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Q: The oceanic crust mainly consists of __________ and __________.
  • A. Iron, Alumina
  • B. Silica, Magnesium
  • C. Magnesium, Alumina
  • D. Silica, Alumina
Correct Answer: Option B - Earth’s crust comes in two varieties, continental and oceanic. Continental crust is silica – rich, or felsic. Oceanic crust is mafic, relatively rich in iron and magnesium.
B. Earth’s crust comes in two varieties, continental and oceanic. Continental crust is silica – rich, or felsic. Oceanic crust is mafic, relatively rich in iron and magnesium.

Explanations:

Earth’s crust comes in two varieties, continental and oceanic. Continental crust is silica – rich, or felsic. Oceanic crust is mafic, relatively rich in iron and magnesium.