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Dynamic Earth > Exam IV Review > Flashcards

Exam IV Review Flashcards

1
Q

Age of the earth

A

4.56 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

Which are most appropriate units for plate tectonic motion, cm/yr, m/yr, km/yr?

A

cm/yr (1-15 to be exact)

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4
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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5
Q

Most abundant mineral in crust of the Earth

A

plagioclase feldspar

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6
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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7
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, hornfel

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8
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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9
Q

Difference between magnitude and intensity

A

Magnitude: measure of energy

Intensity: measure of the effect on humans

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10
Q

Recognize synclines vs. anticlines in photos or diagrams

A

1) anticline (like an A, old rocks on peak)
2) syncline (like a V, young rocks in pinched bottom)

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

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11
Q

Recognize faults: normal, reverse, left-lateral and right-lateral strike-slip in photos or diagrams

A

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

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12
Q

Stresses responsible for folds, normal faults, and reverse faults

A

Normal faults produced by divergent/extensional stress

Reverse/thrust faults produced by convergent/compressional stress

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13
Q

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

A

practice

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14
Q

The geologic time scale: know the order of the three eras of the Phanerozoic eon and the general term for the time before that.

A

Phanerozoic eon’s eras: Paleozoic, Mesozoic, Cenozoic

Time before that: Precambrian

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15
Q

Eon of most of the rocks at the core of the Black Hills

A

Proterozoic

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16
Q

Era that the Appalachian mountains were built

A

Paleozoic era

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17
Q

Which came first, uplift of the Rockies, including the Black Hills, or deposition of the sedimentary rocks in the Badlands?

A

Within the Cenozoic Era, Paleogene period: Rockies/Black Hills are uplifted…then their shedded sediments + ash from distant volcanos form Badlands

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18
Q

Epoch of glaciations and name of most recent glaciation

A

Pleistocene epoch (Quarternary period, Cenozoic era)

Wisconsin Glaciation, 21 ka

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19
Q

Epoch used to describe time since the end of the ice ages

A

Holocene epoch

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20
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

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21
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

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22
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)

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23
Q

What distinguishes a glacier from a permanent snow or ice field?

A

In a glacier, the burden of additional snow without much seasonal melting forces crystals to compact into thick masses that flow under their own weight

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24
Q

~maximum thickness of North America’s past continental ice sheets?

A

3,000 m/10,000 ft thick

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25
Q

Ice shelves vs sea ice

A

Ice shelves source from ice sheets that have extended over onto the ocean

Sea ice is ocean water that has frozen

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26
Q

Be able to recognize different types of glaciers shown in class.

A

Mountain: cirque, valley, piedmont (think alluvial fan), ice caps (not topographically confined)

Continental: ice sheet, ice shelves (basically ice sheet but over the sea…NOT sea ice)

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27
Q

What percentage of fresh water is in glaciers? What percent of that in the two main ice sheets?

A

70% of fresh water is in glaciers

85% of that in Antarctic ice sheet

10% in Greenland ice sheet

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28
Q

What is the equilibrium line? what are the zones on either side, and what distinguishes them?

A

the line above the zone of accumulation and below the zone of ablation

accumulation: more snow/ice falls than melts per year
ablation: more snow/ice melts than falls in a year

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29
Q

Processes of glacial advance and retreat

A

advancing: zone of accumulation overpowers zone of ablation (when flow exceeds melting)
retreating: zone of ablation overpowers zone of accumulation
- glaciers don’t move backwards, they just stop flowing or melt faster than they flow

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30
Q

About how fast do glaciers usually move?

A

10-300 m/yr

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31
Q

What are the two ways that glaciers move?

A

Internal flow + basal sliding

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32
Q

What is distinctive about glacial deposits?

A

It transports material of all grain sizes, making for distinctly poor sorting

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33
Q

Two ways glaciers erode, and the nature of sediment produced by both

A

Abrasion - creates fine sediment

Plucking - creates course sediment

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34
Q

What makes drumlins different from roche moutonnée?

A

Bedrock vs sediment

Steep vs gradual down flow side

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35
Q

Four kinds of moraines?

