Chapter 1:Structure of the Earth: the early geosphere, atmosphere and hydrosphere

The 4 spheres of the Earth

1. Atmosphere: is the gaseous envelope of air surrounding Earth, made up of a mixture of 21% oxygen,78% nitrogen and about 1% other gases and water vapor.

2. Geosphere: rocks, mountains, the lithospheric plates & other physical features of the Earth.

3. Biosphere: The biosphere is made up of all the living organisms in the Earth system & their environments.

4. Hydrosphere: Is composed of all the water in the Earth system- gaseous (water vapour), solid (snow and ice) and etc.

Age of the EarthGeologic time- the vast period of time over which Earth’s rocks have formed.Meteorite evidence A new analysis of the chemical make-up for meteorites has helped scientists work out

when the Earth formed its layers. The research by an international team of scientists confirmed that the Earth’s crust had

formed around 4.5bya.

Exact age of Earth: 4.543 billion years

AtmospherePhase 1: Scientists believe that the Earth was formed about 4.5bya. During the early stages of the earth’s existence there was intense volcanic activity. The earth’s early atmosphere contained little or no oxygen.

Phase 2: The water was in vapour form (steam) in the atmosphere. When the Earth’s surface temperature dropped below 100°C, the water vapour condensed (gas changed

to liquid). The water then fell into the surface of the Earth & our seas & oceans began to form.

Phase 3: When the seas began to form, some of the carbon dioxide was removed from the

atmosphere.

Dissolution: is the process of a solid going through a liquid phase.

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Layers of the EarthCrust- The rigid, rocky outer surface of the Earth,

composed mostly of basalt and granite The crust is thinner under the oceans 8km thick under oceans 32km thick under continents

Lithosphere- Is made up of the crust

Outermost part of the mantle. Has a rigid outer layer Is broken into 30 sections or plates 2 types:

· oceanic lithosphere: oceanic crust and exists in the oceans basins · continental lithosphere: continental curst under land/continents

50-100km thick

Asthenosphere- is the outer layer of the mantle lies between 100 & 200km below the Earth’s surface involved in plate movement has relatively low density 180km thick

Mantle- a rocky layer located under the crust is composed of:

silicon oxygen magnesium iron aluminium calcium

convection (heat) currents carry heat from the hot inner mantle to the cooler outer mantle

2900km thick

Inner core- the solid iron-nickel center of the Earth

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is very hot is under great pressure 1250km thick

Outer core- the molten iron-nickel layer that surrounds the inner core 2180km thick

horizons and makeupO horizon

humus on the ground surfaceHumus: organic matter in soil

A horizon top soil rich in organic matter (typically a dark colour) also called zone of leachingLeaching: the process of extracting substances from a solid by dissolving them in a liquid

B horizon subsoil also called zone of accumulation may contain soluble minerals such as calcite in arid climates (caliche)

C horizon weathered bedrock (rotten rock) bedrock lies below the soil profile

Radiometric dating is the method used to date the age of rocks?

first discovered in 1896, that radioactivity could be used to estimate the age of rocks.

Another technique they use is carbon dating, where they collect the carbon and analyse how long it had been underground for.

All living things contain carbon (a small amount of which is radiocarbon). All living things eventually die, along with their radiocarbon. Radiocarbon has a half-life of 5700 years Archaeologists drill into rocks to determine the age of the materials.

Q. Who discovered radiocarbon dating?A. Willard Libby

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Radioactive half-life Radioactive half-life: the time it takes for half of the radioactive isotopes in a sample to decay to a new form.

The time taken for each of the parent atoms to their respective daughter product varies.Some take million years while some radioactive elements can decay in minutes.

Chapter 2:Rocks, minerals and the rock cycle

The geology of any local environment, such as rocks and rock minerals, play a fundamental role in the overall characteristics of that area. E.g. Granite produces a sandy soil and vegetation adapted to well-drainedconditions.

• Indigenous Australians used and continue to use rocks in their everyday lives and classify different rocks to their uses. Some rocks were used for tools, some for communication (the passing on of information) and creating paints.

Identifying mineralsThe following physical characteristics of rocks can be used in the field to help identify a mineral sample:

HardnessMineral hardness is its resistance to being scratched. Hardness can be determined by rubbing it against a minerals or substances of known hardness if 2 minerals of different hardness are rubbed, the softer mineral becomes scratched; if 2 minerals of equal hardness are rubbed, both will be scratched. The scratch used is called Moh’s hardness scale.

StreakThe observed colour of a mineral can be misleading because of impurities. A mineral’s colour when powdered is its streak. It is seen by scraping the mineral on a white tile. Quartz comes in many different colours like yellow, pink, brown and white but its streak is always white.

LustreLustre refers to how shiny a mineral’s surface is. Lustre is broadly described by subjective terms, such as, metallic and non-metallic. Different non-metallic lustres include glassy, adamantine (diamond like), silky, pearly, greasy, waxy and earthy (dull). Generally, the most common descriptions needed are metallic, glassy and earthy.

