Let's solve this step by step based on the characteristics of the three main types of rocks:
igneous,
sedimentary, and
metamorphic.
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Understanding the Rock Types:
1.
Igneous Rocks:
- Formed from cooled and solidified magma or lava.
- Can form
intrusive (inside Earth) or
extrusive (on surface).
- Examples:
Granite (intrusive),
Basalt (extrusive),
Obsidian (volcanic glass).
2.
Sedimentary Rocks:
- Formed from sediments (fragments of rocks, minerals, organic matter) that are compacted and cemented together.
- Often found in layers.
- Usually softer than igneous and metamorphic rocks.
- Examples: Sandstone, shale, limestone.
3.
Metamorphic Rocks:
- Formed when existing rocks are changed by heat, pressure, or chemically active fluids.
- The original rock (protolith) is transformed but not melted.
- Examples: Marble (from limestone), Schist, Gneiss.
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Now let’s match each statement to the correct rock type:
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Answer Key with Explanation:
1.
Sedimentary Rock – *Can be formed by the sediments of other rocks.*
✔ Explanation: Sedimentary rocks are made from the weathering, erosion, deposition, compaction, and cementation of sediments derived from pre-existing rocks.
2.
Metamorphic Rock – *When heat from magma is applied it changes the composition of a rock creating a new rock.*
✔ Explanation: Metamorphic rocks form under high heat and pressure (often from nearby magma). This changes the mineral composition and texture of the original rock without melting it.
3.
Igneous Rock – *These rocks can be formed on the exterior or interior of the earth’s crust.*
✔ Explanation:
-
Exterior: Extrusive igneous rocks like basalt form when lava cools on the surface.
-
Interior: Intrusive igneous rocks like granite form when magma cools slowly beneath the surface.
4.
Sedimentary Rock – *They are soft and are formed in layers.*
✔ Explanation: Sedimentary rocks are often softer than igneous or metamorphic rocks and are typically deposited in horizontal layers over time.
5.
Igneous Rock – *Some examples of this rock include obsidian, granite, basalt.*
✔ Explanation: These are all classic examples of igneous rocks:
- Obsidian: volcanic glass (extrusive)
- Granite: coarse-grained intrusive
- Basalt: fine-grained extrusive
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✔ Final Answers:
1.
Sedimentary Rock
2.
Metamorphic Rock
3.
Igneous Rock
4.
Sedimentary Rock
5.
Igneous Rock
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Parent Tip: Review the logic above to help your child master the concept of types of rocks worksheet.
