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An introduction to geology
An introduction to geology

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2.16 What type of rock is oceanic crust?

See if you can answer this question by completing the activity below.

Activity 2.3 Oceanic crust

Timing: Allow about 2 minutes

Is oceanic crust igneous, metamorphic or sedimentary?

a. 

igneous


b. 

sedimentary


c. 

metamorphic


The correct answer is a.

Discussion

The answer is igneous. It’s all made in volcanoes at the spreading centres, and cools from a molten state (the definition of igneous). The sea floor does get covered in sediment over time which is sedimentary, but the oceanic crust that it forms on is always igneous.