Earth Layers
&
Plate Tectonics
Parts of the Earth
1.
____Crust________
• Outer most layer. Oceanic and
Continental
• Thinnest layer
• Thickness varies
2.
___Mantle______
• Thickest layer
• 3 different layers
• Convection currents move continental plates
3.
___Outer Core________
• Liquid metal
• Iron and Nickel

• Temperature exceeds boiling point of metals. Pressure keeps them in a liquid state of matter
4.
___Inner Core_______
• Solid sphere of nickel and iron
• Temperature exceeds 5000 º C
• Pressure keeps inner core solid
Continental Drift
• ___Alfred Wegener______
• suggests continents may have been together at one time
• Pangea – name for the supercontinent
• Froze to death in Greenland before theory was accepted
Evidence for Continental Drift
• Continental boundaries seem to fit together

• Fossil record is similar along continental boundaries
• Mineral and natural resources are similar along continental boundaries
• Bands of oceanic rock – alternating magnetic polarity
• Magma seeps up into the oceans where continents drift apart
•Results in beds of iron minerals fixed like stripes, which have magnetic poles based on the position of the north pole at the time the band was formed.
Plate Tectonics
• The theory that describes moving continental and oceanic plates.
• Plates can move 1-16 cm per year.
• Lithosphere lower portion of the crust and upper portion of the mantle

• Asthenosphere – liquid layer of the mantle on witch the plates float.
Plate Boundaries – where pieces of the continental plates are in contact with one another
Divergent –
•Plates move away, magma pours up, new rock on crust
• Mid – oceanic ridges form – mountains on the ocean floor.
Convergent – Plates bump into each other
• Between Oceanic and Continental Plates
• more dense oceanic crust sinks
• creates a subduction zone
• Mountains and volcanoes are formed here.

• Between 2 Continental Plates
• No difference in density
• Plates collide and crumple into one another.
• Mountains like the Himalayas are formed
Transform Fault boundaries
• Continental plates slip by each other
• Fault - crack in the lithosphere caused by plates sliding past each other.
• Earthquakes are caused by plate movements at faults.