Density/specific gravityUsing the formula D=m/V you can find out the density of a specific mineral. Most minerals have a specific density.

CleavageCleavage refers to how a mineral natural breaks or splits. Many minerals have specific lines of weakness owing to their crystal structures and so will break in a particular way.

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3 kinds of rocks1. Igneous rocks

Igneous rocks: a type of rock that forms from the cooling of molten rock at or below the surface

• Igneous rocks form the cooling of molten minerals

Examples: Igneous rocksG: GraniteS: ScoriaO: Obsidian

Chemical composition: changes in chemical composition cause variations in rocks. The overall colour of an unweathered igneous rock, such as light, dark, will give us clues to the minerals that it mostly contains.

Texture: the size of crystals within igneous rocks gives important clues about their formation. Igneous rocks with large crystal visible to the naked eye; have cooled slowly from the molten state. Erosion over long periods of time can remove overlaying rock and expose these coarse grained rocks at the surface.

Sedimentary rocksSedimentary rocks: a rock that forms from compressed layers of sediment.Sedimentary rocks are made up of compacted and cemented sediments. Such sediments can be provided by:

The breakdown of other rocks into smaller pieces, such as pebbles, sand or mud. Chemical precipitates as shallow seas evaporate. Organic remains, such as those of plants and corals.

Examples: Sedimentary RocksS: ShaleS: SandstoneR: Rock salt

Formed in layers called strata. Sedimentary rocks cover about 70% of the Earth’s land surface, they are divided into 2 subgroups: clastic and chemical sedimentary rocks.

Clastic sedimentary rocks: Definition: a sedimentary rock made of broken fragments of pre-existing rock/s. Form from the weathered and eroded pieces of other rocks. They are classified according to the size of the sediment pieces within them. For example: conglomerates contain pebble sized sediments.

Chemical sedimentary rocks: Definition: sedimentary rock that forms when minerals precipitate from a solution or settle from a

suspension. Are formed by chemical precipitation or biological activity. Precipitation: any form of water that falls from clouds and reaches Earth’s surface. For example: coal is another rock formed from organic remains.

Metamorphic rocks

Metamorphic rocks: rocks that have been changed by heat and pressure.Made by sohana

Meta: changeMorphe: form

Such changes can be by exposing rocks either to high temperatures when in close contact with igneous intrusions (bodies of molten rock) or to high pressure when tectonic plate collisions cause rocks to fold.

Metamorphism: the process in which 1 type of rock changes into metamorphic rock because of chemical processes or changes in temperature and pressure.

Foliated metamorphic rocks: contain flaky, minerals such as mica. Non-foliated metamorphic rocks: do not contain foliations; those with larger crystals have a grainy

appearance.

Examples: Metamorphic RocksM: MarbleP: Phyllite C: Chlorite

What igneous rocks tell us:• Light coloured igneous rocks are rich in silicate minerals.• Dark coloured igneous rocks are low in silicate minerals.• Glassy texture indicates a rock cooled rapidly by water or air after erupting from a volcano, like

volcanic glass.

What sedimentary rocks tell us:• Conglomerate indicates fast flowing water.• Sandstone indicates medium flowing water.• Limestone indicates slow flowing water.

What metamorphic rocks tell us:• Low grade metamorphism is caused by regional compression.• High grade metamorphism can also be caused by both more intense compression and folding or close

contact with magma.

Mineral is a naturally occurring, inorganic, crystalline solid with a definite composition e.g. quartz Rock is naturally occurring solid aggregate of one or more minerals e.g. granite

Rock cycle The series of processes that change one type of rock into another type of rock. These changes occur by processes of:

• Weathering and erosion• Melting• Exposure to heat and pressure

What is soil?Soil is a mixture of organic and inorganic, air and water. Soil is very important to life on Earth; it provides biotic and abiotic interactions to occur.

Soil is typically made up horizontal layers, or horizons. From the surface down, these are the A horizon, B horizon, C horizon and R horizon or Bedrock.

Soil formationO horizon

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humus on the ground surfaceHumus: organic matter in soil

A horizon top soil rich in organic matter (typically a dark colour) also called zone of leachingLeaching: the process of extracting substances from a solid by dissolving them in a liquid

B horizon subsoil also called zone of accumulation may contain soluble minerals such as calcite in arid climates (caliche)

C horizon weathered bedrock (rotten rock) bedrock lies below the soil profile

Soil tests A soil test commonly refers to the analysis of a soil sample to determine nutrient content, composition, and other characteristics such as the acidity or pH level.

Q. How many types of soil testing are there? A. There are 3 types of basic types of soil: sand, silt and clay

Q. What is meant by the permeability of the soil?A. Soil permeability is the property of the soil to transmit water and air and is one of the most important qualities to consider for fish culture.

