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Dynamic Earth > Exam III Review > Flashcards

Exam III Review Flashcards

1
Q

Age of the earth

A

4.565 Ga

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2
Q

What distinguishes the mechanical layers? How do they relate to the compositional layers?

A

Lithosphere: rigid solid (crust and upper mantle, including Moho)
Asthenosphere: weak solid (mantle)
Outer core: liquid (core)
Inner core: solid (core)

The lithosphere is primarily oxygen/silicon/aluminum/magnesium, the asthenosphere is primarily oxygen/silicon/magnesium, the outer core is mostly liquid iron, and the inner core is mostly solid iron.

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3
Q

How fast do plates move?

A

1-15 cm/year

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4
Q

Types of plate margins and most highlighted examples of each

A

Convergent: north american plate meeting pacific plate
Divergent: mid atlantic ridge, east african rift
Transform: fracture zones around mid atlantic ridge

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5
Q

In what tectonic environment are volcanic arcs formed?

A

Convergent boundaries/subduction zones

Mariana Islands, Cascades, Andes

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6
Q

What is the difference between a theory and a hypothesis?

A

Hypothesis: An explanation for observations to be tested (may be supported, not confirmed)

Theory: An explanation for observations that have been tested numerous times and is supported by evidence

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7
Q

What are the four components of the definition of a mineral used in lecture?

A

1) solid
2) naturally occurring
3) crystalline structure
4) definable composition

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8
Q

Most abundant mineral in crust of the Earth

A

plagioclase feldspar

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9
Q

What are the three rock types, what differentiates them, and what are their rock forming processes?

A

1) Igneous: made from magma
2) Metamorphic: recrystallizing in solid state
3) sedimentary: rock fragments/dissolved rock components compacted on surface

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10
Q

Common examples of igneous, sedimentary, and metamorphic rocks

A

Igneous: Obsidian, tuff, scoria, pumice, breccia, granite, diorite, gabbro, rhyolite, andesite, basalt, “porphyritic ____”

Sedimentary: coquina, fossiliferous limestone, oolitic limestone, chalk, rock salt, gypsum, coal, conglomerate, breccia, sandstone, chert, mudstone, shale

Metamorphic: slate, phyllite, schist, gneiss, quartzite, marble, amphibolite, hornfels

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11
Q

What is the concept of uniformitarianism; what are simple examples of its application?

A

Definition: processes we see active today were active in the past and explain analogous characteristics observed in rocks

ex: crossbedding=sand dunes, poor sorting and striations=prolly glaciers?

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12
Q

What group of minerals is a product of weathering and common in soils?

A

Clay minerals (Kaolinite?)

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13
Q

Key nutrients in soil

A

Nitrogen, Phosphorus, and Potassium

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14
Q

How is metamorphism different from igneous processes?

A

It recrystallizes in the solid state, not the liquid state

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15
Q

How does foliation orientation relate to directions compressional tectonic stresses?

A

Foliation orientation forms perpendicular to tectonic stress

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16
Q

Epicenter vs focus (hypocenter)

A

Focus/hypocenter: the place inside Earth’s crust where an eq originates

Epicenter: The point on the Earth’s surface directly above the focus

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17
Q

Difference between magnitude and intensity

A

Magnitude: measure of energy

Intensity: measure of the effect on humans

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18
Q

how much more energetic is an earthquake 1 magnitude than another? Difference of 2? etc

A

32x increase per magnitude (going up twice would be 1000x, 32 x 32)

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19
Q

What does the S wave shadow zone tell us? why?

A

that s waves can’t pass through the core/liquid/fluid because of their lower velocity/shear motion??

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20
Q

What does seismic tomography tell us?

A

it creates a 3D image of variations in seismic-wave velocities within the earth to understand where waves will speed up and slow down (with anomalies of course)

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21
Q

Types of Faults (identify in photos)

A

normal (hanging wall block goes down, foot wall block goes up)
reverse
thrust
strike slip

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22
Q

Stress versus strain

A

strain: change in object’s shape in response to application of stress
stress: force applied to a surface which causes strain/deformation

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23
Q

Brittle vs plastic deformation

A

brittle: cracking and fracturing (faults and joints)
plastic: becoming flattened or elongated without cracking/breaking (folds and foliation)

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24
Q

What are strike and dip?

A

Strike: a line where a geologic plane intersects a horizontal plane

Dip: the angle at which the plane enters the earth

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25
Q

What do plunging folds look like on a map or aerial photograph?

A

looks like flattened fold patterns on surface (if you can see folds on a geologic map, it’s plunging)

Sheep Mountain, Wyoming

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26
Q

What kind of stresses cause folding?

