We learned that the presence and location of certain fossil types indicate the order in which rock layers were formed. Then we learned about Earth materials and systems such as water, ice, wind, living organisms, and gravity that breaks rocks, soils, and sediments into smaller particles and moves them around. We learned that the Earth is constantly changing being reshaped by constructive and destructive processes. Constructive processes such as the cooling of lava build up features on Earth’s surface but destructive processes such as strong hurricanes tear down features on Earth’s surface. The process by which glaciers, wind, or water carry sediments to new locations is called erosion. Then we learned that the rate of erosion depends on the type of rock, for example, sandstone rocks break into large pieces but shale rocks break into small pieces. We learned that landforms created by erosion such as the Painted Desert of Arizona contain several layers of different materials. Then we looked at some national parks with unusual landforms and learned how the formations occurred.