How can rocks be categorized

T he protolith can be either an igneous rock or a sedimentary rock, as just indicated. The protolith could also be a previously metamorphosed rock. When a rock is exposed to extreme heat and pressure within the Earth but does not melt, the rock becomes metamorphosed. Metamorphism may change the mineral composition and the texture of the rock. Skip to main content. Search for:. Types of Rocks Lesson Objectives Define rock and describe what rocks are made of. Know how to classify and describe rocks.

Explain how each of the three main rock types formed. Describe the rock cycle. Vocabulary crystallization erosion igneous rock metamorphic rock metamorphism outcrop precipitate rock cycle sediment sedimentary rock sedimentation weathering Introduction There are three types of rocks: igneous, sedimentary and metamorphic. What Are Rocks? Rock samples. This flowing lava is molten rock that will harden into an igneous rock.

This sedimentary rock is made of sand that is cemented together to form a sandstone. James Hutton is considered the Father of Geology. The Rock Cycle. Licenses and Attributions. CC licensed content, Shared previously. Types of Rocks Rocks are not all the same! The three main types, or classes, of rock are sedimentary , metamorphic , and igneous and the differences among them have to do with how they are formed.

Sedimentary Sedimentary rocks are formed from particles of sand, shells, pebbles, and other fragments of material. Together, all these particles are called sediment. Gradually, the sediment accumulates in layers and over a long period of time hardens into rock.

Generally, sedimentary rock is fairly soft and may break apart or crumble easily. Where do igneous rocks form? Give an example of a felsic and a mafic igneous rock. What are the differences between a foliated and non-foliated metamorphic rock? Select a metamorphic rock and describe how it formed from its parent rock.

Learning activity A series of three posters showing the main ways that sedimentary, igneous and metamorphic rocks are classified. Rock classification Downloadable PDF. Complementary activities Learn how to classify fossils Platypus evolution Jigsaw Earth.

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