1 - The Layers of the Earth


In order to understand many (or perhaps even most) geological disasters we must first understand something about the Earth's structure. So before beginning our study of disasters, the first couple of units in this course are designed to introduce you to Planet Earth as a whole. In some ways the Earth is a volatile place where geological disasters occur regularly but in others it is stable because of its unique (as far as we know) characteristics. For instance, the size, mass and position of our planet relative to our star are extremely important; further and we would freeze (like Mars), closer and we would burn (like Venus). This is only part of the story and Earth has a lot of other important characteristics to make it hospitable to life.

Learning Objectives

When you have finished the work for this unit, you should be able to:

1. Describe the structure and composition of Earth’s internal layers.
2. Define density and how the density of Earth materials dictates the structure of the Earth.
3. Define an isotope.
4. Describe in general how scientists think the Earth's magnetic field is generated.
5. Explain the characteristics of the solar wind.
6. Understand why the mantle sometimes exhibits plastic properties and sometimes acts as a solid.
7. Explain how movements on Earth’s surface are caused by mantle convection.
8. Understand how oceanic crust and its layers are formed.
9. Understand the relative densities and major rock composition of oceanic and continental crust.
10. Say where the oldest rocks on Earth are found.
11. Know why the oceans can buffer Earth’s surface from large temperature change.
12. Understand the conditions at which water is most dense.
13. Draw the structure of the atmosphere and label each layer with its main characteristics.
14. Define the ozone layer and know its importance.
15. Explain how the greenhouse effect works

Required Readings

Abbott, P.L., 2014.  Natural Disasters, Ninth Edition:

Readings From the Old Book

Abbott, P.L., 2012.  Natural Disasters, Eighth Edition: Chapter 2: Internal Energy and Plate Tectonics. p. 26-32, p. 38

Glossary Terms

Archean Magnetosphere
Aurora Mantle
Basalt Mass Extinction
Basaltic Magma Microplate
Callisto Mineral
Chlorofluorocarbon MOHO
Convection  Olivine
Core Ozone
Crust Peridotite
Density Pillow Lava
Dike Photochemical Smog
Electron Plagioclase
Europa Proton
Gabbro P-wave
Granite Pyroxene
Great Rift Valley Silicate Minerals
Half-Life Solar Flare
Heat Capacity Solar Wind
Intraplate Earthquake Subduction
Ionosphere Supercontinent
Isotope S-wave
Kimberlite Pipe Ultraviolet (UV) Radiation
Magma Chamber X-Rays
Magnetic Field