Answers to Chapter 1 Review Questions
- Geology requires that we consider vast amounts of time, and think about the effects that accumulate over thousands, millions, or even billions of years.
- 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.
- Ages in years
- 2.75 ka = 2,750 years
- 0.93 Ga = 930,000,000 years
- 14.2 Ma = 14,200,000 years
- 0.2 ka = 200 years.
- 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.
- 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.
- No. Uniformitarianism means that we can use the processes we observe today to help us understand what happened in the past.
- 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.
