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Oceanic crust runs about 6 kilometers thick. How thick is continental crust?
A2 to 7 kilometers
B70 to 200 kilometers
C200 to 700 kilometers
D20 to 70 kilometers
Answer & Solution
Correct answer: D. 20 to 70 kilometers
1. Earth has two kinds of crust with clearly different thicknesses.
2. Oceanic crust is thin, typically about 6 kilometers of basalt.
3. Continental crust is much thicker, running 20 to 70 kilometers of granite.
4. Neither kind reaches 200 kilometers, since the mantle begins well above that depth.
_Source: OpenStax Astronomy (CC BY 4.0), section 8.2 Earth’s Crust_
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