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What is the difference between ductile and brittle deformation?
- ductile: permanently deforming, bending
- brittle: breaking failure, snap
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What factors determine how a rock will respond to stress?
- temp
- pressure
- composition
- rate of strain
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From a bird’s eye view, are older or younger rocks exposed in the core of an anticline? What about a syncline?
- Anticline - older in middle
- Syncline - younger in middle
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Be able to draw a normal fault, a reverse fault, and a strike-slip fault, label the foot wall and hanging wall (for normal and reverse faults). Show the relative motion along the fault (i.e. hanging wall up or hanging wall down?).
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Do normal faults occur under compression or tension? What about reverse faults? What about strike-slip faults?
- Normal: tensional
- Reverse: compressional
- Strike-Slip: shear
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How do basins and domes form? Where are the oldest rocks in a basin? In a dome?
- Basin: bed dips inward, youngest in middle
- Dome: bed dips outward, oldest in middle
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Describe the elastic rebound theory for how earthquakes are generated.
- Plastic strain builds up along fault
- Strain exceeds elastic limit
- Brittle failure
- Sides snap to new low-strain positions
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What is the difference between the measures of earthquake magnitude and intensity
- Magnitude: measure of energy released in EQ, only 1 mag, Richter scale
- Intensity: measure of ground shaking in EQ, depends on distance & material, many intensities
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What factors affect the intensity of shaking felt?
- Distance from epicenter
- Ground material
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What is the difference between body waves and surface waves?
- body: move through earth, faster, P & S waves
- surface: move across surface, slower, more damage, Love & Rayleigh waves
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What is the difference between P-waves and S-waves?
- P-Wave: primary, high velocity, compressional, back & forth, parallel to direction
- S-Wave: secondary, slower, transverse, side to side, perp to direction
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Describe how you determine where the epicenter of an earthquake is.
- Triangulate using the distance and times from 3 stations
- Where all 3 circles overlap is the epicenter
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How much bigger than a magnitude 3 earthquake is a magnitude 7?
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The 1985 Mexico earthquake caused severe damage in some parts of Mexico City but not in others, why was this?
Different geological materials?
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Explain how lithosphere and asthenosphere behave differently
- lithosphere: 100 km thick, rigid/brittle, floats on aesthenosphere
- Aesthenosphere: plastic/fluid
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What is a tectonic plate?
Section of earth's crust
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What are the three types of plate boundary?
- Divergent
- Convergent
- Transform
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Give one example of a transform plate boundary.
San Andreas/California
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What are the three types of convergent margins?
- O-O - older & colder subducts
- O-C - oceanic subducts below cont
- C-C - no subduction, large mtn ranges
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What is the significance of the trench found at subduction zones?
- Large EQs
- Volcanoes
- Very deep
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What geologic hazards are associated with convergent plate margins?
- Large deep EQs
- Volcanoes
- Large mtn ranges
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What types of plate boundary exist in Mexico?
Convergent
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Outline three different lines of evidence that was used to support continental drift
- Fit of continents
- Matching rocks
- Alignment of mountain ranges
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Know what a hot spot is and an example of one
- Hot spot: plume of heat rising from mantle
- Hawaii, Yellowstone
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What is an island arc and an example of one?
- Islands formed by tectonic process, convergent boundaries
- Japan
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Why wasn’t continental drift taken seriously when first proposed in the early 20th century?
No driving mechanism
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What are two characteristics of mountain ranges?
- size & alignment: long and parallel to other ranges
- age: taller ranges tend to be younger
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What is the relationship between how high a mountain range is and its relative age?
Taller = younger, not yet eroded
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What is a craton?
- region of continent that has been structurally stable for prolonged period of time
- thin layer of sed rock
- same density rocks at mtn range
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Be able to explain the term isostacy in terms of a mountain range.
- balance rock masses within earth
- heavier rocks sink
- lighter rocks float
- isostatic rebound
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What is the atmosphere?
- envelope of gases surrounding the planet
- 78% nitrogen, 21% oxygen
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What is the difference between weather and climate?
- weather: daily, given time and place, temp/precip/wind
- Climate: comp of weather patterns over long time, regional, seasons, years
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What were the findings of the IPCC?
- Intergov Panel on Climate Change
- assessment of climate change
- human impact on climate
- emission of GHG highest in history
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What do we know about temperature changes over the last century?
Rising
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What are the probable consequences of climate change?
- sea level rise 23 inch by 2100
- 100M ppl live within 3 feet of sea level
- glaciers melt
- strong hurricanes, droughts, heat waves, fires
- deserts and food shortages
- mass extinction
- ocean conveyor belt altered
- positive feedback effect
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When air sinks and heats up which is more likely, evaporation or precipitation?
precipitation
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How much have global climate temperatures increased over the past 100 years?
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What causes waves to form?
strong winds blowing across the ocean
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What is the difference between a summer beach and a winter beach?
- Summer: gentle waves, wide beach
- Winter: storm waves, small beach
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What is longshore drift and how does it affect the coastline?
- Sand being transported along the beach
- Moves sand by striking at angle
- causes erosion and deposition
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What are groins, jetties and breakwaters and how do they disrupt longshore drift?
- groin: object sticking out from beach, blocks sand from moving, causes dep & erosion
- jetties: extensions from land to prevent waterways from being blocked by deposition
- breakwater: object offshore to break waves early
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What is wave refraction and how does that relate to coastal straightening?
- slowing & bending of waves in shallow water
- one side hits first, starts to bend
- wraps around headlands to hit on both sides
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What man-made measure are used to combat coastal erosion?
- groins
- jetties
- walls
- breakwaters
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Describe two landforms found along an erosional coastline.
- cliffs
- arch
- stack
- marine terrace - bedrock lifting up
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Describe two landforms found along a depositional coastline.
- barrier island
- tombolo - sand bar connecting land & island
- spit
- lagoon - isolated by barrier island
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Know the difference between an emergent coastline and a submergent coastline
- emergent: drop in sea level relevant to sea level fall or tectonic uplift, marine terrace
- submergent: rise in sea level relevant to sea level rise or tectonic downthrow, estuaries
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