Agents of Change: Rill Erosion EarthCache
Agents of Change: Rill Erosion
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Erosion is the process of moving weathered rock, mineral and soil to new locations. It is a natural process but human activity can cause it to speed up. There are several types of erosion: splash, sheet, rill and gully among the types caused by water. Our focus today is rill erosion.
You will need a yard stick, meter stick or tape measure with you to do this earthcache.
Soil is a complex mixture of organic and inorganic material. The organic material comes from recycled plant and animal remains and provide the soil the dark color, air space, moisture and nutrients. This is called humus. It may be many feet thick, very thin or not present at all. You recognize humus by the dark layer above the lighter soil below.
The inorganic material comes from rocks and minerals that break down over time in a process called weathering.
For more information about how soil forms, visit. http://www.soil-net.com/dev/page.cfm?pageid=secondary_intro_formation&loginas=anon_secondary
Erosion happens when soil gets moved by wind, gravity, glaciers or water. Water can move individual particles of soil by splashing, covering the entire ground in sheets, making small parallel hills and valleys (rill) and larger gullies. For more information on other types of erosion, visit this link : http://www.forestrynepal.org/wiki/354
Rill erosion happens when water finds loose soil and carries it away. If the movement happens over and over in the same spot, small valleys next to or near each other occur. These are called rills. Rill erosion is the beginning of a much more damaging type of erosion.
Rill erosion typically starts when soil is exposed on a slope. When we do construction along a bank, soil is exposed. The steeper the slope, the more exposed soil and the more precipitation, the faster and more serious the erosion.
You are visiting a site managed by the North Carolina Department of Transportation. The local manager has given permission for vehicles to pull completely off the road to examine the site.
You are visiting a rill erosion site along the US 220, I-85 interchange. Please pull completely off the road! The shoulder is firm and you will not sink!
Go to the bank and examine the rills. Send the following information via email to MarkCase@aol.com
1. Subject line and first line of your email should be: Agents of Change: Rill Erosion GC3GBJ2
2. Remember humus? Estimate the thickness of the humus.
3. Use a tape measure, yard stick or meter stick. Lay your measuring device perpendicular to the rills. Estimate the number of rills per yard. Measure a couple spots to get an average.
4. How has the humus helped/hurt the formation of the rills? Give your best hypothesis.
5. What could be done to correct, slow down or prevent the formation of these rills?
6. Always optional, but always appreciated, a photo of your crew at the site. Try not to include spoilers in the picture. We want others to come, learn and enjoy.
Additional Hints
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