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Y10 Earthquakes Y10 Earthquakes Geological processes Geological processes

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Y10 Earthquakes. Geological processes. Meulaboh – the epicentre. Earthquake video. What is an earthquake? What happens in an earthquake? What is the effects of an earthquake on the community? What should you do in an earthquake? What shouldn’t you do?. A rupture along a fault line. - PowerPoint PPT Presentation

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Page 1: Y10 Earthquakes

Y10 EarthquakesY10 Earthquakes

Geological processesGeological processes

Page 2: Y10 Earthquakes

Meulaboh – the epicentreMeulaboh – the epicentre

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Earthquake videoEarthquake video

What is an earthquake?What is an earthquake?

What happens in an earthquake?What happens in an earthquake?

What is the effects of an earthquake on What is the effects of an earthquake on the community?the community?

What should you do in an earthquake?What should you do in an earthquake?

What shouldn’t you do?What shouldn’t you do?

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A rupture along a fault lineA rupture along a fault line

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Earthquake commissionEarthquake commissionFix. Fasten. Forget. Fix. Fasten. Forget.

Secure hot water cylinders and header tanks Secure hot water cylinders and header tanks Check that your house is secured to its foundations Check that your house is secured to its foundations Secure your chimney with galvanised metal bands Secure your chimney with galvanised metal bands Secure tall furniture to the wall studs Secure tall furniture to the wall studs Secure wood burners to the floor Secure wood burners to the floor Store heavy objects low down Store heavy objects low down Use non-slip mats under smaller appliances and Use non-slip mats under smaller appliances and objects objects Use plastic putty (Blu Tack) to secure ornaments Use plastic putty (Blu Tack) to secure ornaments Push picture and mirror hooks closed Push picture and mirror hooks closed Have flexible gas and plumbing fittings installed. Have flexible gas and plumbing fittings installed.

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What to do during an EarthquakeWhat to do during an Earthquake

Follow this link for ideas what to do in an Follow this link for ideas what to do in an earthquakeearthquake

FEMA: What to Do During an EarthquakeFEMA: What to Do During an Earthquake

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Te Anau Earthquake videoTe Anau Earthquake video

Click on the links belowClick on the links below

Earthquakes - Earthquake damage, Te Earthquakes - Earthquake damage, Te AnauAnau - Te - Te AraAra Encyclopedia of New Zealand Encyclopedia of New Zealand

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Earthquake DefinitionsEarthquake Definitions

An earthquake is vibrations of the Earth An earthquake is vibrations of the Earth produced by the rapid release of energy.produced by the rapid release of energy.

Surface rocks of the Earth’s crust are Surface rocks of the Earth’s crust are brittle and can break when put under brittle and can break when put under pressure. pressure.

Deeper rocks bend under pressure as they Deeper rocks bend under pressure as they are not so brittle.are not so brittle.

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Focus, epicentre and faultFocus, epicentre and fault

Focus – the point where the rock breaks in Focus – the point where the rock breaks in the Earth’s crust.the Earth’s crust.

Epicentre – The point on the Earth’s crust Epicentre – The point on the Earth’s crust directly above the focus.directly above the focus.

Fault – break in the rocks of the crust Fault – break in the rocks of the crust where the two sides of the break have where the two sides of the break have moved relative to each other.moved relative to each other.

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Fault, focus and EpicentreFault, focus and Epicentre

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Active faultsActive faultsMany fault lines cut the Many fault lines cut the ground’s surface in New ground’s surface in New Zealand; each past fault Zealand; each past fault movement would have movement would have been accompanied by a been accompanied by a large earthquake. large earthquake. Those that are considered Those that are considered likely to move again in the likely to move again in the future are called active future are called active faults. They are known to faults. They are known to have ruptured the ground have ruptured the ground surface once or more in surface once or more in the last 120,000 years.the last 120,000 years. This map effectively This map effectively shows the areas where shows the areas where future earthquakes are future earthquakes are most likely. most likely.

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QuestionsQuestions

Why do Earthquakes occur in the crust Why do Earthquakes occur in the crust and not deeper in the mantle?and not deeper in the mantle?

What is the difference between focus and What is the difference between focus and epicentre?epicentre?

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Weblink to show NZ earthquakesWeblink to show NZ earthquakes

Click on the link below.Click on the link below.

