Objectives- describe the crust, mantle and core; describe how convection currents work
The earth and its inside resemble an apple. Just like an apple has a thin outer layer, thick middle part and inside, so does the earth. The outer layer of the earth is the crust. Like the apple peel, it is very thin. It ranges from 5-40km thick (3-25miles). It is thickest under mountains and thinnest under the sea floor. The crust is a rocky layer. Most of the crust under the ocean is made up of dense rocks such as basalt, which is dark in color and made up largely of iron. The crust under the land is made up of largely granite which is less dense and lighter in color. Granite is made up of oxygen and silicon.
The biggest part of the earth is the mantle. The mantle is represented by the part of the apple that is eaten. The mantle is close to 3,000km (1,800 miles) thick. As you move deeper into the mantle, the temperature increases, which affects the consistency of the mantle. The difference in temperature is used to distinguish between the crust and mantle. Towards the top of the mantle, it is rocky. But towards the bottom it has a consistency more like taffy or hot asphalt. Since the upper part of the mantle are both rocky, they are often considered as the lithosphere (lith = rock). The more liquid like lower part of the mantle is called the asthenosphere.
The core is the innermost part of the earth. It would be comparable to the part of the apple where the seeds are at. The corer is divided into 2 distinct parts. The outer part of the core is melted metal. The estimated temperature of the outer core is around 2,000°C. The outer core extends down about 2,250km (1400 miles) below the mantle. The inner core which is about 1200km (800 miles) thick, and has an estimated temperature of 5,000°C. Even the temperature is so high, the inner core is solid.
This is due to the extremely high pressure pushing in on this layer.
Some of the information about the inside of the earth comes from earthquakes. One of the earthquakes three types of waves does not travel through liquids. When an earthquake occurs, this type of wave does not travel to the opposite side of the earth from where the earthquake happens.
Something must be blocking it. Scientists theorize that there is liquid inside the earth. From using information from several earthquakes, the size of the core can be determined. Evidence like this is called indirect evidence.
Heat can be transferred in three different ways. One of these is convection. Convection happens due to temperature and density differences. As you may know, hot air rises and cold air sinks.
This creates a cycle of moving air called convection currents. The same thing happens with liquids.
Convection helps to explain many things in science including weather patterns, ocean currents and why some birds are able to soar.
Questions:
1. The last paragraph may seem kind of random, but belongs here. Convection occurs in the earth. In what layer could convection occur? What would that do to the layer on top of it?

2. How is the crust like the skin of an apple?
3. How is the mantle like the part of the apple we eat?
4. The inner core is the hottest layer of the earth, yet it is a solid. Does this seem weird? Why?
5. Why must scientist rely on indirect methods to observe Earth’s interior?
6. How do geologists use seismic (earthquake) waves to learn about Earth?
7. Is the following sentence true or false? The temperature increases as you go from the surface towards the center of the Earth.
8. The dark-colored rock that makes up most of the oceanic crust is ________________________.
9. The light-colored rock that makes up most of the continental crust is ________________________.
Matching
_____ 10. Mantle
_____11. Lithosphere a. rigid layer that includes the upper part of the mantle and the crust
b. layer of hot rock between the crust and core
_____12. Astehnosphere
13. What is convection? c. soft layer just below the lithosphere
14. Heat transfer by convection is caused by differences of _______________________ and density within a fluid.
15. Is the flowing sentence true or false? Convection currents flow in the asthenosphere