Factors affecting soil formationBedrock: bedrock is the original that is weathered to provide the inorganic component of the soil. Climate: is the combined effects of rainfall, temperature and seasonal changes. It has a big impact on the formation of soil.Topography: is the effect of slope on soil formations. Soils on a steep slope are typically thinner than a flat land.Water movement: in the soil water movement can be vertical or lateral (sideways).Time: is required for all of the factors. An event like a landslide can mix up the horizons.

Soil & Life all food chains begin with a producer that uses energy from the sun, as well as carbon dioxide from

the air. However, they also require water and nutrients from the soil to be able to produce their own food. If a soil is sandy, water is able to drain out quickly.

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Chapter 3The Geological time scale

The geological time scale is divided into 4 levels:1. Eons: 2. Eras3. Periods4. Epochs

1 An eon is the largest subdivision and there are 4 of these. The Hadean is the oldest eon where there isno evidence of life. Then the Archaean which has the evidence of the beginnings of life. The next eon is the Proterozoic where eukaryotic life form’s occurred. The youngest eon is the Phanerozoic. The Phanerozoic takes up only 7% of the time scale since Earth formed.

2 Each eon is divided into eras. For example, the Phanerozoic eon is divided into the Palaeozoic, Mesozoic and Cainozoic eras.

3 Each era is subdivided into periods such as the Cambrian, Devonian, and Triassic and so on. Professional palaeontologists further subdivide these periods into epochs then into increasingly smaller units, representing smaller units of time.

Geological mapsA geological map shows 2 main features:

1. Symbol showing the rock types2. Colours showing the ages of the rocks.

Determining a rock’s age can be obtained by 2 different means:1. Absolute dating methods2. Relative dating methods

Absolute dating: Definition: a technique used to determine the actual age of a fossil.

Relative dating: A technique used to determine which of 2 fossils is older.

Chapter 4Geological Resources

Renewable & Non-Renewable resourcesRenewable resources

Any resources that can or will be replenished naturally in the course of time. Examples: water, food, natural fibers.

Non-renewable resources A natural resource that forms much more slowly that is consumed. Examples: nuclear energy Fossil fuels Natural gas

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Earth resources Natural resources can be classified in a number of ways, one of which is from an environmental

perspective. Metals are good examples of high value resources. Sand and gravel are good examples of low value resources. 2 vital terms are commonly used in mining geology. A resource is a substance human’s need for

some use(s) and a reserve is an amount of a resource that can be extracted at today’s costs and selling prices.

A resource is economic if the cost of mining is less than the price received so that a profit can be made; it is sub economic when the cost of mining is too high to make a profit.

Modern technology has dramatically increased the size, accuracy and amount of detail with which geologist can work.

Drilling allows the extent of the resource to be determined.

Australia’s non-renewable energy resourcesThe fossil fuels we use today, represent energy stored by the Sun, hundreds of millions of years ago. Photosynthesis trapped the Sun’s energy and incorporated it into the plates.

Coal Coal is a rock produced from a once living plant material. Coal is a rock that can be burnt! Coal is classified by rank, which is a measure of the amount of change the vegetation has undergone

during formation.

Gas There are 2 major sources of gas that can be used as a fossil fuel: Coal seam gas and Natural gas. Coal seam gas (also called coal methane) has become a major source of energy in recent years. Natural gas normally occurs in association with crude oil. Another source of gas is the refinery process. When petroleum is refined, significant amounts of

methane, ethane and propane are produced. Some of this is used to make plastics while the rest becomes part of liquefied petroleum gas (LPG).

Petroleum Petroleum is a complex mixture of organic compounds divided into crude oil and natural gas. It occurs naturally in the ground. Crude oil varies from oil field to oil field in colour and composition from a pale yellow.

Australia’s non-renewable mineral resourcesAn ore is a mineral deposit that can be recovered economically-therefore ore is an economic term. Since most metals are in low concentration in the Earth’s crust, they must be concentrated in some way before the deposit becomes profitable to mine.

The concentration factor of a meta is the ratio of its necessary concentration for profitable mining to its average concentration in the Earth’s crust.

The 5 natural processes that lead to the concentration of minerals:1. Hydrothermal2. Magmatic

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3. Sedimentary4. Placer5. Residual

Divergent plate boundariesDivergent boundaries: a plate boundary where 2 plates move away from each other.

form where 2 plates separate. These spreading centres are where new crust is generated, and the mid-ocean ridge that stretches

around the globe marks the divergent boundary between several plates. mid-ocean ridge: and underwater mountain chain where a new ocean floor is formed. Volcanism at divergent boundaries produces basaltic lava that is low in silica. Little to no metamorphism. Shallow focus earthquakes only. Boundary characterised by an elevated rift valley.

Convergent boundariesConvergent boundaries: a plate boundary where 2 plates move toward each other.

The enormous friction with the overriding plate, causes it to melt. Magma rises and melts its way into the overlying mountain. These boundaries experience both deep and shallow focus earthquakes.

