Ever Changing Earth

What's Going On Under the Sea?

Warm-Up

Describe the floor of the ocean. You may use words and diagrams.

Learning Targets

Organize and describe given data sets that represent the distribution and ages of fossils and rocks, continental shapes, seafloor structures, and the age of oceanic crust, in a way that facilitates analysis and interpretation.

Success Criteria

I have analyzed data sets to identify relationships about Earth's features.
I have used analyzed data to provide evidence for past motion of Earth’s continents.
I can relate what I have observed to The Theory of Continental Drift.

Roles

Organizer, Materials Manager/Technician, Time Keeper, Checker, Reader

A Wartime Discovery

Harry Hess was a Naval Scientist. In the 1950s he was in command of a United States Navy ship equipped with a device called Sonar. Sonar devices send and receive sound waves through the water in order to locate other ships and navigate underwater. It is especially useful for mapping the floor of the ocean. As Hess created maps of the Pacific Ocean floor he noticed several underwater geologic features.

How does Sonar Work?

Skip ahead in the following video to 1:20 to see an explanation of how sonar works.

Google Earth Activity

Procedures

Visit the following Google Earth Links. Pay close attention to what you see on the ocean floor

Part A

Compare the features that you see to the shapes of the surrounding continents. How are they similar and different?

Part B

Compare the features that you see to the shapes of the surrounding continents. How are they similar and different?

Back to your Earthquake and Volcano map

In an incognito window, open your Earthquake and Volcano Map (from Earthquakes around the World.)
- Add new symbols to your map to represent the features that you notice on the map.
- Update your key.
- How do your new symbols compare to the earthquakes and volcanoes you already have on the map?

Ocean Ridges and Trenches

Mid Ocean Ridge

Trench

As a Group...

Discuss the following in a group

How are the ridges and trenches similar and different to the surrounding continents?
Describe the relationship between the ridges and trenches found in the ocean and the fact that the ocean floor is not all the same age. Explain your reasoning.

The Theory of Seafloor Spreading

View this Sea Floor Spreading Animation. Identify on the map where this is most likely occurring. Explain your reasoning.

Take a Stand...

If Seafloor Spreading is happening at the mid ocean ridges, does that mean the earth is getting bigger?
- How do you know?
- What do you still need to know?

Subduction at Trenches

View this subduction animation. Identify on the map where this is most likely occurring. Explain your reasoning.

Back to Continental Drift

What evidence from what is going on under the sea explains the existence of ridges and trenches and supports Alfred Wegener's theory of Continental Drift?

National Geographic Article

Read the following article that explains the concept of Sea-Floor Spreading.

As you read be sure that you can...

explain The Theory of Sea Floor spreading.
describe how Earth's crust is both created and destroyed.
relate Sea Floor Spreading to The Theory of Continental Drift.

MS-ESS2-2. Construct an explanation based on evidence for how geoscience processes have changed Earth's surface at varying time and spatial scales.

MS-ESS2-3 - Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.

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