Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

CAMBRIDGE AS GEOGRAPHY REVISION: ROCKS AND WEATHERING - 3.1 PLATE TECTONICS

•
•
George Dumitrache
George Dumitrache

A comprehensive presentation of subchapter 3.1 Plate Tectonics, from the third chapter of Physical Geography, AS Cambridge, Rocks and Weathering.

1 of 15
ASGEOGRAPHYREVISION ROCKSANDWEATHERING 3.1 PLATETECTONICS
KEYTERMSANDDEFINITIONS Benioff zone is a narrow zone of deep earthquake foci at a subduction zone. Continental crust is that part of the Earth’s crust that forms the continents. Continental drift is the theory that the continents have drifted across the surface of the globe. Convergent plate boundaries are margins where plates are moving towards each other. This can be oceanic–continental, as in the case of the Nazca and South American plates, or it can be continental– continental, as in the case of the Eurasian and Indian plates. Core is the central part of the Earth below 2900 km from the surface.
CAMBRIDGE AS GEOGRAPHY REVISION: ROCKS AND WEATHERING - 3.1 PLATE TECTONICS
KEYTERMSANDDEFINITIONS Crust is the outermost layer of the Earth. It may be divided into continental (sial) and oceanic (sima). Divergent plate boundaries are plate boundaries in which the plates are moving apart, e.g. the North American and European plates. Plates are characterised by a mid-ocean ridge and/or a rift valley. They are also known as constructive plate margins. Earthquakes are a series of shockwaves / vibrations and tremors caused by sudden release of pressure along fault lines, and usually associated with plate boundaries. Hotspot is a relatively small area where magma rises through a continental or ocean plate. As the plate moves across the hotspot a chain of volcanoes may form.
CAMBRIDGE AS GEOGRAPHY REVISION: ROCKS AND WEATHERING - 3.1 PLATE TECTONICS
KEYTERMSANDDEFINITIONS Island arcs are chains of volcanic islands on the continental side of an ocean trench. They are associated with subduction zones. Lava is molten magma that has reached the Earth’s surface. It may be liquid or may have solidified. Lava flow is the movement downslope from a volcanic crater or fissure of molten rock (lava). As the lava flows it cools, most rapidly at the base and surface, and begins to solidify. Lithosphere is the outermost layer of the Earth, comprising the crust and part of the mantle. Magma is molten rock within the Earth. When it reaches the surface it is called lava.
CAMBRIDGE AS GEOGRAPHY REVISION: ROCKS AND WEATHERING - 3.1 PLATE TECTONICS
KEYTERMSANDDEFINITIONS Mercalli Scale is a scale of earthquake intensity based on descriptive data. Mid-ocean ridges are lines of mainly mountains formed where two ocean plates are separating. Oceanic crust is that part of the crust underlying the oceans. It is basaltic in composition. Oceanic trenches are arc-shaped depressions formed at subduction zones where one tectonic plate (usually an oceanic one) plunges under a less dense continental one. These are the deepest parts of the oceans. The Mariana Trench in the Pacific Ocean is over 11 000 m deep.
KEYTERMSANDDEFINITIONS Oceanic ridges are the largest feature of the ocean floor. They are essentially a linear belt of submarine mountains. They occur at divergent (spreading or constructive) plate boundaries. New magma forces it way up between two plates and forces them apart. The ridges are characterised by a wide rift valley in their centre. Richter Scale is an open-ended scale to record the magnitude of earthquakes. Sea-floor spreading is where ocean floors grow as plates move apart at constructive margins. Shield is a continental area that has not been deformed since Pre- Cambrian times. Subduction zone is the area where one plate slides beneath another, where earthquakes occur.
CAMBRIDGE AS GEOGRAPHY REVISION: ROCKS AND WEATHERING - 3.1 PLATE TECTONICS
TOPICSUMMARY The theory of plate tectonics states that the earth is made up of a number of layers. The Earth’s crust is commonly divided up into two main types: continental crust and oceanic crust. The evidence for plate tectonics is varied and includes the distribution of earthquakes; the ‘fit’ of the continents; glacial deposits; and fossil remains of a small aquatic reptile. Convection currents force molten rock (magma) to well up in the Earth’s interior, crack the crust above and force it apart. The zone of earthquakes around the world has helped to define six major plates and a number of minor plates. The boundaries between plates can be divided into two main types: converging and diverging.
CAMBRIDGE AS GEOGRAPHY REVISION: ROCKS AND WEATHERING - 3.1 PLATE TECTONICS
TOPICSUMMARY There are three main theories about movement and include convection currents, the dragging theory and the hotspot theory. Sea-floor spreading allows the continents to drift. Giant submarine mountain chains that rise 2–3 km above the surrounding ocean basins are known as ocean ridges. In contrast, ocean trenches are found at the subduction zone, where oceanic crust plunges under continental crust. Island arc systems are chains of volcanic islands formed when oceanic lithosphere is subducted beneath oceanic lithosphere. Plate tectonics is associated with mountain building. Linear are associated with convergent plate boundaries, and formed on land.
ADDITIONALWORK 1. Comment on the evidence for plate tectonics. 2. With the use of an annotated diagram, distinguish between convergent and divergent plate boundaries. 3. Explain the formation of a ocean ridges and b ocean trenches. 4. Briefly explain how a island arc and b fold mountains are formed.
SUGGESTEDWEBSITES Plate tectonics: www.platetectonics.com Animations of plate tectonics: www.ucmp.berkeley.edu/geology/tectonics.html Crystalinks plate tectonics with access to recent stories regarding plate tectonics: www.crystalinks.com/platetectonics.html http://volcano.und.nodak.edu/vwdocs/current_volcs/montserrat/m ontserrat.html for current volcanic activity. www.montserrat-newsletter.com for the Montserrat newsletter.

