Geography Notes PDF

Geography Monday, July 15, 2024 7:08 PM 11.1 Can we ever know enough about earthquakes and volcanoes to live safely? Earthquakes There are 500,000 earthquake's in the world every year. Only 100,000 of these are strong enough to be felt on the Earth's surface. They're not evenly distribute...

Geography Monday, July 15, 2024 7:08 PM 11.1 Can we ever know enough about earthquakes and volcanoes to live safely? Earthquakes There are 500,000 earthquake's in the world every year. Only 100,000 of these are strong enough to be felt on the Earth's surface. They're not evenly distributed Natural Hazard and Natural Disaster When a natural threatens to cause great damage of loss of life, it becomes natural hazard. They aren't the same. If many lives are lost it becomes a natural disaster. This happens in the lithosphere. The lithosphere is a rigid outer layer of the earth, made up of the upper mantle and crust. 11.2 Do continents fit together like jigsaw pieces? Wegener's theory A German meteorologist in 1912 put a theory known as the continental drift. It is the movement of continents and tectonic plates which is driven by the convection of the mantle. Millions of years ago, there was a large supercontinent called Pangea. He thinks that millions of years ago, the contents we know where joined together by a supercontinent called Pangea It formed 299 million years ago and later on split into smaller land passes. Wegener's Evidence Similar animal fossils and rock types were found on different continents There was an ice age even at the hottest ones There were a formation of old mountain ranges and matching fossil remains 11.3 Where are the world's earthquakes and, volcanoes and mountain belts? Exploring the ocean floor Mountain ridges are called mid-ocean ridges (e.g. Mid-Atlantic Ocean Ridge) They are continuous mountain range found on the ocean floor. There were also ocean trenches (valleys/depressions) The deepest trench is the Mariana Trench, near the Philippines (Pacific Ocean) It is 2400km long and 70km wide, 11km deep (For comparison, Mount Everest is 8.8km) They are long narrow, and very deep depressions on the ocean bed. This is why the ocean is not flat The oldest rocks were further away from the ridge. Mountain Belt They are a group of mountains or very long mountain ranges Examples are Andes Mountain Range, Himalayas, Rockies and The Alps. Distribution of Volcanoes It is around the pacific ocean (Ring of fire) West coast of North and South America, Southeast Asia Center of Atlantic Ocean They are unevenly distributed Pattern Between Mountain Belts, Volcanoes, Earthquakes and Ocean Trenches/Ridges It is because they all form on the edges of tectonic plates. New Section 1 Page 1  It is because they all form on the edges of tectonic plates. Volcanoes form near plate boundaries They are large broken sections of the lithosphere (Solid part of crust and mantle) 11.4 What is happening beneath our feet? The Earth's structure It is built up of several layers. It includes: Continental/Oceanic Crust, Lithosphere, mantle, outer core, Inner Core The oceanic crust is more dense The Lithosphere is very thin and brittle The mantle is a much thicker mass of rock called magma, which is enough to flow. The outer core is a liquid (mostly made out of iron/nickel) The inner core it is mostly solid and mostly made of iron/nickel. It is also as hot as the sun. Theory of Tectonic Plates They have tectonic plate boundaries They're large broken sections of the lithosphere (Solid part of crust and mantle) It is divided into seven major and eight minor lithospheric plates, 125km thick. It moves from the heat from the earth's core, which moves magna then moves the tectonic plates. The plates constantly move causing volcanoes, earthquakes, mountain ridges, trenches to form. 1.5 What happens at plate boundaries New Section 1 Page 2 1.5 What happens at plate boundaries Types of plate boundaries Types of Plate Boundaries What It is Convergent (Destructive) It is when plates moved together, and where two continental lithospheric plates meet. They fracture and push upwards to form a high mountain belt, causing earthquakes. If the oceanic plates move towards a continental plate, the heavier oceanic plate sinks (one goes down). It is how trenches form. Where oceanic plate goes down the continental plate is the subduction zone. As it sinks, it form violent earthquakes and volcanoes. E.g. Andes Mountain, South America (Oceanic/Continental) and Himalayas (Continental/Continental) Divergent (Constructive) It is when two lithospheric plates are forced apart so magma rises , hot rocks melt, forms a ridge of volcanoes and a new oceanic lithosphere. It also builds up a mid-ocean ridge. E.g.: Mid Atlantic Ridge. Iceland Conservative (Transform) It is when two plates slowly slide past each other. Friction causes the two plates to stick together and pressure builds up. When the friction is overcome, it causes a severe earthquake. There are no volcanoes. E.g.: San Andreas Fault, California, USA How the plate moves Theory 1: The Earth's internal heat, creates convection currents in the mantle, transferring heat which rises and cools in a circular motion, moving the tectonic plates. Theory 2:It moves by gravity as it is extremely heavy, pulling them apart, the older/denser part goes down first. (Slab Pull/ Ridge