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Geography > Tectonics, Earthquakes, & Volcanism > Flashcards

Tectonics, Earthquakes, & Volcanism Flashcards

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1
Q

What is an eon?

A

the longest time period in the geologic time scale; we are currently in the Phonerezoic Eon

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2
Q

What is an era?

A

the longest time period in the eon; we are in the Cenozoic Era

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3
Q

What is a period?

A

the longest time period in the era; we are currently in the Quaternary Period

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4
Q

What is the difference between absolute and relative time?

A
  • absolute: measured in years

- relative: measured in events

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5
Q

What is stratigraphy?

A

the study of the formation of rocks over relative time

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6
Q

What is the Principle of Superposition?

A

the idea that rock layers are younger towards the surface and older below the surface

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7
Q

What is the Principle of Uniformitarianism and why is it significant?

A
  • the same processes we see today have always occurred throughout geologic time
  • allows us to make assumptions about how rock formations were created
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8
Q

How do we know about the interior of the Earth?

A
  • information that has been collected via earthquakes

- seismic waves travel through different materials in the interior at different rates

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9
Q

How did the Earth form (3)?

A
  • condensed from a nebula of dust, gas, and icey comets about 4.6 billion years ago
  • as they cooled, they solidified and sorted by density
  • more dense material was sorted towards the center and less dense material was sorted towards the surface
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10
Q

What is Earth’s energy source (2)?

A
  • interior is hot and heat migrates outward towards the surface
  • drives movement of material and volcanic activity
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11
Q

What is the content of Earth’s core (2)?

A
  • inner core: solid, pure iron; above melting point but does not melt due to pressure and weight of overlying material; very dense
  • outer core: molten iron
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12
Q

What is the content of Earth’s mantle (4)?

A
  • hot; not as hot as core
  • mostly solid
  • represent greatest volume of Earth
  • consists of lower mantle, upper mantle, and asthenosphere
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13
Q

What is the content of Earth’s lithosphere (2)?

A
  • uppermost mantle: rigid

- mhorovicic (moho) discontinuity: boundary between uppermost mantle and crust; seismic waves

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14
Q

What is the content of Earth’s crust (2)?

A
  • oceanic crust thinner

- continental crust thicker`

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15
Q

What is the Geologic Cycle (3)?

A
  • the rock cycle: the production of different types of rocks
  • the tectonic cycle: the movement and deformation of the crust
  • the hydrologic cycle: erosion, weathering, and movement of eroded material
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16
Q

What are the elements that combine to make rocks (8)?

A
  • oxygen
  • silicon
  • aluminum
  • iron
  • calcium
  • sodium
  • potassium
  • magnesium
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17
Q

What are minerals?

A

inorganic natural substances with a specific formula and some sort of crystalline structure

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18
Q

What are the seven properties of minerals?

A
  • hardness
  • color
  • density
  • luster
  • fracture
  • taste/smell
  • magnetism
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19
Q

What are rocks?

A

an assemblage of minerals that are bound together as part of the lithosphere

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20
Q

What are the three types of rock?

A
  • igneous
  • sedimentary
  • metamorphic
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21
Q

How do igneous rocks form?

A

form from material that has melted under high pressure/temp. inside the mantle/crust

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22
Q

What is the difference between magma and lava?

A
  • magma: moleten rock below the surface

- lava: molten rock above the surface

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23
Q

What is the difference between intrusive and extrusive igneous rocks?

A
  • intrusive: cooled below the surface at a slower rate; course grain
  • extrusive: cooled above the surface at a faster rate; smooth grain
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24
Q

What is a pluton?

A

intrusive igneous rock formation; mass of slowly cooling rock

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25
Q

What is a batholith?

A

massive structure comprised of a number of plutons

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26
Q

How much of the Earth’s crust consists of igneous rock?

A
  • 90%

- typically granite for continental crust and basalt for oceanic crust

27
Q

How do sedimentary rocks form?

A

form from eroded rock/sediment that is deposited in low-lying areas

28
Q

What are the three types of sedimentary rock?

A
  • clastic: form from other rock sediments
  • organic: form from organic material
  • chemical: form from minerals suspended in water
29
Q

How do metamorphic rocks form?

A
  • experience a change in structure after encountering intense heat/pressure
  • tend to be harder and more resistant to erosion/weathering
30
Q

What is the difference between regional and contact metamorphism?

A
  • regional: occurs when rocks are buried below the surface and subjected to high heat/pressure over a long period of time
  • contact: occurs when rocks come into contact with something very hot
31
Q

What is the difference between foliated and nonfoliated rocks?

A
  • foliated: wavy lines (gneiss, schist)

- nonfoliated rocks: uniform (marble, quartzite)

32
Q

What is the Theory of Continental Drift (3)?