Earthquakes - New Zealand earthquakes, Earthquakes - New Zealand earthquakes, 1990–94 - Te 1990–94 - Te AraAra Encyclopedia of New Zealand Encyclopedia of New Zealand

Page 14: Y10 Earthquakes

New Zealand New Zealand regions at regions at greatest risk of greatest risk of ground shakingground shaking

The difference The difference between each between each level is 10%.level is 10%.

What do you What do you notice about the notice about the distribution of distribution of more severe more severe earthquakes?earthquakes?

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The 1848 Marlborough Earthquake The 1848 Marlborough Earthquake and 1929 Murchison Earthquake.and 1929 Murchison Earthquake.

Click on the links belowClick on the links below

Historic earthquakes - The 1848 MarlboroHistoric earthquakes - The 1848 Marlborough earthquake - Te ugh earthquake - Te AraAra Encyclopedia of New Zealand Encyclopedia of New Zealand

Historic earthquakes - The 1929 Arthur’s PHistoric earthquakes - The 1929 Arthur’s Pass and Murchison earthquakes - Te ass and Murchison earthquakes - Te AraAra Encyclopedia of New Zealand Encyclopedia of New Zealand

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Earthquakes - Seismic WavesEarthquakes - Seismic WavesWaves travel outwards from the focus Waves travel outwards from the focus Three types, in the order they arrive:Three types, in the order they arrive:

1.1. P Waves (primary) – longitudinal waves P Waves (primary) – longitudinal waves causing compression and extension of causing compression and extension of rocks. Moves through solid an liquid.rocks. Moves through solid an liquid.

2.2. S waves (secondary) – transverse waves S waves (secondary) – transverse waves sideways and vertical shaking. Can’t sideways and vertical shaking. Can’t move through liquids.move through liquids.

3.3. Surface waves – slow. Travel through Surface waves – slow. Travel through crust like ocean waves. Cause most crust like ocean waves. Cause most damage.damage.

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Earthquake wave animationEarthquake wave animation

Earthquakes - Primary and secondary wavEarthquakes - Primary and secondary waves - Te es - Te AraAra Encyclopedia of New Encyclopedia of New Zealand#breadcrumbtopZealand#breadcrumbtop

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SeismologistsSeismologists

Seismologist are scientists who study Seismologist are scientists who study Earthquakes.Earthquakes.

Seismographs are instruments which Seismographs are instruments which record seismic waves.record seismic waves.

Seismograms are the recordings they Seismograms are the recordings they make.make.

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A seismographA seismograph

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seismographseismograph

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A seismogramA seismogram

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Seismologist, ha ha!Seismologist, ha ha!

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Finding an epicentreFinding an epicentre

Seismologist use the time interval between Seismologist use the time interval between the arrival of the P and S waves to the arrival of the P and S waves to determine their distance from the determine their distance from the epicentre.epicentre.

When the arrival times of P and S waves When the arrival times of P and S waves from three seismographs in different from three seismographs in different locations are recorded, the epicentre can locations are recorded, the epicentre can be calculated.be calculated.

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Measuring EarthquakesMeasuring Earthquakes

Measured by Measured by IntensityIntensity and and MagnitudeMagnitude

Intensity – Mercalli scale – based on Intensity – Mercalli scale – based on people’s experiences and effects on people’s experiences and effects on buildings and the environment.buildings and the environment.

Magnitude – Richter scale – based on Magnitude – Richter scale – based on amount of energy released. amount of energy released. Measurements of ground movements and Measurements of ground movements and seismographs.seismographs.

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Damage from EarthquakesDamage from Earthquakes

Depends on size, distance from focus, Depends on size, distance from focus, type of rock, strength of buildings and type of rock, strength of buildings and depth.depth.

Richter scale – not linear, each step Richter scale – not linear, each step releases 30x more energy. releases 30x more energy.

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Make your own seismograph Make your own seismograph

Make an earthquake and bring Make an earthquake and bring in your seismograph and in your seismograph and

seismogramseismogram

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Earth’s StructureEarth’s Structure

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Structure of EarthStructure of Earth

Crust Crust - 6km thick under oceans – solid- 6km thick under oceans – solid

- up to 70 km thick under - up to 70 km thick under continents. Av: 30-40 km continents. Av: 30-40 km

MantleMantle - 3 000 km thick – plastic – flows- 3 000 km thick – plastic – flows

- upper 100 km – rigid- upper 100 km – rigid

Outer core – 2,300 km thick – liquid Outer core – 2,300 km thick – liquid

Inner core – 1,200 km thick - solidInner core – 1,200 km thick - solid

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The bitsThe bits

Continental crust is under the continents, Continental crust is under the continents, its light and floats on the mantle. Oldest its light and floats on the mantle. Oldest rocks. rocks.

