who was alfred wegener?

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Who was Alfred Wegener? Alfred Wegener was a young German scientist who in 1910 proposed that the continents moved. What was Wegener’s hypothesis?

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Who was Alfred Wegener?. Alfred Wegener was a young German scientist who in 1910 proposed that the continents moved. What was Wegener’s hypothesis?. What was Wegener’s hypothesis?. - PowerPoint PPT Presentation

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Page 1: Who was Alfred Wegener?

Who was Alfred Wegener?

• Alfred Wegener was a young German scientist who in 1910 proposed that the continents moved.

• What was Wegener’s hypothesis?

Page 2: Who was Alfred Wegener?

What was Wegener’s hypothesis?

• Continental Drift: all continents were once joined together in a single landmass and have since drifted apart.

• What evidence did Wegener have?

Pangea means “All lands.”

Page 3: Who was Alfred Wegener?

What evidence did he have?

• Wegener gathered evidence from different scientific fields to support his ideas about continental drift.

• Wegener studied land features, fossils, and evidence of climate change.

Please turn to page 138 -139 of your textbook.

Page 4: Who was Alfred Wegener?

Drifting Continents• Wegener’s idea of a

supercontinent was not accepted by the world because he could not provide a satisfactory explanation for the force that pushes or pulls the continents.

• What force do you think moves the continents?

http://www.livescience.com/images/pangea_animation_03.gif

Page 5: Who was Alfred Wegener?

Who is Arthur Holmes?• Around 1930, Arthur Holmes

suggested the power of convection.

• Currents of heat and thermal expansion in the Earth's mantle, he suggested, could force the continents toward or away from one another, creating new ocean floor and building mountain ranges.

• He warned that his ideas were "purely speculative" and could "have no scientific value until they acquire support from independent evidence."

Page 6: Who was Alfred Wegener?

What is Convection?• Convection is the

movement of molecules within fluids.

• Movement is caused by differences of temperature and density within a fluid.

Page 7: Who was Alfred Wegener?

• 1. As a liquid is heated, the particles move faster and spread apart.

• 2. As a result, the particles of a heated fluid occupy more space.

• 3. The fluid’s density decreases.

• THE HOTTER (less dense) LIQUID MOVES UP.

• 4. But when a fluid cools, its particles move more slowly and settle together more closely.

• 5. As the fluid becomes cooler, its density increases.

• THE COOLER (more dense) LIQUID SINKS DOWN.

Heat Rises!

Page 8: Who was Alfred Wegener?

So… what possible force can there be that might push or pull the continents?

http://www.geoham.net/6/fys/tekton/recon.gif

Page 9: Who was Alfred Wegener?

What force moves the continents?

• Heat from the core and the mantle cause convection currents in the mantle.

• These currents are believed to be what moves the plates.

• Although Holmes had an explanation, he could provide no evidence.