plate tectonics 1

• Structure of the Earth:

  • Mantle is the largest layer of the Earth with temperatures reaching 3800 degrees C and extends to a depth of 2900km
  • Outer core has characteristics similar to the Inner Core and is located approximately 2880km to 5180km from the Earth’s surface
  • Inner core is the hottest layer with temperatures ranging from 4300 to 5500 degrees C and is located 5180km to 6400 km from the surface of the Earth
  • Crust is the solid and thinnest layer of the Earth, broken into 2 types, extending about 5km below the ocean and 20-65km below continents
• Upper Mantle extends from the Crust to a depth of about 410km and consists of the Lithosphere and the Asthenosphere

  • Asthenosphere is made up of partially melted rock
  • Lower Mantle is a dense, semi-solid layer made up of iron, magnesium, and silicon
  • Outer Core is mostly made of iron and nickel in liquid form, generating the Earth’s magnetic field
  • Inner Core is an extremely dense and solid layer made mostly of iron and nickel
  • Crust is the solid, coolest, and most rigid outer layer of the Earth called the Lithosphere, consisting of Oceanic and Continental types
• Plate Tectonic Theory:

  • The Earth’s Crust is broken up into several plates that move or glide over the mantle
  • There are two types of plates: Continental Plates and Oceanic Plates
  • Continental Plates are up to 70km thick and common minerals are silica (Si) and aluminium (Al)
  • Oceanic Plates are between 6 and 10km thick and common minerals are silica (Si) and magnesium (Mg)
• Plate Tectonic Theory:

  • Studies show that all Continents were once joined as one giant land mass
  • Scientist Alfred Wegener in 1912 proposed the theory of Continental Drift where land masses slowly drifted apart from one Super-Continent into their present locations
• Evidence of Continental Drift:

  • The Fit: Continents fit alongside each other like a ‘jigsaw’
  • Plants: Similar plants found on different continents (India and Antarctica)
  • Fossils: Similar animal fossils found in now separated continents (South Africa and Brazil)
  • Rocks: Rocks of similar type and age found at edges of previously joined continents
• Why Plates Move:

  • Core is hot
  • Mantle is mobile
  • Crust lies above the Mantle
  • Intense heat from the core causes magma to move upwards to the crust and then sink back down, known as convection currents, causing the plates on the Earth’s crust to move
• Types of Plate Movements:

  • Divergent
  • Convergent
  • Transform
• Plate Movement:

  • Plates move due to convection currents caused by the intense heat from the core, moving magma up to the crust and back down
• Between 2 Oceanic Plates, new crust is formed at Constructive Zones
• Between 2 Continental Plates where land moves apart, Rift Valleys are formed
• Divergent Plate Boundaries are described as Sea-Floor Spreading when it happens underwater
• When 2 Continental Plates collide, Fold Mountains are formed
• When an Oceanic and a Continental Plate collide, the heavier plate subducts (is pushed below)
• Convergent Plate Boundaries are known as Destructive Zones where plates are either restructured or destroyed
• As the plate is pushed into the Mantle, it begins to melt due to the increase in temperature, creating New Magma
• The New Magma is lighter than the Mantle and rises along a line of weakness in the Crust, forming Volcanoes and Volcanic Arcs
• When 2 Oceanic Plates collide, Subduction Zones are formed
• The heavier plate between the two subducts, creating Volcanic Islands and a Deep Sea Trench
• At Conservative Plate Boundaries, plates slide past each other causing major earthquakes
• Transform Plate Boundaries experience earthquakes when pressure build-up is suddenly released
• Volcanoes occur at both Convergent and Divergent plate boundaries
• Earthquakes occur at both Convergent and Transform plate boundaries
• Earthquakes and volcanoes are most violent at convergent boundaries
• No volcanic activity occurs at Collision Zones, only earthquakes
• Landform features at plate margins include Volcanoes, Earthquakes, and different types of plate boundaries
• The Caribbean Plate moves towards Montserrat, Soufriere, Martinique, Mt. Pelee, St. Vincent, Soufriere, and Grenada, Kick 'em Jenny