Tema 2.3 Sciences

How do we classify rocks? / ¿Cómo clasificamos las rocas?. The surface of the Earth is made of rock. There are three many types of rocks. igneous. sedimentary. metamorphic.

Igneous rock: When very hot lava cools down, it becomes solid and hard. It forms igneous rock. Granite and obsidian are igneous rocks. People use granite in construction and for kitchen worktops.

Sedimentary rock: Small particles of rock form layers under the sea. The layers on top press down the layers underneath. The layers stick together and form sedimentary rock. Sandstone and chalk are sedimentary rocks. Sometimes bodies of animals become stuck between the layers. These can fossils. Sedimentary rock is normally softer than igneous and metamorphic rock.

Metamorphic rock: High temperature or a lot of pressure can make one type of rock change to another type. This produces metamorphic rock. Metamorphic rock is very hard. Marble is a metamorphic rock. People use marble to make tiles or sculptures.

Vocabulary: hard. grey. igneous rock. granite. obsidian. sedimentary rock. small particles. layers. sandstone. chalk.

Vocabulary: stuck. softer. metamorphic rock. pressure. high temperature. low temperature. high. low. marble. tile.