Amy Spoonhower

Geosphere Unit 3

Extension Activity

11/13/99

Tectonic Plates: On the Move

Introduction:

In 1620 Sir Francis Bacon acknowledged that "the geometric similarity between the western coast of Africa and the eastern coast of South America can hardly be denied".

This simplistic and rather obvious observation prompted scientists to uncover that the ground under our feet is on the move. This lesson delves into discovering how.

Objectives:

Students will:

  1. Define lithosphere, and asthenosphere.
  2. Investigate the properties of plasticity.
  3. Observe the jigsaw puzzle fit of the continents.
  4. Research proposed plate movement mechanisms.
  5. Investigate topographic features that result from plate movement.

Materials:

Methods:

Part 1: Lithosphere vs. Asthenosphere

  1. Log onto the computer. Yahoo will automatically launch.
  2. In the box that now contains the URL for Yahoo, type:

http://www.johnco.cc.ks.us/~dpatter/powerpoint/ut4review/sld130.htm

  1. According to this presentation, what layers of the Earth make up the lithosphere? ______________, __________ ___________ (crust & upper mantle)
  2. Click on the > symbol. What is the color of the line that represents the asthenosphere? (blue)
  3. The asthenosphere is described as behaving like hot tar.

Discover by Doing

To discover how the asthenosphere behaves combine 1 cup of cornstarch with 1/2 cup water. Squeeze this mixture in you hand and note how it behaves in your science journal.

 

Part 2: The Jigsaw Puzzle Fit of the Continents

The lithosphere of the Earth is broken up into a dozen or so tectonic plates. For the sake of simplicity you can refer to these tectonic plates as "big slabs of rock".

  1. To see these big slabs of rock log onto :

http://pubs.usgs.gov/publications/text/slabs.html

  1. Pick 5 places that you would like to visit. Next to that location, type the name of the plate that it is on.

Ex)       New York - North American Plate

            ____________________________                _______________________

            ____________________________                _______________________

            ____________________________

           

3. To see how these big slabs or rock have moved over time log onto:

http://pubs.usgs.gov/publications/text/historical.html

 

Part 3: How Do These Big Slabs of Rock Move?

  1. Log onto :

http://jersey.uoregon.edu/~mstrick?RogueComCollege/RCC_Lectures/ConDrift_PlateTec.html

  1. Read the Rogue Community College lecture notes.
  2. What is the strangest explanation for plate movement? (Giant catfish in the center of the Earth)

4. What is currently the popular theory? (Mantle Convection)

5. Take 20 minutes to look at these web sites to get a better understanding of mantle convection.

http://sop.geo.umn.edu/images/sxz_1.jpg

http://sop.geo.umn.edu/images/Tp2_2.jpg

http://www.cotf.edu/ete/modules/volcanoes/mantleconv.html

http://otn.uoregon.edu/skmiller/project/Convection.visual.html

http://ees.lanl.gov/EES5/planet.html - figure 4

http://www.acl.lanl.gov/Viz/terra/terra.html

Discover By Doing:

Create 7 tin foil "tectonic plates". Place them into a pan of water. Place the pan of water onto a hot plate. Take note of the movement of the tin foil tectonic plates. What causes these "plates" to move? (Convection of the water)

Part 4: What Types of Topographic Features Result from the Movement of the Plates?

When mantle convection sets the plates in motion, these big slabs of rock can:

Click on the link that corresponds to each type of plate movement.

  1. Converge - Smash together
  1. Diverge - Pull apart
  1. Slide past each other

 

Part 5: Putting the Pieces Back Together

  1. Log onto:

http://www.letsfindout.com/subjects/space/contdrft.html

  1. Read this to summarize what you have learned today.

Extra Credit - How Much Does A Tectonic Plate Weigh?

A.K.A. How BIG are these "Big Slabs Of Rock?"

1. Given the following information, calculate how much the North American Plate weighs in pounds.

*Average continental crust weighs in at about 10 cubic feet to then ton.

North America is approximately:

*2500 miles from east to west

*5000 miles from north to south

*35 miles thick

(Answer: 2.4 quintillion pounds)

Students who turn in this answer will be asked to log onto the following site to obtain whether their calculation was correct.

http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry35.html

Discussion Questions:

Idea & Applicability to My Situation:

Tectonic Plates: On the Move is an interesting way to introduce plate tectonics by focusing on the basic components of plate movement. Often research into this topic can get too high level for my eighth grade students. By pre-selecting the specific web pages, this lesson allows for analysis of plate tectonics while preventing analysis paralysis. (A.k.a. doable & fun) By leading my students to the right page, and then allowing them to explore as little or as much as they would like, I can incorporate a tiered lesson approach for students of all ability levels.

This lesson integrates mathematics at the end by means of a bonus question. Due to the variety of skill levels, integration of math can be challenging. I like the idea that students could log onto the web site to get an explanation of the answer and the steps to get there. This is great when a student is absent, and the time to go personally go over the answer is just not there, or if a student needs more time to understand the methods used to arrive at the final answer. Eighth grade students would particularly appreciate not having to look like they don't get it while asking their teacher or fellow classmates for an explanation.

 

Teaching Standards:

This lesson addressees the following Virginia Standards of Learning:

ES.1 The student will plan and conduct investigations in which * volume, area, mass, elapsed time, direction, temperature, pressure, distance, density, and changes in elevation/depth are calculated utilizing the most appropriate tools;

* Evaluating evidence for scientific theories related to plate tectonics, the structure of the Earth

_ES.3 The student will investigate and understand how to read and interpret maps, globes, models, charts, and imagery.

ES.4 The student will investigate and understand the characteristics of the Earth including * plate tectonics;

ES.8 The student will investigate and understand geologic processes including plate tectonics.

* tectonic processes (subduction, rifting and sea floor spreading, and continental collision).

General Discussion:

I was extremely disappointed in the limited number of sites that had action or animation. Through doing this lesson, I have found that my laserdisc Understanding Earth is a better tool for getting the idea of plate tectonic across to eighth graders.

In my school, computers are limited. When alternatives to using them are equally proficient (like the laserdisc player), I am more apt to use them.

 This lesson would, however, go over well in my classroom, and I do plan to use it. This lesson does just scratch the surface of plate tectonics, and I would like to create a more in depth internet based lesson in the future.