A 
lateral
medial 
end 
recessional
ground
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36
Q

Be able to identify the following glacial features discussed in class on photographs: lateral moraine, medial moraine, end moraine, drumlin, roche moutonnée, cirque, tarn, horn, hanging valley, arete, kettle

A

lateral m: on the sides

medial m: in between multiple glaciers

end m: at the end, obvi

drumlin: sediment hill thingy

roche moutonne: bedrock hill thingy

cirque: glacier that’s carved the bedrock into a bowl
tarn: meltwater lake in cirque
horn: sharp peak carved by glacier

hanging valley: created when a smaller, shallower glacier intersects with a bigger, deeper one

arete: bedrock ridges

kettle lake: chunk of ice breaks off and melts

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37
Q

Be able to determine ice flow direction from a photo or diagram of a drumlin or roche moutonnée

A

Remember:
rouch moutonee: bedrock, steep on the downflow side

drumlin: sediment, gradual on the downflow side

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38
Q

What is an esker (from reading)

A

A ridge of sorted sand/gravel that snakes across a ground moraine

Sediment was deposited in subglacial meltwater tunnels

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39
Q

What kind of streams flow from glaciers

A

braided streams (outwash)

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40
Q

Significance of pluvial lake

A

show cooler/wetter climage of ice ages + location of old glaciers bc these are lakes in now arid regions

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41
Q

Name of highlighted pluvial lake and highlighted meltwater lake, and what kinds of lakes occur all over eastern SD and Minnesota?

A

Pluvial lake (ice age lake now in arid area): Lake Bonneville in Great Basin

Meltwater lake: Glacial Lake Agassiz

-kettle lakes (prairie potholes)

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42
Q

What is loess, and how does it relate to glaciers?

A

It’s fine sediment/silt deposited by glaciers into braided streams, picked up by wind, and then deposited elsewhere.

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43
Q

How does the land surface respond when a continental ice sheet melts away? (uplift, subsidence, or stays the same?) (from reading)

A

Gradually, the surface rises back up (aka post glacial rebound). The lithosphere/asthenosphere rises up at millimeters per year, so it takes years for ice-depressed continents to rebound.

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44
Q

Difference between zone of saturation and the unsaturated zone, and why it matters

A

saturated zone is where all available voids are filled, sitting below the unsaturated zone.

Wells can only pulls water form the saturated zone; if they tried to pull the water from the unsaturated zone, they’d only pump up air (think of a slurpee)

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45
Q

What is groundwater

A

water occupying void spaces in the solid earth in the saturated zone (where all available voids are filled)

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46
Q

How is the water table defined?

A

the surface at the top of the saturated zone

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47
Q

How does groundwater flow relative to contours of the water table?

A

Perpendicular to contour

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48
Q

Top three overall water uses in U.S. (in order)

A 
#1 thermoelectric power
#2 irrigation
#3 public supply
49
Q

What % of U.S. public water supply from groundwater?What % of South Dakotans get their water from groundwater?

A

39% of US public water supply is groundwater

78% of South Dakotans get water from groundwater

50
Q

Porosity vs. permeability?

A

porosity: amount of open space in a rock/sediment
permeability: ability of a rock/sediment to transmit water

51
Q

What is an aquifer

A

a rock/sediment unit from which groundwater can be extracted

52
Q

What kind of rocks or sediments makes the best aquifers?

A

sand, sandstone, limestone, well sorted gravel

53
Q

Basics of two highlighted aquifers in South Dakota discussed in class

A

Big Sioux: east river, in glacial “outwash” and other stream sediments

High Plains: in Miocene-Pliocene stream deposits, south-central part of state, extends into Texas, severely overdrawn

54
Q

Clay & shale has have high porosity; why can’t these make good aquitards?

A

They have high porosity but LOW permeability because their pore space is small

55
Q

What is a confined aquifer?

A

an aquifer with a capping, confining layer

56
Q

What creates a perched aquifer?

A

a shallow aquitard of limited extent

57
Q

What is the zone of recharge?

A

where the water enters the aquifer

58
Q

How does a cone of depression form, and what are the potential consequences?