A
  • developed by Alfred Wagner in 1912?
  • explains why continents fit together like a puzzle
  • over time the continents drifted apart
33
Q

What are two pieces of evidence that support Wagner’s theory?

A
  • matching fossil records across continents

- matching rock formations across continents

34
Q

What is the Theory of Plate Tectonics?

A

the idea that the Earth’s crust is divided into 14 tectonic plates which float on the asthenosphere

35
Q

What are the four processes of plate tectonics?

A
  • upwelling of magma: occurs along some plate boundaries
  • lithospheric plate movements: upwelling of magma forces lithospheric plates away from one another
  • seafloor spreading: creation of new oceanic rock pushes everything outward
  • subduction: older crust dips down below another tectonic plate
36
Q

What are you likely to encounter near subduction zones?

A

volcanoes and earthquakes

37
Q

What are the two mechanisms of plate motion?

A
  • ridge push: upwelling of magma at mid-ocean ridge

- slab pull: oceanic crust is pulled below continental crust

38
Q

What are the three interactions at plate boundaries?

A
  • divergent: occurs at mid-ocean ridge and rift zones
  • convergent: two plates converge together and create a subduction zone
  • transform: lateral side-to-side movement causes earthquakes but no volcanoes
39
Q

What are hot spots (4)?

A
  • volcanic activity not found along tectonic plate boundaries
  • 50-100 hotspots worldwide
  • example: Hawaii and Yellowstone
  • can be stationary or appear to move due to plate movement
40
Q

What is deformation?

A

how stress affects rock

41
Q

What are the three types of deformation?

A
  • tension: stretching
  • compression
  • shear: twisting/lateral movement
42
Q

What are the impacts of deformation (2)?

A
  • folding: rock is slowly bent

- faulting: rock breaks

43
Q

What is the difference between ductile and brittle rocks?

A
  • ductile: malleable/bendable

- brittle: more likely to break

44
Q

What is the difference between an anticline and a syncline?

A
  • anticline: top end of folding curve

- syncline: bottom end of folding curve

45
Q

What is warping?

A
  • continental crust curves upwards

- forms basins/domes

46
Q

What are the three types of faults?

A
  • normal: tensional stress; divergent; hanging-wall side moves down, footwall side moves up; results in fault scarp/escarpment
  • reverse: compressional stress; convergent; hanging-wall side moves up, footwall side moves down
  • strike-slip/transform: shear stress; right lateral vs left lateral
47
Q

What are earthquakes?

A

buildup of energy on both sides of fault is released

48
Q

What is the focus?

A

location along the fault plain where the earthquake actually originates

49
Q

What is the epicenter?

A

where the earthquake occurs at the surface

50
Q

What is aftershock?

A

earthquake that occurs after the main earthquake

51
Q

What is a seismograph?

A

instrument that records vibrations when earthquake occurs; can pinpoint epicenter and focus

52
Q

What is the difference between a qualitative and quantitative scale?

A
  • qualitative: based upon the impact of the earthquake

- quantitative: measures the magnitude of energy released by the earthquake

53
Q

What are the three scales used to measure earthquakes?

A
  • moment magnitude
  • modified mercalli
  • richter
54
Q

What are seismic hazard zones?

A

plate boundaries

55
Q

What was the magnitude of the Loma Prieta earthquake

A

6.9

56
Q

Where does volcanic activity usually occur (3)?

A
  • subduction zones
  • mid-ocean rifts
  • hot spots
57
Q

What are the two defining characteristics of volcanic lava?

A
  • high viscosity: thick and slow

- low viscosity: thin and fast

58
Q

What are the two types of volcanic eruptions?

A
  • effusive: gentle; low viscosity; shield volcanoes; basalt rock
  • explosive: violent; high viscosity; composite volcanoes; pyroclastic material
59
Q

What are the two types of lava?

A

aa: jagged edges
pahoehoe: thin crust cools; remains melted below

60
Q

What are cinder cones?

A

much smaller than volcanoes; no lava; formed under a series of eruptions spewing only pyroclastic material

61
Q

What is a caldera?

A

depression which forms when summit of volcano collapses

62
Q

What are the three types of orogenesis?

A
  • oceanic-continental convergence: more dense oceanic crust dips down below less dense continental crust (Andes Mountains)
  • oceanic-oceanic convergence: older sea floor dips down below newer sea floor (Japan, Indonesia, Philippines); creates trenches
  • continental-continental convergence: continental plates crumple into each other (Himalyan Mountains); volcanoes don’t usually occur, but earthquakes do
63
Q

What are fault block mountains (4)?

A
  • pairs of normal faults act together to create a mountainous environment
  • horst: upfaulted block
  • graben: downfaulted block
  • example: Basin & Range, United States

Geography (11 decks)

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