A

Reverse/thrust faults, convergence

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27
Q

Recognize the five kinds of folds

A

1) anticline (like an A, old rocks on peak)
2) syncline (like a V, young rocks in pinched bottom)
3) Monocline: one sloping surface between the horizontal
4) Dome: upward focused on a point
5) Basin: downward focused on a point

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28
Q

Recognize map patterns of synclines and anticlines based on ages of rocks and/or strike and dip symbols

A

Remember: old in middle is anticline, young in middle is syncline

study strike and dip maps

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29
Q

Stresses responsible for normal vs reverse faults

A

Normal faults produced by divergent/extensional stress

Reverse faults produced by convergent/compressional stress

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30
Q

How are joints and faults different?

A

Joints: planar fractures in rocks along which no movement has taken place, caused by divergent tension?

Faults: fractures/break in rock along which movement has taken place

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31
Q

What kind of structure is responsible for the Basin and range landscape in the western US?

A

horsts and grabens (ranges and valleys)

Tectonic divergence/extension

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32
Q

What are thrust faults? Where are fold and thrust belts found in the US (two examples)

A

Thrust faults are reverse faults with a low angle

Fold and Thrust belts: form during continental collisions and subduction zones

Ex: Appalachians, Rockies, Black Hills?

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33
Q

What does the term orogeny mean?

A

Orogeny: mountain building event

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34
Q

What modern technology can track deformation in ‘real time’? at what rate?

A

GPS (mm/year)

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35
Q

Difference between relative and numerical age

A

relative: describes ages of features with respect to another but doesn’t directly involve a numeric age
numeric: specific age dating based on radioactive decay

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36
Q

highlighted techniques other than radiometric dating that yield numerical ages

A

tree rings, varves (lake beds), annual ice layers in glaciers

37
Q

principles used to document relative age and correlation of geologic units (there’s 6)

A 
"principle" of superposition
"" cross cutting relationships
""inclusions
"" original horizontality 
"" lateral continuity 
"" fossil succession
38
Q

be able to interpret the relative ages of two geologic features in a photo or diagram

A

practice

39
Q

the geologic time scale: knowing geologic time scale elements requested in class (look at photo)

A

look at photo, cuz I’m struggling lol

Ugh, now I gotta pull up that photo

Yeah. Sorry bout that lol

40
Q

Three kinds of unconformities (recognize in pictures)

A

angular unconformity
nonconformity
disconformity

41
Q

How are unconformities interpreted?

A

They’re interpreted as breaks in the geologic record; missing time

42
Q

Concepts of radioactive decay, parent/daughter, half/life

A

radioactive dating: utilizes time dependent decay of radioactive isotopes

parent: isotopes of elements that are unstable and undergo spontaneous change, releasing energy
daughter: the new isotope of a new element created by the decaying parent

half life: the time required for 1/2 of a quantity of an isotope to undergo decay

1/2, 1/4, 1/8

43
Q

know parent-daughter element pairs highlighted in class that are used for age dating

A

K > A
C > N
U > Pb

44
Q

eon during which most continental crust formed

A

Archean eon

45
Q

general term for old cores of continents

A

cratons

46
Q

eon of most of the rocks at the core of the black hills

A

Proterozoic eon

47
Q

era and period that life diversifies and there was improved preservation of fossils, and the name given to this “event”

A

Era: Paleozoic
Period: Cambrian

Cambrian explosion

48
Q

era that the Appalachians were built

A

Paleozoic era

49
Q

era in which the rockies, including the black hills, popped up (and name of orogeny)

A

Cenozoic era (laramide orogeny)

50
Q

in what era and period did a great inland sea last cross most of South Dakota?

A

Mesozoic era, Cretaceous period

51
Q

what event frequently marks the boundaries between units of the geologic time scale?

A

extinctions

52
Q

highlight mass extinction, timing, and cause

A

K-Pg extinction (end of Mesozoic, start of Cenozoic era) 66 Ma

meteorite impact in Yucatan peninsula in Mexico

53
Q

eon of oldest fossils

A

Archean Eon (3.2 Ga)

54
Q

era of dinosaurs

A

Mesozoic Era

55
Q

era that the badlands rocks were deposited?

A

Cenozoic era, Paleogene period

56
Q

significance of banded iron formations in history of planet?

A

Indicates the oxygenation of atmosphere which causes the iron to settle out of the water and into banded formations in the ground (happened in Archean eon)

57
Q

epoch of glaciations and name of most recent

glaciation

A

Pleistocene epoch (Quarternary period, Cenozoic era)

Wisconsin Glaciation, 21 ka

58
Q

epoch since the ice ages

A

holocene (most recent epoch)

59
Q

eon of oldest rocks in SD

A

Archean eon (millbank granite)

60
Q

name of most recent glaciation

A

Wisconsin Glaciation, 21 ka

61
Q

three aspects of mass movements that bear on their classification

A

material, velocity, type of movement

62
Q

recognize photos of clear examples of different types of mass movement highlighted in class

A

rock fall, rock slide, debris flow, mud flow, creep, slump, solifluction, lahar

63
Q

what effects might you see in an area where creep has been occurring?

