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Physical Geology Exam 3 > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Invented in 1920s
Primary instrument for measuring depth
Reflects sound from ocean floor

A

Echo Sounder

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2
Q

Employs an array of sound sources and listening devices
Obtainsa profile or a narrow strip of seafloor

A

Multibeam Sonar

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3
Q

Found along most coastal areas that surround the atlantic ocean
Not associated with plate boundaries
Experience little volcanism and free earthquakes

A

Passive Continental Margin

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4
Q

Flooded extension of the continent
Varies greatly in width
Gently sloping
Contains important mineral deposits
Some areas are mantle by extensive glacial deposits

A

Continental Shelf

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5
Q

Marks the seaward edge of the continental shelf
Relatively steep structure
Boundary between continental crust and oceanic crust

A

Continental Slope

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6
Q

Found in regions where tranches are absent
Continental slop merges into a more gradual incline - the continental rise
Think accumulation of sediment
At the base of the continental slope turbidity currents deposit sediment that forms deep-sea fans

A

Continental rise

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7
Q

Primarily in pacific
Trench
Accretionary wedge

A

Active Margins

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8
Q

Long, relatively narrow features
Deepest parts of the ocean
Most are located in the pacific ocean
Sites where moving lithospheric plates plunge into the mantle
Associated with volcanic activity

A

Deep Ocean Trench

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9
Q

Likely the most level places on Earth
Sites of thick accumulations of sediment
Found in all oceans, especially atlantic

A

Abyssal Plains

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10
Q

Isolated volcanic peaks
Many form near oceanic ridges
May emerge as an island

A

Seamounts

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11
Q

Vast outpourings of basaltic lavas on the ocean floor create extensive volcanic structures

A

Oceanic Plateaus

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12
Q

Broad, linear, swells along divergent plate boundaries

A

Oceanic ridges

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13
Q

Axis of some ridge segments exhibit deep down-faulted structures

A

Rift Valleys

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14
Q

Concept formulated in early 1960s by Harry Hess
Occurs on relatively narrow zones, called rift zones, located at the crest of ocean ridges

A

Seafloor spreading

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15
Q

Newly created oceanic lithosphere is hot and occupies more volume than cooler rocks
As the basaltic crust travels away from the ridge crest it is cooled by seawater
As the lithosphere moves away it thermally contracts and becomes more dense

A

Why are oceanic ridges elevated

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16
Q

sequence of unconsolidated sediments

A

Layer 1 of oceanic crust

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17
Q

consisting of pillow lavas (basalt)

A

Layer 2 of oceanic crust

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18
Q

numerous interconnected dikes called sheet dikes (basalt)

A

Layer 3 of oceanic crust

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19
Q

gabbro, in a sequence of rocks called an ophiolite complex

A

Layer 4 of oceanic crust

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20
Q

Basaltic magma originates from partially melted mantle peridotite
Molten rock injected into fractures above the magma chambers creates the sheeted dike complex
The submarine lava flows chill quickly and the congealed margin is forced upward to provide large tube-shaped protuberances known as pillow basalts

A

Formation of oceanic crust

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21
Q

Hydrothermal fluids dissolve ions of various metals and precipitate them on the ocean floor as particle filled clouds

A

Black smokers

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22
Q
  1. Mantle plumes/ hotspots
  2. Slab pull/slab suction
A

Two mechanisms that have been proposed

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23
Q

Concept of floating crust in gravitational balance
If weight is added or removed from the crust, isostatic adjustment will take place as the crust subsides or rebounds

A

the principle of isostasy

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24
Q

Buoyancy of hot rising mantle material accounts for broad upwarping in the overlying lithosphere

A

vertical motions and mantle convection

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25
Q

the processes that collectively produce a mountain belt
Including folding, thrust faulting, metamorphism, and igneous activity

A

Orogenesis

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26
Q

region where subduction g oceanic lithosphere bends and descends into the asthenosphere

A

Deep ocean trench

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27
Q

built upon overlying plate
Island arc if on ocean floor or
Continental arc if oceanic lithosphere is subducted beneath a continental block

A

volcanic arc

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28
Q

As the subducting plate sinks in creates a flow in the asthenosphere that pulls the upper plate toward the trench

A

Extension and back arc spreading

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29
Q

Where two oceanic plates converge and one is subducted beneath the other
Volcanic island arcs result from the steady subduction of oceanic lithosphere
Continued development can result in the formation of mountainous topography consisting of igneous and metamorphic rocks

A

Island arc mountain building

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30
Q

Mountain building along continental margins
Involves the convergence of oceanic plate and a plate whose leading edge contains continental crust
Andes mountains

