Oceanic crust

High school (ages 12+)
Environment & Earth

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/oceanic-crust

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the location?Forms the foundation of Earth's major ocean basins
2. What is the primary rock types?Basalt (upper), gabbro and ultramafic cumulates (lower)
3. How is new oceanic crust created?New oceanic crust is made at mid‑ocean ridges where hot magma rises, cools into pillow lavas, and builds up the seafloor.
4. Why does oceanic crust sink into the mantle?It is heavier (about 3.0 g/cm³) than continental crust, so at subduction zones it dives beneath other plates and melts again.

Mafic Igneous Rocks: Rocks rich in magnesium and iron, formed from cooled magma, characteristic of oceanic crust.
Seafloor Spreading: The process by which new oceanic crust is generated at divergent plate boundaries (mid-ocean ridges).
Subduction Zone: An area where one tectonic plate is forced beneath another, typically oceanic crust under continental or younger oceanic crust.
Hydrothermal Alteration: Chemical changes in oceanic crust rocks due to interaction with hot, circulating seawater.