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Geog 101 > Geomorphology > Flashcards

Geomorphology Flashcards

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1
Q

The largest component of earths materials

A

Rock

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2
Q

Earths circumference and radius

A

Circumference = 40,000 km
Radius = 6,371mm

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3
Q

Planets with high mass and low density (Jovian)

A

Outer, cooler planets

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4
Q

Planets with low mass and high density (terrestrial)

A

Inner, hotter planets

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5
Q

Earths compositional layers

A
  1. Core: high density metallic
  2. Mantle: high density rock
  3. Crust: low density rock
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6
Q

Layering based on physical properties

A

Inner core: solid
Outer core: molten
Mesosphere: hot, strong
Asthenosphere: hot, plastic
Lithosphere: cool, rigid

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7
Q

Exogenic energy/heat flow

A

Solar radiation

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8
Q

Endogenic energy/heat flow

A

Nuclear reactions within the earth

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9
Q

The outcomes of energy and heat flow within the earth (thermogenesis)

A
  1. Convection currents
  2. Changes in solid/liquid/gas phases of rock
  3. Creation of magma
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10
Q

The rock cycle is a _____ material system

A

Closed

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11
Q

Dual drivers of rock cycle

A
  1. Endogenic processes
  2. Exogenic processes
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12
Q

Crust is made up of how many major plates

A

Seven

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13
Q

What drives the motion of plate tectonics

A
  1. Thermally driven heat from the core
  2. Gravitationally driven
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14
Q

Founder of the theory of tectonic plates

A

Alfred Wegener

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15
Q

The most recent and most sucessful concept that uniies ideas about the nature of the earths crust

A

Theory of plate tectonics

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16
Q

Evidence of tectonic plate motion

A
  1. Landmasses fitting like a jigsaw puzzle
  2. Fossil patterns across continents
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17
Q

What does thermally driven plate tectonics entitle

A
  1. Partial melting under pressure (10% liquid)
  2. Convection currents in the mantle
  3. Coupling/decoupling at the 50-100km depth (Litho-Asthenosphere boundary)
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18
Q

Results of gravitationally driven tectonic plates

A
  1. Ridge-push
  2. Slab-pull
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19
Q

Large scale topographic evidence of plate tectonic motion

A
  1. Mountains
  2. Mid oceanic ridges
  3. Trenches
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20
Q

Basic large-scale processes of plate tectonic motion

A
  1. Rifting
  2. Sea-floor spreading
  3. Subduction
  4. island arcs
  5. Continental collision
  6. Orogenesis
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21
Q

Three types of plate boundary

A
  1. Divergent
  2. Convergent (destructive, collision)
  3. Transform
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22
Q

Forms of convergent plate margins

A
  1. Steady state
  2. Collision
    • Oceanic-oceanic crust
    • Oceanic-continental crust
    • Continental-continental
      crust
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23
Q

What happens at a oceanic-continental plate boundaries

A
  1. Subduction of oceanic plate bneath a continental plate
  2. Frictional heating leads to a rising magma plume
  3. Granite intrusions are emplaced within the mountain mass and volcanic activity develops
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24
Q

What happens at transform margins

A

Relative plates sliding past each other can grip and create oblique-slip margins causing earthquakes.

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25
Q

The alpine fault and its two subduction zones

A

The pacific plate is subducted in the north
The Indo-Australian plate is subducted in the south

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26
Q

What visible features occur at
1. Continental-continental margins
2. Oceanic-oceanic margins
3. Oceanic-continental margins

A
  1. Suture zones exhibited, where one continental margin subducts below the other and form a mountain range with an extensive upland plateau on one side and a longitudinal river system parralel to the range on te other side
  2. Oceanic plate subducts below another oceanic plate creating a volcanic arc and an adjacent deep sea trench
  3. Oceanic plate subducts below continental plate resulting in terrestrial volcanic arcs and a deep trench just offshore.
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27
Q

Collisional plate boundaries result in

A
  1. Orogenesis
    • high rates of crustal deformation
    • high rates of incision
    • steep slopes and frequent landslides
    • very high rates of landscape change
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28
Q

Southern alps average motion

A

40mm of transform motion per year
22mm of convergence per year

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29
Q

Southern alps rising rates

A

11mm uplift per year
11mm erosion per year

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30
Q

Outcomes of mountain ranges on subduction zones

A
  1. Uplift
  2. Thickenening
  3. Increased relief
    • Steeper slopes
    • Decreased slope stability
  4. Development of faults
    • Decrease in strength
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31
Q

