Answers to Chapter 1 Review Questions

  1. Geology requires that we consider vast amounts of time, and think about the effects that accumulate over thousands, millions, or even billions of years.
  2. There are many ways that geologists contribute. Geologists provide information to reduce the risk of harm from hazards such as earthquakes, volcanoes, and slope failures; they play a critical role in the discovery of important resources; they contribute to our understanding of life and its evolution through paleontological studies; and they play a leading role in the investigation of climate change, past and present and its implications.
  3. Ages in years
    1. 2.75 ka = 2,750 years
    2. 0.93 Ga = 930,000,000 years
    3. 14.2 Ma = 14,200,000 years
    4. 0.2 ka = 200 years.
  4. 215 – 65 = 150 Ma. Since the age of the Earth is 4570 Ma, this represents 150/4,570 = 0.033 or 3.3% of geological time.
  5. At 1 mm/y 30,000,000 mm of sediment would accumulate over that 30 million years. This is equivalent to 30,000 m or 30 km. Few sequences of sedimentary rock are even close to that thickness because most sediments accumulate at much lower rates, more like 0.1 mm/y. Also, over time the sediments are compressed.
  6. No. Uniformitarianism means that we can use the processes we observe today to help us understand what happened in the past.
  7. Plate tectonics is the idea that Earth’s outer layer is broken into rigid plates. The plates move around and interact with each other along their margins.