Push) What do we know about earthquakes? How does an earthquake occur? It is a sudden violent movement in the Earth's surface It occur when two plates suddenly past each other. The area where they slip is a fault. It is where two tectonic plates meet (Plate Boundaries). The waves of energy caused by earthquakes are called seismic waves. (0-10 Magnitude) The focus is where the seismic wave is the strongest, and where the earthquake starts. The area on the surface directly above the earthquake is the epicenter. A seismograph is to measure the earth's movements Earthquake in Nepal, 2015 On Saturday 25 April 2015, At 11.56 am a massive earthquake struck Magnitude: 7.8 It was the biggest earthquake in Nepal for 80 years. The epicenter was Barkpak village, 75km north-west of Kathmandu in the Gorkha region. It thrown the population into chaos, it affects villages within a 100km radius. 75% of the city damaged, an avalanche on Mouth Everest. 22000 injured. Nepal lies in the Convergent (Destructive) plate. 11.7 Can people manage risk living in earthquake zones? You can: Drop, over and hold on. Less people die in high income countries because: Strict building code (laws) - safer materials New Section 1 Page 3  Strict building code (laws) - safer materials Make earthquake resistant buildings Urbanization controlled Citizens are more prepared and educated 11.8 What do we know about volcanoes? Volcanoes They are opening or cracks in the lithosphere where magma from the inside the Earth can escape onto the surface First, as liquid lava flows from the event or cracks Volcanic bombs, lumps of molten rock that solidify as they explore out of the vent Hot ash and dust are thrown in the atmosphere, falling back to Earth Steam and gas which may be poisonous. Fast moving hot lava, dangerous gases and ash are called pyroclastic flow. Volcanic hotspots are far away from tectonic plates, they form over hot regions in the mantle. (E.g: The island of Hawaii) When they cool, they form igneous rocks Types of Volcanoes and Stages Active Volcano - It is erupting and likely to erupt again Dormant volcano - It is a volcano that not erupted for a long time but could become active again Extinct Volcano - It is a volcano that hasn't erupted for a million years, and will never erupt again. Shield Volcanoes - Volcano with gentle slopes, they form runny lava that spreads far. (E.g.: Mauna Loa, Hawaii) Composite or Stratovolcano - Volcanoes that are tall with steep sides, a symmetrical cone. They form thick/sticky lava. E.g.: Mount Fuji, Japan ; Mount Etna, Italy 11.9 Can people manage risk living near volcanoes? Around 800 million people live within 100k, and 29 million people within 10km active volcanoes. A volcanic threat is a measure that combines the level of hazard and the number of people exposed to it. The highest is Indonesia. Volcanoes are predictable. Benefits Fertile soil that is good for agriculture Minerals Geothermal energy to produce electricity Tourism, attracts millions of tourists every year New Section 1 Page 4  Tourism, attracts millions of tourists every year You can predict volcanoes with: Tiltmeter, GPS, Surveying, Earthquake Sensor, Thermal Imaging, Satellite, Airborne and Ground. 12.1 What are the challenges and opportunities facing Africa? Africa is the second-largest continent in the world, both by area and population. It is home to 1.4 billion people across 54 countries, where over 1,500 different languages are spoken. Africa is rich in natural resources, yet it is often viewed in a stereotypical way by other parts of the world While Africa indeed faces enormous challenges, not every African is in need, nor is every African nation in crisis. 12.2 What is the physical landscape of Africa Physical Geography Africa is different from other continents as it is very old and composed of hard rocks. Africa is pretty flat. Africa is between two oceans, the Atlantic and Indian ocean. The Great Rift Valley is being formed in East Africa due to tectonic activity, forming new plates. Most of Africa is formed under of one tectonic plate. As the plates do not collide the continent, there are a few mountain be lts in Africa. Atlas mountain is a mountain Africa up to the north, it is a very cold place with snow. The Sahara desert, it’s the world's largest hot desert. Antarctica is the largest desert. The longest river in the world is the Nile River which is in Africa. 6000 km long spreading through 11 countries. Africa has one of the largest rainforests in the world (The Congo Rainforest - 2nd largest). Natural Resources. Over half of the world's diamonds are from Africa 22% of the world's golds are from Africa. Africa exports 16% uranium, used to produce nuclear energy and electricity. 58% of the world's cobalt are from Africa used for smartphones and electric cars. 30% of earth's remaining minerals are from Africa. 10% of the world's oil and gas are From Africa. Even with large production, minerals aren't evenly distributed. 60% of gold are from Ghana and South Africa. 69% of diamonds are from Botswana and DRC (Democratic Republic of Congo). 