A

when the hydraulic gradient changes directions and contaminants are transported into groundwater (wells are drilled where the gradient is declining instead of where it is rising)

59
Q

Difference between stalactites & stalagmites

A

stalactites: deposited from ceiling
stalagmites: deposited on floor

60
Q

What term describes a landscape created by groundwater dissolution?

A

karst/tower karst

61
Q

In what rock type does groundwater most commonly create a distinctive landscape?

A

limestone

62
Q

How do sinkholes form? and where, in the U.S., are they most abundant?

A

Dissolution creating caves causes collapse at the surface

most abundant in Florida….?

63
Q

% of earth covered by water? What % of that is oceans?

A

71%

97% of that is oceans

64
Q

% salt in saltwater

A

3.5%

65
Q

Relationship between wavelength and depth at which waves “feel bottom” and term for this depth

A

The depth is called the wave base and is about 1/2 a wavelength (one crest to another)

displacement of water particles happens in orbital motion

66
Q

How does sediment get transported parallel to shore?

A

via the longshore current

67
Q

How do waves refract? Effect on headlands and coves

A

Waves slow as they reach shore. some parts are closer to the shore than others so they bend/refract to approach more directly

Energy lessened on coves; energy concentration on headlands straightens coastlines

68
Q

Difference between longshore current and longshore drift

A

The current is the motion of the crashing waves along the land

The drift is the moving sediment

69
Q

How do we attempt to control longshore drift?

A

Groins (curved on one side), jetties (straight on both sides), and breakwaters (curved on both sides)

70
Q

Recognize in photos/diagrams spits, baymouth bars, barrier islands, marine
terraces, tidal deltas

A

sand spit: longshore current comes from the side the sand spit is connected to

baymouth bar: comes form both sides

barrier islands: just think of the east coast islands

marine terraces: mountains/shores/cliffs with levels cut into them

tidal deltas: sandy, watery, grassy mess

71
Q

Be able to interpret the direction of longshore current by examining sand spits and jetties/groins

A

Look for the direction of accretion

72
Q

Have a basic understanding of the cause of tides (why two a day?)

A

Caused by the tide generating force (gravitational and centrifugal forces)

Two high and low tides; once when Moon is on same side and once when Moon is on opposite side

73
Q

In general terms, how much sea level changed in the last century? Since the last
ice age?

A

20 cm since 1900

100s of meters since last ice age

74
Q

In what ways does future sea level rise pose a threat? (two general ways)

A

1) some areas will become submerged

2) increased impact of storms

75
Q

Recognize and understand the formation of submergent and emergent
landscapes.

A

submergent: form when sea level rises and submerges landscaped carved above sea level (estuaries and fjords)
emergent: wave erosion + sea level drop/land surface rise (marine terraces)

76
Q

What country, where, is most threatened by sea level rise?

A

Maldives (Indian Ocean)

77
Q

What officially defines a desert, climatologically?

A

<25 cm (10 in) of rain per year

78
Q

How many U.S. states have deserts?

A

12

79
Q

% of land in deserts

A

25% of land surface is desert

80
Q

Controls on global wind patterns

A

moisture in air

whether air is rising or sinking

81
Q

Five different causes of deserts, and highlighted examples

A

descending air at 30 degrees: Subtropical (Sahara)

moisture lost over mountains: rain shadow (Great Basin)

moisture lost over great distance: continental interior (Gobi)

cold coastal currents, warm air above prevents rising: coastal (Atacama)

cold air holds little moisture + descending air + high pressure?: Polar (antarctica)

82
Q

How rising vs. sinking air affects atmospheric moisture and precipitation vs. dry

A

cells of rising/sinking air affect where places are dry wet

rising air carries water and precipitates it as it rises/shrinks

sinking air is dry and carries no water for precipitation

83
Q

Why are there deserts at 30 degrees north and south?

A

Because there are cells of sinking air there that are both dry and warm

84
Q

Where is the driest place on Earth (non-polar)?

