GO IN DEPTH

# Solving the Puzzle Under the Sea

### Introduction

Maps and two animated videos will introduce you to the concept of plate tectonics and Marie Tharp's role in confirming the theory.

### Exploration

To begin your exploration of the ocean floor, go to Google Maps. Make sure you choose the Satellite view by clicking on the box in the lower left corner. Zoom out by clicking the "minus" (-) button in the lower right corner. Keep going until you see most of the Atlantic Ocean. Then locate the ridge in the middle of the Atlantic Ocean.

• What might this ridge be? What might it be telling us about the earth?

Watch an animated video called How One Brilliant Woman Mapped the Secrets of the Ocean Floor.

As the video shows, it took scientists a long time to agree that continents moved. What are some of the steps shown in the video that convinced most scientists that the continents actually moved? You should list these steps on your student sheet.

Next, look the map of the ocean floor that was created by Marie Tharp.

First, can you locate where you live on the map?

Next, look for the Atlantic Ocean. Most maps show the ocean as plain blue, because it is filled with water. Marie Tharp's map shows the ocean floor instead. Are you surprised to see that the floor isn't flat?

Once you've found the Atlantic Ocean on this map, can you find the ridge in the middle of the ocean? What does this look like? In the video, it was described as a "long, v-shaped cleft."

You can zoom in close to see the details, or zoom out to look at the entire map. Take a look around to see the interesting features of the world's ocean floors. Follow the mid-ocean ridge all around the world. This ridge is actually a mountain range. Look for mountain ranges on the land, and see if you can find one that is longer than the one on the ocean's floor.

For more about the theory of plate tectonics, watch the short animated video titled Plate Tectonics Explained at the top of this page. It goes pretty fast, but it should give you a good idea about how plate tectonics works. As you watch this video, answer these questions on your student sheet:

• How old is the idea that the continents drift around the globe?
• When did most geologists believe in continental drift?
• How do we track the movement of tectonic plates?
• The video states that tectonic plates are carried along on currents in the upper mantle. What is the upper mantle?
• What type of current drives two plates into each other?
• What type of current pulls two plates apart?
• Do all the plates move at the same speed?
• When an oceanic plate collides with a continental plate, which will be forced under the other?

### Knowledge Check

Now you will do an earthquake mapping project. Use the information here and on your Earthquake Mapping Project student sheet to do this activity.

1. Download and open up the Earthquake Mapping Project spreadsheet. Either choose two earthquakes yourself or use the ones assigned by your teacher. Use the information from the spreadsheet to answer questions 1-5 on the student sheet.
2. You can click on the country names for the earthquakes you've been assigned and the links will take you to the spot on Google Maps where the earthquakes took place.
3. Click on the "plus sign" (+) in the lower right corner to zoom in.
4. Click on the "minus sign" (-) in the lower left corner to zoom out.
5. Once you know where the earthquakes happened,find the locations on the large Map of Tectonic Plates your teacher has. Then answer questions 6-9 on your student sheet.

This esheet is a part of the Solving the Puzzle Under the Sea lesson.