Why do some rocks have layers?
Quick Answer
Many rocks are layered because sediments were deposited over time in beds that later hardened into rock. Layers can also form in volcanic flows or by metamorphic banding.
The Full Story
Sedimentary rocks often show layers because sand, mud, and other particles settle in successive episodes, such as in rivers, lakes, or oceans. As pressure and cementation turn these sediments into rock, the layers become preserved. Some igneous rocks also show layering from repeated lava flows or crystal settling in magma chambers. In metamorphic rocks, high pressure and heat can align minerals into bands, creating foliation rather than sedimentary strata.
Key Facts
YouTube Angle
Suggested video title for this topic:
"Rocks can keep a timeline of Earth’s past — literally in layers."
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