Unit 2: Earth's Resources

Question 1

Natural Resources: Renewable

Answer 1

These resources can be replaced:

The gases in the air - O2 produced in photosynthesis, CO2 in respiration, N2 through the nitrogen cycle.
Water, recycled in the water cycle involving evaporation from the sea/, condensation as clouds in the atmosphere, cooling to release precipitation, surface run off back to the sea.
Living things, plants and animals are able to reproduce themselves.

Question 2

Natural Resources: Non-Renewable

Answer 2

These resources are finite and cannot be replaced within a human lifetime (approx. 70 years):

Some natural resources are non-renewable or finite e.g. coal, oil, natural gas, soils, rocks and minerals, metallic ores, uranium etc.
Many of the resources around us are not renewable, they are man-made e.g. buildings, transport, machinery.

Question 3

Resource Definitions

Answer 3

Physical resources are primarily inorganic materials, including rocks, minerals, water and aspects of the climate.
Biological resources refer to the living landscape and include the plants, animals, microorganisms and other aspects of nature.
Flow resources don’t remain in one location and move about because of natural actions in the physical environment. Examples include: running water, radiation, wind and tides.
Stock resources are resources that can be permanently expended, and therefore non-renewable. Examples are coal and petroleum.

Question 4

The Earth’s Spheres

Answer 4

The atmosphere, The Hydrosphere, The Biosphere, The Geosphere

Question 5

Examples of Geosphere

Answer 5

Atmosphere: Impact of weather and storms (e.g. hurricanes) on landscapes. Volcanic eruptions causing ash clouds and changing weather

Question 6

Examples of Hydrosphere

Answer 6

Atmosphere: Exchange of water vapour between oceans and atmosphere (e.g. evaporation, condensation). Greenhouse effect (water vapour). Ocean currents. El Nino event - climate variability.

Geosphere: Weathering or the break down of rocks (e.g. freeze thaw) and erosion of rocks by water (coastal, river). Groundwater stores of water in underground rocks such as sandstone (aquifers). Tsunamis (undersea earthquakes).

Question 7

Examples of Biosphere

Answer 7

Atmosphere: Photosynthesis in green plants. Respiration. Transpiration in plants.

Geosphere: Production of fossil fuels from organic remains (coal, oil, gas) over long periods of time. Geosphere provides mineral nutrients for plant growth.

Hydrosphere: Photosynthesis in green plants. Soil formation. Natural flood control (absorption of water by vegetation).

Question 8

Earth Structure and Processes

Answer 8

Crust: outer shell of rock which ranges from 5km to 80km thick.
Outer Core: liquid layer of nickel and iron between 4000 and 6000C.
Mantle: makes up 80% of the earth’s volume. It is a semi-molten layer of magma with temperature between 500 to 4000C.
Inner Core: solid ball of nickel and iron estimate to be around 6000C.
Plate Boundaries: exist where plates converge and are important areas for volcanoes, earthquakes and mineral development.
Tectonic Plates: crust is made up of over 25 slabs of rock.

Question 9

The Earth’s core is a heat engine which drives the process of plate tectonics. It has a temperature believed to exceed 6000C due to 3 main reasons:

Answer 9

1. Residual heat from when the planet formed and accreted (from collisions of material in space), which has not yet been lost.
2. Frictional heating, caused by denser core material sinking to the centre of the planet.
3. Heat from the decay of radioactive elements such as uranium and thorium. This is believed to produce about 50% of the Earth’s inner heat.

Question 10

Plate Tectonics

Answer 10

Convergent Zones: where plates collide. Oceanic plates which are thinner, but denser are forced under the continental plates in a process known as subduction.

Divergent Zones: where plates separate, leaving a void where hot magma form underneath can be forced up creating volcanoes and rock formations. The Atlantic Ridge on which Iceland sits was formed in this way.

Conservative/ Transform Zones: where plates move past each other in opposite directions or at different speeds. The friction produced can create earthquakes.

