Lesson 4:
Splash Zone:
Erosion in Action
• Erosion is the wearing away of land by natural forces.
• Erosion is a natural process.
• Erosion can be increased or decreased by human activity.
• Natural Bridge- created by
water erosion
• Mammoth Cave- created by
water 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
• 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:
• 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
• 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
• 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 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
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?

Lesson 4 - Splash Zone, Erosion in Action