Draw a rough topographic profile of the United States from San Francisco to Washington, D.C., and label the major tectonic provinces.
Why is the topography of the North American Cordillera higher than that of the Appalachian Mountains? How long ago were the Appalachians at their highest elevation?
Describe the tectonic province in which you live.
Are the interiors of continents usually younger or older than their margins? Explain your answer using the concept of the Wilson cycle.
Four processes of continental accretion are described in Figure 10.12. Illustrate two of them with examples of accreted terrains in North America.
Two continents collide, thickening the crust from 35 km to 70 km and forming a high plateau. After hundreds of millions of years, the plateau is eroded down to sea level. (a) What kinds of rocks might be exposed at the surface by this erosion? (b) Estimate the crustal thickness after the erosion has occurred. (c) Where in North America has this sequence of events been recorded in surface geology?
How many times have the continents been joined in a supercontinent since the end of the Archean eon? Use this number to estimate the typical duration of a Wilson cycle and the speed at which plate tectonic processes move continents.
How was orogeny in the Archean eon different from orogeny during the Proterozoic and Phanerozoic eons? What factors might explain these differences?
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