Lesson 4: Splash Zone: Erosion in Action Erosion • Erosion is the wearing away of land by natural forces. • Erosion is a natural process. • Erosion can be increased or decreased by human activity. Erosion • Natural Bridge- created by water erosion • Mammoth Cave- created by water erosion Erosion • Erosion can be increased or decreased by human activity. • Water mixed with the soil from the ground run down hills and into our water bodies, which can be harmful to the environment. Weathering • Weathering is the breaking down of rocks • Different types of weather can push and wedge spaces between rocks that cause it to break down over time. • Weathering can occur due to: – – – – – Freezing Thawing Plants Wind Pressure • Physical weathering is the breaking down of rocks due to water, wind and ice. Erosion and Ecosystems • Some erosion is needed for healthy ecosystems. • An ecosystem is a complex set of relationships among living resources, habitats or residents of a region. • Small amounts of sediment can act as soil and help grow healthier crops. • Large amounts of sediment from erosion can be very hard on our stream ecosystems because it can block sunlight for plants and suffocate animals. Protecting the Environment • To help keep plants and animals safe when hill sides start to erode, vegetation can be planted. • Vegetation includes various plants and vegetables that grow in a certain area. • Vegetation allows soil to stay in place so sediment does not enter the waterways in large quantities. • Sediment is the material, soil and debris deposited by water and the number one cause of pollution in the waterways. Scavenger Hunt Activity • Today, we will go outside to find evidence of erosion at our school. • You will have 15-20 minutes to find the given items. • *Bonus: List any potential point source and non-point sources of pollution. Runoff • Runoff is the portion of precipitation that does not get absorbed into the ground and reaches streams, often with dissolved or suspended material like dirt and sediment. The process of runoff Scavenger Hunt Activity • What evidence of erosion did you find? • Were the cracks in the sidewalks and potholes always there? • What caused them? • How do humans increase erosion? • How can we decrease erosion? • What items from our scavenger hunt help direct storm water away from buildings and roads? Splash Zone • Each group will have: – “Rain dropper” – Recorder – Observers Extended Response Questions • Examine the line graph you made carefully and think about what the trend of the graph is. What does this graph show about your experiment? • How do you think a rain storm would affect a bare patch of soil at a construction site? What about cut grass? A forest?