Seafloor Spreading worksheet with corrected statements on ocean floor mapping and geological processes.

Task: Solve the problem by finding mistakes in the statements about seafloor spreading and rewriting them correctly.

#### Step-by-Step Solution:

1. Statement:
> During the 1940s and 1950s, scientists began using radar on moving ships to map large areas of the ocean floor in detail.

Mistake: Scientists did not use radar to map the ocean floor; they used echo-sounding devices (sonar).

Corrected Statement:
> During the 1940s and 1950s, scientists began using echo-sounding devices on moving ships to map large areas of the ocean floor in detail.

2. Statement:
> The youngest rocks are found far from the mid-ocean ridges.

Mistake: The youngest rocks are actually found near the mid-ocean ridges, not far from them.

Corrected Statement:
> The youngest rocks are found near the mid-ocean ridges.

3. Statement:
> The scientist Henry Hess invented echo-sounding devices for mapping the ocean floor.

Mistake: Henry Hess did not invent echo-sounding devices. He was a key figure in developing the theory of seafloor spreading but did not invent the technology.

Corrected Statement:
> The scientist Henry Hess contributed significantly to the development of the theory of seafloor spreading, but he did not invent echo-sounding devices.

4. Statement:
> As the seafloor spreads apart, hot saltwater moves upward and flows from the cracks.

Mistake: It is not hot saltwater that moves upward; it is magma (molten rock) from the mantle.

Corrected Statement:
> As the seafloor spreads apart, hot magma rises from the mantle and flows from the cracks at the mid-ocean ridges.

5. Statement:
> As the new seafloor moves away from the ridge and becomes hotter, it moves upward and forms still higher ridges.

Mistake: As the new seafloor moves away from the ridge, it cools and sinks due to its increasing density, not becoming hotter or forming higher ridges.

Corrected Statement:
> As the new seafloor moves away from the ridge, it cools and sinks due to its increasing density.

6. Statement:
> The research ship Glomar Challenger was equipped with a drilling rig that records magnetic data.

Mistake: The Glomar Challenger was equipped with a drilling rig to extract rock samples from the ocean floor, not primarily to record magnetic data.

Corrected Statement:
> The research ship Glomar Challenger was equipped with a drilling rig to extract rock samples from the ocean floor.

7. Statement:
> Rocks on the seafloor are much older than many continental rocks.

Mistake: This statement is incorrect. Rocks on the seafloor are generally younger than many continental rocks because seafloor spreading constantly creates new crust at mid-ocean ridges.

Corrected Statement:
> Rocks on the seafloor are generally younger than many continental rocks because new crust is constantly formed at mid-ocean ridges.

8. Statement:
> When plates collide, the denser plate will ride over the less-dense plate.

Mistake: When plates collide, the denser plate typically subducts (dives beneath) the less-dense plate, not the other way around.

Corrected Statement:
> When plates collide, the denser plate typically subducts beneath the less-dense plate.

9. Statement:
> Earth’s magnetic field has always run from the north pole to the south pole.

Mistake: Earth's magnetic field has reversed polarity multiple times throughout history, meaning it has not always run from the north pole to the south pole.

Corrected Statement:
> Earth’s magnetic field has reversed polarity multiple times throughout history and does not always run from the north pole to the south pole.

10. Statement:
> The magnetic alignment in rocks on the ocean floor always runs from the north pole to the south pole.

Mistake: The magnetic alignment in rocks on the ocean floor reflects Earth's magnetic field at the time the rocks were formed. Since Earth's magnetic field has reversed multiple times, the alignment does not always run from the north pole to the south pole.

Corrected Statement:
> The magnetic alignment in rocks on the ocean floor reflects Earth’s magnetic field at the time the rocks were formed and does not always run from the north pole to the south pole.

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Final Answer:

Here are the corrected statements:

1. During the 1940s and 1950s, scientists began using echo-sounding devices on moving ships to map large areas of the ocean floor in detail.
2. The youngest rocks are found near the mid-ocean ridges.
3. The scientist Henry Hess contributed significantly to the development of the theory of seafloor spreading, but he did not invent echo-sounding devices.
4. As the seafloor spreads apart, hot magma rises from the mantle and flows from the cracks at the mid-ocean ridges.
5. As the new seafloor moves away from the ridge, it cools and sinks due to its increasing density.
6. The research ship Glomar Challenger was equipped with a drilling rig to extract rock samples from the ocean floor.
7. Rocks on the seafloor are generally younger than many continental rocks because new crust is constantly formed at mid-ocean ridges.
8. When plates collide, the denser plate typically subducts beneath the less-dense plate.
9. Earth’s magnetic field has reversed polarity multiple times throughout history and does not always run from the north pole to the south pole.
10. The magnetic alignment in rocks on the ocean floor reflects Earth’s magnetic field at the time the rocks were formed and does not always run from the north pole to the south pole.

Boxed Final Answer:
\boxed{
\text{See corrected statements above.}
}