Question 11

Geothermal Energy

Answer 11

Is thermal energy generated and stored in the Earth. It is a clean and renewable energy, with very low carbon emissions and in countries on plate boundaries it can make significant contributions to energy consumption (25% of Iceland’s energy) where water pipes can run underground to heat water, generate steam which turns turbines and produces electricity. Alternatively the hot water can be used to heat homes and buildings directly. The Geothermal energy can create tourist attractions (e.g. Blue Lagoon in Iceland) which can raise money for the country. However, start up and installation costs can be high and it requires high water use, which can be contaminated with sulphur compounds.

Question 12

There are three main rock categories:

Answer 12

1. Igneous rocks develop in the volcanic areas. Extrusive rocks form from lava which cools on the Earth’s surface, producing small grained rocks such as basalt. Intrusive rocks cool form underground magma, creating rocks with larger crystals such as granite.
2. Sedimentary rocks are formed from grains of sediment (sand, mud) or organic material which has been laid down underwater (lake or sea beds and compressed over time. Examples include sandstone, chalk, limestone, coal and shale).
3. Metamorphic rocks have been changed by heat and pressure within the Earth’s crust. Limestone can metamorphosis to form marble and shale to slate.
   The three rock types can interchange over long periods of time within the rock cycle

Question 13

Minerals and Ores

Answer 13

A mineral is a naturally occurring inorganic solid, with a definite chemical composition, and an ordered atomic arrangement. An ore is a naturally occurring solid material from which a metal or valuable mineral can be extracted profitably.

Question 14

Destructive Plate Boundaries

Answer 14

Where plates meet (converge), denser material (usually oceanic plates) is forced underneath continental plates (known as subduction). Water and sediment can also be dragged down towards sources of heat, creating super-heated hydrothermal fluids, which can dissolve minerals. When these fluids are cooled mineral deposits (e.g. copper) can be created.

Question 15

Constructive Plate Boundaries

Answer 15

At divergent plate boundaries, convection currents in the mantle force plates apart. Seawater seeping into cracks in the sea bed come into contact with igneous rocks. Superheated fluids travel upwards and contact with cold seawater results in the deposit of metallic elements such as iron and zinc, adjacent to features known as “black smokers”.

Question 16

Minerals Formed Within the Earth: 1. Deposits from Hydrothermal Fluids

Answer 16

(a) Porphyry copper (chalcopyrite ore)
At destructive plate boundaries; water can penetrate into cracks under the sea bed and be heated by hot magma to high temperatures to form hydrothermal fluids. Step 1: Water which has been separated from magma, Molten magma, Cooling magma forms granite. Step 2: Water is superheated and causes surrounding rocks to fracture, Minerals dissolved by hydrothermal fluids cool down in cracks forming minerals.
(b) Vein deposits
Similar to porphyry copper, as hot magma forces its way up through cracks and fissures underground, it can heat up groundwater which dissolves minerals from surrounding rocks near to the intrusion. These rising hydrothermal fluids can deposit ore minerals in these tiny fractions, including lead (galena ore) and tin (cassiterite).
(c) Sea-Floor Sulphide Deposits (form at constructive plate boundaries)
Seawater seeps into cracks and is heated by rising magma. These superheated fluids dissolve rocks. Black smoker deposits form at the surface. Sudden cooling of these fluids when they reach the ocean creates mineral deposits of copper and zinc (sphalerite) ore on the sea bed.

Question 17

Minerals Formed Within the Earth: 2. Magmatic Segregation

Answer 17

As magma cools in magma chamber, heavier minerals e.g. chromite (ore of chromium can form). Step 1: As magma cools slowly, heavy minerals sink to the bottom of the magma chamber. Step 2: Layer of ore minerals.

Question 18

Minerals Formed Within the Earth: 3. Contact Metasomatism

Answer 18

This refers to a process of chemical change in rocks adjacent to volcanic intrusions. This process helps produce ores of iron (haematite) and lead (galena). Step 1: Superheated acidic fluids react with neighbouring rocks e.g. alkali limestone, Granitic magma (acidic). Step 2: Mineral ores of iron and lead have replaced limestone, Solid granite forms.

Question 19

Minerals Formed Within the Earth: 4. Pegmatite’s

Answer 19

Pegmatite’s are igneous rocks that form during the final stage of a magma’s crystallisation. The magma which is left after granite has crystallized is often rich in pockets of superheated water, which cool very quickly to form very large crystals of ores such as uranium (uraninite) and lithium.