A

The Atacama Desert in Chile/Peru

85
Q

On what side are dunes steepest? (upwind or downwind)

A

downwind

86
Q

Be able to recognize barchan, and transverse dunes in pictures or diagrams

A

Barchan (shaped like a parabola/horseshoe)

Transverse (perpendicular to the wind, more long looking)

87
Q

Be able to determine wind direction based on pictures of dunes

A

lol good luck

88
Q

Playas

A

evaporated desert lake

89
Q

The role of water in desert landform formation (and examples)

A

main landscaping agent
often in brief but intense rainfall events

playas, alluvial fans, mesas and buttes, cliff retreats

90
Q

Material that accumulates to make oil (and natural gas) vs. coal

A

buried algae and plankton (around.5 mm diameter) accumulated in a basin

91
Q

Under what conditions does natural gas form? (relative to oil)

What is natural gas made of mostly?

A

at higher temperatures, associated with crude oil deposits

it’s mostly methane, CH4

92
Q

Four things necessary to have an economic oil deposit

A

source, reservoir, seal, and trap

93
Q

Where is there more high-quality (more efficient, less polluting) coal being mined,
Appalachians or Wyoming?

A

I think it’s Wyoming?

94
Q

What is the leading renewable energy technology?

A

wind power

95
Q

Fossil fuel resource that the U.S. is the leader in reserves? (but not the leading
producer)

A

Coal

96
Q

Two fossil fuel resources that the U.S. is a leading producer, but not the leader in reserves?

A

Oil and natural gas?

97
Q 
Recent changes in U.S. electricity production. one declining technology, two 
rapidly growing (using fairly general categories)
A

Coal is declining

Natural gas and renewables are increasing

98
Q

What kinds of folds can make traps for oil/natural gas? (2)

A

domes and anticlines

99
Q

What is the process of “fracking”?

A

A means of acquiring shale oil and natural gas by creating artificial porosity to free oil from fine-grained shale

100
Q

Two states that have greatly increased oil production by fracking

A

North Dakota + Texas?

101
Q

Negatives of tar sands as a fossil fuel resource

A
  • destructive mining practices
  • requires energy and water to process
  • more CO2 released in processes
102
Q

What are cheapest energy technologies for new electrical power plants?

A

wind and solar

103
Q

What is special about energy production in Iceland?

A

25% relies on geothermal energy (mid ocean ridge AND hotspot)

104
Q

What is the range of concentration factors of important metals? (two highlighted
elements and concentration factors from lecture)

A

Aluminum: 3-4
Gold: 4,000-5,000

105
Q

Highlighted way in which igneous processes create ore deposits

A

igneous processes: settling of minerals in magma chamber

hydrothermal processes: hot fluids concentrate elements in or near intrusion

106
Q

How do placer deposits form?

A

in the beds of streams/lakes/channels

107
Q

Important material quarried for gravel and dimension stone near Sioux Falls
(southeast South Dakota)

A

Sioux Quartzite

108
Q

State whose oil production has declined substantially in recent decades

A

Alaska

109
Q

Rock that goes into making cement

A

Limestone

110
Q

What greenhouse gas is produced by cement production, and about how much
of it comes from this source?

A

CO2 (carbon dioxide), about 5-8%

111
Q

Astonishing fact presented in lecture about cement production in another country

A

China used more cement in 2011-2013 than the US used in the entire 20th century

112
Q

What are the differences between unidirectional changes, physical cycles, and
biogeochemical cycles?

A

Unidirectional changes can’t be reversed

Physical changes happen on a tangible observable level

Biogeochemical cycles happen at the molecular level over great distances

113
Q

Know highlighted examples of each of the types of global change

A

Unidirectional: planetary differentiation

Physical: supercontinent, rock

Biogeochemical: hydrologic, carbon

114
Q

Recognize examples of positive and negative feedback (if I give you a new example, recognize it as positive feedback or negative feedback)

A

Positive: self-reinforcing/promoting…a thing happening makes the thing happen more, and more effectively in the future (dam failure)

Negative: self-defeating (homeostatic thermoregulation)

115
Q

What makes a gas a greenhouse gas?

A

If it can trap long wavelength radiation in atmosphere

116
Q

Most abundant greenhouse gas

A

water vapor (but carbon dioxide is the most impactful)

117
Q

Understand the difference between climate and weather

A

Climate is the average and range of weather conditions for region

Weather is just what’s happening at a select point in time

118
Q

aquitard vs aquifer

A

aquifer: rock that holds the water
aquitard: Layer with low permeability

Dynamic Earth (4 decks)

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