In this topic, you will learn about what makes up rocks. Rocks are not all alike. There are about 600 kinds of rocks. Although rocks look and feel different from each other, all rocks are made of the same type of material. All rocks are made of minerals. A mineral is a substance found in nature that is not a plant or an animal. Minerals are the building blocks of rocks.

All of Earth's rocks are formed in one of three ways. Some rocks, like granite, are formed when melted rock below the surface of Earth cools and hardens. Other rocks, like basalt and obsidian, are formed when melted rock flows out onto Earth's surface, where it cools and hardens. Other rocks are formed when bits of soil, mud, and rock in the bottoms of rivers, lakes, and oceans pile up over time. As the layers build up they get cemented together, forming solid rock. Sometimes rocks get squeezed and heated below Earth's surface. When this happens new rocks are formed.

Earth is an enormous ball with an outer "crust" of rock. The surface of Earth has many different shapes, such as mountains. The different shapes on Earth's surface are landforms. A landform is a feature on the surface of Earth. The land along the edge of a body of water is a beach. Beaches are flat, narrow stretches of land. A beach is made up of sand, gravel, or pebbles. Another landform is a plain. A plain is a large area of land with few or no hills. Plains have thick layers of soil. A third landform is a valley. A valley is an area of land lying between hills or mountains. Rivers or streams often flow through valleys. A plateau is also a landform. A plateau is a flat area of land that rises above the land that surrounds it.