exam coverage SOCIAL STUDIES YEAR 6.pdf

8.10 An introduction to Volcanoes The Earth’s Structure​ Key Words To understand how volcanoes form,​ we first need to know about the structure of the Earth.​ The Earth is made of layers.​ The two important ones for volcano formation are:​ The mantle — made of melted rock, which is called magma.​ vo...

8.10 An introduction to Volcanoes The Earth’s Structure​ Key Words To understand how volcanoes form,​ we first need to know about the structure of the Earth.​ The Earth is made of layers.​ The two important ones for volcano formation are:​ The mantle — made of melted rock, which is called magma.​ volcanoes mantle crust core conduit lava vent crater magma chamber The crust — made of huge tectonic plates that move on top of the mantle.​ What is a Volcano?​ A volcano is a crack, like a chimney, that runs deep into the Earth’s crust. This crack is called a conduit and it opens downwards to a pool of molten rock known as a magma chamber.​ Volcanoes erupt when magma rises up through these cracks and spills out onto the Earth’s surface as lava.​ Sometimes magma rises up too quickly or is really thick and this can cause gases to get trapped beneath it. If the gases build up too much – BOOM!!! You get an explosive eruption. ​ How is a volcano formed? ​ A volcano is a crack, like a chimney, that runs deep into the Earth’s crust. This crack is called a conduit and it opens Tectonic plates overlap downwards to a pool of molten rock known chamber.​ 156 as a magma The crust melts and a build-up of heat and gas occurs The heat and gas forces its way out as a volcanic eruption 8.11 Inside a volcano What Does a Volcano Look Like?​ Key Words A volcano usually looks like a mountain/hill in the volcanoes constructive destructive lava vent composite shield cinder active dormant extinct shape of a cone. ​ The hole at the top is called the main vent.​There are usually secondary vents too; these are smaller holes on the side of the volcano where magma comes out.​ Volcano Formation​ A volcano is an opening in the Earth’s crust.​ At constructive plate boundaries, the tectonic plates move apart.​ This creates a gap in the Earth’s crust, so hot magma can escape to the Earth’s surface.​ At destructive plate margins, ​the heavier plate gets pushed down into the Earth’s mantle.​ This is so hot that the plate ​melts into magma.​ This magma is less dense than the rest of the mantle, so it rises to the surface, forcing through any cracks in the Earth’s crust.​ Volcanoes can also form over hot spots. These are parts of the mantle that are naturally hotter, so the magma​ becomes less dense and rises through cracks in the Earth’s crust.​ Hawaii is a volcanic hot spot.​ 157 8.11 Inside a volcano Volcanoes all grow in a similar way, regardless of how they formed originally.​ When magma escapes from the vent of the volcano, it cools and forms a solid rock. This creates the crust of the volcano.​ As the volcano erupts over time, more magma escapes, cools and hardens.​ Eventually, this forms the mountain​ shape we associate with volcanoes.​ When volcanoes erupt violently, this can cause the top of the volcano to ‘blow out’!​ Types of Volcano​ A volcano is an opening in the Earth’s crust.​ Composite volcanoes​ Composite volcanoes have steep sides. This is because the lava is very thick and sticky so doesn’t flow far before it goes solid. These volcanoes tend to have very explosive and violent eruptions.​ Shield volcanoes have gentle, sloping sides and are not steep. This is because the lava comes out thin and runny so flows quite far before going solid. These volcanoes don’t tend to be violent when they erupt.​ Shield volcanoes​ Cinder cones​ CInder cones are the most common types of volcanoes. Small fragments of magma are blasted from the vent, up into the air. These fragments cool down quickly and fall as cinders forming a crater around the volcano’s summit. 158 8.11 Inside a volcano Volcano States​ Volcanoes are categorised according to their level of activity. There are 3 states.​ Active​ A volcano is active if it has erupted recently and if it is likely that it will erupt again.​ Kilauea is an active volcano​. The Ring of Fire is a horseshoe shaped area around the Pacific ocean. It is known as the Ring of Fire because most of the world’s active volcanoes are here.​ Dormant​​ A volcano is dormant if it has not erupted for a long time but there is a chance that it might erupt again one day.​ Kilimanjaro is a dormant volcano​. Extinct A volcano is extinct if it hasn’t erupted for thousands of years and if it is unlikely that it will ever erupt again.​ Ben Nevis in Scotland is an extinct volcano​ Mapwork Use database software to create a database of facts about volcanoes around the world. 