Page 42 - Geotechnical Engineering Soil and Foundation Principles and Practice

Igneous Rocks, Ultimate Sources for Soils
Igneous Rocks, Ultimate Sources for Soils 37

2.4. Contact the USGS web site for a map showing recent earthquake and
volcanic activity around the world, and see if it relates to plate tectonics.
2.5. The rate of plate movement varies between about 1 and 10 cm/yr. What are
the corresponding upper and lower limits for how far two plates may have
separated in 4.5 billion years? How does this compare with the circumference
of the Earth at the equator, where the diameter is 12,757 km?
2.6. Name two major occurrences of granite-like rocks. How are the occurrences
related?
2.7. Rounding of granite boulders sometimes is attributed to rolling by running
water. Is there any other explanation? Which explanation is more likely to
dominate?
2.8. Most sands are believed to derive from disintegration of granite that is about
one-fourth quartz and three-fourths feldspar. Explain why these percentages
typically become reversed in river and beach sands. Which do you expect is
the harder mineral, quartz or feldspar?
2.9. A slow-moving lava flow threatens a village. What steps might be taken to
try and stop it? (Human sacrifice is not an acceptable answer.)
2.10. Name three widely divergent ways that a volcanic eruption can take human
life. Which takes the most?

References and Further Reading

Attewell, P. B., and Farmer, I. W. (1976). Principles of Engineering Geology. Chapman &
Hall, London.
Fristrup, Borge (1966). The Greenland Ice Cap. Rhodos, Copenhagen, and University of
Washington Press.
Kehew, Alan B. (1995). Geology for Engineers and Environmental Scientists, 2nd ed.
Prentice-Hall, Englewood Cliffs, N.J.
Kious, W. J., and Trilling, R. I. (1996). This Dynamic Earth. U.S. Government Printing
Office, Washington, D.C. Online version at: pubs.usgs.gov/gip/dynamic/dynamic.html
Winchester, Simon (2003). Krakatoa. HarperCollins, New York.

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