Conservative plate boundaries (transform)

These plate boundaries are called conservative due tothe fact that they neither create or destroy crust material.

These boundaries occur along transform faults where 1 plate will slide past another, separating sections of the MOR.

Definitions: Crust: made up of both continental and oceanic crust. It is the outermost layer of the Earth.Lithosphere: is the solid outer layer-incudes the crust and solid upper mantle.Asthenosphere: apart of the mantle, that is made of molten rock and therefore is able to move slowly.

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Sedimentary processes: transport of sediments by wind, water and glaciers.Weathering processes: a biological, chemical, or physical process that helps form soil from rock; during weathering, the rock is gradually broken down into smaller and small particles.

Mineral and coal exploration Coal exploration

Coal was first found in Australia 1791 near Newcastle NSW and was being mined 6 later (1797). Brown coal generates a lot of heat when it dries out on exposure to air. Ash is an inorganic material, such as clay and sand, that has to be removed from smoke or remains

after the coal is burnt. Coal needs to be low in sulfur. When sulfur burns, it yields sulfur dioxide gas. Since sulfur dioxide is responsible for acid rain, it must be removed from the waste gases produced.

The less sulfur, the lower the cost of waste disposal.

Seismic techniques The seismic technique for finding a potential oil or gas trap is based on the identification of areas that

have experienced a high amount of seismic activity to determine the propagation of natural fractures and unconformities in the subsurface.

Seismic methods are commonly used in oil and coal exploration.

Drilling The act of drilling a hole in the Earth in the hope of drilling petroleum. The selection of a suitable drilling method is governed by such factors as the nature and depth of the

deposit, location and access factors associated with drill site and cost.

Methods of extractionAboriginal quarrying and mining methods

More than 40 000 years ago Aboriginal people quarried and mined high quality ochre and stone. Ochre was used in Aboriginal religious’ ceremonies as well as in their artwork. The stone that was mined in many ways, including shaping wood, grinding seeds, as well as marking

axes and weapons used in hunting and welfare. Ochre was mined as a fairly soft clay which was then crushed and made into a paste by mixing it

with water. Sometimes it was mixed into small balls for travel. There is evidence that good quality ochre was traded far and wide as it was so important in

ceremonies.

Extracting coalThere are 2 main methods of mining coal-underground and open cut mining.

coal-underground mining: involves opening one or more shafts into the earth that follow coal seam that are too deep for surface mining methods.

Open-cut mining: a method of mining mineral ores that are close to the surface—a large hole is madeto expose the rocks, which are then broken up using explosives.

Extraction of petroleum The extraction of petroleum is the process by which usable petroleum is drawn out from beneath the

Earth’s surface location.

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This pressure comes from natural gas present, as well as the weight of water above the oil.

Offshore drilling Definition: looking for oil and natural gas underneath the ocean floor.

Mineral ores Are non-renewable resources Is any mineral that has a sufficient amount of the value element or compound that can be

economically mined.

Chapter 5Evidence for plate tectonics

The modern theory states that the crust on Earth is divided into numerous rigid slabs called plates.

Rock type & geological structures Geological features such as folding and faulting occurring on a large scale, as well as rock units

along many sections of continental coastline.

Fossils Wegener identified several different types of fossils that could be matched across different

continental landmasses. The fossilised remains of a shallow aquatic reptile known as a Mesosaurus have only been found

along the eastern coast of South America and in southern Africa. Climatic indicators

Are a good source of supporting evidence for continental drift. Continental drift: the hypothesis that the continents slowly move across Earth’s surface. Glaciers carry a wide range of different sized material, ranging from sand to large boulders and even

tree slumps. Once the glacier melts, it drops the poorly sorted sedimentary material that it was carrying which

forms a rock called tillite

Ocean floor age• the ocean floor is a relatively new area of exploration. • In the 1960s’ large ships were used to drill into the ocean floor and take core samples from different

regions.

PalaeomagnetismThe word palaeo means old or ancient and the word magnetism refers to the Earth’s magnetic field. Therefore, palaeomagnetism is concerned with the pattern of Earth’s magnetic field over time.

Earth’s magnetic fieldConvection currents flowing in the earth’s molten core produced because of heat from ongoing radioactive decay.

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Oceanic lithosphere• Oceanic crust is produced at mid ocean ridges.• Molten magma rises to the surface and solidifies to form dark mafia rocks on contact with ocean

water.• Mafic rocks are rich in magnesium and iron.• Definition: made out of basalt; denser that’s why it sits lower in the asthenosphere.

Continental lithosphere• Continental crust is thicker and more complex than oceanic crust/oceanic lithosphere and is mainly

composed of felsic rocks, such as granite and the minerals quartz.• This type of crust is lower in density than the atmosphere.

Mechanisms for plate movement Sea floor spreading provides a mechanism for continental drift. Gravity is also thought to play an important role in plate movement. Oceanic crust is composed almost entirely of Basalt. Basalt has a greater density than most

continental crustal material.

Mid Oceanic Ridge (MOR)

Wraps around the globe like seams on a baseball, stretching an impressive 65,000km The majority of the system is underwater, with an average water depth to the top of the ridge of

2,500m. MORs are geologically important because they occur along divergent plate boundaries, where new

ocean floor is created as the Earth’s tectonic plates spread apart. 2 of the most carefully studied mid-ocean ridges are the Mid-Atlantic Ridge and the East Pacific

Rise. At a MOR there is no subduction of a plate. This means that even though there is a volcano, there is

no rock being melted and recycled. This means that the lava produced is basaltic in nature and very consistent, due to no new material being added to the mix.

Rift valleys Rift valleys represent the embryonic stage of formation of a MOR. They are formed when a series of normal faults occur opposite each other. The largest and most spectacular rift valley on a continent is the Greatest east African rift valley

system.

Mountains caused by convergent boundariesThere are 2 main types of mountains caused by convergent boundaries;

1. Fold mountains (tectonic)2. Volcanic mountains

Fold mountains Are the mountains formed from the folding of the Earth’s crust. These mountains are produced by compressional forces and are known as fold mountains.

Volcanic mountains Mountains that form when molten rock erupts onto the Earth’s surface.

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Where are they formed? Volcanic mountains can be found in 2 places on Earth: the first is the boundary between oceanic and continental plate where the denser oceanic plate is subducted beneath the continental plate.

Basalt eruptions often involve fire fountains where red hot lava spurts hundreds of metres into the air, then falls to the ground and flows rapidly way in rivers of glowing red lava.

There are 2 main reasons why andesite lava is so much explosive than basaltic lava. They are:1. The amount of gases dissolved in the magma2. The viscosity of the magma

Composite or strato volcano A tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials.

Shield volcano a widely, gently sloping mountain made of layers of lava and formed by quiet eruptions.

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The Hawaiian island volcanoes are classic examples of shield volcanoes and are among the largest volcanoes on Earth.

Regional metamorphism A change in texture, structure, or chemical composition of rock due to changes in temperature and

pressure over a large area, generally as a result of tectonic forces. Because so many minerals in the squeezed rock are parallel, the rock itself is usually able to split in

that direction. If the rock is fine grained, then very thin sheets can be produced. The best example of this is regionally metamorphosed schist.

Shale is a very common sedimentary rock, and its main constituent is clay. These clay minerals are unstable under pressure. As a result, shale forms a series of metamorphic rocks depending on the grade of metamorphism

Contact metamorphism A change in the texture, structure, or chemical composition of a rock due to contact with magma. This type of metamorphism occurs over hundreds of square kilometres and is associated with fold

mountains or tectonic mountains. However, rocks can also be changed or metamorphosed by intense heat after contact with hot and molten igneous rock rather than from the pressure associated with folding or burial. This type of metamorphism is referred to as contact or thermal metamorphism, and occurs on a more localised scale.

Igneous intrusion An igneous intrusion is a mass of magma which has forced its way into pre-existing rock known as

country rock. Some examples include plutons, dykes and sills. Plutons are large scale magma chambers that have risen up through the country rock from the upper

mantle. Dykes are vein-type intrusions that cut across rock layers, whereas skills are intrusions that follow

along rock layers. Dykes and sills will often be injected into the country rock from plutons. Contact metamorphism also produces changes in the texture and mineralogy of country rock.

Chapter 6Role of energy in the Earth’s processes

Heat energy can be transferred by 3 different processes: conduction, convection and radiation.

1. Convection: the transfer of heat by movement of a fluid. • Occurs when particles with a lot of heat energy in a liquid or gas move and take places of particles

with less heat energy,• Heat energy is transferred from hot places to cooler places by convection.• Liquids and gases expand when they are heated. This is because the particles in liquids and gases

move faster when they are heated than they do when they are cold.• Convection currents can be seen in lava camps. The wax inside the lamp warms up, becomes less

dense than the liquid and so rises. When it rises, it cools and becomes denser again, and so it sinks.• Convection explains why hot air balloons rise, and why it is so often hotter in the lofts of houses than

downstairs.

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2. Conduction: the direct transfer of heat from 1 substance to another substance that it is touching.

3. Radiation: energy that is radiated or transmitted in the form of rays or waves or particles.

Heat transfer by radiation Heat can be transferred by infrared radiation. Infrared radiation: a form of energy with wavelengths that are longer than visible light. Infrared radiation is a type of electromagnetic radiation that involves waves. The sun’s energy controls a lot of processes on Earth. It helps to control the water cycle and provide

energy for ecosystems via photosynthesis, both of these are essential for life on Earth.

Photosynthesis Is the process of green plants (autotrophs) using the sun’s energy to create food. This food is then broken down to make energy (respiration-which all living things do).