Question 20

Minerals Formed of the Earth’s Surface: Gold

Answer 20

Process: Placer deposits.
Description: Theses are deposits within alluvial (river washed materials). Within sedimentary processes, heavier metal elements, often in their pure form such as golds, sink to the bottom of features such as waterfall plunge pools and potholes (e.g. in rivers) and collect. Erosion and weathering of the rock above can expose the minerals.

Question 21

Minerals Formed of the Earth’s Surface: Aluminium (Bauxite)

Answer 21

Process: Residual deposits.
Description: In tropical climates, the chemical weathering of granite and sandstone bedrock produces laterite soils. The chemical weathering occurs due to acidic conditions from rainwater and humus content. Soluble rock particles are dissolved and washed out, leaving behind the insoluble compounds such as aluminium oxide (a major component of bauxite ore).

Question 22

Minerals Formed of the Earth’s Surface: Nickel (Limonite)

Answer 22

Process: Residual deposits
Description: Where coarse grained igneous rocks (peridotites) are weathered, deposits of nickel silicate develop between the soil and the bedrock.

Question 23

Important Minerals: Aluminium

Answer 23

Qualities: Low density (so has a low weight). Strong, even at low temperatures. Anti-corrosive. Non-toxic. Good reflector of heat and light. Can be easily shaped and machined. Easy to recycle (requiring only 5% of the energy to make it).
Formation: Bauxite (the main aluminium ore) forms by the chemical weathering of acidic tropical soils. The insoluble mineral (bauxite) contains aluminium oxide which is left behind as a clay type compound.
Extraction/ Production: Bauxite is mined in Australia, Guinea, Brazil and other tropical areas by open-cast mining. The clay is washed off and the ore is crushed and refined with caustic soda and lime to produce alumina (purer aluminium oxide) which is then dried to a powder. Powder is dissolved in cryolite and heated to over 1000C and a current is passed through - process known as electrolysis. The molten metal is drained off.
Main Uses: World’s second most widely used metal, used in;
- Vehicle, aircraft and train panels.
- Engines (blocks, cylinder heads and transmission units).
- construction (aluminium and wall cladding).
- Cabling (to reinforce steel).

Question 24

Important Minerals: Baryte (main ore of barium)

Answer 24

Qualities: Very heavy element. Very low solubility. Non-toxic. Has ability to block x-ray and gamma-ray emissions.
Formation: Forms in carbonate rock (limestone) which have been heavily weathered. Large baryte deposits are found at the soil-bedrock contact. It can also be formed in hydrothermal veins (volcanic areas).
Extraction/ Production: Extracted by both surface and underground mining. Mined material is then processes using straightforward methods to produce correctly sized product and to remove waste materials.
Main Use: Weighting fluid in oil and gas drilling. Biomedical imaging - barium meals highlight clear parts of the digestive system during x-ray photography. High density filler for paper, rubber, plastics.

Question 25

Important Minerals: Clay (purest forms are chins clays/ kaolin)

Answer 25

Qualities: Typically insoluble. Plasticity and flexibility. Shrinkage under firing and air drying. Easy to colour and glaze.
Formation: Formed by surface weathering of rocks such as the chemical decomposition of granite and the solution of limestone. Clays are the insoluble residues left behind.
Extraction/ Production: Most clay is mined by open-pit methods. Some kaolin is extracted by dredging and hydraulic processes (high pressure hoses).
Main Uses: Making bricks and roof tiles. Ceramics, porcelain. Paper making (kaolin used to make glossy paper). Fuller’s Earth (remove colour in oils - bleaching agent). Fining agent in beer/ wine making (removes cloudiness). Cat litter.

Question 26

Formation of Shale

Answer 26

Shale is a fine-grained sedimentary rock that forms from the compaction of silt and mud on sea and lake beds between 150 and 500 million years ago. where organic remains (plants, micro-organisms) died and decomposed pockets of oil and gas were trapped within the shale, which is porous.