12.3 How has Africa's past shaped its present? The slave trade Between 1600-1800, 12-15 million Africans were sold as Slaves. They bought people in West Africa for exchange of goods, to bring civilization and natural resources. Slavery was abolished in 1833. Britain (1st) and France (2nd) were the main traders. The Scramble for Africa The Industrial Revolution started and nations wanted to exploit the resources and labor of Africa. They were bring civilization to savage people. There were 14 countries in the Berlin Conference, starting 1884-1885. Slave Triangle included trade between Europe, Africa and America. (New Worlds). Rich Africans wanted guns from selling slaves. The Belgian Congo King Leopold II of Belgium took control of the Congo Rainforest. He wanted to make it a better life but that was not the case, he collected rubber in the rainforest. He forced local people to collect sap from rubber trees, an estimate of 10 million Congolese died due to abuse. Things like cocoa, coffee, sugar, peanuts, cotton, rubber, tea and more were traded rather than feeding the population of Africa, this New Section 1 Page 5  Things like cocoa, coffee, sugar, peanuts, cotton, rubber, tea and more were traded rather than feeding the population of Africa, this leads to poverty. 12.4 How Developed are African countries Africa is very stereotyped, most people think of things like poverty, famine or hunger. Only a small amount said business, ed ucation or beautiful landscapes. Not all areas have poverty or famine. HDI HDI stands for Human Development Index made by the United Nations. Used to measure development of a country It measures income, education and health Negatives of Africa It had tribal conflicts which in a year in which hundreds of women and children are killed in attacks on villages due to war. Africa is not poor, it is poorly managed. It is plagued by poverty even if it has a lot of natural resources. The gap between the rich and poor are growing more and more. The colonial period caused slow development in economy. Manufacturing was behind because competition were there such as Britain and France. Positives Immense deserts, vast rainforests and a big savanna Africa has a lot of natural resources, it has been an export of raw materials and natural produce. 12.5 What is the pattern of climate biomes in Africa? Regions of Africa Very Desert/semi-desert with little rain Savanna, a little wet and dry season Rainforest, rains all year round How this happens Trade winds take warm air back to the Equator Trade winds causes warm air to rise and creating low pressure Air cools and condenses to give rainfall Some air is pushed north and cooled, Cool air decreases Final step is when air warms up again in the high pressure zone, moisture evaporates of little or no rain New Section 1 Page 6  Final step is when air warms up again in the high pressure zone, moisture evaporates of little or no rain Biomes in Africa A biome is a large area characterized by its vegetation, soil, climate, and wildlife. There are biomes such as Grassland, Savanna, Deciduous Woodland, Tundra, Tropical rainforests. Savannas have wet and dry seasons. The rainfall comes which makes the savanna colds Tundra biomes are cold and have no trees. Two deserts in Africa which are Sahara (at the north) and Kalahari (at the south). 12.6 Is there a future for the Sahel? Sahel A Sahel is a region in North Africa. It lies on the southern edge of Sahara. It is vulnerable on drought so it leads to crop failure and no water. This region is known have frequent famines. Livestock and people have also has eaten all vegetation. This is overgrazing. As more and more vegetation is removed from land, soil is exposed to water and wind. This leads to soil erosion. As more and more soil erodes, desert spreads. This is called desertification. Erratic rainfall Higher levels of rainfall were there in 1950's which caused people to move to the Sahel The rain has failed in the late 1960's so the soil would not grow crops and this caused famine Man that stopped the desert Yacouba Sawadogo who is a peasant farmer found a way to stop the desert. He called his technique Zai based of traditional farm practice. He filled the dug holes with compost and planted seeds at the start of the rainy season. These attracted termites which built tunnels helping retain the rain. He planted trees to hold back the desert. He has a forest covering 25 hectares. Africa's Green Wall It had a goal to replant trees in Africa and providing jobs and money to thrive in the harsh environment. It started in 2007. Funded by United nations (UN), World Bank, African Union, European Union (EU). It is expected not to be completed till 2030. The project costed 8 billion dollars. 12.7 What are the challenges and opportunities of population change in Africa? About Africa Africa has a population of 1.5 billion with an uneven distribution. This causes high population density. It is second most populated continent with 20% of the world's population. Africa is very young as 60% of the population is under 25. This causes death rate to be low, and birth rate to be high. By 2050, Africa is predicted to be around 2.4 billion people Nigeria is the most populated country and Niger has the highest birth rate. Lowest population growth is South Africa. Reasons for population increase and struggles The global rate of children is 2.5 per woman but in Africa it is 4.7 per woman. In Niger it is more than 7. The high birthrate and population would make it harder for governments who are already struggling with reducing poverty, hung er and improving living standards or education. The young people would limit job opportunities, rising unemployment and limited voices heard as there are less adults. Opportunities The high population would help with innovation and economic opportunities in big cities. China will be replaced by Africa. The African labor force will be young and cheap. It is expected that businesses would move to Africa instead of Asia due to cheap labor. New Section 1 Page 7  instead of Asia due to cheap labor. 