| Term | Definition |
|---|
| Alfred Wegener | scientist who looked at the continents as pieces of a puzzle |
| When did Wegener write about his theory of continental drift. | Early 1900's |
| Continental drift | theory that continents can drift apart from one another and have done so in the past. |
| Continental drift theory seemed to explain observations that... | the continents looked like pieces of a puzzle that fit together. |
| Continental drift also explained... | why fossils of the same plant and animal species are found on both sides of the Atlantic Ocean |
| Continental drift also explained puzzling evidence left by... | ancient glaciers. |
| Ancient glaciers left grooves in the ground that indicate... | the direction they traveled. |
| evidence #1 that support continental drift | Continents fit together like puzzle |
| evidence #2 that support continental drift | Glacial grooves in the crust |
| evidence #3 that support continental drift | Fossil evidence on different continents |
| What was Pangaea? | belief that all the separate continents of today were once a single landmass |
| Pangaea is Greek for | “all Earth”. |
| When Wegener put forth his theory of continental drift, | many scientists would not accept his ideas. |
| They thought there wasn’t a force in nature... | that could move entire continents. |
| The theory of sea-floor spreading | helped to prove Wegener’s theory. |
| Mid-Atlantic Ridge | a chain of submerged mountains running through the center of the Atlantic Ocean. |
| Mid-ocean ridges are | underwater mountain chains that run through Earth’s ocean basins. |
| Mid Ocean Ridges are where | sea floor spreading occurs. |
| Sea floor spreading is | the process by which new oceanic lithosphere is created as older materials are pushed away. |
| As tectonic plates move away from each other, | the sea floor spreads apart and magma rises to fill the gap. |
| Example of sea floor spreading:The crust increases in age the farther it moves away from the mid-ocean ridge, which means (1) | newer rock is closest to the ridge and older rock is farther away. |
| Example of sea floor spreading:The crust increases in age the farther it moves away from the mid-ocean ridge, which means (2)) | The oldest crust in the Atlantic Ocean is found near the edges of the continents. |
| The proof of sea-floor spreading | supported Wegener’s idea that continents move. |
| The Theory of Plate Tectonics | theory that Earth’s lithosphere is divided into tectonic plates that move around on top of the asthenosphere. |
| Three different ways plates are able to move: | convection, slab pull, and ridge push. |
| Convection | hot material from deep within the Earth rises while cooler material near the surface sinks. |
| Ridge Push | At mid-ocean ridges, the oceanic lithosphere is higher than it is where it sinks beneath continental lithosphere. |
| Slab Pull | Because oceanic lithosphere is denser than the asthenosphere, the edge of the oceanic plate sinks and pulls the rest of the tectonic plate with it in a process called slab pull. |
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