Question 27

Discovery of Shale

Answer 27

In the mid 19th century, the Scottish chemist James “Paraffin” Young devised a method of distilling paraffin from oil shale (torbanite). Production grew for the next century until petroleum became widely available after WW2. Discovered in the late 1700s, the tar sands in Alberta, Canada are the biggest energy project in the world. currently producing 1.9 million barrels of oil a day.

Question 28

Extraction of Shale

Answer 28

With conventional oil reserves becoming harder and more expensive to access, geologists are returning to shale as a means of providing oil and gas. Modern extraction techniques include hydraulic fracturing (or fracking) where water, chemicals and sand are pumped at high pressure into underground shale deposits to allow gas to flow into wells where it can be pumped to the surface.

Question 29

Advantages of Fracking

Answer 29

Allows access to more reserves of natural gas and oil. Keeps fuel prices low which benefits the overall economy. Using natural gas from fracking to generate electricity instead of coal is cleaner and reduces CO2 emissions. The movement from coal to natural gas in the USA has significantly reduced nitrogen and sulphur oxide emissions (which cause acid rain). Decreased dependency on foreign oil particularly the “volatile” Middle East area. Creates highly skilled engineering jobs in extraction and processing. Government revenue (and GDP) increased via taxation of oil companies.

Question 30

Disadvantages of Fracking

Answer 30

Doesn’t reduce a nation’s dependency on fossil fuels and hinders investment in alternative renewable technologies. Process still contributes to CO2 emissions. Methane leaks from fracking wells are argued to effectively reduce any net gain from emissions (switching from coal to gas). Chemicals used could contaminate groundwater (drinking) supplies. Uses large quantities of water creating conflict with other users in arid areas (e.g. central USA). Drilling process can trigger small earthquakes. Localised noise pollution from drilling rigs. Lack of research into impact of fracking (relatively new branch of environmental science).

Question 31

Geodiveristy

Answer 31

Is the variety of rocks, minerals, fossils, landforms, sediments and soils, together with the natural processes which form and alter them. Geodiveristy is important to humans for a number of social, economic and environmental reasons:

• It is crucial to the delivery of ecosystem services (e.g. soil formation, filtering and storage of water) upon which the existence of all living things depend.
• Provides us with raw materials (fossil fuels, metals, building and construction resources).
• Provides us with landscapes for aesthetic pleasure and recreation.
• A unique teaching and scientific resource, helping us understand issues such as climate change, and sea level rise and the Earth’s past (e.g. fossil studies).

The overall responsibility for Scotland’s geodiversity rests with Scottish Natural Heritage (SNH), the arm of government which deals with landscape conservation. They will work in partnership with other organisations including charities and environmental groups to conserve Scotland’s rich and varied geological heritage.

Question 32

Geoparks

Answer 32

Are areas supported by UNESCO to improve knowledge and awareness of these special landscapes and to promote sustainable development. Scotland has 3 Geoparks; the North West Highlands, Lochaber and Shetland.

Question 33

National Parks

Answer 33

Scotland has 2; Loch Lomond and the Cairngorms, where there are severe restrictions on the use of the landscapes of outstanding scenery. They are managed by National Park Authorities.

Question 34

Local Geodiveristy Action Plans (LGAPs)

Answer 34

Promote awareness of these landscapes at local level involving charities and local councils.

Question 35

Site of Special Scientific Interest (SSSI)

Answer 35

These designations give additional protection to unique geological or scenic areas (it is legal).

Question 36

Scottish Fossil Code

Answer 36

Aims to provide advice on best practice in the collection, identification, conservation and storage of Scottish fossil specimens.

Question 37

Uses of Barley

Answer 37

Animal Feed: Half of the UK’s barley crop (almost all winter barely) is used to feed livestock.
Whiskey Distilling and Brewing: Malt whiskey is a distilled alcoholic beverage made from water, barley and yeast. It goes through a number of stages:

• Malting. Barley husks are steeped in water to release sugars, then dried.
• Fermenting. Malted husks are milled into a fine grain, mixed with water in a max at between 60 and 90C and yeast is added to ferment the liquid (3 - 4 days). Nitrogen based yeast compounds perform a key role.
• Distilling. The liquid ‘wash’ is heated to 80C in a copper still and the alcohol vapour evaporates and can be condensed.
• Maturation. The alcohol is stored in used barrels for 12 - 21 years which provide additional colour and flavoured to the whiskey.

