1. Lab 4-3: Sea-Floor Spreading
Pages 155 – 158

2. Vocab Sea-Floor Spreading:
Ocean crust is created at a divergent boundary as plates pull apart and molten material rises from deep within the Earth.

3. Mid-Ocean Ridge:
Boundary between two plates where new crust is created.

4. Rift Valley:
Valley between diverging plates.

5. Seamount:
Underwater mountain

6. Continental Shelf:
An undersea extension of a continent which can stretch for many miles out to sea.

8. What prominent sea floor feature Is found in the central Atlantic Ocean?
The Mid-Atlantic Ridge

9. What feature is found at a distance of 4,100 kilometers on the ocean bottom profile you constructed?
An island (it’s above 0!)

10. What motion of the sea floor is responsible for the formation of the Mid-Atlantic Ridge’s rift valley?
The ocean crust is moving in opposite directions (diverging).

11. As distance from the Mid-Atlantic Ridge increases, what change in the age of the sea floor is observed?
Rocks get older as you move away from the ridge.

12. How old are the oldest rocks of the Atlantic sea floor?
Jurassic / 142 – 206 million years old

13. Skip #6 ☺

14. Describe the features of the North Atlantic Ocean bottom that are forming due to sea floor spreading.
The Mid-Atlantic Ridge with a rift valley.