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