A

cracked roads, cracked parking lots, tilted power poles, bent tree trunks, tilted vertical sedimentary beds

64
Q

equation for force

A

force = mass x acceleration

65
Q

with respect to forces associated with mass movements, under what conditions will mass movements occur?

A

increasing mass: add more geologic material, water, or construction

increasing acceleration: earthquakes

(decreasing resisting forces: steepen slopes, weaken slopes, decrease friction)

66
Q

why does a modest amount of water actually increase the strength of sand?

A

Surface tension causes cohesion between water and grains

67
Q

Under what condition does water allow unconsolidated material to flow?

A

liquefaction!

extreme saturation + shaking decreases friction between grains and weakens the material

68
Q

What is solifluction?

A

slow flow of saturated soil (like creep but with a bit more flow)

happens due to ice deep within soil that thaws and expands/contracts, making lobes

69
Q

Parts of a slump?

A

scarp/head scarp + slip surfaces + toe

70
Q

ways in which human activities promote mass wasting and increase exposure to the hazard

A 
we build right up to the edge of steep surfaces (both  at bottom and at top)
water mismanagement (farms)
construction
71
Q

what is the term for a volcanic mudflow/debris flow?

A

lahar

72
Q

What is a stream?

A

water flowing downslope in a channel (rivers, creeks, &c)

73
Q

Three geologic functions of a stream

A

Erosion
Transportation of sediment
Deposition of sediment

74
Q

different ways that streams erode

A

scouring (eroding), plucking (breaking and lifting), abrasion (abrading bedrock)

75
Q

Recognize in photos or diagrams the regional stream patterns and what simple geology causes them

A

dendritic (homogenous geology)

rectangular (jointed)

radial (volcano)

trellis (folded)

76
Q

Be able to calculate discharge and gradient

A

Discharge: width x depth x velocity

Gradient: drop in elevation (top – bottom) /distance

77
Q

Major watersheds (3) which are partly in SD (eg Missouri River)

A

Missouri River, Mississippi River, Minnesota/Red/Hudson?

78
Q

Three types of load, how is material moved in each?

A

Bed load (rolling and saltation)

Suspended load (small particles stay off of bed)

dissolved load (transported as ions in solution)

79
Q

What is the shape of a graded stream profile? straight, concave-up, or convex-up

A

Concave up

80
Q

What is base level?

A

the elevation below which a stream cannot cut (sea level is ultimate base level)

81
Q

Three kinds of stream channel patterns: what makes them different? where do they occur in stream systems?

A

straight: confined by topography/bedrock in mountain stream systems
braided: smaller, weaving channels that clog themselves with sediment, found near mountain fronts
meandering: large loopy bends across floodplains

82
Q

Recognize in photos, and understand the origins of, point bars, cut banks, natural levees, alluvial fans, deltas, terraces, and ox bow lakes

A

point bars: inner sides of bends

cut banks: outside of bends

natural levees: created when a stream floods

alluvial fans: created when a stream gradient decreases

deltas: created when stream hits still water
terraces: stream floods, creates floodplain, then starts to down cut and create stream terraces

oxbow lakes: meandering stream cuts through a meander neck (cutting off its loops)

83
Q

compare and contrast regional and flash floods

A

flash floods: in upper parts of basins, caused from intense downpour in small area but may not cause flooding in large rivers downstream, causes largest number of deaths

regional/seasonal floods: produced by storms of long duration or periods of sudden snowmelt, causes most damage

84
Q

know the basics of the floods discusses in class (China 1931, Rapid City 1972, Vermillion 1881, Midwest 1993, Johnstown 1889 [reading])

A

China 1931: 3.7 million killed (worst nat disaster ever)

Rapid City 1972: 500 yr flood, 238 killed, 3,057 injured, $160 million in damage, Rapid Creek reached 50K cfs

Vermillion 1881: 3/4 of town destroyed, ice dam in yankton broke, town relocated to top of bluff

Midwest 1993: 50 killed, $15 billion in damage, happened between June and August, >190 days

Johnstown 1889: 2,300 dead, poorly made dam collapsed

85
Q

How does development change flood behaviour?

A

examples of development: paving, building, destroying wetlands, reducing forest

effect: allows water to move more rapidly through system, duration of floods is shorter but the peak intensity is higher

86
Q

Can a record of flooding be used to analyze floods of greater recurrence interval than the length of the record?

A

Yes (38 yr record can predict 100 yr flood)

87
Q

What is the recurrence interval used by FEMA for floodplain mapping?

A

the average time between a flood and next occurrence of a flood of the same or greater magnitude

1/RI (x 100 for %)

The probability of having a 100 year flood in any given year is 1% (1/100 x100)

88
Q

Determine probability of an RI-year flood in any given year (simple ones, so as to not require a calculator)

A

1/RI (x 100 for %)

The probability of having a 100 year flood in any given year is 1% (1/100 x100)

Dynamic Earth (4 decks)

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