12.8 What are the challenges and opportunities of urbanization Urbanization Urbanization is the increase of people moving into urban areas such as cities or towns. Africa has the highest rate of urbanization. This fast urbanization could lead to poverty and increase in slums. Ethiopia Ethiopia is the most second largest population in Africa with over 100 million people. A country in east Africa. It is landlocked which means there are no coastlines which means they have no seaports. Addi Ababa is the capital city. Due to the large urbanization, 80% of the population lives in slums The slum life is not easy as it lacks hygiene, it is dirty, limited access to water and diseases. Solution Low cost housing/apartments are funded by governments Government projects to improve infrastructure such as railways Attract multinational companies to build factories which offers jobs 12.9 Does China want to help develop Africa? Landlocked Country Ethiopia has no ports and It takes a day or more to transport materials to Djibouti. 90% of imports and exports are transported by road to/from Djibouti. The most important invention is how they made the railway to Addis Ababa to Djibouti (750 km) This made Ethiopia have easier access to the sea and Djibouti will have greater access to Ethiopia's market. It would reduce the time transport which reduces costs. This would make it easier to trade which grows the economy. This was a 4 billion dollar project and funded 70% by Chinese banks. Trade between China and Africa 15% of Africa's exports which are mainly natural resources, go to China China provides 21% of Africa's imports (machinery, transportation etc.) China is now Africa's largest trading partner. Building more infrastructure in Africa like schools, ports, hospitals or more. 1 million Chinese workers moved to Africa in the past decade. African countries can fall into debt trap with Chinese investment (loan) money. Many Chinese workers are used on projects in Africa, not Africans Africa is opening up to a ‘new form of imperialism’ China may be interested in extracting Africa’s natural resources China is exporting more to African countries than importing from them, which means China ends up benefiting more from trading.  China's trillion dollar project around the world is called the BRI (Belt and Road Initiative). 13.1 How does ice change the world? What are glaciers? Made of snow that, over hundreds of years, has been pushed down or compressed into large, thickened ice masses. Contain rock and sediments Glaciologists are Earth scientists who investigate glaciers all over the world. They measure glaciers to see how they change and how they alter landscapes through time. Where are glaciers found? Glaciers are mostly in Antarctica and Greenland. Formed in locations where: Average annual temperatures are near freezing point New Section 1 Page 8  Average annual temperatures are near freezing point Large amounts of snow fall during winter months Temperatures throughout the year are not high enough to melt the previous winter’s buildup of snow. Formed the largest reservoir of fresh water on the planet. Stored 75% of the world’s fresh water Cover around 10% of the Earth’s total land area and are found 47 countries What are the different types of glacier? Alpine glaciers, which form on mountainsides and move down slopes through valleys. Continental ice sheets, which spread out and cover larger areas. 13.2 How and why do glaciers form and move? What is an Ice Age? Ice ages are when temperatures are low enough for ice to form glaciers and ice sheets. During the last ice age, the world was, on average, around 5 ° C colder than today. Currently about 10% of the Earth’s land surface is covered in glacial ice. During the last ice age, ice covered up to 30% of land How do glaciers form and move? Glacial ice forms in upland or polar areas above the snowline where snow and ice cover the ground throughout the whole year as it takes a long time for snow to become ice. Snow accumulates (gains ice), it is compressed by its own weight. Gradually, dense and hard ice forms which starts to flow down-slope under its own weight. Where more ice is gained that lost over a year, it is called zone of accumulation. If temperatures remain low, with heavy snowfalls, glaciers advance down-slope. If accumulation (the amount of ice gained) is greater than ablation (the amount of ice lost is more than gained/melted), then the amount of ice stored in a glacier increases and the glacier advances. If the ablation is greater than the accumulation then the glacier reduces in size and retreats. This occurs in the zone of ablation. The ice can move at different speeds. This creates wrinkles in the surface of the ice, forming great cracks called crevasses. The end of the glacier is called the snout where water is released. 