Beer making actually follows a similar process, but a process of lautering where the mash is separated into the clear liquid wort and the residual grain and hops are added for additional flavour.
Food Processing: Used in the production of flour, malt vinegar, breakfast cereals, syrups, baby foods and confectionary.

Question 38

Uses of Seaweed

Answer 38

Fertiliser: Fertilisers are rich in potassium, nitrogen and magnesium have been used by coastal communities for centuries in Western Scotland and Ireland. Commercially produced seaweed fertilisers are becoming widely available.
Food Processing: Molecules extracted from seaweeds known as hydrocolloids are used in food processing. These include:

• Alginates (formed from crushing and drying brown seaweeds) are jelly-like carbohydrates used for their water holding, gelling, emulsifying and stabilising properties. Used as an additive in dairy and ice-cream products.
• Carrageenan’s (extracted from reed seaweeds by cooking in hot alkali) are used to stabilise foods such as ice cream and chocolate milk. Also used as a setting agent.

Medicines: Agars (from red seaweeds) are used as a solid substrate for the growth of bacteria and fungi and perform a vital role in microbiology. Seaweeds are also a source of iodine (used in sterilising and treating inflammations).
Cosmetics: Carrageenan’s are thickening agents used in toothpaste, skin care products, shaving creams, shampoos and hair conditioners.
Fuel: Although seaweed has been dried and burned for centuries, large scale fuels from seaweeds (“marifuels”) are at development stages.

Question 39

First Generation Biofuels (made from conventional processes): Bioethanol

Answer 39

Feedstock & Processes: Produced by the fermentation of sugar, from a wide range of crops with a starch or sugar content e.g. sugar cane, corn, maize, wheat and sorghum.
Advantages: Can use any plant for production, it only has to contain sugar and starch. Burns cleanly with reduced exhaust gases.
Disadvantages: Valuable farmland used for growing crops, leads to an increase in global food prices. Deforestation of habitats (rainforests) to bring land into ethanol production. Hygroscopic - it absorbs water from the air and is highly corrosive. Difficult to start vehicles in cold weather.

Question 40

First Generation Biofuels (made from conventional processes): Biodiesel

Answer 40

Feedstock & Processes: Transesterification, which involves the separation of methyl esters (the fuel) and glycerine (useful by-product).
Advantages: Burns cleaner than conventional diesel. Less particulates released into air. Glycerine used in pharmaceuticals.
Disadvantages: More corrosive than started diesel. Vehicles need heating systems to start in cold weather which increases engine conversion cost.

Question 41

Second Generation Biofuels (advanced biofuels, that can be manufactured from various types of biomass, often using experimental technology): Biomethanol

Answer 41

Feedstock & Processes: Pyrolysis (distillation of wood).
Advantages: Can be derived from non-food biomass (grasses, leaves, wood chips, husks). Can be derived from waste products. Needs less farmland to produce.
Disadvantages: Produces less energy by volume compared to petroleum based fuels. Health risk - causes burning in contact with skin.

Question 42

Second Generation Biofuels (advanced biofuels, that can be manufactured from various types of biomass, often using experimental technology): Bio-crude Oil

Answer 42

Feedstock & Processes: Uses a thermochemical reaction where organic material is rapidly heated to help decomposition into usable parts.
Advantages: Made from algae (easy to cultivate). No net gain of CO2 is released into the air. Potential yields are substantially higher per hectare.
Disadvantages: Technology is small scale and not fully developed at present. Process is currently expensive to produce large quantities.

Question 43

The Hydrogen Economy

Answer 43

The hydrogen economy is a proposed system of delivery energy using hydrogen for heating and powering vehicles. However, hydrogen does not occur in its pure form on Earth and has to be extracted using a number of methods, including;

• Steam reforming. Steam is combined with natural gas and heated to over 1800C with steam to produce syngas which can be separated into other gases including hydrogen.
• Coal gasification. Coal is pulverised and heated to over 1800C with steam to produce syngas which can be separated into other gas, including hydrogen.
• Electrolysis. A current is passed through a water or alkali solution which produces both hydrogen and oxygen at different electrodes.