159 Investigation Find out about some famous volcanic eruptions around the world – Mount Vesuvius and the destruction of Pompeii, Mount St Helens (1980). Linkit: Visit Volcano Discovery to find out which volcanoes are erupting now. 8.12 Eruption Drama What causes volcanoes to erupt?​ Key Words To know what causes eruptions,​ we first need to know what the inside of a volcanoes lava vent conduit simple volcano​looks like. magma chamber The vent is where ash, ​gas and lava escape from.​ The conduit is where ash, gas and lava travel up when the volcano is erupting.​ The magma chamber is where magma from the mantle collects.​ Volcanoes erupt when there is too much pressure inside them.​ Magma, ash and gas from the mantle collect inside the magma chamber.​ 160 Over time, the pressure inside the chamber builds up. Eventually, the pressure is too great and magma gets forced up through the conduit.​ The excess pressure eventually causes the volcano to erupt.​ 8.12 Eruption Drama What causes magma to build up?​ Magma can increase the pressure in the magma chamber in several ways:​ Earthquakes can cause more magma to rise​into the crust and magma chambers.​ Slight plate movements can cause magma to move.​ Natural hotspots can cause less dense magma to rise,​ which eventually increases the pressure inside the​magma chamber.​ During a volcanic eruption, hot melted rock called magma escapes from a vent, or opening, in Earth’s surface, or crust. Magma released from a volcano is known as lava. Fresh lava ranges from 1,300 to 2,200 °F (700 to 1,200 ° C) in temperature. It glows red as it flows out of the volcano’s opening. As it cools, it hardens into rock. Data Bank: The word “volcano” comes from the Roman name “Vulcan”. Approximately 350 million people live within “danger range” of an active volcano. Volcanoes don’t just occur on land. They can be found on the ocean floor and under ice caps, too! Lava from a volcano can reach 1,250°C! The world’s largest active volcano is Mauna Loa in Hawaii. Standing a whopping 4,169m tall, this geological giant last erupted in 1984. Volcanoes exist throughout the solar system! In A.D. 79, the Italian town of Pompeii was destroyed and buried by a volcano called Mount Vesuvius. About 1,900 volcanoes on Earth are considered active, likely to explode again. Yikes! Volcanoes can produce rich, fertile land. Mapwork Use maps to identify locations of Tonga, Iceland and any other location of recent volcanic activity. In pairs, children discuss and make notes about what they think it would be like to stand close to a volcanic eruption. What effects do they think an eruption might have on the region and its people? 161 8.13 Where in the world are volcanoes? How many volcanoes are there in the world? Key Words The ‘Ring of Fire’ contains 75% of the world’s volcanoes. 452 volcanoes stretch from the tip of South America, up the coast of North America, down through Japan and into New Zealand. Hawaii Hawaii was created by five volcanoes. Kilauea has been continually erupting since 1983! Loihi is an underwater volcano. North America Mount St Helens is close to the town of Portland, Oregon. In 1980 it erupted with the loss of 57 lives. It last erupted in 2008 and scientists believe it is only a matter of time before it erupts again. Africa Mount Kilimanjaro in Tanzania is a dormant volcano. This means it is inactive - for now. Its last eruption is thought to have been about 200,000 years ago. 162 eruption volcanoes elevation Iceland Home to 130 volcanoes, Iceland has a volcanic eruption on average once every five years. The most famous and active volcano in Iceland is mount Hekla, which has erupted 18 times since 1104, the last time in 2000. Europe Records from as long ago as 1500BC show how active Mount Etna is. Vesuvius famously destroyed the Roman town of Pompeii and on the Greek island of Santorini, a huge eruption tore the island in half. Philippines Mount Pinatubo is an active volcano. It had been dormant for almost 500 years but erupted in 1991 and is regarded as one of the most destructive volcanic eruptions of recent times. 