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Planet Earth > Exam 2 Review > Flashcards

Exam 2 Review Flashcards

1
Q

Pahoehoe

A

basaltic lava forming smooth undulating or ropy masses.

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2
Q

Viscosity

A

the state of being thick, sticky, and semifluid in consistency, due to internal friction.

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3
Q

Flood basalts

A

A flood basalt is the result of a giant volcanic eruption or series of eruptions that coats large stretches of land or the ocean floor with basalt lava.

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4
Q

Erupting column

A

cloud of hot volcanic ash suspended in volcanic gas emitted during an explosive volcanic eruption

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5
Q

Gas thrust region

A

At the base of the column, material is forced upwards out of the vent by the pressure of expanding gas, mainly steam. The gas expands because the pressure of rock above it rapidly reduces as it approaches the surface

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6
Q

Convective region

A

covers most of the height of the column. The gas thrust region is very turbulent and surrounding air becomes mixed into it and heated. The air expands, reducing its density and rising. The rising air carries the solid and liquid material from the eruption entrained in it upwards.

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7
Q

Umbrella region

A

As the column rises into less dense surrounding air, it will eventually reach an altitude where the hot, rising air is of the same density as the surrounding cooler air. In this neutral buoyancy region, the erupted material will then no longer rise through convection, but solely through any upward momentum which it has

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8
Q

Liquifaction

A

describes a phenomenon whereby a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid.

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9
Q

Hypsometric curve

A

histogram or cumulative distribution function of elevations in a geographical area. Differences in hypsometric curves between landscapes arise because the geomorphic processes that shape the landscape may be different.

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10
Q

Isostasy

A

the equilibrium that exists between parts of the earth’s crust, which behaves as if it consists of blocks floating on the underlying mantle, rising if material (such as an ice cap) is removed and sinking if material is deposited.

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11
Q

Craton

A

A portion of a continental plate that has been relatively undisturbed since the Precambrian Era.

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12
Q

shield

A

exposed part of the craton

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13
Q

platform

A

covered part of the craton

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14
Q

active margin

A

found on the leading edge of the continent where it is crashing into an oceanic plate

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15
Q

passive margin

A

transition between oceanic and continental lithosphere that is not an active plate margin.

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16
Q

lithosphere

A

0-100km

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17
Q

low velocity zone

A

100-200km

partial melt in asthenosphere

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18
Q

upper mantle

A

0-400km

between 200-400km, atoms pack more tightly

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19
Q

transition zone

A

400-600km

olivine transforms to spinel structure and to perovskite structure

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20
Q

lower mantle

A

600km-100km

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21
Q

layers of ocean crust

A 
sediment
pillow basalt
dikes
gabbro
lithosphere mantle
22
Q

hot spot

A

volcanic surface expression of a mantle plum

23
Q

mantle plume

A

– very hot, thin, cylinders of rising mantle

– may originate at the core mantle boundary

24
Q

rifting

A

Inception of rifting along the East African rift system

25
Q

east african rift system

A

look at picture in slides

26
Q

convergent boundary

A

is an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide.

27
Q

Benioff Zone

A

These earthquakes can be produced by slip along the subduction thrust fault or by slip on faults within the downgoing plate as a result of bending and extension as the plate is pulled into the mantle. Also known as the Wadati-Benioff zone

28
Q

Lithostratigraphy

A

Units are defined based on lithology

29
Q

Chronostratigraphy

A

Units defined based on time- equivalent stratal surfaces, natural stratigraphic subdivisions

30
Q

relative dating

A

how old rocks are in relation to one another

31
Q

absolute dating (isotopic dating)

A

exact age of rock body

32
Q

Steno’s Laws

A

Principle of Original Horizontality Principle of Lateral Continuity
Principle of Superposition

33
Q

Principle of Original Horizontality

A

Layers of sediment, when originally deposited, are fairly horizontal

34
Q

Principle of Lateral Continuity

A

ayers of sediment form fairly continuous sheets over a region

35
Q

Principle of Superposition

A

In a sequence of sedimentary rock layers, each layer must be younger than the one below

Rock layer above is younger than the ones below it

36
Q

Correlation

A

lithologic correlation = matching same rock types. by formations

also means establishing equivalency

37
Q

Unconformity

A

A surface of nondeposition and/or erosion

38
Q

Hiatus

A

Interval of time not represented at an unconformity

39
Q

Angular

Unconformity

A

Subsidence and subsequent deposition buries erosional surface

40
Q

Principle of Cross-Cutting Relationships

A

An igneous intrusion or fault that cuts through rocks is younger than the rocks it cuts.

41
Q

william smith

A

in 1815 published first geologic map of England

42
Q

faunal succesion

A

Faunas (fossils) succeed one another over time in a regular and determinable order (e.g. evolution)

– Similar fossils = similar rocks

– Relative ages determined from fossil content

43
Q

Biostratigraphy

A

study of layered rock using fossils

44
Q

Absolute geochronology

A

Adding ages to the Geologic Time Scale

45
Q

Dendrochronology

A

the science or technique of dating events, environmental change, and archaeological artifacts by using the characteristic patterns of annual growth rings in timber and tree trunks.

46
Q

Isotopic Dating

A

adioactive elements (parent) decay to nonradioactive (stable) elements (daughter).

The rate at which this decay occurs is constant and known

47
Q

Radioactive Decay Mechanisms

A

Three modes of decay

48
Q

Alpha Decay

A

A. 2 neutrons and 2 protons lost

49
Q

Beta Decay

A

neutron loses an electron and becomes a proton

50
Q

electron capture

A

a proton capture an electron and becomes a neutron

51
Q

Half-life = 4.5 Ga

A

The half-life of a radioactive isotope is defined as the time required for one-half of the parent to decay to the daughter

Planet Earth (3 decks)

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