13.3 How do glaciers change landscapes? Glacial processes Weathering, erosion, transportation and deposition occur in different ways with glaciers than with rivers and the sea. Freeze-thaw weathering takes place more often in cold temperatures. It t can occur under and at the sides of the valley glacier. Rock fragments of the mountainside continually break off and fall into the glacier ice. How do glaciers transport and deposit material? As the glacier moves down-slope it is transporting vast amounts of rock that have mixed with the ice. This debris is called moraine. frost-shattered rock debris and sides, transported and deposited by glaciers Moraine varies in size from huge angular boulders to fine clay. Down-slope temperatures eventually become warmer and the ice will begin to melt, at the glacial snout. New Section 1 Page 9  Down-slope temperatures eventually become warmer and the ice will begin to melt, at the glacial snout. As the ice melts, the material it was transporting is deposited. The water from the melting ice runs down-slope, feeding a river or lake. This is called meltwater. How do glaciers erode landscapes? There are two ways which are plucking and abrasion Plucking takes place where loosened bedrock become frozen to the base of the glacial ice. The rock has already been loosened by freeze-thaw weathering. The rock moves forward, the rock is frozen to the ice as it moves with it. It is then plucked from the bedrock. Another process is where the ice moves forward, these rocks scrape against the bedrock which wears it away. That is called abrasion. This leaves smooth, polished rocks. 13.4 How are landforms shaped by glacial erosion? Part 1 What landforms are created by glacial erosion? During glacial periods in the last ice age, ice caps covered mountain areas. River valleys were slowly filled by moving ice which straightened and deepened them. Corries A corrie is where a glacier begins to develop as a sheltered hollow on the sides of a mountain. As snow builds up and turns to ice, it starts to flow. As ice builds up in the hollow, the increased weight of ice and movement down-slope leads to the ice gouging and deepening the hollow. It make (a groove, hole, or indentation) with or as with a sharp tool or blade The ice rotates as it moves and flows down-slope. After an ice age, a lake may form in the hollow called tarn. A corrie has three distinctive features: a steep back wall, an over-deepened hollow and a lip. Arete and pyramidal peaks Where two Corries develop side by side, the glaciers erode the rock between them leaving a knife-like edge called an arete. When three or four Corries develop around the mountain top, a pyramidal peak is formed. The formation of valleys High in the mountains, the river is narrow and fast-flowing. Mountains are steep, so the river flows downhill very quickly. Its water carries pebbles and boulders that erode (wear away) the sides and bottom of the river bed, deepening the river and cutting New Section 1 Page 10  Its water carries pebbles and boulders that erode (wear away) the sides and bottom of the river bed, deepening the river and cutting down The mountain in a V-shape, called a valley. Before During After 13.5 How are landforms shaped by glacial erosion? Part 2 The formation of U-shaped valley One of the most dramatic changes to a landscape caused by glacial erosion is the formation of U-shaped valleys. A series of small corrie glaciers move down-slope from the hollow on the mountainside where they formed. They slowly join together to form one large glacier-like river tributaries flowing into a main river. This large glacier can erode more powerfully. It therefore creates a deeper valley with sheer,(steep) straight sides and a flat bottom. This valley looks like the letter “U”, hence the name- U-shaped valley. After the ice, the river that flows in the U-shaped valley seems far too small for the huge valley it did not erode. It is called a misfit river, a river that is either too large or too small to have eroded he valley in which it flows New Section 1 Page 11 Hanging valleys and truncated spurs When a U-shaped valley is created, the glacier cuts through the interlocking spurs that previously formed the river valley. This leaves behind steep cliffs along the sides of the U-shaped valley- these are called truncated spurs. Once the ice melts and the river flows once more, the tributary streams and their small valleys are left hanging high above the U-shaped valley floor. This landform is called a hanging valley. Often the tributary streams fall from this hanging valley as waterfalls. Ribbon lakes Sometimes the floor of a U-shaped valley is filled with long thin lakes called ribbon lakes. Where a glacier transports big rock debris over softer rock it sometimes erodes a deeper narrow through in the flat valley floor. As the ice melts, this fills with meltwater, creating a lake. New Section 1 Page 12 Fjords Fjords are flooded, glaciated valleys. They are found in places where current or past glaciation occurred below the sea level. Fjords are formed when a glacier retreats, after eroding its typical U- shaped valley, and the sea fills the resulting valley floor. This forms a narrow, steep-sided inlet (sometimes deeper than 1,300 m) connected to the sea. The term “fjord” is of Norwegian origin. Fjords have sheer cliff sides, often with hanging valleys and truncated spurs. New Section 1 Page 13