| A | B |
|---|
| What did Alfred Wegener do? | young German scientist who came up with the hypothesis known as Continental Drift |
| What was Wegener's hypothesis? | Wegener's hypothesis was that all the continents were once joined together in a single landmass and have since drifted apart. |
| What is the name of the supercontinent? | Pangaea |
| What evidence did Wegener use to support his hypothesis? | land features, fossil evidence, and climate change |
| How did land features support Wegener's hypothesis? | Africa and South America can be pieced together |
| How did fossil evidence support Wegener's hypothesis? | Glossopteris found on Africa, South America, Australia, India, and Antarctica |
| How did climate change support Wegener's hypothesis? | Fossils of tropical plants found on Spitsbergen, which is located in the Arctic Ocean |
| Why was Wegener’s hypothesis rejected? | Wegener could not provide a satisfactory explanation for the force that pushes or pulls the continents. |
| What did most scientists during Wegener’s time believe caused mountains? | mountains formed because the Earth was slowly cooling and shrinking. mountains formed when the crust wrinkled. |
| What did Wegener believe cause mountains? | that the continents colliding caused the formation of mountains |
| What are mid-ocean ridges? | an undersea mountain chain where new ocean floor is produced |
| What instrument was used to map the ocean floor? | sonar |
| Who was the geologists that proposed the process that is known as sea floor spreading? | Harry Hess |
| What is sea-floor spreading? | the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added. |
| What evidences supported Hess’s theory of sea floor spreading? | magnetic stripes, molten lava, and drilling samples |
| Explain how evidence from molten material support Hess’s theory. | pillow shaped rocks, which only form when molten materials harden quickly...located along the mid-ocean ridge |
| Explain how evidence from magnetic stripes support Hess’s theory. | recorded pole reversals are evident on both sides of the mid-ocean ridge |
| Explain how drilling samples support Hess’s theory. | rocks from either side of the mid-ocean ridge are the same age. Also, the youngest rocks are found along the mid-ocean ridge. |
| What are deep-ocean trenches? | a deep under water canyon, where subduction occurs |
| What is subduction? | the process by which ocean floor sinks beneath a deep-ocean trench and back into the mantle |
| How does the process of subduction and sea floor spreading change the size and shape of the earth’s surface? | Because of these processes, the ocean floor is renewed about every 200 million years. That is the time it takes for new rock to form at the mid-ocean ridge, move across the ocean, and sink into a trench. |
| How long does it take for the ocean-floor to be renewed? | About 200 million years |
| What is happening to the Atlantic and Pacific Oceans? | The Atlantic Ocean is getting wider, while the Pacific Ocean is getting smaller. |
| Where would you expect to find the oldest rock on the ocean floor? | at or near deep-ocean trenches |
