1. INFERRED PROPERTIES OF EARTH’S INTERIOR Interpreting and Analyzing the Structure of the Earth

2. Earth’s Structure  To understand the structure of the Earth, Scientist delineate the layers of the Earth by defining its composition, temperature, pressure and density as it changes with depth.  This examination provides a concept diagram of Earth’s basic structure.

3. Earth’s Crust  The crust is the outermost layer of our planet and contains the continents and ocean floor.  The thickness of the crust is between 5 to 100 km.  The continents along the tallest mountains can range up to 100 km thick.  In the oceans, it is between 5 to 10 km.

4. Earth’s Upper Mantle  The upper mantle, the asthenosphere or the plastic mantle, is partially melted and able to bend and flow slowly.  The asthenosphere lies between the crust and the lower mantle. It is approximately 400 km thick.

5. Earth’s Lower Mantle  The lower mantle is rigid and more dense than the upper mantle due to the enormous pressure it is under.  The lower mantle is approximately 2500 km thick.

6. Earth’s Outer Core  The deepest layers of Earth begin with the outer core.  Geologists believe that this layer is mostly composed mostly of iron mixed with smaller amounts of nickel. They think this layer is liquid because S-waves cannot pass through the outer core.

7. Earth’s Inner Core  The deepest layer of Earth is the outer core.  Geologists believe that this layer is composed mostly of iron mixed with smaller amounts of nickel similar to the outer core. However, the inner core seems to be a solid because P- and S- waves pass through it.

8. Earth’s Core  Although, the outer and inner core are both composed of iron and nickel, the higher pressures at the Earth’s center causes the inner core to be a solid.

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