More Related Content

CAMBRIDGE AS GEOGRAPHY REVISION: ROCKS AND WEATHERING - 3.1 PLATE TECTONICS

  • 2. KEYTERMSANDDEFINITIONS Benioff zone is a narrow zone of deep earthquake foci at a subduction zone. Continental crust is that part of the Earth’s crust that forms the continents. Continental drift is the theory that the continents have drifted across the surface of the globe. Convergent plate boundaries are margins where plates are moving towards each other. This can be oceanic–continental, as in the case of the Nazca and South American plates, or it can be continental– continental, as in the case of the Eurasian and Indian plates. Core is the central part of the Earth below 2900 km from the surface.
  • 4. KEYTERMSANDDEFINITIONS Crust is the outermost layer of the Earth. It may be divided into continental (sial) and oceanic (sima). Divergent plate boundaries are plate boundaries in which the plates are moving apart, e.g. the North American and European plates. Plates are characterised by a mid-ocean ridge and/or a rift valley. They are also known as constructive plate margins. Earthquakes are a series of shockwaves / vibrations and tremors caused by sudden release of pressure along fault lines, and usually associated with plate boundaries. Hotspot is a relatively small area where magma rises through a continental or ocean plate. As the plate moves across the hotspot a chain of volcanoes may form.
  • 6. KEYTERMSANDDEFINITIONS Island arcs are chains of volcanic islands on the continental side of an ocean trench. They are associated with subduction zones. Lava is molten magma that has reached the Earth’s surface. It may be liquid or may have solidified. Lava flow is the movement downslope from a volcanic crater or fissure of molten rock (lava). As the lava flows it cools, most rapidly at the base and surface, and begins to solidify. Lithosphere is the outermost layer of the Earth, comprising the crust and part of the mantle. Magma is molten rock within the Earth. When it reaches the surface it is called lava.
  • 8. KEYTERMSANDDEFINITIONS Mercalli Scale is a scale of earthquake intensity based on descriptive data. Mid-ocean ridges are lines of mainly mountains formed where two ocean plates are separating. Oceanic crust is that part of the crust underlying the oceans. It is basaltic in composition. Oceanic trenches are arc-shaped depressions formed at subduction zones where one tectonic plate (usually an oceanic one) plunges under a less dense continental one. These are the deepest parts of the oceans. The Mariana Trench in the Pacific Ocean is over 11 000 m deep.
  • 9. KEYTERMSANDDEFINITIONS Oceanic ridges are the largest feature of the ocean floor. They are essentially a linear belt of submarine mountains. They occur at divergent (spreading or constructive) plate boundaries. New magma forces it way up between two plates and forces them apart. The ridges are characterised by a wide rift valley in their centre. Richter Scale is an open-ended scale to record the magnitude of earthquakes. Sea-floor spreading is where ocean floors grow as plates move apart at constructive margins. Shield is a continental area that has not been deformed since Pre- Cambrian times. Subduction zone is the area where one plate slides beneath another, where earthquakes occur.
  • 11. TOPICSUMMARY The theory of plate tectonics states that the earth is made up of a number of layers. The Earth’s crust is commonly divided up into two main types: continental crust and oceanic crust. The evidence for plate tectonics is varied and includes the distribution of earthquakes; the ‘fit’ of the continents; glacial deposits; and fossil remains of a small aquatic reptile. Convection currents force molten rock (magma) to well up in the Earth’s interior, crack the crust above and force it apart. The zone of earthquakes around the world has helped to define six major plates and a number of minor plates. The boundaries between plates can be divided into two main types: converging and diverging.
  • 13. TOPICSUMMARY There are three main theories about movement and include convection currents, the dragging theory and the hotspot theory. Sea-floor spreading allows the continents to drift. Giant submarine mountain chains that rise 2–3 km above the surrounding ocean basins are known as ocean ridges. In contrast, ocean trenches are found at the subduction zone, where oceanic crust plunges under continental crust. Island arc systems are chains of volcanic islands formed when oceanic lithosphere is subducted beneath oceanic lithosphere. Plate tectonics is associated with mountain building. Linear are associated with convergent plate boundaries, and formed on land.
  • 14. ADDITIONALWORK 1. Comment on the evidence for plate tectonics. 2. With the use of an annotated diagram, distinguish between convergent and divergent plate boundaries. 3. Explain the formation of a ocean ridges and b ocean trenches. 4. Briefly explain how a island arc and b fold mountains are formed.
  • 15. SUGGESTEDWEBSITES Plate tectonics: www.platetectonics.com Animations of plate tectonics: www.ucmp.berkeley.edu/geology/tectonics.html Crystalinks plate tectonics with access to recent stories regarding plate tectonics: www.crystalinks.com/platetectonics.html http://volcano.und.nodak.edu/vwdocs/current_volcs/montserrat/m ontserrat.html for current volcanic activity. www.montserrat-newsletter.com for the Montserrat newsletter.