Physical first year

• What are the characteristics of the inner and outer core?


  Inner core - Solid ball of iron/nickel

  Very hot due to pressure and radioactive decay (contains elements such as uranium that give off heat when they decompose)

  This heat is responsible for earth's internal eneray, and spreads throughout

  
  

  Outer core - semi-molten, iron/nickel
• What are the characteristics of the mantle, asthenosphere and lithosphere?


  Mantle - mainly solid rock, and the rocks are high in silicon. However the very top layer is semi molten Manama, known as the asthenosphere.

  
  

  Asthenosphere- semi molten layer constantly moves due to flows of heat called convection currents. Movements are powered by heat from core.

  Lithosphere - broken up into plates. The majority of the lithosphere is within the mantle. The top of the lithosphere is the crust which is the land and sea we live on.
• What are the characteristics of the crust?


  The crust crust is the thin top of the lithosphere. Oceanic crust is dense and it's destroyed by plate movement, continental crust is less dense and is not destroyed.
• Why do tectonic plates move?

  Plates move due to the convection currents in the asthenosphere, which push and pull the plates in different directions. Convection currents are causes when the less dense magma rises, cools, then sinks. The edges of where plates meet are called plate boundaries (or plate margins).
• What are different movements at plate boundaries?

  Move towards each other (destructive/convergent)

  
  

  Away from each other (constructive/divergent)

  
  

  Parallel to each other (conservative)
• What happens at destructive/convergent plate boundaries with different types of plates?


  Continental and oceanic - denser oceanic plate subduction below the continental. The plate is subduction leaves a deep ocean trench. Fold mountains occur when sediment pushes upwards during subduction. The magma created when the ocean crust subduction into the asthenosphere creates pressure. High pressure volcanoes can form in the weak areas of the plate these are know as composite volcanoes.

  
  

  Oceanic and oceanic - heavier plate sub-ducts leaving an ocean trench and also fold mountains. Built up pressure can cause underwater volcanoes. Lava then cools and forms island arcs.

  
  

  Continental and continental - as both plates are not as dense as oceanic pressure builds up. There is no subduction of continental crust. A pile up of continental crust is formed due to pressures between the plates. These are called fold mountains.
• What happens at constructive/divergent plate boundaries with different types of plates?


  Oceanic and oceanic - magma rise between the two gaps left by the separating plates, forming new land as it cools. Less explosive underwater volcanoes are formed as magma rises. The new land forming on the sea floor is knows as sea floor spreading.

  
  

  Continental to continental - Any land in the middle of the separation is forced apart creating a Rift Valley. Volcanoes form where the magma rises. Eventually the gap will most likely fill with water and separate from the main island.See an expert-written answer!We have an expert-written solution to this problem!
• What happens at conservative plate boundaries?

  The parallel plates may move in different directions or at different speed. No plates are destroyed so no landforms are made. The movement can create build up of pressure which on continental crusts are called fault lines.
• What are hotspots?


  Areas of volcanic activity that are not related to plate boundaries. Hot magma plumes from the mantle rise and burn through weaker parts of the crust. This can crate volcanoes and islands. The plume strays in the same place but as plates continue to move it sometimes causes chains of islands to form such as Hawaii.