--- title: "Types of rocks" description: "Use rock and landscape vocabulary, including igneous, sedimentary, metamorphic, weathering, erosion, deposition, fossil, sediment, strata, permeable and impermeable, to explain how rocks form and how " canonical: https://lightmysky.com/learn/science/types-of-rocks-mt_bqL8DD1SbV source: https://lightmysky.com/learn/science/types-of-rocks-mt_bqL8DD1SbV.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Types of rocks Use rock and landscape vocabulary, including igneous, sedimentary, metamorphic, weathering, erosion, deposition, fossil, sediment, strata, permeable and impermeable, to explain how rocks form and how material moves Subject: Science · Area: Earth's Systems · Ages 9 to 11 Page: https://lightmysky.com/learn/science/types-of-rocks-mt_bqL8DD1SbV ## Ready when they can - Correctly classify igneous, sedimentary, and metamorphic rocks and explain in one sentence how each type forms - Use 'weathering', 'erosion', and 'deposition' correctly to describe rock breaking down, pieces moving, and sediment settling - Explain how fossils form using 'sediment' and 'sedimentary rock' correctly ## Lesson: Types of rocks Rocks are grouped by how they form: igneous, sedimentary or metamorphic. Igneous rock forms when melted rock cools and becomes solid. Melted rock underground is magma; at the surface it is lava. Slow cooling usually allows larger crystals to grow. Fast cooling usually makes small crystals, or rock with no crystals. Sediment includes loose rock grains, sand and mud. It can settle in layers called strata. Pressure compacts buried sediment, and minerals can cement grains together to make sedimentary rock. Some sedimentary rocks form from shells or minerals left by water. Permeable rock lets water pass through connected spaces. Impermeable rock lets very little water pass through. *(drawing: Weathering, erosion and deposition describe different parts of this journey.)* Weathering breaks rock down where it is. Erosion moves rock pieces or soil. Deposition happens when moving material settles. A river may carry pieces that were already broken, so its journey need not include fresh weathering. **Example.** A dead fish may be buried by sediment in a lake. Burial can help protect bones or an imprint. More sediment adds layers called strata. Pressure compacts the sediment, and minerals can cement it into sedimentary rock. Evidence of the fish may remain inside as a fossil. Most dead living things do not become fossils. Metamorphic rock forms when heat and pressure change an existing rock while it stays solid. Shale can change into slate this way. Melting followed by cooling makes igneous rock. Large crystals alone do not identify metamorphic rock: slowly cooled igneous rock can have them too. **Recap.** Rock types describe how rocks form. Weathering breaks rock down, erosion moves material, and deposition is when it settles. *The lesson, questions and flashcards were written for this dataset.* ## Practice 8 questions on this page, each with its working shown. ## Opens up - [Finding patterns in data](https://lightmysky.com/learn/science/finding-patterns-in-data-mt_-G6erQvLig) - [Rock layers and Earth's history](https://lightmysky.com/learn/science/rock-layers-and-earths-history-mt_0_K-GrKQpd) - [Rock layers as evidence of change](https://lightmysky.com/learn/science/rock-layers-as-evidence-of-change-mt_GheLsWvrJ4) - [How Earth systems interact](https://lightmysky.com/learn/science/how-earth-systems-interact-mt_LKagN9GJPX) - [Erosion and weathering](https://lightmysky.com/learn/science/erosion-and-weathering-mt_vAP_A986IQ)