Continental Drift Theory–Accept or Reject?

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Alfred Wegener: The more I learn about his life, the more I admire the man.

Alfred Wegener: The more I learn about his life, the more I admire the man.

“Scientists still do not appear to understand sufficiently that all earth sciences must contribute evidence toward unveiling the state of our planet in earlier times, and that the truth of the matter can only be reached by combing all this evidence. … It is only by combing the information furnished by all the earth sciences that we can hope to determine ‘truth’ here, that is to say, to find the picture that sets out all the known facts in the best arrangement and that therefore has the highest degree of probability. Further, we have to be prepared always for the possibility that each new discovery, no matter what science furnishes it, may modify the conclusions we draw.”
Alfred Wegener, The Origin of Continents and Oceans

Key idea from the Lessons:
  • Matching coastlines, similarities in rock types, glacial grooves, and fossil record suggest that today’s continents are separated parts of what was long ago a single continent.
Summary of Lessons:

Lesson 1: We start with a warm up: Name the continents and oceans. Have they always been where they are now? I tell the story of Abraham Ortelius, the Dutch map maker, who in his work Thesaurus Geographicus (1596), suggested that the Americas were “torn away from Europe and Africa . . . by earthquakes and floods” and went on to say: “The vestiges of the rupture reveal themselves, if someone brings forward a map of the world and considers carefully the coasts of the three [continents].” I show them a copy of Ortelius’ map and we compare and contrast it to today’s world maps.  Then I read Alfred Wegener’s quote that was in a letter to his wife:

“Doesn’t the east coast of South America fit exactly against the west coast of Africa, as if they had once been joined?” wrote Wegener to his future wife in December 1910. “This is an idea I’ll have to pursue.”

Tell students that this is an idea that we are going to pursue just like Wegener did. Ask if it looks like any other of the continents could fit together like puzzle pieces? What could that suggest? If Earth looked different in the past, how could we tell? Students will scan the globe in Google Earth (or other resources) to see if any places besides South America and Africa look as if the continents seem to fit together.  This is page 1 of the Continental drift packet (I created this packet using a number of resources–I credited these resources in the resource section below the summary).

Lesson 2: Segue into fossil evidence by asking, “Do different continents such as Africa, Antarctica, and Australia have different plants and animals today? Why? How could knowing what plants and animals lived on the different continents millions of years ago provide evidence that the continents were once together? What evidence helps scientists prove what life lived on continents millions of years ago? Tell the students that Alfred Wegener also had the same ideas and began collecting fossil evidence just like we will be doing. Complete the Far Flung Fossil collection (page 2-3 of the packet) and discuss analysis questions. (You will need the The Mystery of the Far Flung Fossil kit to do this part. I posted a link in the resources.) Turn on the “Fossil Finds” folder (download the Continental Drift Google Earth file found here) and rotate the globe to see where each of the four fossils has been found. Use the legend to see which fossil each color dot represents. Students must next decide whether continents containing the same fossils were connected when those species were alive or if Mesosaurus, Cynognathus, Lystrosaurus, and Glossopteris could have crossed the oceans. To decide this, students need to read some research about these organisms. Students complete page 4-7 in packets. Ask students to underline evidence that supports or refutes the ability for these animals to cross the ocean. Add new evidence to CER chart on the last page of the packet.

Lesson 3: Discuss glaciation marks discovered by scientists on the southern continents. Many students have limited background knowledge of the massive size of glaciers or how they can leave grooves on the rocks. I use Google images to show some pictures of glaciers and then show a time-lapse video of uunderneath a glacier. They then complete page 8 in the packet which encourages them to analyze and interpret this data. How do these glacial grooves support or reject the idea of continental drift?  Add the new evidence to the CER chart.

Lesson 4: Segue into landform evidence by asking: Have you ever seen a mountain range? What did it look like?  (I show some google images of mountain ranges) What about coal beds? (Show images and explain how coal beds form). Students analyze the graphics on page 9 of the packet and add the new evidence into their CER chart. Read about Spitsbergen on page 10 and add that evidence to the CER chart.  Show this animation. Now review all the evidence that supports the idea of continental drift. Debate whether or not Wegener’s hypothesis should have been accepted. Students will write a claim, evidence, and reasoning essay using their packet as a guide.

Lesson 5: Tell students that Wegener’s Continental Drift theory was rejected!! Begin a discussion as to why. What are “issues” with his theory? Then watch this PBS 4 minute video on Wegener and this award winning video. After the video discuss why his theory was rejected. What reasons are legitimate? What evidence was he lacking? How can we gather this evidence?

Resources:

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