Niagara Falls is a big waterfall on the border of Canada and the United States. Each year the edge of the waterfall moves back a couple of centimeters because the water is breaking apart the rocks on the edge. What is this an example of? Why?
This is an example of erosion. Erosion is when something is “washed” away (or eroded) over time (usually by water). The rocks are breaking apart because the rushing water is slowly eroding the edge a couple of centimeters every year.