1. Plate Tectonics
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53 terms
Terms | Definitions |
|---|---|
 6,000 km | What is the diameter of the core? |
| Magnetic field | _______ affects navigation and protects the Earth from radiation. |
| 3,000 km | How thick is the mantle? |
| 7/8 | What fraction of the volume of Earth is the mantle? |
| Heat inherited from the formation of the Earth | What is primordial heat? |
| Uranium, Thorium, Potassium | What are three radioactive elements that decay to generate Earth's internal heat? |
| From the sun (in the form of electromagnetic waves). Does not occur within the Earth. | Where does heat transfer through radiation occur? |
| Conduction | ________ is the transfer of energy through the vibration of atoms. |
| False. Heat conduction in rocks is slow. (This is why heat is held in the Earth for so long.) | Conduction is effective in rocks. T/F |
| True | Air is in a continuous state of convective movements. T/F |
| True | Thunderclouds are an example of convection. T/F |
| Convection | Density movements caused by temperature movements is a process of _______. |
| Glaciers and naturally-forming salt | Other than the mantle, what are other examples of "flowing" solids? (2 things) |
| 100 km | How thick is the lithosphere? |
| lithosphere | The __________ is the cool upper mantle plus the overlying crust. |
| True | In the lithosphere, heat transfer is by conduction. T/F |
| Asthenosphere | The ________ is the hot upper mantle (squishy) beneath the lithosphere that can flow. |
| Lithospheric plates | ___________ ___________ are large fragments that the lithosphere is broken into. |
| True | Plates can include a continent and the adjacent ocean. T/F |
| African, S. American, N. American, Eurasian, Indo-Australian, Antarctic, Pacific | Name the 7 major plates. |
| Oceanic | The Pacific plate is different because it is the only plate made entirely of ______ crust. |
| Divergence, convergence, strike-slip (transform) | What are the three kinds of faults? |
| 1. large-scale motions of continents (continental drift), 2. distribution of earthquakes and volcanoes, 3. magnetic anomalies on the sea floor | What are three types of evidence for plate tectonics? |
| Alfred Wegender. (It was 50 years before his theory was accepted.) | Nearly 100 years ago, German meteorologist, ______ _______ proposed the hypothesis of continental drift. |
| 1) puzzle-like fit of the continents around the Atlantic, 2) geologic match-ups between continents. 3) similar fossils on widely separate continents, 4) similar climates in the past on continents that are not at very different latitudes. (glacial features) | What is the continental drift hypothesis based on? (4 things) |
| Sea floor spreading | Magnetic anomalies are related to the concept of ____ _____ _________. |
| True | The formation of lava at mid-ocean ridges records the magnetic field of the time. T/F |
| True | The magnetic north does not coincide with the North Pole. T/F |
| 180 km | The magnetic north has moved about _____ north since discovery. |
| Chaotic processes in the Earth's core | Why does the magnetic field reverse polarity at irregular intervals? |
| 10 million, 10,000 | What are the longest and shortest timescales of magnetic reversal? |
| True | Observations of the magnetic anomalies off the coast of Western North America in the 1960s led to the theory of plate tectonics. T/F |
| 180 | The oldest ocean floor we have is only _____ million years old. |
| Magma | Partial melting of the mantle creates _______, which forms the ocean crust. |
| 1,300 | The asthenosphere is _______ degrees centigrade. |
| Decreases | As you bring the hot mantle up, the pressure ______. |
| Temperature range | There is not a single melting point, but instead a _________ ________. |
| True | New crust solidifies because it cools and melts partially because of the decrease in pressure. T/F |
| Mid-ocean ridges | Divergent plate boundaries are often marked by giant submarine mountain ranges on the ocean floor called ___________________. |
| 50 | Submarine mountain ranges were largely undiscovered until about ____ years ago as a result of submarine surveys. |
| True | Iceland is oceanic crust that is getting bigger at a rate of about 3 cm per year. |
| True | The divergent plate boundary along the mid-Atlantic ridge emerges above sea-level in Iceland. |
| Between Arabian Peninsula and Africa, East African Rift | Name 2 other divergent plate boundaries. |
| Subduction zone | One plate slides under the other at a convergent plate boundary in the ________ _________. |
| True | Only oceanic crust can be subducted. |
| Continental rifts | __________ _________ are one kind of divergent plate boundary. |
| Japan | Earthquake locations beneath _______ delineate the inclined slab of subducting lithosphere. |
| Benioff zone | Deep active seismic area in a subduction zone: ________ _________. |
| Velocities | ____________ of seismic waves help image the cold subducting slab beneath the Tonga Arc. |
| Deep trenches and volcanoes | Convergent plate boundaries are marked by ______ ______ and _____________. |
| collision | Continental __________ causes squashed and thickened crust. |
| transform | At a ______ plate boundary (also known as strike-slip), the plates slide horizontally past each other without any gain or loss of lithosphere. |
| offset | Most transform boundaries offset mid-ocean ridges. |
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