The Earth’s Structure

1.  two ways scientists study the inside of the Earth are drilling and seismographic information
2. seismographic information comes from studying earthquakes.
3.  four layers of the Earth are the crust, mantle, outer core, and inner core
4.  depth of Earth from crust to inner core is 6,370 km or about 4,000 miles.
5. world’s deepest drill site is 12 kilometers or about 7 miles
6. models are made by scientists about the structure of the Earth
7. lithosphere is what scientists call the crust and the very top part of the mantle, the crunchy part.
8.  crust-the thin outer layer of the Earth, is composed of two layers. The top layer is granite and the bottom layer is basalt and is denser than the granite. 
9. ocean crust is thinner and is made of ONLY basalt, is about 5-7 km thick.
10. continental crust averages about 35 km thick.  Is thickest under mountains

11. temperature at top is 20C and about 870 C at the bottom.
12.  Mohorovicic Discontinuity is called the Moho.
13.  Moho is the boundary between the crust and the mantle.
14.  Adrija Mohorovicic was a Yugoslavian scientist who used seismic data to discover this area between the crust and the mantle.

15.  mantle is the second layer of the Earth.  Is about 2900 km thick.  Temperature is 870 C at the top and about 2200 C at the bottom.  The mantle is composed of same materials as the crust only has more iron.  The deeper you go the more iron content.  The deeper you go, the denser the mantle becomes.

16. the mantle also contains molten rock, called magma, which sometimes makes it to the surface as lava in volcanoes.  Earth’s heat and pressure causes the magma to flow.

17.. Earth’s core-is two parts, outer core and the inner core.  Both cores are made of iron and nickel.  Outer core is liquid and the inner core is solid.  18. Outer core is about 2250 km thick and temperature goes from 2200 C to 5000 C.  Is liquid!!!
19. liquid outer core causes the Earth’s magnetic field.
20.  Inner core is about 1300 km thick, temperature is 5000 C.  Incredible pressure inside the Earth causes the inner core to be solid.  Pressure is 2 million times greater than here on the surface.
21. density of the Earth increases as we go deeper and deeper and temperature gets hotter.  The amount of iron also increases as we get deeper.

IMPORTANT FACT!  As we go deeper and deep into the Earth, both pressure and temperature increase!