Exploring Earth's Layers: The Composition and Structure of Our Planet

1. In this presentation you will: Earth Model • explore the structural layers of Earth Next >

2. Introduction The Earth is somewhat like an onion, in that it is made from lots of different layers. The different layers are composed of different materials. This gives the Earth some of its characteristics. Next >

3. Composition of the Earth Each of the layers has different characteristics. Crust The crust is the outer layer of the Earth, made from solid rock. It is much thinner than the lower layers of the Earth. Next >

4. Composition of the Earth The crust has two main parts: Oceaniccrust Continental crust • Continental crust – this forms the continents. Its thickness varies from 20 km to 80 km. • Oceanic crust – the thin crust under the oceans. It is around 10 km thick. Next >

5. Composition of the Earth The mantle is underneath the crust. It is made of rock but, due to intense heat, it behaves like an extremely thick liquid! Mantle The mantle moves very slowly. So slowly in fact that its motion would only be noticeable over hundreds of years. Next >

6. Composition of the Earth The mantle has two parts: Upper mantle Lower mantle • Upper mantle – the more solid portion. At the top, the temperature is around 1,000 °C. • Lower mantle – the less solid portion. At the bottom, the temperature is around 3,700 °C. Next >

7. Composition of the Earth Below the mantle is the outer core. It is mostly made of iron but, because of the extremely high temperatures, the iron has melted and become liquid. Outer core A solid inner core is suspended in the outer core. Although the temperatures at the core are around 4,300 °C, the pressure is so great that the iron stays solid. Inner core Next >

8. Depths The inner core is about 2,440 km in diameter. Crust The outer core is about 2,250 km thick. Upper mantle The lower mantle is about 2,130 km thick. The upper mantle is about 670 km thick. Lower mantle The crust ranges from 10 km to 80 km thick. Outer core Inner core The thickest parts of the crust are the mountain ranges, while the thinnest are the ocean floors. Next >

9. Structure Regions The top of the upper mantle and the crust form the lithosphere – the solid outer layers of the Earth. Lithosphere Asthenosphere The upper mantle and the top section of the lower mantle make up the semi-liquid asthenosphere. Next >

10. Question 1 Which of the following mostly consists of liquid iron? A) Crust B) Mantle C) Outer core D) Inner core Next >

11. Question 1 Which of the following mostly consists of liquid iron? A) Crust B) Mantle C) Outer core D) Inner core Next >

12. Question 2 “The lithosphere is made up of the crust and part of the lower mantle”. Is this statement true or false? Next >

13. Question 2 “The lithosphere is made up of the crust and part of the lower mantle”. Is this statement true or false? False Next >

14. Modeling the Planet! We cannot dig down to the center of the Earth to find out exactly how it’s made. So, models have to be used to represent this information. Drill Models can be made in a variety of ways: Mantle Crust 12 km (max) • drawing • mathematically Outer core Inner core • physical • computer generated Next >

15. Predictions Models can be used to predict future events. This is accomplished by using information from previous events and by applying mathematical probability of events happening again. This is what is happening when you watch a weather forecast! A weather model has been used to predict what will happen in the coming hours, days or weeks. Next >

16. Predictions A detailed model of the Earth can be built using scientifically recorded data. This model can then be used to predict, for example, how the Earth’s magnetic field will change over the coming years. USGS Kristian Birkeland's electrical terella (Field-aligned currents) Next >

17. Predictions By looking at models of the Earth’s crust, scientists are working towards being able to predict when and where geological events may occur. Examples of geological events are earthquakes and the eruption of volcanoes. USGS Next >

18. Visualization Sometimes it is difficult to understand the scale of a concept. Building a 3D model or drawing a model can make it easier to understand. 0.5 mm thick For example, a 3D model of Earth’s structure the same size as a soccer ball would require the crust layer to be less than 0.5 mm thick! Next >

19. Question 3 Why might scientists want to model the structure of the Earth? A) To predict future events that relate to movement in the Earth’s crust B) To make it easier to explain what is going on under the surface C) To better understand why geological events occur D) All of the above Next >

20. Question 3 Why might scientists want to model the structure of the Earth? A) To predict future events that relate to movement in the Earth’s crust B) To make it easier to explain what is going on under the surface C) To better understand why geological events occur D) All of the above Next >

21. Summary In this presentation you have seen: • the structure of the Earth including, inner and outer core, mantle and crust • the layers making the asthenosphere • the layers making the lithosphere • advantages and disadvantages of modeling the natural world End