Varves: Dating Sedimentary Strata (PDF file format—requires Adobe Acrobat Reader)
Erosion and sedimentation are opposing geologic forces that have shaped the surface of the Earth since its origin some 4.5 billion years ago. Evidence for the Earth's antiquity is abundant and is vital for laying a foundation for the evolution of life since its origin. Varved sediments from the Green River Formation allow students to determine sedimentation rates and estimate a minimum age of the Earth in the millions of years.
Questions for discussion or short essays:
Students will find these exercises akin to a pre-test, largely evaluating one's understanding either based on prior knowledge or on the brief presentation in the Prologue. They are therefore meant to provoke critical thinking. Much more information regarding each of these questions will be developed in greater detail in the principal epochs of this Web site.
1. Name the four major pieces of evidence supporting the theory of plate tectonics, and explain them briefly. In what scientific disciplines were these discoveries made?
2. What is the origin of the continents, and what was Earth like prior to 200 million years ago?
3. Briefly explain the process likely responsible for continental drift.
4. Assuming a tectonic plate velocity of 2 centimeters/year, how long will it take Australia to collide with the Eurasian landmass?
5. What is the most likely source of Earth's magnetic field?
6. Briefly explain the origin of Earth's modern atmosphere, as well as the reason and evidence for the idea that it is not Earth's original atmosphere.
7. State the main idea behind the "big-burp" theory of oceanic formation. What are the alternatives to the development of the oceans?
8. Why are earthquakes more prevalent in Turkey than in Brazil, and in California than in Vermont?
9. Describe the role probably played by volcanoes in the early history of the Earth.
10. Explain the role played by dust in the modern, condensation model of our Solar System's origin.
11. Choose two general observational properties of our Solar System and explain how the condensation theory can account for them.
12. Summarize the status of the search for planets surrounding stars other than the Sun.
True or False:
1. True or False: One piece of evidence supporting the tectonic plate theory is the presence of fossilized fish on top of Mount Everest. _____ Explain your answer.
2. True or False: Paleomagnetism is the study of fossilized magnetism. _____ Explain.
3. True or False: Earth's atmosphere is remarkably similar to the cosmic abundances of elements. _____ Explain your answer.
4. True or False: On average, the Jovian Planets are pretty much the same as the Terrestrial Planets. _____ Explain your answer.