Geo 101 – The Dynamic Earth
Exam 3 Study Guide
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1. How are diagenesis and metamorphism related to each other and what causes each. What kinds of changes occur during metamorphism? Diagenesis is caused by deeply buried sediment put under SOME heat and pressure, but not enough to change the rock. If diagenesis continues, it becomes metamorphism. Metamorphism is caused by MORE heat and pressure that changes the rock with NO MELTING.
2. How do geologists classify metamorphic rocks? By the parent rock and the texture (foliated or nonfoliated)
3. What causes foliation? The rotation and recrystallization of elongated minerals; only by compression
4. What does metamorphic grade tell us? It tells us how much heat and pressure was used to create the rock.
We also discuss several other topics like What is the formula for 1-dimensional error measure?
5. What do metamorphic facies and index minerals tell us? Metamorphic facies tells us what temperature and pressure conditions were used to create the rock, while index minerals tell us the specific temperature and pressure range.
6. Where does metamorphism happen?
1. Contact Metamorphism: Rock heated by intruding magma or hot rock 2. Regional Metamorphism: Associated with mountain building 3. Burial Metamorphism: Very deeply buried sediment 4. Dynamic Metamorphism: Fault zones
5. Subduction Zones: High pressure, low temperature 6. Shock: Meteorite impact
7. What is the rock cycle? Any rock can become any other type of rock 8. What causes earthquakes?
9. Know the major types of faults, the sub-categories under each, what kind of movement occurs at each fault type, and why that particular type of movement occurs with that fault.
We also discuss several other topics like What does germ line denote in the context of hereditability of mutation?
- Dip Slip Faults: angle on which they slip
* Normal Fault: hanging wall moves down to relative to footwall due to extension
* Reverse and Thrust Fault: hanging wall moves up relative to footwall due to shortening
* Oblique Fault: moves two directions at once (such as up and to the side) due to either extension or shortening - Strike-Slip Faults: horizontal motion
* Left-Lateral Fault: other plate moves to the left * Right-Lateral Fault: other plate moves to the right Don't forget about the age old question of Why do people use twitter?
10.Where are you most likely to find each type of fault? - Normal Fault: divergent boundaries
- Reverse and Thrust Faults: convergent boundaries
- Strike-Slip Faults: transform boundary
11.What is elastic rebound theory and what does it explain? It is the theory that a plate is put under so much pressure that it snaps, like a stick would if bent too much; it explains why earthquakes might happen
12.What are the kinds of displacement that occur along faults? Fault creep (continuous release of energy); periodic energy release (medium earthquakes); store up energy (earth suddenly releases energy and causes high-energy earthquakes)
13.Be able to explain foreshock, aftershock and earthquake triggering. Foreshock: the fault is starting to move
Aftershock: the plate is settling into its new position
Earthquake Triggering: an earthquake triggers other earthquakes outside the aftershock zone
14.What are the types of seismic waves and their characteristics? - Body Waves: Travel through the Earth
* P (Primary) Waves: compressional waves; particle motion is parallel to wave motion We also discuss several other topics like Is anxiety adaptive?
* S (Secondary) Waves: shear waves; particle motion is perpendicular to wave motion
- Surface Waves: Travel on Earth’s surface
* Rayleigh Waves: counter-clockwise elliptical wave motion (similar to ocean waves); creates the most damage
* Love Waves: Moves like a snake (side to side); decreases with depth
15.How are earthquakes recorded, measured, and located? - Recorded: Seismogram measures the intensity, direction, and duration of an earthquake; records it on seismograms
- Measured: Two different ways
1. Magnitude: energy released
2. Intensity: damage caused
- Located: determine difference of S and P waves (S - P); Distance = 8*(S - P) time
16.Which earthquake magnitude measurement scale is considered the most accurate? Why? Moment magnitude because it measures several wave types, rock properties, the area of fault, and amount of slip
17. Where do earthquakes occur, and where will you find shallow or deep earthquakes?
- Shallow at divergent plate boundaries, continental rift zones, continental collision zones, and transform plate boundaries; all depths at subduction zones If you want to learn more check out What are the general rules for accento?
17.How and why does each earthquake hazard happen and what are the results?
1. Ground Shaking: different waves cause different kinds of shaking; damage to buildings
2. Ground Displacement: faults cause giant cracks in ground 3. Landslides: shaking causes movement of rocks and sediments downslope
4. Liquefaction: water mixes with soil and creates quicksand that sinks everything Don't forget about the age old question of How does an outfielder catch a fly ball?
5. Fires: caused by gas lines and stoves
6. Tsunamis: pressure release undersea creates wide wave that pushes anything in its path
7. Disease: sewage gets into drinking water and transportation is down
18.Can earthquakes be predicted? What can we do to mitigate the damage? Only the location of earthquakes can be predicted, but not the time; reinforced buildings help mitigate the damage
19.What are the factors that determine the kind of deformation that will take place?
1) Type of rock
4) Rate of deformation
20.Which geologic features are caused by deformation? What are their characteristics?
1) Faults: Large cracks with opposing movement 2) Jointing: Cracks with no opposing movements 3) Folding: No breaking or cracking
21.What information does a geologist get from strike and dip? - Which direction the formation is facing and the angle it deformed
22.What happens at each place where orogenies occur? - Mountains are built
23.What is isostasy?
- The lithosphere “floating” on the asthenosphere
24.What is a craton? What are the parts of a craton?
- A craton is where no deformation has occurred for at least 1 billion years; parts of a craton are shield (Precambrian rock is exposed) and platform (Precambrian rock is covered with sediment)
I announced in class when we deviated from the textbook. Please remember, as stated in the syllabus, that when the lecture and textbook deviate from each other, the lecture is where you should get your information.
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Monday, October 17 from noon until 2:00pm
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