Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

UNIT 2. Geosphere


Published on


Published in: Education
  • Be the first to comment

  • Be the first to like this

UNIT 2. Geosphere

  1. 1. INDEX 1. The internal structure of the Earth. 1.1. The Geosphere. 1.2. Plate tectonics. 2. Relief formation. 2.1. Internal forces. 2.2. External agents. 3. Types of relief. 3.1. Continental relief. 3.2. Coastal relief. 3.3. Ocean relief. 4. The Earth´s continents.
  3. 3. 1.1. THE GEOSPHERE  According to their chemical composition, it is divided into three layers:  Crust: it is the outermost and thinnest layer. It is made up of rock and it is divided into oceanic and continental crust.  Mantle: it is the largest layer and contains magma (mixture of molten and semi-molten rock that is extremely hot). When magma is ejected by a volcano, is called lava. It is divided into upper and lower mantle.  Core: the innermost layer. It is believed it is made up of heavy minerals, such as iron and nickel in a solid or viscous state.  According to the rigidity of the materials, it is divided also into three layers:  Lithosphere: composed of the crust and upper mantle. Mainly solid and rigid.  Mesosphere: lower mantle. Made up of molten materials (magma).  Endosphere: another name of the core. Remember that Geosphere is the solid part of the Earth. It is made up of rocks and other solid elements.
  4. 4. .
  5. 5. 1.2. PLATE TECTONICS  The lithosphere is fragmented into several blocks called tectonic plates that float on the top of the molten materials in the mantle.  Consequently, Earth´s surface is in a state of constant motion and evolution.  There are plates under the ocean, called oceanic plates, and plates under the continents, called continental plates.  The movement of the tectonic plates is constant and pretty slow.  There are two basic movements: 1. Collision : when two plates collide 2. Separation : when two plates separate
  6. 6. Collision When two plates collide, it can result in: a) The formation of a very unstable area known as a fault, which is a break in the crust where earthquakes are common. b) Mountain formation, when the edges of the plates fold and rise. If the thinner edge is buried under the thicker one, it causes part of the crust to disappear.
  7. 7. Separation When two plates separate.  This create a fissure where the magma from inside the Earth comes up to the surface.  When lava cools, it forms a new layer of crust, called ridge or mountain range.
  8. 8. THEORY OF CONTINENTAL DRIFT Wegener’s theory, the first step to theory of tectonic plates  Alfred Wegener (1880 - 1930)  Alfred Wegener proposed the theory of continental drift at the beginning of the 20th century (1915). His idea was that the Earth's continents were once joined together, but gradually moved apart over millions of years. It offered an explanation of the existence of similar fossils and rocks on continents that are far apart from each other. But it took a long time for the idea to become accepted by other scientists.  For more information: similarities-between-continents-provide-evidence-of-continental
  9. 9. 2. RELIEF FORMATION The relief formation is the result of: 1. The internal forces of the Earth (orogenesis). 2. The action of external agents. 1. INTERNAL FORCES.  Are the cause of the formation of elevated landforms (mountains).  This process is called OROGENESIS. We can identify four process in orogenesis:  Volcanic mountain formation (orogenia volcánica).  Fault-block mountain formation (orogenia por falla).  Mountain formation by folding (orogenia por plegamiento).  Mountain formation by folding and subduction (orogenia por plegamiento y subducción).
  10. 10. Volcanic mountain formation - Occurs when two tectonic plates separate, creating a ridge. - Magma erupts from the volcano. - This lava cools and solidifies, forming mountain ranges and volcanic cones. Fault blocks - Occur when forces act on blocks of hard materials which cannot fold. - These forces produce earthquakes, which break up the blocks. - This forms a relief made of raised and lowered blocks.
  11. 11. Folding - Occurs when two tectonic plates with edges made of relatively soft materials collide. - The edges of the plates fold and rise, creating large mountains. Folding and subduction - Occur when a thinner oceanic plate and a thicker continental plate collide, and the oceanic plate sinks forming a trench. - The edge of the continental plate folds and rises, forming a mountain range.
  12. 12.  Elevated landforms are modified by the action of external agents: water, wind and living beings.  External agents shape the Earth’s relief through the interaction of three geological processes:  Erosion is the disintegration of landforms by the external agents (fluvial erosion, coastal erosion, wind erosion…).  Transportation is the movement of the eroded materials.  Deposition is when the transported materials are deposited in areas of low relief. 2. THE ACTION OF EXTERNAL AGENTS
  13. 13. 3. TYPES OF RELIEF There are three main types of relief: continental, coastal and ocean. CONTINENTAL RELIEF Plateaus (mesetas): these are flat or gently undulating areas located at an average altitude of about 650 m above sea level. On its, erosion leaves the hardest rocks exposed. Important: high plateaus (altiplanos) are located between major mountain ranges at altitudes above to 3.000 m. Plains (llanuras): these are flat areas located at altitudes below 150 m. The materials they are made up of are the result of transportation and deposition processes.
  14. 14. CONTINENTAL RELIEF Valleys: these are sunken areas between mountains and plateaus. They usually have a river running through them. Important: when river valleys are very large, they are called depressions or basins. Mountains: these are the highest landforms. They have steep slopes and rugged terrain. The average height of a mountain is between 1.000 and 3.500 metres above sea level. Depending on their height, structure and size, mountains are classified as:  Independent mountains  Mountain range
  15. 15. COASTAL RELIEF (Zonas costeras o litorales)  It is located in areas where the emerging land is in contact with the sea.  If the continental area is flat and has a low altitude : BEACHES.  If the continental area is mountainous: high coast with slopes and cliffs .  Coastal relief is made up of several landforms: 1. Peninsulas: area of land connected to the mainland and surrounded by water on three sides, except of one called isthmus. 2. Capes: pieces of land which extend into the sea. If the cape is small, it is called a point. 3. Gulfs: areas of the sea surrounded by land except on one side. If a golf is small, it is called bay. 4. Inlets: areas where the sea floods into a deep and narrow valley. When inlets are formed in glacial valleys, they are called fiords. For instance, in Galician inlets are very typical: they are called rías. 5. Islands: are pieces of land surrounded by water on all sides. A group of islands is an archipelago.
  16. 16. OCEAN RELIEF  We can say there are five major types of landform: 1. Continental shelves: are large, flat areas which extend form the coast and reach a depth of around 300 m. 2. Continental slopes: are steep slopes that connect continental shelves with ocean basins. 3. Ocean basins: are large plains at a depth of between 3000 and 6000 metres that cover most of the bottom of the sea. Sometimes, volcanic islands emerge form them. They are also called abyssal plains. 4. Ocean ridges: are very high under water mountain ranges located in the middle of the oceans. Their highest areas may emerge from the water, creating islands or archipelagos. 5. Ocean trenches: are narrow crevices located along the edges of ocean basins. They are some of the deepest areas of the planet, in which the water pressure is enormous and sunlight does not reach to the depths.
  17. 17. 4. The Earth´s continents
  18. 18. From largest to smallest 1. Asia 2. America 3. Africa 4. Antarctica 5. Europe 6. Oceania Look at these interesting links:  por/aprender-sobre/%C2%BFcu%C3%A1ntos-continentes-hay-en-la- tierra-1  general/%C2%BFcuantos-continentes-hay-y-cuales-son/