The water cycle The water cycle (or hydrological cycle) is simply the complete journey that water makes in its life,

from 1 place to the next, and from 1 state to another. There is no starting point. This means that we can begin at any point and follow its path until it gets

to where we started again.

Why plates move?The plate tectonic theory helps explain why the Earth can remain in its present shape and have new material added to the plates at constructive margins. The theory states that the lithosphere is recycling down the trenches at subduction zones. As new seafloor is being produced at the MOR, old sea floor is being removed at trenches.

There are 2 main hypotheses to explain why plates move on the Earth ‘surfaces.1. Convection currents2. The push pull model (slab pull)

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1. Convection currents: a current caused by the rising of heated fluid and sinking of cooled fluid. They are produced from radioactive decay in the Earth’s core. The heat rises through the asthenosphere, asthe molten material cools; it travels horizontally until finally sinking back into the Earth (circular motion).

Convection cell:

2. the push pull model (slab pull): the push pull theory uses gravity as its main driving force. The increased density of cold rock on the ocean floor compared to hot new rock because the cold rock to be dragged down into the asthenosphere.

The push part of the model is called the ridge push. It occurs at the MOR, where new material is hot and lower in density pushing the plates apart.

The pull part of the model is called slab pull. It is occurring at the subduction zone where gravity is pulling the plate down into the mantle.

Subduction zone: the region where oceanic plates sink down intothe asthenosphere.

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Plate movement and densityConvection currents in the upper mantle provide, one mechanism for plate tectonics. When something is heated, it usually expands. This means that the same amount now occupies a larger volume.

Density= mass/ volumeThis states that as the volume increases, the density decreases.

Earthquake wavesEarthquake waves or seismic waves occur when built up tension due to compression or tensional forces are released when rocks break and move. This energy stored in the rocks under stress is defined as elastic potential energy.

A seismometer is a device used to record earthquake tremors and the reading taken is called a seismogram.

Seismic waves produced by earthquakes provide geologists with the best tool for indirectly observing the Earth’s interior.

2 types of seismic waves: body waves surface waves= Rayleigh & love waves

2 types of body waves: P waves (primary waves): are compression waves that can travel through Earth S waves (secondary waves) are transverse waves and can travel through Earth, but not

through the core.

Q. In what directions do the S, P, and the surface waves move?A: S wave: up and downP wave: CompressionSurface wave: convection currentQ. Which is faster S or P wave?A: S wavesQ. which seismic wave refracts and cannot penetrate the core?A. Surface waves

Volcanoes Volcanoes are generally made from erupted material and can be found at divergent and convergent

boundaries. MOR are fissure volcanoes, where a ‘crack’ between the 2 plates allows the magma to escape.

Volcanic eruptions Volcanoes vary a great deal in their destructive power. Some volcanoes explode violently, destroying everything in a mile radius within minutes, while

other volcanoes seep out lava so slowly that you can safely walk all around them. The severity of the eruption depends mostly on the structure of the magma.

Characteristics of magmaTypes of magma are determined by the chemical structure of the magma. 3 general types are recognised:

1. Basaltic magma2. Andesitic magma3. Rhyolitic magma

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The structure of the gases in magma are:• Mostly water vapour and carbon dioxide• Minor amounts of sulfur, chlorine and fluorine gases.

The amount of gas in a magma is also related to the chemical structure of the magma. Rhyolitic magmas usually have higher gas contents than basaltic magmas.

Temperature of magmas is difficult to measure (due to danger involved), but laboratory measurement and limited field observation indicate that the eruption temperature of various magma.

Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends on primarily on the composition of the magma, and temperature.

Eyjafjallajokull-2010: an explosive eruption that disrupted air traffic The 2010 eruption at Eyjafjallajokull occurred beneath a glacier, which caused a highly explosive

eruption. When hot magma comes into contact with ice; it turns to steam and rapidly expands.

Chapter 7The role of energy in the Earth’s atmosphere, oceans and cryosphere

waterwater is a simple compound with unique chemical and physical properties that make it crucial to all life. Water also plays an important role in controlling weather and shaping the Earth’s surface.

Water as a solventWater is important in life as a solvent. Water dissolves more substances than any other liquid and is referred to as the universal solvent.

Some definitions; MIXTURES– a mixture is two or more substances combined. Aqueous mixtures can be defined in

terms of solute, solvent and solution. SOLUTE – refers to the particles of substance dissolved in the aqueous mixture, for example, salt. SOLVENT – is the substance in which the solute is dissolved, for example, water. SOLUTION – refers to the mixture, for example, salt water.

Water is a solvent for many substances, such as;o Polar molecules – those with uneven charge distribution, such as ammoniao Ionic solids – usually metals joined with non-metals, like sodium chlorideo Gases, such as oxygen and carbon dioxide.

Due to water being such a good solvent, it allows biological processes to occur rapidly in solutions. All forms of life must maintain a high proportion of water within their cells.