Oceanic crust is heavier, thinner, less Oceanic crust is heavier, thinner, less buoyant, sinks into mantle.buoyant, sinks into mantle.

Mantle rock is hot and under pressure so Mantle rock is hot and under pressure so isn’t actually melted.isn’t actually melted.

Core is mainly iron and nickel. Core is mainly iron and nickel.

Circulation of iron produces magnetic field.Circulation of iron produces magnetic field.

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Tectonic platesTectonic plates

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Tectonic plates in 3DTectonic plates in 3D

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Convection currents in mantleConvection currents in mantleHeat from the Heat from the core heats the core heats the magma magma causing it to causing it to rise towards rise towards the crust in the crust in currents which currents which push on the push on the plates, moving plates, moving them.them.

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What happens when plates move?What happens when plates move?

Spreading zonesSpreading zones – – plates move apart at plates move apart at mid-oceanic mid-oceanic ridgesridges. . Magma rises to form Magma rises to form new crust in the gaps.new crust in the gaps.

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Where does the old oceanic crust Where does the old oceanic crust go?go?

Collision zonesCollision zones – plates collide at – plates collide at boundaries.boundaries.

Rocks can fold into mountains like the Rocks can fold into mountains like the Southern Alps.Southern Alps.

Earthquakes commonEarthquakes common

Subduction – Subduction – a less dense oceanic plates a less dense oceanic plates goes in under a continential coast – east goes in under a continential coast – east of the North Island.of the North Island.

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Subduction of the pacific plate Subduction of the pacific plate under the north islandunder the north island

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Mountain building – folding rocksMountain building – folding rocks

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Movement of tectonic platesMovement of tectonic plates

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Plate Plate boundaries boundaries through New through New Zealand.Zealand.

The pacific The pacific plate is plate is subducting subducting under the under the Australian in Australian in the north and the north and colliding in colliding in the south.the south.

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Valley formed by the Valley formed by the subsidence of a block subsidence of a block of the Earth's of the Earth's crustcrust between two or more between two or more parallel parallel faultsfaults..

Rift valleys are steep-Rift valleys are steep-sided and form where sided and form where the crust is being the crust is being pulled apart, as at pulled apart, as at mid-ocean ridgesmid-ocean ridges, or , or in the Great Rift in the Great Rift Valley of East Africa. Valley of East Africa.

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Active volcanoes of the PacificActive volcanoes of the Pacific

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The Geological History of NZThe Geological History of NZ

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GondwanaGondwana

NZ was formed off NZ was formed off the coast of the the coast of the great southern great southern supercontinent – supercontinent – Gondwana. Gondwana.

The oldest rocks in The oldest rocks in NZ are about 500 NZ are about 500 MY old.MY old.

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150 mya150 mya

Rocks formed Rocks formed from sediments from sediments eroded off eroded off gondwana are gondwana are uplifted due to a uplifted due to a subduction zone subduction zone forming.forming.

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Greywacke forming at the edge of Greywacke forming at the edge of Gondwana Gondwana

This is the This is the sediments sediments that make that make the rocks the rocks building up building up off the off the coast of coast of Gondwana.Gondwana.

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70 mya70 mya

Spreading Spreading ridge in future ridge in future tasman sea tasman sea starts NZ starts NZ moving away moving away on its long on its long journey.journey.

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10 mya10 mya

NZ starts to NZ starts to take shape. take shape.

Land mass is Land mass is large, one large, one island.island.

Tectonic Tectonic collisions are collisions are similar today.similar today.

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ResearchResearchHow do we know that NZ was once past of How do we know that NZ was once past of Gondwana?Gondwana?

What was the climate like?What was the climate like?

What sort of life lived on Gondwana?What sort of life lived on Gondwana?

How long were the Southern continents together How long were the Southern continents together before they separated?before they separated?

What caused NZ to separate from Gondwana?What caused NZ to separate from Gondwana?

What are some species of plants and animals What are some species of plants and animals whose ancestors were on NZ when it whose ancestors were on NZ when it separated?separated?

