Seafloor spreading

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/seafloor-spreading

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 of formation?Mid-ocean ridges, divergent plate boundaries
2. What is the process?Decompression melting of asthenosphere generates basaltic magma, forming new oceanic crust
3. How does new ocean floor form at mid‑ocean ridges?Hot rock from the mantle rises, melts, and erupts as basaltic magma. When it cools, it makes pillow lavas and sheeted dikes that become new crust.
4. Why do the ocean floor and continents move slowly?The new crust pushes older crust away from the ridge, and the whole plate moves at about 1 to 18 centimeters each year, which is too slow for us to notice.

Lithosphere: The rigid outer layer of Earth, consisting of the crust and upper mantle.
Asthenosphere: The highly viscous, mechanically weak and ductile region of the upper mantle.
Decompression melting: Melting of rock due to a decrease in overlying pressure.
Paleomagnetism: The study of the record of the Earth's magnetic field in rocks.