Earth Science
Wear and Tear
Have you noticed how things wear out? We have to keep our homes in repair, replace worn out shoes, buy new or at least newer cars every so often (depending on our budgets), and take care of dozens of things because of wear. The same process of wear and tear happens to the earth. Actually, there are three actions that wear on Earth's landscape:
· Weathering - breakdown of rock at or near Earth's surface
· Erosion - movement of Earth materials by water, wind, or ice
· Mass Wasting - transfer of rocks downslope because of gravity
Weathering happens in two ways: 1) mechanical, such as frost wedging breaking up rocks, and 2) chemical, as from acid rain. Before we get the idea that weathering is a totally bad thing, we need to remember that it is the breakdown of rocks that give us soil. And without soil, there just would not be any life on planet earth!
Unfortunately, the soil created by weathering is subject to erosion. Your book mentions that the 24 billion metric tons of soil are washed out to sea each year. No wonder there are enormous efforts toward soil conservation!
Landslides are the result of rapid mass wasting. Again, our textbook sheds some interesting light on the effects of mass wasting. Each year in the United States alone, landslides are responsible for 25-50 deaths and more than $1.5 billion in losses. Taken a step further on a worldwide scale, landslides cause an average of 600 deaths each year!
Upon successful completion of this discussion, you will be able to:
· Differentiate the main processes of mechanical and chemical weathering.
· Describe why soil health is important and how it can be maintained.
Resources
· Textbook: Physical Geology, Chapter 5
· Website: United States Department of Agriculture (USDA) Natural Resource Conservation Service. Soils.
· Website: Soil Health – Home
· Website: Soil Health Management
Background Information
Dirt or soil? How many times do we remind children not to track dirt in the house, to wash the dirt off their hands, or in some cases, not to eat dirt? No wonder kids grow up thinking that dirt is, well, a dirty word!
The process of weathering results in soil formation, a process that is critical to life on Earth. You read about soil formation in chapter 5 of your Physical Geology textbook. In this discussion, you will use additional web-based resources to learn more about soil health and the role you can play in preserving healthy soil.
Instructions
1. Review the rubric to make sure you understand the criteria for earning your grade.
2. Read Chapter 5 in your Physical Geology text and the following USDA Natural Resource Conservation Service webpages:
a. United States Department of Agriculture (USDA) Natural Resource Conservation Service. Soils.
3. In your discussion post, please include answers to the following prompts.
a. Using your text as a resource, describe at least one way that soil is formed.
b. Using the USDA websites as a resource, describe at least one reason why it is important to maintain soil health.
c. Using the USDA websites as a resource, describe at least one way that soil health can be managed.
d. Thinking about your interactions with soil, whether in your yard, in your garden, or perhaps in a local park, what is one thing that you can do to help preserve soil health?
4. Your answers should be written in complete sentences.
5. Your original thread is due by the fourth day of the workshop.
6. Read and respond to the original thread of at least one of your classmates by the end of the workshop. An example would be to identify something you learned by reading your classmate’s post and why you found it interesting. Another possibility is that you could post a comment on classmate’s thread that describes an interaction with soil that you would like to learn more about.