Water-density

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The density of water is vital for the survival of many living things. When water freezes it becomes larger (bigger spaces between particles) and therefore it becomes less dense. Water is the only liquid to do so, as most other liquids condense (get smaller) are they freeze and therefore take up less space.

Water-thermal capacityHeat capacity or thermal capacity is a measurable physical quantity that looks at how much energy would need to be added (or taken away) to cause that substance to change in temperature. Water has quite a high thermal capacity and this is important because it means that it does not change temperature rapidly.

Water- boiling point The boiling point of water can change depending on the air pressure it is under and the dissolved chemicals it contains. At sea level the boiling point of water is 100 °C but as you increase in altitude the boiling point decreases slightly due to the decrease in air pressure. The opposite is also true, as you go below sea level into the depths of the ocean the boiling point increases.

Water-surface tension

Surface tension of water refers to water’s ability to bond to other water molecules, making it ‘stick’ together (cohesion). This is why when you jump from a high height into water it can feel like you are hitting concrete when you enter the water - as you are breaking through those bonds between molecules.

currentsThe term "current" describes the motion of the water. Some currents you may be familiar with are the motion of rainwater as it flows down the street, or the motion of the water in a creek, stream, or river flowing from higher elevation to lower elevation. This motion is caused by gravity. The speed and direction (velocity) of currents can be measured and recorded.

Oceanic currents are driven by several factors. One is the rise and fall of the tides, which is driven by the gravitational attraction of the sun and moon on Earth's oceans. Tides create a current in the oceans, near the shore, and in bays and estuaries along the coast. These are called "tidal currents." Tidal currents are the only type of currents that change in a very regular pattern and can be predicted for future dates.

A second factor that drives ocean currents is wind. Winds drive currents that are at or near the ocean's surface. These currents are generally measured in meters per second or in knots (1 knot = 1.15 miles per hour or 1.85 km per hour).

The Coriolis effect

The effect of Earth's rotation on the direction of winds and currents.

El Nino and La Nina

El Nino-southern Oscillation: A warm ocean current that flows along the coast of Peru every seven to fourteen years

La Nina: A cooling of the ocean surface off the western coast of South America, occurring periodically every 4 to 12 years and affecting Pacific and other weather patterns.

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During el nino, the trade winds weaken in the central and western pacific. Surface water temperatures off South America warm up, because there is less upwelling of the cold water from below to cool the surface.

La nina is caused by a build-up of cooler-than-normal waters in the tropical Pacific, the area of the Pacific Ocean between the Tropic of Cancer and the Tropic of Capricorn.

What are the 3 stages of the ENSO?The 3 phases of the El Nino-Southern Oscillation (ENSO)

1. The neutral phase2. El nino3. La nina

What is the cryosphere?The cryosphere is the frozen water part of the Earth system. There are places on Earth that are so cold that water is frozen solid. These areas of snow or ice, which are subject to temperatures below 0°C for at least part of the year, compose the cryosphere. The term “cryosphere” comes from the Greek word “krios,” whichmeans cold. The components of the cryosphere play an important role in the Earth’s climate. Snow and ice reflect heat from the sun, helping to regulate our planet’s temperature.

Chapter 8Human impacts

Water treatmentQ. What are the 3 main types of water that need to undergo treatment?A. (1) Industrial waste water (2) Sewage (3) Stormwater

-----------Industrial waste waterQ. What is industrial waste water? It is the water that is produced at industrial or commercial purposes.

Q. How is it treated & potentially reused?(1) Solids are removed(2) Sludge digestion system (where most remaining organic waste) is converted to methane gas.(3) Reverse osmosis to remove salts(4) Remaining solids get removed by flotation system(5) Bacteria gets used to digest most of the remaining organic material (6) Waste water goes through 3 more filtration processes before being released

-----------SewageQ. What is sewage?Sewage is waste matter such as faeces or dirty water from homes and factories which flows away through sewers.

Q. What is recycled water?Recycled water (also known as non-potable water) is water that is not suitable for drinking, cooking or bathing. It is less treated than drinking water.

Q. How is it treated and potentially reused?

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It requires less treatment and therefore costs less to produce. Reuse may include irrigation of gardens and agricultural fields or replenish surface water and groundwater.

-----------Storm waterQ. What is storm water?Is the water that flows on surfaces after rains, often flows from property drains to street gutters operated by local councils.

Q. How is it treated and potentially reused?The reused water is treated to a high standard removing stormwater pollutants and disinfecting the water using ultraviolet technology. The Bondi storm water scheme is designed to save and reuse the storm water, the water can then be used for parklands, sporting fields and it also overall improves the water quality.

Drains and other waterways have been constructed to rapidly drain and dispose of storm water. However, this approach exerts pressure on the natural and human environments by causing:

ª flooding downstreamª erosion and turbidityª contamination of waterwaysª loss of recharge zones

Site managementPutting control into place to minimise pollutants in storm water is site management.

Bush regeneration programsBush regeneration programs help consolidates soil especially on areas that have been extensively cleared.

