UNIT 1: Physical Geography Contents 1. Relief formation 2. The Earth’s relief 3. The continents 4. Water 5. Rivers and lakes around the world 6. Climates and landscapes 7. The relief of Spain 8. Water in Spain 9. Climates and landscapes in Spain 2 Keywords - Relief: relieve. - Average altitude: altura media. - Landforms: formas del relieve. Groundwater: acuífero. - Tectonic plates: placas tectónicas. - Glacier: glaciar. - Crust: corteza terrestre. - Landscape: paisaje. - Limestone: calizas. - Climate zones: zonas climáticas. -Karstic: relieve kárstico (calizas). - Climate chart/graph: climograma. -Siliceous: rocas silíceas. - Tides: mareas. - Clay: arcilla, relieve arcilloso. - Waves: olas. - Plains: llanuras. - Marine currents: corrientes marinas. -Plateau: meseta. - Scarce resource: recurso escaso. - Depression: depresión. - Flat areas: planicies. - Cliffs: acantilados. - Overexploitation: sobreexplotación. -Capes: cabos. - Human consumption: consumo humano. - Gulf: golfo. - Fresh water: agua potable. - Cape: cabo. - Mountain range: cadena montañosa. 3 1. Relief formation What is relief? The landforms of the Earth’s surface are called relief. These variations are found on the surface of our continents and also on the ocean. How is relief formed? Relief formation is explained by Theory of Plate Tectonics. The Earth’s crust is made up of plates which float on the top layer of the mantle. It could be compared with an orange, these plates separate, slide against each other or collide. When the plates separate rifts (cracks) are formed in the oceanic or continental crust. The magma inside the earth pushes up through the cracks and then when it cools forms another crust (with new landforms). For example the Rift Valley in Afica. A plateau on the ocean’s crust sometimes collides with the edge of a continental plate, and it pushed down into the Earth’s interior. It forms faults and folds. Magma pushes up through the continental crush, creating volcanoes on the Earth’s surface (for example Teide). Two continental plates sometimes collide, and the high pressure forms ondulations in the Earth’s surface. It forms the biggest mountains like the Himalayas in Asia or the Alps in southern Europe. 4 The movement of tectonic plates 5 Exogenous (external) processes In addition to internal forces relief is also formed by external processes: - Erosion of rocks, which are worn away, fragmented and dissolved. - Transport of the eroded materials. - Sedimentation or the deposition of materials in another place. The erosion of rocks is caused by the interaction of external agents over a long time. These forces are water, wind and temperature. Rivers carve out deep valleys. Glaciers also cause erosion when they move. The force of the sea erodes cliffs, changing the coastline. Sea water transports the materials from the cliffs forming new beaches. Sharp changes in temperatura can break up the rocks. Sometimes water filters down through the cracks of rocks and then when the water freezes may break rocks in to pieces. Limestone and gypsum do not fragment but dissolve, it forms a karstic relief. 6 2. The Earth’s relief The main forms of continental relief are the following: - Mountains, higher than 1000 metres, isolated or grouped together in mountain ranges. - Valleys which are áreas of low land between mountains. - Plains are flat áreas of land near the coast or in the basins of large rivers. - Plateaus are high raised plains between 400-600 metres. - Depressions are very low areas under the sea level. - On the coast we find relief forms such as cliffs, which are steep rock formations, and beaches, which are found in the coastal áreas. Gulfs and bays (small gulfs) are where the sea extends inland. Capes and penínsulas are áreas of land that extend into the sea. 7 The main forms of ocean floor are the following: - A continental shelf, is a large plateau that surrounds a continent, reaching a depth of 200 metres. A continental slope leads down from the continental shelf into the deeper part of the ocean. - Abbysal plains are vast plateaus at a depth of 3000-7000 metres. Mid- ocean ridges are long mountain ranges that are found on the abbysal plains. - Ocean trenches are long and deep cracks in the ocean floor. 8 The influence of relief in our lives The nature and altitude of relief influences climate, vegetation and land use. It affects both population and economic activity. Most of the world population lives in flat areas bellow 500 metres of altitude near the coast and in river valleys. The climate over there is mild and conditions are very good for agriculture and communications. However, technological advances have reduced our dependence on environment. 9 3. The continents Africa. The continent has a high average elevation of 750 metres because of its many plateaus. There are great deserts (Kalahari, Sahara) and many mountain ranges (Atlas, Drakensberg). The Great Rift Valeys is in the east. The coastline is regular. 