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GEOG 121 > Chapter 14 > Flashcards

Chapter 14 Flashcards

1
Q

Continental Drift

A

Alfred Wegner
old theory that continental landmasses were “drifting” across the earth (Pangea)
evidence: similar fossils and glaciated continents fit

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2
Q

Plate Tectonics Theory

A

lithospheric plates move as a result of slow convection in Earth’s mantle; plates float on the asthenosphere

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3
Q

Evidence of plate tectonics

A

paleomagnetism: iron cooled magma orients itself with the magnetic poles of earth; this is used to verify age of ocean floor rock and seafloor spreading

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4
Q

Divergent Boundaries

A

plates move away from each other
- midocean ridges; earthquakes and volcanoes; seafloor spreading

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5
Q

Oceanic-continental convergent boundaries

A

oceanic plate sinks bc it is more dense (SUBDUCTION)
- forms oceanic trenches and continental mountains
- earthquakes and volcanoes along this boundary
- forms metamorphic rocks

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6
Q

Oceanic-Oceanic convergent boundaries

A

results in an undersea trench formation
- deep shallow earthquakes
- Pacific Ring of Fire (75% of volcanoes are here)
* SO MUCH SUBDUCTION HERE

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7
Q

continental-continental convergent boundaries

A

NO SUBDUCTION bc plates are highly buoyant
- builds huge mountain ranges
- shallow earthquakes
- no volcanoes

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8
Q

Transform boundaries

A

two boundaries slip past each other laterally
- transform faults (san andres fault)
- produces earthquakes

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9
Q

Mantle Plumes

A

localized hot areas NOT associated with plate boundaries
- move with the plate so eventually become inactive
- explains anomalous volcanoes

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10
Q

Accreted Terranes

A

piece of lithosphere carried by a plate that eventually collides and fuses with another plate

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11
Q

Extrusive Volcanism

A

occurs on Earth’s surface; lava cools quickly->no time for atoms to bond->fine igneous rocks

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12
Q

Intrusive volcanism

A

occurs below the surface; plutonic activity; lava cools slowly->atoms have time to bond-> coarse-grained igneous rocks

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13
Q

viscosity

A

resistance to flow
high silica: high viscosity: SLOW FLOW
low silica: low viscosity: FAST FLOW

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14
Q

Explosive Eruptions

A

high silica, high viscosity, pyroclastic, granite

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15
Q

Gentle Eruptions

A

low silica, low viscosity, basalt

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16
Q

Volcanic HAZARDS

A

volcanic gases: can cause acid rain, alter global climate
eruption clouds: gas and ash material clouds
pyroclastic flows: avalanche of hot gases
volcanic mudflows (LAHARS): result from heavy rain and or snow melt during an eruption

17
Q

Volcanic POSITIVES

A
  • much of earth’s water originates from water vapor from volcanoes
  • magma contains elements required for plant growth
  • provides soil fertility
18
Q

Flood Basalt

A

A vast accumulation of lava build up; correlated with mass extinctions

19
Q

Shield Volcanoes

A

layer upon layer of solidified lava flows; little pyroclastic material; not steep (Hawaiian islands)

20
Q

Composite Volcanoes

A

emit higher silica lava (andesite lava); form symmetric, steep sided volcanoes; pyroclastics from explosive lava flows alternate with nonexplosive lava; pyroclastic flow produces steep slopes, lava holds it together

21
Q

Lava Domes

A

masses of viscous lava that does not flow far; lava bulges from the vent, done grows by expansion from below and lava within; some domes form inside composite volcanoes

22
Q

Cinder Cones

A

baby volcanoes; grow on big volcanoes; basaltic magma is common; slopes form from pyroclastic materials

23
Q

Calderas

A

result from a volcano that explodes, collapses, or both; immense basin-shaped depression; larger than original crater

24
Q

volcanic necks

A

pipe or throat of an old volcano that filled with solid lava

25
Q

Diatrophism

A

the deformation of earth’s crust through two processes (folding and faulting)

26
Q

Folding

A

when rock is subjected to lateral compression
- anticline/upfold: can be forced to have reverse orientation, an overturned fold (upside down U)
- syncline/downfold: overthrust fold (U)

27
Q

Faulting

A

occurs when rock breaks accompanied by displacement
- occurs along zones of weakness in the crust, fault zones
- begin as sudden ruptures, end in big faults

28
Q

Normal fault

A

going away from each other

29
Q

Reverse fault

A

going towards each other

30
Q

thrust fault

A

older rocks are pushed towards younger rocks

31
Q

strike slip fault

A

blocks move horizontally; create linear fault troughs; sag ponds; offset drainage channels; shutter ridge

32
Q

Earthquakes

A

vibration in Earth resulting from sudden displacement along a fault; the ground above the origin (the epicenter) experiences strongest jolt

33
Q

P waves vs S waves

A

P waves go from long to short to long
S waves stay at a consistent cycle

34
Q

Hazards of Earthquakes

A

damage from ground shaking
liquefaction of moist sediments
landslides
tsunamis

GEOG 121 (7 decks)

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