Chapter 5; Section 3Chapter 5; Section 3Drifting ContinentsDrifting Continents

Question…Question…

Do you see the pieces of the jigsaw-puzzle?

• You and a partner will have 5 minutes to You and a partner will have 5 minutes to complete the puzzle…complete the puzzle…

Here’s what to do…Here’s what to do…

1.1. Cut it up!Cut it up! Cut out each puzzle piece; cutting as Cut out each puzzle piece; cutting as close to the lines as possible (it doesn’t have to be close to the lines as possible (it doesn’t have to be perfect).perfect).

2.2. What’s the code?What’s the code? Use the legend to identify the Use the legend to identify the symbols on each island or continent.symbols on each island or continent.

3.3. Puzzle me thisPuzzle me this.. Look at the shapes of continents Look at the shapes of continents and islands. What landmasses seem to fit and islands. What landmasses seem to fit together? together?

4.4. Let’s ROCKLet’s ROCK!! Examine the evidence and try to Examine the evidence and try to match up landmass boundaries that show similar match up landmass boundaries that show similar rock strata, fossilized desert belts, and dinosaur rock strata, fossilized desert belts, and dinosaur fossils.fossils.

5.5. Hold that Pose!Hold that Pose! Look over the arrangement of Look over the arrangement of the continents and islands and decide if the the continents and islands and decide if the position of any of them should change. When you position of any of them should change. When you are satisfied with your map of Pangaea, glue it are satisfied with your map of Pangaea, glue it down on the world map. down on the world map.

• 1700’s – geologists thought that the 1700’s – geologists thought that the continents had always remained in continents had always remained in the same placethe same place

• Early 1900’s – Alfred Wegener Early 1900’s – Alfred Wegener (VAY guh (VAY guh

nur)nur) thought continents could have thought continents could have once been joined together as one once been joined together as one landmasslandmass

Wegener hypothesized…Wegener hypothesized…

• All continents were once joined All continents were once joined together in a single landmass together in a single landmass and have since drifted apartand have since drifted apart– This idea became know as This idea became know as continental continental

driftdrift

According to Wegener…According to Wegener…• Continents drifted together to form Continents drifted together to form

PangaeaPangaea (the supercontinent)(the supercontinent)– Means “all lands”Means “all lands”– Existed about 300 million years agoExisted about 300 million years ago

• Over 10’s of millions of years ago, Over 10’s of millions of years ago, Pangaea began to break apartPangaea began to break apart– Continents slowly moved to positions Continents slowly moved to positions

they are todaythey are today

Wegener gathered Wegener gathered evidence…evidence…

• From different areas in science to From different areas in science to support his ideassupport his ideas– Land featuresLand features– FossilsFossils– Climate changeClimate change

Evidence from Land Evidence from Land Features…Features…

• Mountains of Africa & S. America Mountains of Africa & S. America lined uplined up

• European coal fields matched up with European coal fields matched up with fields in N. Americafields in N. America

Evidence from Fossils…Evidence from Fossils…• FossilFossil – any trace of an ancient – any trace of an ancient

organism that has been preserved in organism that has been preserved in rockrock– Glossopteris Glossopteris ((glaw SAHP tuh ris) glaw SAHP tuh ris) found in found in

rocks in Africa, S. America, Australia, rocks in Africa, S. America, Australia, India, & AntarcticaIndia, & Antarctica

– MesosaurusMesosaurus & & LystrosaurusLystrosaurus (fresh (fresh water reptiles) found on different water reptiles) found on different continentscontinents

Evidence from Climate…Evidence from Climate…

• As continent moves toward equator, As continent moves toward equator, climate becomes warmerclimate becomes warmer

• As continent moves toward poles, As continent moves toward poles, climate becomes colderclimate becomes colder

• Continents carry with it fossils and Continents carry with it fossils and rocks formed at old locationrocks formed at old location

Evidence from Climate Evidence from Climate cont…cont…• Example…Example…

– Fossils of tropical plants found on island Fossils of tropical plants found on island in Arctic Oceanin Arctic Ocean

– Deep scratches in rocks show glaciers Deep scratches in rocks show glaciers covered S. Africa (too warm for this to covered S. Africa (too warm for this to happen today)happen today)

Wegener’s Hypothesis….Wegener’s Hypothesis….

• Wegener suggested continents plowed Wegener suggested continents plowed across ocean floorsacross ocean floors

• Wegener could not provide a Wegener could not provide a satisfactory explanation for the force satisfactory explanation for the force that pushes or pulls the continentsthat pushes or pulls the continents

• Could not identify cause of Could not identify cause of continental drift so…continental drift so…