What is erosion? What impact does erosion have on the Earth? Objective Students will be able to describe erosion. They will also be able to list at least three causes of erosion. Background Start the lesson by asking students to tell you what erosion is. Erosion is the displacement of solids (soil, mud, rock and other particles) by the agents of wind, water, ice, or living organisms, or by down-slope movement in response to gravity. (New World Encyclopedia) Show students the short video of an Alaskan coastal area eroding at: http://dotearth.blogs.nytimes.com/2008/09/25/video-alaskas-eroding-ar Duration: 60 Minutes.