Endogenic-exogenic interactions

A
  1. Slope processes
  2. Fluvial processes
  3. Glacial processes
  4. Coastal processes
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32
Q

Evolution of ocean basins key dates

A

Break up of Pangaea 225 mya
Continental seperation 180 mya

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33
Q

What has caused the pacific to shrink

A

Formation of the Atlantic from the seperation of America and Africa
Atlantic growth +160%
Pacific growth -35%

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34
Q

Ocean basin architecture

A
  1. Ridges
  2. Abyssal planes
  3. Seamounts
  4. Continental shelves
  5. Trenches
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35
Q

Oceanic ridges

A

Symmetrical ridge and trough structures 100-1000 km wide, produced by sea floor spreading

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36
Q

Abyssal plains

A

4000-6000m deep flat plains between ridges, trenches or continental shelves that are made up of cool older ocean crust

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37
Q

Seamounts

A

Submarine mountains that were former volcanos that can break the surface and develop reefs

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38
Q

Continental shelves

A

Shallow areas beyond continental margins covered in terrigenous sediment that are most affected by sea level changes

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39
Q

Trenches

A

Created at subduction zones where the oceanic plate subducts under another plate

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40
Q

Sea level fluctuations

A
  1. Short term
    • tides and waves
    • minutes-years
  2. Intermediate term
    • eustatic changes
    • Isostatic changes
    • 10-100,000 years
  3. Long term
    • tectonic changes
    • 1-100 ma
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41
Q

Eustatic sea level changes

A

Global, immediate, ocean volume changes which can be steric or coupled

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42
Q

Steric eustatic changes

A

Density changes (temperature and salinity), loss in density equals loss in sea level

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43
Q

Coupled changes

A

Water storage changes (glacial and interglacial periods)

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44
Q

Isostatic sea level changes

A

Results from isostasy:
- gravitational equillibrium
- bouyancy
- thin, low density crust “floats” on high density crust

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45
Q

Loading and unloading of the crust

A
  1. Removal and addition of rock mass (erosion/deposition)
  2. Removal and addition of water/ice (ice sheet growth/decay)
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46
Q

Is fresh or salt water more dense and basic than the other

A

Salt water

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47
Q

Denudation methods

A
  1. Wearing away the land surface
    • surface lowering
    • weathering, mass movement, erosion, transportation
  2. Potentential energy
    • uplift
  3. Kinetic energy
    • solar powered
    • water movement
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48
Q

Denudation

A

The process of the earths surface being eroded

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49
Q

Weathering

A
  1. Physical and chemical alteration of rock at the earths surface
  2. A passive process distinguished from the dynamic role of fluids, wind and ice
  3. An equillibrium process
    • rocks formed in one environment moved to another
    • instability
    • reduced to more stable forms
  4. Does not involve transportation of materials
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50
Q

Physical weathering

A

Physical break up of rocks caused by a variety of processes which generate stresses within or upon rock masses

51
Q

Types of physical weathering

A
  1. Freeze-thaw activity
  2. Crystal growth
  3. Hydration
  4. Pressure release
52
Q

Chemical weathering

A

Decomposition of minerals in rocks with reactions between air, water and minerals

53
Q

Regolith

A

Residual materials that have resisted weathering (soil)

54
Q

Types of chemical weathering

A
  1. Hydrolosis - breakdown of silicate minerals
  2. Oxidation - reaction of O2 forming oxides (rusting)
  3. Carbonation - water reacts with c02 forming weak carbonic acid
  4. Solution - water dissolving a mineral
55
Q

Karst landscapes

A

Landscapes particularily susceptible to chemical weathering

56
Q

Karst landscape requirements

A
  1. CaCo3 rich limestone
  2. Joint patterns to allow water penetration
  3. Aerated zone between ground and water table
  4. Vegetation cover
57
Q

Factors controlling the amount of dissolved Co2

A
  1. Concentration of Co2 in the air
  2. Temperature (cooler water absorbs more Co2 than warmer water)
  3. Biological processes (decaying humus source of Co2)
58
Q

Three components of shear strength

A
  1. Friction characteristic (angle of friction)
  2. Effective normal stress
  3. Cohesive forces
59
Q

Coulumb-Terzaghi shear strength equation

A

Shear strength = Cohesion + effective normal stress x tan angle of friction

60
Q

Driving and resisting forces

A

Driving: gravity acting on slope materials
- weight
- size, shape
- moisture
- slope angle
Resisting: friction
- cohesion
- frictional strength (weight component)