8.13 Where in the world are volcanoes? What Are the World’s Most Dangerous Volcanoes? Mount Vesuvius Location: Naples, Italy Volcano Type: Stratovolcano Last erupted: 1944 Elevation: 1,281m Interesting Facts Best known for the eruption of 79AD that destroyed the Roman towns of Pompeii and Herculaneum. Overshadows the city of Naples, 5 miles to the east. Home to 3 million people. Plinian eruption, characterised by huge columns of ash and gas. Mount Nyiragongo Location: Goma, Democratic Republic of Congo Volcano Type: Stratovolcano Last erupted: 2016 Elevation: 3,470m Interesting Facts Best known for its large lava lakes. During a recent eruption, lava travelled at 60km per hour. The people of Goma were rescued, but 147 people were killed and 4,500 buildings were destroyed. Popocatépetl Location: Near Mexico City, Mexico Volcano Type: Stratovolcano Last erupted: 2005-2016 (ongoing) Elevation: 5,426m Interesting Facts Known as ‘Popo’. In 2016, a plume of ash which travelled 5km into the sky was recorded. Covered in a glacier, it has the potential to create vast mud slides should it erupt. Mexico City, home to 20 million people, is only 70km away. 163 8.13 Where in the world are volcanoes? Krakatau Location: Between Java and Sumatra, Indonesia Volcano Type: Stratovolcano Last erupted: 2014 Elevation: 813m Interesting Facts Famous for the eruption in 1886 which caused the death of 36,000 people. The 1886 eruption also caused devastating tsunamis on Java and Sumatra. Galeras Location: Pasto, Colombia Volcano Type: Stratovolcano Last erupted: 2010 Elevation: 4,276m Interesting Facts 450,000 people live in Pasto on its eastern slopes. Became active again in 1988. In 1993, an eruption killed nine people who were on a scientific expedition to the volcanic summit. Since 2000, Galeras has erupted almost every year. Taal Volcano Location: Manila, Philippines Volcano Type: Complex or compound volcano Last erupted: 1977 Elevation: 311m Interesting Facts Since 1572, there have been 33 recorded eruptions. Situated 31 miles from Manila, home to 1.6 million people. Activity with earthquakes and steam recorded since 1991. 164 8.13 Where in the world are volcanoes? Mount Merapi Location: Java, Indonesia Volcano Type: Stratovolcano Last erupted: 1977 Elevation: 2,911m Interesting Facts Mount Merapi means ‘mountain of fire’. Has produced more lava flow than any volcano in the world. Has erupted regularly since 1548. Lava flow has been recorded as travelling at 70 mph. In the 2010, 353 people were killed and 320,000 were made homeless. Mauna Loa Location: Hawaii Volcano Type: Shield volcano Last erupted: 1984 Elevation: 4,169m Interesting Facts Largest volcano in the world. One of five volcanoes making up Hawaii. Has been erupting regularly for 700,000 years with 33 eruptions since 1843. Mauna Loa means ‘long mountain’. It rises 4km above sea level, but is 17km high from its base on the sea bed. Mount Etna Location: Catania, Sicily Volcano Type: Stratovolcano Last erupted: 2017 Elevation: 3,350m Interesting Facts Europe's highest and most active volcano. Astronauts on the International Space Station photographed the ash plume from an eruption in 2002. ‘Operation Volcano Buster’ attempted to stem the lava flow using explosives but was unsuccessful. 165 UNIT 9: PEOPLE AND RESOURCES 9.1 Population and Distribution 9.2 World Population 9.3 Urbanisation 9.4 Climate Change 9.5 Sustainability 9.6 Sustainable Cities 9.7 Deforestation 9.8 Global Trade 9.1 Population and Distribution Population distribution and density Throughout history, human populations have spread across the surface of the planet, to live wherever they could adapt to the local conditions and wherever their basic needs for water, food and shelter could be met. In the past these Key Words population density migration patterns were mostly caused by different conditions of climate, topography and vegetation. These varied and so the distribution of populations was not even and the population density also varied. When people move from one area to another, this is called migration. Past migrations of people have occurred for various reasons. In some cases, the climate altered so that people were either confined within a particular area or if favourable conditions were found in wider areas, could spread out into new areas. Migration was also often driven by the ability of a given area to support a population. If the population grew too large, then some people would leave and seek out a new place to settle. Factors such as economic development, and the exploration and exploitation of resources have added to the survival factors that influenced early settlement patterns. As human societies have developed there has been an increasing use of the Earth's resources and an increasing range of human activity. The need to live close to resources such as food and water has slowly decreased as methods of production and transportation have changed. The location of human populations now has as much to do with economic activity and work opportunities as with being near essential resources. This is partly why so many people now live in cities. 