10 Asia. Mountain ranges are mainly in the centre. The Himalayan mountain range contain top peaks in the world (Everest, K2). Plateaus include the Plateau of Tibet, the highest in the world. Vast plains are crossed by big rivers (Yangtze, Yellow River, Mekong). The main basins contain inland seas (Caspian, Aral and Dead Seas). The coastline is irregular with many gulfs (Bay of Bengal, Persian Gulf), peninsulas and archipelagos (Japan, the Philippines or Indonesia). 11 America. The great mountain ranges are the Rocky Mountains, Sierra Madre and the Andes, they run parallel to the Pacific Coast. Inland plateaus include the Marro Grosso and the Bolivia Altiplano. The Great Plains are in North America. The coastline of North America is more irregular than that of South America. 12 Europe. Great plains occupy the centre and east of the continent. The oldest mountains are in the north (Scandinavian Mountains) and east (Urals) by the are not very high because of erosion. High, Young mountain ranges from an arc round the Mediterranean Sea (Pyrenees, Alps, Carpathian, Balkans and Caucasus. The coastline is irregular with islands (Iceland, Sicily) and peninsulas (Iberian, Italian, Escandinavian). 13 Oceania. Relief varies from one island to another. Australia has coastal plains, low desert in the interior and the Great Dividing Range in the east. New Guinea and New Zealand are mountanious while Pacific Islands are mainly low. 14 • Antarctica. It has the highest average altitude (2000 metres) and is mainly covered by ice. 15 4. Water Water covers more than 70% of the Earth’s surface. Continental water Rivers, lakes, groundwater and ice contain fresh water (3% of all the Earth’s water). - Rivers are continuous flows of water that originate in rain, melting ice or groundwater. They flow into the a sea, a lake or another river. Rivers are important cause they provide water for human consumption, farming and hydroelecric energy. - Lakes are enclosed masses of water which accumulate in depressions. - Groundwater accumulates when rain and river water infiltates porous ground until the water flow reaches a layer of impermeable rock and forms an aquifer. - Ice is found in the polar ice caps an in mountain glaciers. 16 Marine water Oceans and seas hold 97% of the Earth’s water, they are in constant movement: - Marine currents are masses of water which move like rivers trough the oceans, they could be warm or cold currents. - Tides are the daily rise and fall of the sea level caused by the gravitional movement of the Moon and Sun. - Waves are the ondulating movements of the water on the surface of the sea caused by wind. 17 Water as a scarce resource - Water is a precious resource, most water is not suitable for human consumption. - Overexploitation of the Earth’s water has led to empty aquifers and lakes. - The distribution of water in the Earth is uneven and it could vary between seasons and years. - Hydraulic engineering (reservoirs, canals, wells) helps to make available all around the world but they have a deep impact on lanscapes and environment. 18 5. Rivers and lakes of the world -AFRICA: rivers Nilo, Congo, Niger and Zambeze. Lakes Victoria and Tanganyka. - ASIA: rivers Mekong, Tangtze, Yellow, Ganges. Lakes Aral, Caspian, Black and Baikal -AMERICA: rivers Mississipi, Amazon, Orinoco. Great lakes and Titicaca. -EUROPE: rivers Danube, Volga, Rin. Lakes Ladoga and Onega. -OCEANIA: rivers Murray and Darling 19 6. Climates and landscapes The sun does not warm all the Earth’s surface to the same extend. The Sun’s rays are perpendicular in the ecuator and oblique in the poles. As a result of that we have five climate zones: a hot zone between the tropics, two temperate zones in both hemispheres and two cold zones around the poles. Altitude, relief and proximity to the sea also influence climate. There are different types of climates within each climate zone: hot (equatorial, tropical and desert), temperate (Mediterranean, Oceanic and Continental) and cold (Polar and Mountain). Climate has a great influence on human societies. 20 21 Making and reading a climate chart 22 Mind mapping. Landscapes temperate zone. 23 24 Mountain climate Mountain climate is different and very important in Spain as there are mountains all across the Iberian Peninsula. The temperature on mountains becomes colder the higher the altitude gets (minus 0’6 degrees per 100 metres). Mountains tend to have much wetter climates than the surrounding flat land (Föehn effect): 25 . 7. The relief of Spain 26 GEOLOGY. A long mountain range was formed in the West of Iberian Peninsula about 300 millon years ago. Over long time, it was eroded and formed a large plateau. During the Tertiary Era (65 millon to 2 millon years ago), the internal forces of the Earth caused great changes: - The Plateau fractured and became the Inner Plateau. - Other blocks rose and became Galician Massif, Cantabrian Range, the Mountains of Toledo and Sierra Morena.