes form

hotspots, divergent plate boundaries, convergent plate boundaries

how do volcanoes form at hotspots?

extra heat causes rocks to melt + magma to rise through crust → tectonic plate moves + carries volcano away from hotspot

how do volcanoes form at divergent plate boundaries?

2 tectonic plates move apart → magma rises to fill the space

how do volcanoes form at convergent plate boundaries?

continental + oceanic plates collide → oceanic plate is subducted → oceanic plate gets hotter + melts → produces magma → magma rises through fractures in crust

recall the 5 major issues related to volcanic eruptions

toxic gases, lava flows, pyroclastic flows, lahars (mudflows) , volcanic ash release