Education programsEducation programs for industry as well as the general public can lead to changed attitudes and then changesin practices.

Storm water management plans These plans are developed in conjunction with local councils to put into action environmental

management plans so as to improve the quality of storm water runoff. One of the problems facing large cities in Australia at the moment is the coordination of catchment

plans. Sydney for example, has a storm water catchment controlled by 38 local councils and Sydney Water. As a result, coordination is difficult as water may flow through five or more regions of different

authorities’ responsibility before making its way to a river or a sea.

Storm water treatment technologies A number of processes can be employed to help remove or reduce these contaminants Private companies in an increasingly competitive market build and supply storm water treatment systems to

interested clients such as local governments and councils.

Water recycling Water recycling is becoming a bigger part of the way we use water in NSW. One of the flirt sites was Sydney Olympic Park at Home bush.

Ground water

Represents a significant component of the total global freshwater reserve.

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It is by far the largest reservoir (artificial lake) for drinking water. Comes from rainfall soaking its way through the soil into the underlying rocks, where it slowly

makes it way downhill under the pull of gravity. Porous rocks= have internal spaces that are capable of storing water. Permeable rocks= have interconnected spaces which allow water to flow through them.

Problems with ground water1. Variable quality2. Over extraction3. Saltwater intrusion4. Pollution

How does water get into the ground?When rail falls to the ground, the water does not stop moving. Some of it flows along the land surface to streams or lakes, some is used by plants, some evaporates and returns to the atmosphere, and some seeps into the ground. Water seeps into the ground much like a glass of water poured onto a pile of sand.

- Ground water can become unusable if it becomes polluted and is no longer safe to drink. In areas where thematerial above the aquifer is permeable, pollutants can seep into ground water.

Salt water intrusion Salt water intrusion is a natural process that occurs in virtually all coastal aquifers. It consists in salt water (from the sea) flowing inland in freshwater aquifers. It becomes an environmental problem when excessive pumping of fresh water from an aquifer reduces the water pressure and intensifies the effect, drawing salt water into new areas.

Salinity in soil and rocks may result from a number of processes. Clearing of vegetation and irrigation practices can cause salinity.

Eutrophication Is a process where pollutants cause a body of water to become over rich in organic and mineral

nutrients. This causes algae grow rapidly and deplete the oxygen supply.

The growth of algae on the surface stop most of the light penetrating deep into the water, which can then killthe bottom dwelling aquatic plants. If the bottom dwelling plants are killed off then this affects the whole ecosystem killing off higher level organisms.

Salinity• Salts are present in all natural waters (for the definition of a salt see appendix).• The vast majority of earth’s water is in the oceans and is highly saline (salty). • Even if the water is seen as ‘fresh’, this does not mean that it is pure. • Water is such a good solvent and therefore contains various dissolved minerals. • Ground water is often so laden with dissolved minerals, that it is unsuitable for drinking.• Salinity is regarded as the biggest single environmental issue facing Australian farmland.

Dryland salinityThere are 2 main causes of salinity on land;

1. Land clearing2. Irrigation

Land clearing:

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Describes the removal of native vegetation; and as plants are removed from an area, the root zone is also removed.

When you remove plants you no longer have a use for the groundwater and the water table is able to rise bringing the salt higher towards the surface.

Irrigation: Is the watering of land to make it ready for agriculture. If there is too much added to the crop, then the water table will rise and bring salts closer to the surface in the

same way discussed in land clearing.

Erosion and weatheringWeathering is the breakup of rocks into smaller pieces when exposed to water and air. There are 2 main types of weathering:

1. Mechanical or physical weathering2. Chemical weathering

Mechanical weathering: Is when a physical process causes the rock to break.

Chemical weathering: Is when air or water comes into contact with rock and a chemical reaction occurs.

Soil erosion Is the removal of surface layers from an area. The main problem faced by management bodies is soil erosion.

Effects of introduced species

• Australia’s flora and fauna have evolved over time into the distinct ecosystems that humans encountered approx. 60 000 years ago.

• Indigenous peoples caused changes to the environment by, for example; their use of fire and hunting of the megafauna.

• Europeans turned up in the late 18th century. Whether they were brought deliberately or accidently large numbers of plants and animals were introduced to Australia.

• Some survived; others perished. Those that survived went on to have a massive impact on our aquatic and terrestrial environments by successfully competing with or preying on native species.

What are introduced species? An introduced specie is one that is not indigenous to a particular locality. Introduced species may be “native” to the country but not to the locality or district. E.g. Acacia

saligna (a wattle) is a native of Western Australia so is an introduced species to Sydney.

Lantana camara Lantana is an introduced plant that is very common in our local

environment. The flower head can come in a variety of colours butis mostly seen in pink and yellow.

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Equus ferus cadballus the brumby is an introduced animal that is part of the culture of Australia, which had made it hard for

the government to eradicate or cull the species from national parks in Australia.

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