8 Chapter 1 Summary

Steven Earle

The topics covered in this chapter can be summarized as follows:

1.1 What Is Geology? Geology is the study of Earth. It is an integrated science that involves the application of many of the other sciences, but geologists also have to consider geological time because most of the geological features that we see today formed thousands, millions, or even billions of years ago.
1.2 Why Study Earth? Geologists study Earth out of curiosity and for other, more practical reasons, including understanding the evolution of life on Earth; searching for resources; understanding risks from geological events such as earthquakes, volcanoes, and slope failures; and documenting past environmental and climate changes so that we can understand how human activities are affecting Earth.
1.3 What Do Geologists Do? Geologists work in the resource industries and in efforts to protect our resources and the environment in general. They are involved in ensuring that risks from geological events (e.g., earthquakes) are minimized and that the public understands what the risks are. Geologists are also engaged in fundamental research about Earth and in teaching.
1.4 Minerals and Rocks Minerals are naturally occurring, specific combinations of elements that have particular three-dimensional structures. Rocks are made up of mixtures of minerals and can form though igneous, sedimentary, or metamorphic processes.
1.5 Fundamentals of Plate Tectonics Convection currents move through Earth’s mantle because the mantle is being heated from below by the hot core. Those convection currents cause the movement of tectonic plates (which are composed of the crust and the uppermost rigid mantle). Plates are formed at divergent boundaries and consumed (subducted) at convergent boundaries. Many important geological processes take place at plate boundaries.
1.6 Geological Time Earth is approximately 4,570,000,000 years old; that is, 4.57 billion years or 4.57 Ga or 4,570 Ma. It’s such a huge amount of time that even extremely slow geological processes can have an enormous impact.

Questions for Review


  1. In what way is geology different from the other sciences, such as chemistry and physics?
  2. How would some familiarity with biology be helpful to a geologist?
  3. List three ways in which geologists can contribute to society.
  4. Describe the lattice structure and elemental composition of the mineral halite.
  5. In what way is a mineral different from a rock?
  6. What is the main component of Earth’s core?
  7. What process leads to convection in the mantle?
  8. How does mantle convection contribute to plate tectonics?
  9. What are some of the processes that take place at a divergent plate boundary?
  10. Dinosaurs first appear in the geological record in rocks from about 215 Ma and then became extinct 65 Ma. For what proportion (%) of geological time did dinosaurs exist?
  11. If a typical rate for the accumulation of sediments is 1 mm/year, what thickness (metres) of sedimentary rock could accumulate over a period of 30 million years?

  1. Answers to Review Questions at the end of each chapter are provided in Appendix 2.


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