Throughout history, natural stone has been used to create monuments, build cathedrals, sculpt masterpieces, and build bridges. If you look around your own community today, you may find stone used in many different ways as a building material. Stone can be a very strong material, and may seem to be nearly indestructible, but as you have seen, it can be subject to weathering over time.

The examples in the course text of the Parthenon in Greece, Kilwa Kisiwani off the coast of Tanzania, Mesa Verde in Colorado, and Machu Picchu in Peru demonstrate that stone structures—like natural formations—are inevitably worn down by biological, chemical, and physical weathering. Factors such as rainfall, temperature, rock type, elevation, and vegetation all play a part in the rate of weathering. In this week’s Discussion, you will consider the characteristics of the Parthenon, Kilwa Kisiwani, Mesa Verde, and Machu Picchu, and whether or not some sites are more prone to mass wasting and weathering than others.

To prepare for this Discussion:

• Analyze the following four World Heritage Sites listed in figure 9.1 in Chapter 9 of the course text for physical, chemical, and biological weathering. Use Table 9.1 on page 240 to assist you with your analysis.
  • Parthenon, Greece
  • Kilwa Kisiwani, Tanzania
  • Mesa Verde, U.S.A.
  • Machu Picchu, Per
• Determine which site is at the greatest risk of weathering. Rank the locations 1 through 4 on their potential for weathering (with 1 being the highest risk).
• Determine which one site is at greatest risk from mass wasting.

By Day 3

Post a paragraph with your ranking of the four locations, from the highest risk (1) to the lowest risk (4) from weathering, and explain why you have ranked them this way. Address the type of rock relevant to each location and the type(s) of weathering that impact this site. Then, in a second paragraph, explain the term mass wasting. State which site is most at risk for mass wasting and explain your rationale. If you believe none of the four sites are at risk, explain why.