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G108 > My Notes for Unit 3 > Flashcards

My Notes for Unit 3 Flashcards

1
Q

What does lava help to tell us?

A

What is down deeper

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2
Q

Composition of meteorites is like that of___.

A

Earth

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3
Q

Earth is made of___stuff inside, ___stuff outside.

A
  • heavier

- lighter

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4
Q

What is gravitational differentiation?

A
  • iron and nickel
  • sink down to the bottom
  • density separation of elements
  • heavier elements sink down
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5
Q

What percent of Earth’s core is iron? Nickel?

A
  • Iron = 93%

- Nickel = 3%

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6
Q

What is silica?

A

silicone and oxygen

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7
Q

What is silicate

A

silica and some other element

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8
Q

What is the mantle almost entirely made out of?

A

silicate minerals

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9
Q

What happened to the primitive crust?

A

We don’t have any of the primitive crust left. Buried by geological processes.

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10
Q

What is the continental crust the result of?

A

Ca, K Na, Al (silicates)

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11
Q

What is the oceanic crust made out of?

A

Fe, Mg, Ca, Al (silicates)

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12
Q

What is the inner core made out of?

A

Solid Earth: Fe, Ni

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13
Q

What is the outer Core made out of?

A

Liquid Earth: Fe, Ni

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14
Q

What is mantle made out of?

A

Fe, Mg, Ca, Al (silicates)

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15
Q

Solidus?

A

The temp at which melting begins A mixture of solid and liquid.

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16
Q

What is the solidus controlled by?

A

controlled by lithosphere and pressure

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17
Q

Why are planetary bodies hot inside?

A

1) Gravity (accretion pressure and impact of asteroids and comets)
2) Atomic Fission (breakup up of atomic isotopes)

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18
Q

What is isostasy?

A

The lithosphere-crust and upper mantle is not actually sitting on the mantle–it is floating on it. Rocky crust is floating on lithosphere (floating equilibrium).

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19
Q

What happens when a glacier flows on X-Sections (isostasy)?

A

When a glacier flows, it is the additional weight added to the crust by the weight of the glacier that creates floating. When a glacier melts, the land surface will come backup. depresses lithosphere into mantle.

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20
Q

What happens after volcanism?

A

Ground will “rebound” after volcanism ceases for good and erosion strips away the top.

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21
Q

What are the two different ways to discuss the outer part of Earth?

A

1) Chemical composition (rock type)

2) Physical strength

22
Q

What are the two crustal parts?

A

continental and oceanic

23
Q

What is the depth of the continual crust?

A

35 km depth (shallows towards ocean)

24
Q

What is the depth of the oceanic crust?

A

8 km depth (close to ocean)

4 km depth (rocky depth)

25
Q

What is the contact between mantle and base of crust called?

A

Moho

26
Q

Physical strength of outermost part of mantle is similar to___ ___.

A

crustal ricks

27
Q

What is under the lithosphere?

A

A unit that is physically weak called the asthenosphere.

28
Q

What is the asthenosphere?

A

weak sphere

29
Q

What is the lithosphere?

A

strong sphere

30
Q

What makes up the upper mantle?

A

asthenosphere and lower part of lithosphere

31
Q

What is the weakest part of the earth system?

A

asthenosphere.

32
Q

What is broken into tectonic plates?

A

lithosphere

33
Q

What do the tectonic plates move over?

A

the asthenosphere

34
Q

What is the material the lithosphere is composed of?

A

rock

35
Q

When were the major ice ages (4 of them)?

A

~600-700 (Paleozoic)
~450 (Paleozoic)
~300-250 (Mesozoic)
~3-now (Cenozoic)

36
Q

What is planetary magnetism off-set with?

A

Geographic poles (spin axis), but this is temporary

37
Q

Magnetic poles___with time.

A

shift

38
Q

What is magnetic polar shift?

A

The fact that magnetic poles shift several km/year (irregular), so their positions move over the globe (mainly polar regions) a considerable amount.

39
Q

Is the strength of magnetism set or varied?

A

Varied, but may not drop to zero

40
Q

Is the strength of magnetism increasing or decreasing at present?

A

decreasing

41
Q

What is magnetic polar reversal?

A

After weakening it becomes chaotic (theory), then builds back up…sometimes in the opposite sense.

42
Q

Earth’s magnetic field varies in___[___] by perhaps___% over a time scale of decades to ventures. Does___appear to drop to zero.

A

vaires

  • intensity
  • 50
  • not
43
Q

What is polar shifting?

A

the poles “walk”…variable rate (~50 km/year for the past 20 years).

44
Q

What is the average position of the poles for that past are thousand years?

A

At the spin axis.

45
Q

On average, how ofter does the vector reverse with magnetic polar reversal?

A

3 times per million years

46
Q

Magnetism of planet Ear is___to what it would be if in the centre of the earth ere was a magnet.

A

similar

47
Q

What happens with basalt from volcanoes and Earth’s magnetism?

A

Basalt lavas always have a small amount of magnetite (FeO4). When basalt is still hot, not affected by magnetic field (1000 degrees C). When it reaches 700 degrees C, it becomes affected –> called Curie Temp.

48
Q

What are magnetic pole position sin northern hemisphere based on?

A

The remnant magnetism in igneous rocks for the last 20 ma.

49
Q

For how long has magnetic polar reversal been going on? How long do we have detailed measurements for?

A

at least the last 3 Ga – but we have detailed measurements only for the last ~160 Ma

50
Q

Magnetism will always be appalled with___ ___ ___.

A

force field lines

51
Q

What could be the 3 causes of Earth’s magnetism?

A

1) flowage of Fe material in liquid core (convective flow)
2) differential rotation – spin
- inner solid core spins slightly differently than rest of core because of liquid core.
3) force field follows ~ spin axis (self-exciting organism)

G108 (23 decks)

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