2. Which of the following was not a source of heat for the early Earth? a. meteor bombardment b. gravitational contraction c. radioactivity d. hydrothermal energy
3. What are small asteroids called? a. comets b. meteoroids c. cratons d. microcontinents
4. What is the process by which a planet becomes internally zoned when heavy materials sink toward its center and lighter materials accumulate near its surface? a. photosynthesis b. dewatering c. accretion d. differentiation
5. Where is most of the North American Precambrian shield exposed at the surface? a. Canada …show more content…
What characteristics of continental crust allow it to "float" higher on the mantle than oceanic crust?
19. Why are orogens deformed?
20. What is the significance of the Ediacara fauna?
21. Discuss the evidence that suggests that most members of the Ediacara fauna were immobile.
22. Explain how the production of oxygen through photosynthesis by cyanobacteria affected the composition of the atmosphere and the development of other organisms.
23. A rock sample from Mars is reported to contain fossil evidence of life. What kind of fossil would you expect it to be? Explain your answer.
24. Where in North America would you look if you wanted to find evidence of Archean life? Explain your answer.
25. When making a map of geologic age provinces, as you did in the Mapping GeoLab in this chapter, why did you draw the lines between the data points instead of connecting them?
26. How might Earth's surface be different if water vapor had not been a product of outgassing?
1. Which of the following is NOT a likely source of the Precambrian Earth's heat? a. radioactivity b. asteroid impact c. increased solar