A

Andean arc mountain building

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31
Q

Subduction and particle melting of mantle rock generates primary magmas
Magma is less dense than surrounding rock so it begins to buoyantly rise
Differentiation of magma produces andesitic volcanism dominated by pyroclastics and lavas

A

Building a volcanic arc

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32
Q

An accretionary wedge is a chaotic accumulation of deformed and thrust-faulted sediments and scraps of oceanic crust
Prolonged subduction may thicken an accretionary wedge enough so it protrudes above sea level
Descending sediments are metamorphosed into a suite of high-pressure, low-temperature minerals

A

Development of an accretionary wedge

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33
Q

The growing accretionary wedge acts as a barrier to sediment movement from the arc to the trench
This region of relatively undeformed layers of sediment and sedimentary rock is called forearc basin

A

Forearc basin

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34
Q

a summary of the circulation of Earth’s water supply

A

hydrologic cycle

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35
Q

Begins as sheetflow
Infiltration capacity is controlled by
Intensity and duration of rainfall
Prior wetted condition of the soil
Soil texture
Slope of the land
Nature of the vegetative state

A

Running water

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36
Q

Sheetflow develops into tiny channels

A

Rills

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37
Q

Gradient, or slope
Channel characteristics including shape, size, and roughness
Discharge - the volume of water moving part a given point in a certain amount of time

A

Factors that determine velocity

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38
Q

Laminar flow

A

slower flow

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39
Q

turbulent flow

A

faster flow

40
Q

Cross-sectional view of a stream
Viewed from the head (headwaters or source) to the mouth of a stream
A smooth curve
Gradient decreases downstream

A

profile

41
Q

Velocity
Discharge
Chanel size

A

increase downstream

42
Q

Gradient
Channel roughness

A

decrease downstream

43
Q

Lifting loosely consolidated particles by
Abrasion
Dissolution
Stronger currents lift particles and move them more effectively

A

stream erosion

44
Q

the stream’s load
Types of load
Dissolved load
Suspended load
Bed load

A

transported material

45
Q

the maximum load a stream can transport

A

capacity

46
Q

Indicates the maximum particle size the stream can transport
Determined by the stream’s velocity

A

competence

47
Q

Competence is reduced
Sediment begins to drop out

A

decrease in velocity

48
Q

Generally well-sorted
Stream sediments are known as alluvium

A

stream sediments

49
Q

Back swamps
Yazoo tributaries

A

floodplain deposits

50
Q

Develops where high-gradient stream leaves a narrow valley
Slopes outward in a board arc

A

alluvial fans

51
Q

Form when a stream enters an ocean or lake
Consist of three types of beds
Foreset beds
Topset beds
Bottomset beds

A

deltas

52
Q

V-shaped
Downcutting toward base level
Features often include rapids and waterfalls

A

narrow valleys

53
Q

Steam in a ner base level
Downward erosion is less dominant
Stream energy is directed from side to side forming a floodplain

A

wide valleys

54
Q

a this mass of ice that originates on land from the accumulation, compaction, and recrystallization of snow

A

glacier

55
Q

Exist in mountainous areas
Flow down a valley from an accumulation center at its head

A

valley glaciers

56
Q

Exist on much larger scale than valley glaciers
Two major ice sheets on earth (greenland and antarctica)

A

ice sheets

57
Q

Air infiltrates snow
Snowflakes become smaller, thicker, and more spherical
Air is forced out
Snow is recrystallized into a much denser mass of small grains called firn
Ocne the thickness if the ice and snow exceeds 50 meters, firn fuses into a solid mass of interlocking ice crystals

A

formation of glacial ice

58
Q

Occurs within the ice
Under pressure, ice behaves as a plastic material

A

plastic flow

59
Q

Entire ice mass slipping along the ground
Most glaciers are thought to move this way

A

Basal slip

60
Q

the area where a glacier forms
Elevation of the snowline varies greatly

A

zone of accumulation

61
Q

the area where there is a net loss to the glacier due to
Melting
Calving - the breaking off of large pieces of ice (icebergs where the glacier has reached the sea)

A

zone of ablation

62
Q

lifting of rocks

A

plucking

63
Q

Rocks within the ice acting like sandpaper to smooth and polish the surface below

A

abrasion

64
Q

Rock flour (pulverized rock)
Glacial striations (grooves in the bedrock)
Landforms
Glacial trough
Arêtes
Horns
Hanging valleys
Cirques
Fjords
Truncated spurs

A

glacial abrasion products

65
Q

refers to all sediments of glacial origin
Types of glacial drift
Till - material that is deposited directly by the ice
Stratified drift - sediments laid down by glacial meltwater