167 9.1 Population and Distribution The effects of migration People in one area may feel that there are limited opportunities for employment where they currently live. These people may therefore migrate to another area or country in search of work. The area from which such people come may have fewer facilities and amenities, such as energy and water supplies, shops and healthcare. As more people leave, the level of provision of these facilities and amenities will drop even further, prompting more people to leave. Meanwhile, in the places to which these people move, the systems for education and health, water and energy supplies experience greater pressure. Did you know? The most densely populated country in the Arabian Gulf is Bahrain, with 1, 646 people per square kilometre. The most densely populated area in the world is the Macau region of China, with 18, 534 people per square kilometre. People and tourists on the busy streets of Macau, China Investigation Write a brief report that explains the factors that influence the pattern of human population distribution and density. Give examples of how this pattern is reflected in three different parts of the world. 168 9.2 World Population Issues connected with population The population of the world currently exceeds 7 billion. 78 million more people are added to the global population every year. The United Nations predicts that Keywords birth rate poverty by 2050 the world's population will reach 9 billion. Almost all the growth is taking place in less economically developed countries (LEDs). Approximately 97 out of every 100 births are in these countries. Many of these countries already struggle to provide the basic needs of the existing population. Nations across the globe face different situations. People are living longer in more economically developed countries (MEDs), due to improvements in healthcare. These countries have to consider what happens when more of the population is elderly. LEDs have fast-growing populations which puts pressure on services such as education and health and on water supply and waste disposal systems. Population growth and poverty Germany is a rich developed country with a population of approximately 83 million. Ethiopia is a less developed country also with a population of 83 million. Germany has a low birth rate and the population is predicted to fall to 75 million by 2050. Ethiopia's birth rate is 4.6 and its population could almost double to 145 million over the same period. In 2011, 70 per cent of the people in Ethiopia lived on less than USS2 a day. 169 9.2 World Population Benefits of education and smaller families A key factor in addressing population growth and reducing poverty is the education of women and girls. Poverty brings a lack of choices because of a lack of money. Research shows that when women and girls in less developed countries receive education than the birth rate drops. Without so many children to feed, it becomes more likely that a family will be able to rise out of poverty. If parents choose to have fewer children, then a family is more able to meet its needs. If there is more time between births, the health of the mother and child is better. Women have more options to work, earn money and increase the income of the family. All this benefits the community too. If a country has a fixed amount to spend on education and health, then a smaller population will mean that resources are shared between fewer people so the quality of these services improves. Investing in the future human resources of the country means that the long-term prospects for the country improve. Mapwork Work in a group to suggest some ideas that would mean that everyone in the world had enough to eat. Investigation Carry out some research to find out where in the world people are undernourished or go hungry through lack of food. 170 9.3 Urbanisation For most of human history, the majority of people have worked in agriculture Keywords and so have lived in rural areas. The minority of people who lived in the urban urbanisation areas of towns and cities relied on the much greater numbers of agricultural workers to provide food. The 18th and 19th centuries saw a great change in agriculture in a number of countries that were becoming industrialised. Changes in agricultural practices meant fewer people were needed to keep the supply of food available. With no work in the local rural area. people moved elsewhere, often to a town or city. As more countries around the world have become industrialised, so an increasing proportion of the world's population is living in cities. This process of increased urban living is called urbanisation. Around the world, people feel attracted to the benefits of urban areas. These include a greater range of services like health and education, better facilities, including water, sanitation and electricity supplies, and more amenities such as parks and entertainment venues. Many people also feel pushed from the rural areas because there is little work and few prospects for improvement. Problems