Once the hydrogen gas has been produced it can be stored or transported. Hydrogen fuel cells (HCFs) are electrochemical devices that combine hydrogen and oxygen to produce electricity, with water and heat as its by-products.

Question 44

Advantages of Hydrogen Economy

Answer 44

HCFs are more efficient than traditional engines (80% to 30% efficiency comparison). HCFs have less moving parts than a combustion engine, and are more reliable and quieter. HCFs don’t degrade and can provide a continuous source of power unlike batteries which will eventually lose charge. HCFs are typically more portable than combustion engines, locations. HCFs are easier to install, reducing costs for users.

Question 45

Disadvantages of Hydrogen Economy

Answer 45

Very high cost of extracting the hydrogen from steam reforming or gasification (high energy inputs). The reduction in greenhouse gas emissions via HCFs may be offset by how the hydrogen gas was produced in the first instance; using fossil fuels. Initial HCFs were extremely expensive and large, (new mass produced fuel cell should reduce costs). A family car running on a HCF costs over £60000. Fuel cell technologies aren’t fully developed and it may be another 15 or 20 years before the technology becomes widespread. There is a lack of infrastructure such as hydrogen fuel stations and maintenance outlets to support a changeover form vehicles powered by petrol or diesel.

Question 46

Climate Variability

Answer 46

Climate is the average pattern of weather for a particular place over several decades. Changes in climate are hard to detect without very long-term records.
Climate Variability generally refers to natural fluctuations within the climate system. This includes the EL Nino/ La Nina oscillations. The EL Nino originates irregularly approx. every 2 - 7 years and involves the warming of the Eastern Pacific and the declining influence of ocean currents which can have dramatic influence on weather patterns around the globe.
Climate Change refers to the long-term anthropogenic (man-made) modifications of the Earth’s climate. Over the last century there has been a definite pattern of warming (up to 2C in places) and many scientists believe this is due to the build up of greenhouse gases (e.g. CO2, methane, CFCs) trapping heat energy radiated from the Earth’s surface. These gases are linked to human activities, principally the burning of fossil fuels in power stations, industry ad in transport systems and also in agriculture and deforestation of the Earth’s forest cover. This could have a significant impact on sea level changes as oceans warm they expand and on the melting of ice on land masses (Greenland, Antarctica) in addition to the threats to ecosystems, biodiversity and agriculture across the planet.

Question 47

There are a number of methods by which wave power can be harnessed:

Answer 47

• Buoyant Moored Device. This floats on the surface of the water or just below and is moored to the seabed and rotates around a long linkage generating power e.g. The ‘Salter Duck’ machine which requires a sea depth of at least 80m.
• Hinged Contour Device. This follows the motion of the waves; it creates power using the motion at the joints. It is commonly moored slackly to hold it in place. The Pelamis ‘snake’ device was an attempt to pilot this type of technology.
• Oscillating Water Column. this works by using a column of water as a piston to pump air and drive a turbine to generate power. This type of device can be fixed to the seabed or installed on shore such as the “Limpet 500” device.

Question 48

Wave Power Advantages

Answer 48

Few greenhouse gas emissions. Renewable (energy source is the sun which powers the atmosphere and winds). Huge energy potential, up to 40kW for every metre of wave along the shore. This increases with distance off-shore. More reliable than solar and wind - usually a swell out at sea. Larger potential in winter when there is peak electricity demand. Reduced environmental impact off-shore (in contrast to other sources). At shore devices can help reduce coastal erosion.

Question 49

Wave Power Disadvantages

Answer 49

High cost and lack of investment in developing the required technology (e.g. Pelamis Wave company folded in 2014), although costs could drop in future. Aesthetic impact (unsightly) could impact on coastal tourism. Maintenance costs (corrosive, salt environments). Impact on shipping lanes. Lack of knowledge of impact on coastal ecosystems (noise, construction) although mooring reefs could help create new underwater habitats. Best generating areas are usually more remote from National Grid (cost of building infrastructure and connections.)