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 the fundamental research about Earth that informs practical applications.
1.4 Geologists Use the Scientific Method to Study the Earth
Serious scientific inquiry requires a careful process of making a hypothesis and then testing it. If a hypothesis doesn’t past the test, it’s time for a new one. A theory is a hypothesis that has been tested repeatedly and never failed a test. A law is a description of a natural process.
1.5 Three Big Ideas: Geological Time, Uniformitarianism, and Plate Tectonics
Geologic 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.
Uniformitarianism: Processes that occur today also occurred in the geologic past. We can use our observations of the present to understand the processes that shaped the Earth throughout it’s history.
Plate tectonics: Earth’s surface is broken into plates that move and interact with each other. The interactions between these plates are key for understanding the mechanisms behind geologic processes.
Questions for Review
Note: Answers to Review Questions at the end of each chapter are provided in Appendix 2.
- How is geology different from the other sciences, such as chemistry and physics?
- How would some familiarity with biology be helpful to a geologist?
- List three ways in which geologists can contribute to society.
- Express the following in years (e.g., 2.3 Ma = 2,300,000 years): 2.75 ka, 0.93 Ga, 14.2 Ma, 0.2 ka.
- 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.
- 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?