Earth Systems
Standard 3, Objective 1
Title: Where are the Plates?
Description: Students will use the trenches, ridges and rises to determine the plate boundaries on Earth.
Materials: Red, blue, black fine line markers, colored pencils. Map of the world showing labeled features of the seafloor. One is included on this web site under “seafloor map”. You will need to print it off the website on the best printer you have and make copies from it. It will be most readable if copied on to legal size paper. You might want to have some better maps available for students to look at to help decipher the names. Student Sheet (see below)
Time Needed: 50 minutes
Background: Students need to know that plates are moving away from ridges or rises and sinking and disappearing in trenches. They should have had experience with cutaway diagrams showing convection currents under the crust moving the plates. Emphasis that this activity looks at the plates from the top and not the sides and uses geographic features to identify types of plate boundaries. Students should notice that nearly every plate has an area where new plate is being formed and moving outward from and an area where the plate is sinking and being remelted.
Procedures
1. Discuss the ideas from the “background” if you have not already.
2. Read the procedures with the students.
3. Give students time to label the ridges and trenches. Do not direct them to their textbooks, which typically have maps of the plates.
4. The map provided on this web site has a darkened, dotted line to help students find all the plate boundaries. Every part of this line should be colored either red, blue or black. If you would rather use a more accurate map try: . http://pubs.usgs.gov/pdf/planet.html, and print off the “This Dynamic Planet” map. Make a black and white copy for each of your students.
5. Students should label the plates and MOST importantly, draw arrows on them showing which way they are moving (away from the red ridges, towards the blue trenches) and naming them.
6. Some plates are being crushed like the Philippines and Africa is moving towards the Mediterranean Sea.
7. If there is time, the plates can be colored with colored pencils.
If you wish to extend this activity and have access to computers (one per 4 students) the following directions may be added:
6. Obtain the latitude and longitude coordinates of the 10 most recent earthquake epicenters in the world at http://wwwneic.cr.usgs.gov/neis/bulletin/bulletin.html. Plot the location of the epicenters on your world map using a red dot.
7. Obtain the latitude and longitude coordinates of the 10 most recent volcanic eruptions in the world at http://volcano.und.nodak.edu/vwdocs/current_volcs/current.html Plot the location of the volcanoes on your world map with blue triangles. An alternative site to use is http://www.volcano.si.edu/gvp/reports/usgs/index.cfm
Scoring Guide:
1. Student identifies plate boundaries correctly…………………..4
2. Student labels plate movement and names it correctly………4
3. Analysis questions are answered correctly…………………….4
Answers:
1. to the West 2. to the North 3. Iceland 4. Mid Atlantic Ridge 5. Mid Indian Ridge
6. Mid Atlantic Ridge 7. Middle American and Aleutian Trenches 8. Between North and South America
Student Sheet Name______
Title: Where Are the Plates?
Introduction: Maps that show the seafloor were first developed during World War II as ships used sonar to look for submarines. Surprisingly, the shape of the seafloor was revealed and it had mountain ranges (ridges) and deep trenches. Using this new information, the theory of plate tectonics was given a great deal of support. Now scientists could see where continents were split apart and where plates were recycled. In this activity you will outline the plates by using geographic features like ridges and trenches to identify plates and their movement.
Materials: Map, colored pencils and markers, book
Procedure:
1. On the map, trace the dotted lines red that are on ridges or rises.
2. Trace the dotted lines on trenches with blue.
3. Color any other part of the dotted lines black.
4. Draw an arrow showing, which way the plate moves. The arrow should point away from the ridge or rise and towards the trench. The arrow should be straight. Only one plate will not be moving.
5. Use your book to help you label each plate. Color the plates if you have time.
Prediction: What direction is North America moving?
Data: on map
Analysis:
1. Which direction is South America moving?
2. Which way is Africa moving?
3. Which large island was formed on a high point in a ridge?
4. What separated Africa from South America?
5. What separated Australia from Africa?
6. Which ridge is the divergent (moving away) boundary for North America?
7. Which trench is the convergent (moving towards) boundary for North America?
8. Which plate is not moving?
Conclusion: 2 things you learned: