Earth’s Changing Surface Vocabulary

rocks – Earth’s surface is made of many different kinds of rocks. Scientists classify rocks based upon their properties and how they form.

forces – Natural forces change rocks. Wind, water, ice, and gravity are natural forces that can change rocks.

weathering – Natural forces can cause rocks to break down. Weathering is a process that breaks down and changes rocks.

erosion – Natural forces can move small pieces of rock from one place to another. This movement is called erosion.

gravity – The force of gravity can cause erosion. The pull of Earth’s gravity causes rocks to slide down a canyon wall and windblown sand to fall back to the ground.