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Local features and geological Local features and geological formationsformations

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Alpine fault and Wairau faultAlpine fault and Wairau faultThe alpine fault branches into the Wairau fault The alpine fault branches into the Wairau fault that passes through Marlborough.that passes through Marlborough.It is a break in the Earth’s crust caused by the It is a break in the Earth’s crust caused by the collision of the Australian and Pacific plates.collision of the Australian and Pacific plates.Collision of tectonic plates causes mountain Collision of tectonic plates causes mountain building around the fault.building around the fault.The Wairau fault divides Marlborough and is still The Wairau fault divides Marlborough and is still active.active.The Wairau earthquake of 1848 caused The Wairau earthquake of 1848 caused subsidence of 5 ft in the lower Wairau Valley and subsidence of 5 ft in the lower Wairau Valley and was widely felt throughout the southern part of was widely felt throughout the southern part of the North Island. the North Island. The Sounds are flooded river valleys.The Sounds are flooded river valleys.

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The alpine fault on the East of the The alpine fault on the East of the AlpsAlps

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Marlborough Sounds - flooded valleysMarlborough Sounds - flooded valleysWhen the strong tidal currents of Cook Strait flow through the narrow When the strong tidal currents of Cook Strait flow through the narrow entrances of the Marlborough Sounds, complex currents are entrances of the Marlborough Sounds, complex currents are produced. Whirls and current paths are visible in this photograph, produced. Whirls and current paths are visible in this photograph, taken from space. The waters seen here have different levels of taken from space. The waters seen here have different levels of turbidity (sediment held in suspension). turbidity (sediment held in suspension).

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Marlborough rocksMarlborough rocksMany of the rocks that form Marlborough are Many of the rocks that form Marlborough are sedimentary rocks like greywacke, formed in the sedimentary rocks like greywacke, formed in the oceans off the coast of Gondwana.oceans off the coast of Gondwana.

Schist is commonly found – a metamorphic rock Schist is commonly found – a metamorphic rock that makes up the mountains surrounding us. It that makes up the mountains surrounding us. It was formed deep in the Earth when the plates was formed deep in the Earth when the plates were colliding.were colliding.

We can see the rocks because colliding plates We can see the rocks because colliding plates has pushed them up out of the ocean and the has pushed them up out of the ocean and the rocks covering them have been eroded away.rocks covering them have been eroded away.

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Marlborough Schist from Queen Marlborough Schist from Queen Charlotte sounds – a metamorphic Charlotte sounds – a metamorphic

rock.rock.

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Marine FossilsMarine FossilsFossils can be found in many Marlborough Fossils can be found in many Marlborough rocks.rocks.When organisms died their skeletons were When organisms died their skeletons were fossilised in the rocks then uplifted and exposed.fossilised in the rocks then uplifted and exposed.Coastal areas such as Marlborough have only Coastal areas such as Marlborough have only been pushed up to become land in the last been pushed up to become land in the last 50,000 years so we don’ have many old fossils.50,000 years so we don’ have many old fossils.Rich deposits of beautifully preserved Rich deposits of beautifully preserved Pleistocene sea shell fossils can be found at Pleistocene sea shell fossils can be found at Motunau Beach (Marlborough). They are Motunau Beach (Marlborough). They are evidence for shallow, sandy bottom seas. evidence for shallow, sandy bottom seas.

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Erosion in actionErosion in action

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WeatheringWeatheringEarth's surface is constantly being shaped and Earth's surface is constantly being shaped and reshaped by natural processes like earthquakes reshaped by natural processes like earthquakes and volcanic eruptions, weathering and erosion.and volcanic eruptions, weathering and erosion.

Weathering causes rocks at Earth's surface to Weathering causes rocks at Earth's surface to fragment, crack, crumble, or otherwise degrade fragment, crack, crumble, or otherwise degrade due to physical, chemical, or biological due to physical, chemical, or biological interactions. interactions.

Because different kinds of rocks form in different Because different kinds of rocks form in different settings, they react differently when exposed to settings, they react differently when exposed to temperature swings, moisture in the air, or temperature swings, moisture in the air, or pressure changes. pressure changes.

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Formation of a V-shaped valleyFormation of a V-shaped valley

V-shaped valleys are found in the upper course V-shaped valleys are found in the upper course (mountainous) part of a river. (mountainous) part of a river.

Vertical erosion creates a steep narrow gorge.Vertical erosion creates a steep narrow gorge.

The sides of the gorge are made less steep by The sides of the gorge are made less steep by the weathering creating a V shape. the weathering creating a V shape.