of urbanisation Urbanisation does create some problems. Most people do not live very near their place of work and so they have to travel. Traffic congestion means that the roads become blocked. The emissions from all the vehicles can affect the quality of the air. Although the services in an urban area may be better than those in rural areas, they are put under greater pressure as more people move into that area. Increasing numbers of people have to be supplied with drinking water, for example. Greater numbers of people mean that more waste has to be dealt with. When more people want to live in a particular area it makes the price of land and housing increase. Sometimes this means that only a certain group of people can afford to live there. When people leave their rural communities there is an even smaller population left to work in local agriculture and to support local businesses. These businesses may have to close and other services may be cut. Investigation 171 Write an article for a magazine that describes the process of urbanisation and explains some of its causes and effects. 9.4 Climate Change What is climate change?​ Climate change is when the typical weather in particular place shows signs of change. ​ Keywords climate change greenhouse global warming This is not just an occasional very cold or very warm day, but a change in the weather conditions, in general, all the time.​ Climate change refers to long-term changes to global or regional climate. This could be changes in temperature, rainfall or other weather patterns.​ What is causing climate change?​ The Earth’s atmosphere is made up of gases which trap some of the warmth from the Sun. This makes the Earth warm enough for humans to survive.​ We call these gases ‘greenhouse gases’. A variety of human activity has created more of these gases. This means that more and more of the Sun’s heat is being trapped and therefore the Earth is getting hotter.​ Greenhouse gases occur naturally too, but humans have greatly increased the amount of them in the atmosphere.​ This is known as global warming. These small changes can have a dramatic impact on different places. Human Activity and Climate Change​ Human activities that increase these gases include:​ Deforestation ​ Burning fossil fuels ​ (as there are less trees to absorb carbon dioxide)​ (oil, coal, gas)​ 172 9.4 Climate Change Sending lots of waste to landfill ​ Lots of agriculture​ (this produces gas when it decomposes)​ Why is climate change referred to as a ‘crisis’?​ There are many side effects to the rising temperature of the Earth:​​ Sea levels around the world are rising. This will affect coastal areas especially.​ Extreme weather is causing flooding and droughts in some areas. Long periods of drought can lead to forest fires. Snow-covered areas like the Arctic are melting. This impacts the wildlife that lives there.​ Hotter weather means more demand for water. This can lead to water shortages in some places.​ Tropical storms in some areas are increasing in intensity.​ Increased temperature means that the seas and oceans are getting hotter. This is harmful for sea life.​ Climate change is a big problem and therefore needs big action. Such as:​ Governments agreeing on policies for the amount that they need to reduce their greenhouse gas production by.​ Large companies switching to renewable energy sources (like wind, solar and hydro) instead of burning fossil fuels.​ Reforestation – more trees need to be planted.​ Governments and big companies have a responsibility to change things on a larger scale.​ 173 9.4 Climate Change Some important changes have already been taking place around the world. These include: Building wind farms, solar farms and other means of creating ‘clean’ electricity. Stopping the manufacture of petrol and diesel powered transport. Introducing electric vehicles. What can we do to help reverse climate change?​ On a smaller scale, there are changes that we can make ​in our lives that make a difference. For example:​ Reusing and recycling where we can. ​ Walking or taking This reduces the need public transport where for new items to be possible manufactured (which driving.​ instead of burns fossil fuels).​ Minimising our use of plastics.​ Use less water by making small changes like turning off the tap when brushing your teeth.​ Eat local food — this means that it hasn’t travelled that far which uses less fuel.​ Mapwork Create a fact file of climate change using the following questions: What is climate change? What is being affected by climate change? Why is it happening? What can we do about climate change? Interesting facts. 174 Investigation Carry out some research to find out where in the world people are undernourished or go hungry through lack of food.