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geology midterm
geology exam 1
| Question | Answer |
|---|---|
| what kind of continental margin is the east coast of the US? | passive |
| how much energy is released in a magnitude 7 earthquake than a magnitude 6? | 30x |
| when did the oceans first form? | 4.4 Ga |
| from what source did the oxygen in today's atmosphere originally come from? | photosynthesizing life forms |
| when did life first move onto land from the oceans? | 438 Ma |
| how did earth form? | accretion of asteroids |
| how old is the earth? | 4.6 Ga |
| what kind of plate boundary do we live on in SF? | transform |
| where in the oceans is the newest ocean crust found? | at seafloor spreading centers |
| from what two main sources did the water in today's oceans originate? | outgassing and comets |
| from which layer does earth's magnetic field originate? | the outer core |
| what characteristic of the outer core produces the magnetic field? | convecting liquid iron |
| which earth layer is responsible for plate tectonics (without this layer there would be no tectonic movement)? | asthenosphere |
| what characteristic of this layer produces plate tectonics? | hot, plastic, convects |
| what causes an oceanic trench? | subduction |
| what causes a rift valley? | divergence |
| which seismic waves arrive first at a seismograph after an earthquake? | p-waves |
| what types of seismic waves are capable of traveling through all materials? | p-waves |
| based on the principles of isostatic equillibrium or adjustment what happens to mountains when the top is eroded away? | they rise |
| what major processes formed earth's layers? | differentiation |
| when did this layering process take place? | 4.6 Ga |
| when did life first evolve on this planet? | 3.8 Ga |
| what is the age of the oldest ocean floor today? | 200 Ma |
| what are the most destructive seismic waves? | body waves |
| give three ways that continental crust differs from oceanic crust? | thicker, less dense, older |
| volcanic activity can be found in three different geologic settings. what are these? | hot spots, subduction zones, rift valleys |
| provide at least two conditions that would cause plastic (as opposed to brittle) deformation | high temperature, slow application of stress over long period of time |
| through what two main processes do continents grow? | accreted terrain, volcanism |
| what causes earthquakes? | stress is applied to rocks/faults, stress builds where strong rocks/locked faults withstand it, faults deform elastically, rocks break, stress released as energy waves traveling in all directions, faults rebound elastically, rocks settle and stress |
| name 4 layers of ocean crust known as ophiolite sequence | top layer 1 - oceanic sediment layer 2 - pillow basalts layer 3 - sheeted basaltic dikes layer 4 - massive gabbro |
Created by:
missmollusk
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