1. Inside the Earth By Properties
ONACD –Editable Curriculum designed for teachers by teachers

2. The apple analogy organized the earth in terms of layer composition
The apple analogy organized the earth in terms of layer composition. We can understand the interior even better if base the layers on physical properties. We already did this when separated the core into two regions (one liquid, one solid).   
In 1909, Andrija Mohorovicic observed that P-waves generated at a certain depth (5km below ocean crust and around 40km below average continental crust) traveled much faster than expected. This region is now called the Mohorovicic discontinuity, Moho for short, and is the boundary between earth’s rigid / brittle outer layer and a semi-fluid like layer at the top of the mantle.

3. Lithospheric Plates
The Crust and the uppermost portion of the mantle are very similar in physical properties and thus can be considered as one layer. The lithosphere is rigid but brittle and broken into several large sections called plates.
Asthenosphere
This portion of the outer mantle contains a thin ductile layer of partially melted rock. As a result this layer can “flow” at about the same rate that your fingernails grow. This enables the lithospheric plates to move (much like the thin layer of melted ice beneath an ice skate can enable a skater to move).

4. Use the large diagram bellow to answer the questions
Use the large diagram bellow to answer the questions. The arrows along the plate boundaries indicate the direction they are moving.

5. Questions
1. Can you find an example of two plates going in opposite directions?
Answer – Along the middle of the Atlantic ocean (look at Iceland)
2. Can you find an example of two plates colliding in the ocean?
Answer – Along the west side of the Pacific plate (look at the “Filipino” –Philippine- plate)
3. Can you find an example of two plates colliding on continents?
Answer – Indian plate with the Eurasian plate (this forms the highest mountains)

6. Composition of the Earth
The earth is made of three main layers when based on composition:
Crust Ocean = Basalt Continental = Granite
Mantle (Radioactive Uranium; Oxides of Iron, Silicon, and Magnesium)
Core (Iron and Nickel)
The earth is made of five main layers when based on physical properties:
Lithosphere (crust and very upper portion of mantle together)
Asthenosphere (semi melted upper portion of mantle)
Mantle (becomes more solid with depth and pressure)
Outer core (liquid), Inner core (solid)