Any material that falls from the valleys sides Any material that falls from the valleys sides usually rolls into the river below and when the usually rolls into the river below and when the velocity of the river is fast enough the material is velocity of the river is fast enough the material is transported away.transported away.

The animation below shows this process:The animation below shows this process:

V shaped valleyV shaped valley

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ErosionErosion

Erosion loosens and carries away rock debris formed by Erosion loosens and carries away rock debris formed by weathering.weathering. Without erosive agents, including water, wind, and Without erosive agents, including water, wind, and glaciers, rock debris would accumulate where it formed.glaciers, rock debris would accumulate where it formed.Moving water is the most potent erosive force on Earth. Moving water is the most potent erosive force on Earth. Powered by the force of gravity, the world's rivers deliver Powered by the force of gravity, the world's rivers deliver about 20 billion tons of loose rock fragments, or about 20 billion tons of loose rock fragments, or sediment, to the oceans each year.sediment, to the oceans each year.Moving air, or wind, is another important transporter of Moving air, or wind, is another important transporter of sediment, especially in dry regions. When tiny sand sediment, especially in dry regions. When tiny sand grains are lifted and carried by the wind, the wind also grains are lifted and carried by the wind, the wind also becomes an erosive agent, capable of sculpting rocks becomes an erosive agent, capable of sculpting rocks into a variety of shapes, as evidenced in the still imagesinto a variety of shapes, as evidenced in the still images

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GlacierGlacierA glacier is a frozen flowing river that A glacier is a frozen flowing river that moves slowly, retreating in summer and moves slowly, retreating in summer and growing in winter. (Franz Joseph)growing in winter. (Franz Joseph)

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TerracesTerraces

Terraces are produced by erosion. The Terraces are produced by erosion. The pink and white terraces of Rotorua pink and white terraces of Rotorua distroyed in the 1888 eruption of Mt distroyed in the 1888 eruption of Mt TaraweraTarawera

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MorainesMoraines

A moraine is found at A moraine is found at the base of a glacier the base of a glacier where large rocks and where large rocks and sediments (glacial sediments (glacial drift) are deposited drift) are deposited after being after being transported by the transported by the glacierglacier

A moraine at the base A moraine at the base of the Southern Alpsof the Southern Alps

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A end moraine in CanadaA end moraine in Canada

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FiordsFiordsA long narrow inlet A long narrow inlet with steep sides with steep sides created in a valley created in a valley that was created by that was created by glacial activity.glacial activity.

The Southern The Southern sounds are actually sounds are actually fiords. fiords.

These areas were These areas were once glaciated.once glaciated.

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FiordlandFiordland

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Rocks and the Rock CycleRocks and the Rock Cycle

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Sedimentary RocksSedimentary RocksSedimentary – formed from eroded Sedimentary – formed from eroded sediments off other rocks that are washed sediments off other rocks that are washed down into river, lakes and oceans, down into river, lakes and oceans, deposited on the sea floor. deposited on the sea floor. Pressure and chemicals cement them Pressure and chemicals cement them together. together. We see them when plate movements push We see them when plate movements push them up.them up.Eg, greywacke, limestone (fossils), Eg, greywacke, limestone (fossils), sandstone, mudstone, conglomerate.sandstone, mudstone, conglomerate.

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Igneous RocksIgneous Rocks

Harder rocks that form from magma that Harder rocks that form from magma that solidifies.solidifies.

Extrusive or volcanic form from lava that Extrusive or volcanic form from lava that comes out of Earth. Cool quick some small comes out of Earth. Cool quick some small crystals. Eg, scoria, pumice, obsidiancrystals. Eg, scoria, pumice, obsidian

Intrusive or plutonic form from lava that Intrusive or plutonic form from lava that cools slowly inside crust – larger crystals. cools slowly inside crust – larger crystals. Eg, granite.Eg, granite.

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Metamorphic RocksMetamorphic Rocks

Any rock can change into a metamorphic Any rock can change into a metamorphic rock.rock.

Formed by deep burial of rocks in the Formed by deep burial of rocks in the crust.crust.

Caused by intense heat and or pressureCaused by intense heat and or pressure

Rocks recrystalise and become hard.Rocks recrystalise and become hard.

Often attractive, contain gemsOften attractive, contain gems

Eg, pounamu, marbleEg, pounamu, marble

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Rock cycleRock cycle

Interactive Rock Cycle AnimationInteractive Rock Cycle Animation

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All doneAll done

congratulationscongratulations