Chapter 13. Weathering and Soils.
1. using the analogy of digestion of food, distinguish between mechanical and chemical weathering and give an example of each.
2. describe the typical methods of mechanical weathering such as frost wedging, salt crystallization, sheeting, exfoliation, spheroidal weathering, and the weathering effects of living things.
3. briefly give an explanation of the three major reactions of chemical weathering: direct solution, hydrolysis, and oxidation. Give an example of each.
4. show how chemical weathering is nearly inverse to the sequence of crystallization in Bowen's reaction series.
5. in general terms, describe the role of climate and microclimate in weathering.
6. describe the process of soil formation beginning with regolith and ending with a rich soil. Be sure to include percolation, leaching, and chemical precipitation. Estimate how long this might take in NEPA's climate.
7. draw a side view of a soil profile to indicate the various horizons: O, A, B, C.
8. describe the climate type which results in the following soil types: laterite, caliche, and podosols
9. describe the sources of parent material which are fluvial, aeolean, or palustrine.
Critical Thinking Questions and Activities:1. Investigate the soils map for this area. How can there be so many soil types in such a relatively small area as Keystone's campus?
2. Describe how the processes of leaching and nutrient cycling keep a soil in balance.
3. Consider the weathering of pyrite, a common contaminant of coal deposits in this area. the process produces sulfuric acid and leads to acid-mine drainage. How does this parallel the effects of acid rain described in this chapter?
Resources:1. Hodder, A. 1990. Practical Weathering for Geology Students. Journal of Geological Education
2. Tiner, R. and P. Veneman. 1989. Hydric Soils of New England. University of Massachusetts Cooperative Extension. Revised Bulletin C-183R, Amherst, MA. 27pp.
Field Trip Opportunities:1. Dig pits to expose soils profiles in a variety of areas on campus. Use a Munsell color chart to characterize the horizons. Check the pH of the soil in each layer.
2. Visit a wetland and dig pits along a transect from wet to xeric areas. This is perhaps the most important, relatively easy way in which to delineate the boundary of a wetlands.