The Structure of the Earth Flashcards
How old is the Earth?
Over 4.5 billion years old.
Name the 4 layers of the Earth?
Crust.
Mantle.
Outer core.
Inner core.
How big is the crust?
0-70km thick.
Coolest and least dense rock.
What is the crust made out of?
Rocks rich in sodium, silicon, aluminium and potassium.
What is the crust divided up into?
Continental crust.
Oceanic crust.
What is continental crust?
Old - mostly over 1500 million years old.
Permanent and less dense.
10-70km thick.
What is continental crust made up of?
SIAL.
Granite, silicon, aluminium and salt.
What is oceanic crust?
Young - less than 20 million years old.
Created and destroyed.
6-10km thick.
Denser then continental.
What is oceanic crust made up of?
SIMA.
Balsalt, silicon, magnesium and oxygen.
How big is the mantle?
2900km thick.
What does the mantle consist of?
Apart from the rigid upper mantle, most of the asthenosphere is semi-molten containing lighter elements of silicon and oxygen.
Temperature near the core?
5000 degrees which generate convection currents in mantle.
Where is the hottest part of the Earth?
Inner and outer core.
Over 5000 degrees.
What is the inner and outer core like?
Outer - liquid.
Inner - solid made up of iron and nickel ore.
What is the mohorovicic boundary?
Boundary between crust and mantle.
Lithosphere and Asthenosphere
Where do the rigid plates float on top of?
A soft ductile material known as the asthenosphere.
How is the heat in the core produced, name 2 processes?
Primordial heat left over from Earth’s formation.
Radiogenic heat produced by radioactive decay of isotopes - uranium-238, thorium-232 and potassium-40.
What is the core made up of ?
Dense rocks containing iron and nickel alloys
Temp of outer core
5,000 degrees
Where does the heat in the core come from ?
Primordial heat left over from earths formation
Radiogenic heat produced by the radioactive decay of isotopes
Size of oceanic Crust
6-10km
Size of continental crust
30-40km
What should the crust and upper mantle be divided into ?
Lithosphere and asthenosphere
What does the lithosphere consist of ?
Crust she rigid upper section of mantle
80km thick
This section is divided
into 7 large plates - oceanic / continental
What is the asthenosphere
Layer beneath lithosphere
semi molten