A

glacial drift

66
Q

Smooth, elongated, parallel hills
Steep side faces the direction from which the ice advanced
Occur in clusters called drumlin fields
Formation not fully understood

A

drumlins

67
Q

line that marks the contact between land and sea - moves during the day with tides

A

shoreline

68
Q

extends between the lowest tide level and the highest elevation affected by storm waves

A

shore

69
Q

area exposed at low tide and submerged at high tide

A

foreshore

70
Q

area found landward of the high-tide mark

A

backshore

71
Q

lies between the low-tide shoreline and the point where waves break at low tide

A

nearshore zone

72
Q

seaward of the nearshore zone

A

offshore zone

73
Q

an accumulation of sediment found along the landward margin of an ocean or lake

A

the beach

74
Q

extends inland from the shore as far as ocean-related features are found

A

coast

75
Q

marks the coast’s seaward edge

A

coastline

76
Q

he horizontal distance between two crests
Below a depth of ½ wavelength, water movement is no longer felt
If you are scuba diving in the ocean, you will not feel the effects of a storm passing the surface

A

wavelength

77
Q

turbulent water that washes up a beach
Greater on flat beaches
at an angle

A

swash

78
Q

is water flowing back into the ocean after swash
straight down

A

backwash

79
Q

Currents parallel to shoreline produced in surf zone by waves reaching shore at an angle

A

longshore current

80
Q

Wave cut cliffs
Wave cut platform
Marine terraces (old wave cut platforms elevated by changing sea level or local uplift)
Sea arches
Sea stacks

A

erosional coast features

81
Q

Composed of sediment that is eroded, transported, and deposited by wave energy

A

depositional coasts

82
Q

an elongated ridge of sand that projects into the mouth of an adjacent bay

A

spit

83
Q

a sandbar that crosses a bay, cutting it off, from open ocean

A

bar

84
Q

Low ridges of land parallel to the coast
Gebrally 3-30 km offshore
1-5 km wide, 15-30 km long

A

barrier islands

85
Q

built perpendicular to the shoreline and extend into the ocean near the mouths of rivers and harbors
Usually built in pairs to develop and maintain harbors
Results in deposition and up-current and erosion down-current

A

jetties

86
Q

Built perpendicular to the beach and extend into the ocean
Designed to maintain or widen beaches: causes erosion downstream

A

groins

87
Q

Creates a region of sand accumulation between the breakwater and the shoreline
Built offshore to protect property from breaking waves
Causes deposition landward of breakwater

A

breakwater

88
Q

Built onshore to protect property from breaking waves
Focuses wave energy at seawall, increases backwash
Causes severe erosion seaward of seawall

A

seawall

89
Q

Adding large quantities of sand to the beach
Costly and not a permanent solution

A

nourishment

90
Q

Develop because of uplift of an area or a drop in sea level
Generally erosional

A

emergent coasts

91
Q

Caused by subsidence of land adjacent to the sea or a rise in sea level
Usually depositional
Features:
Estuaries (drowned river mouths)
Highly irregular shorelines

A

submergent coasts

92
Q

Atmosphere
Hydrosphere
Geosphere
Biosphere
Cryosphere (ice and snow)

A

the climate system

93
Q

Plates tectonics (very long term)
Variations in Earth orbit (long term)
Eccentricity, obliquity, and precision
Volcanic activity (short term)
Changes in the sun’s output associated with sunspots

A

natural causes of climate change

94
Q

Humans have been modifying the environment for thousands of years as ground cover has been altered by
Fire
Overgrazing
Modification of climatological factors such as reflectivity, evaporation rates, and surface winds (windmills for power)

A

anthropogenic climate change

95
Q

Because the climate system is so complex, predicting specific regional changes to increased levels of CO2 is speculative
However, some possible consequences include
Rise in acidic as well as sea level (virtually certain)
Altering the distribution of the world’s water resources (very likely)
Changes in the extent of Arctic sea ice and permafrost (very likely)
Frequency of heavy precipitation (very likely)
Areas affected by drought (likely)
Loss of glaciers will accelerate (likely)
Greater intensity of tropical cyclones (not sure)

A

consequences of global warming

96
Q

Changes that reinforce the initial change are called positive-feedback mechanisms
Warmer surface temperatures cause an increase in evaporation, increases temperatures as water vapor absorbs more radiation, warmer surface temperatures
Warm ocean. Longer melting, decline in ice, reduced reflectivity (albedo), increased absorption of solar energy, warm ocean…

A

climate feedback mechanisms

97
Q

Produce results that are opposite of the initial change and tend to offset it
Example - negative effect of increased cloud cover, ash, and haze on the amount of solar energy available to heat the atmosphere

A

negative feedback mechanisms

Physical Geology Exam 3 (1 decks)

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