61
Q

Slope instability is

A

Episodic (progressive)

62
Q

Types of mass movementa

A
  1. Fall - material airbourne
  2. Avalanche - snow/debris is falling/tumbling
  3. Landslides - cohesive materials planar or curved to slope
  4. Flow - high moisture content
  5. Creep - slow, expansion
63
Q

Cohesive materials

A

Materials stuck together ie soil

64
Q

Anhropogenic effects on slope unstability

A

Deforestation, overgrazing, drainage, earthworks

65
Q

Sedimentary part of the rock cycle driven by

A

Exogenic processes (weathering, erosion, depositon)

66
Q

Clastic sediments

A

Composed of particles (clasts) from:
1. Pre existing rocks
2. Weathered products of igneous, metamorphic and sedimentary rocks
3. Weathered products transported away by running water, wind or ice

67
Q

Sediment characterization

A

Size, shape, variability, colour, lithology

68
Q

Grain size techniques

A

Φ scale, sieves, settling tubes, laser

69
Q

Statistical description of grain size

A
  1. Mean
  2. Sorting (standard deviation)
  3. Skewness of distribution
  4. Kurotosis (peakedness)
70
Q

Sorting statistical description

A

Coarse, poorly sorted, subangular

71
Q

What does shape and size of grains tell us

A
  1. More rounded = more abrasion
  2. Smaller = more communition over time
  3. Better sorting = viscosity of fluid
72
Q

Diagram that explains transportation in water

A

Hjulstrom curve

73
Q

Higher water velocities =

A

Larger particles

74
Q

Sediment transport in water requires energy that

A
  1. Can initiate transportation
  2. Can maintain transportation
  3. Allows deposition
75
Q

Biological sediments

A

Composed of animal and plant remains

76
Q

Carbonate sediments

A

Made of CaCO3 such as limestone

77
Q

Terrestrial sediments

A

Peats, (plant matter, moss) coal

78
Q

Chemical sediments

A

Minerals precipitated from lake or sea water

79
Q

Chemical sediments from least soluble to most soluble

A

Calcite - CaCO3
Gypsum - CaSO4
Halite - NaCl

80
Q

Cave precipitites

A

Speleotherms
- stalagmites, stalactites, travertine (flowstone)

81
Q

Types of sedimentary environments

A
  • Continental
  • Coastal and marine
82
Q

Stream flow characteristics

A
  1. Driving forces and resisting forces
  2. Material characteristics
  3. Velocity
  4. Discharge
83
Q

Stream flow driving force and resistence

A

Driving force: gravity
Resistence: friction and sediment transport, channel boundary, water/particle

84
Q

Discharge continuity equation

A

Discharge = flow width x flow depth x mean flow velocity
Q = w.d.v

85
Q

Stream power (potential to do work) equation

A

Stream power = density of water x acceleration due to gravity x discharge x channel gradient
Ω = p.g.Q.S

86
Q

Types of sediment transport depending on stream velocity and sediment characteristics

A
  1. Solution
  2. Suspension
  3. Saltation
  4. Traction
87
Q

Bed rock channels

A

Erosion of the channel boundary

88
Q

Channel boundary erosion processes

A

Abrasion, Plucking, Cavitation

89
Q

Direct sediment into bed rock channels supplied by

A

Slope processes into streams

90
Q

Alluvial channels

A

Unconsolidated fluvial channel systems

91
Q

Stream power > sediment supply =
Stream power < sediment supply =

A

Channel degradation
Channel aggradation

92
Q

Channel degradation and aggradation

A

Degradation is the lowering of a stream channel caused by increase in stream power carrying sediments away
Aggradation is the deposition of material in the stream

93
Q

How are sediments in alluvial channels transported

A

Bed and suspended load dominated

94
Q

Alluvial fans

A

Fan shaped accumulations of stream deposit

95
Q

Meandering streams result when

A

Sinuosity > 1.5
Sinuosity = channel length/valley length

96
Q

Flood plain morphology

A

Levees, oxbow lakes, crevasse splays, abandoned channels

97
Q

Braided streams

A

Channel multiplicity that is formed ans dissected by bars

98
Q

Braided stream characteristics

A
  • high width/depth ratio
  • high slope
  • high sediment load
  • bed load dominated
99
Q

Recorders of environmental change

A

Terraces through their, precipitation, vegetation, hydrology, sediment supply.

100
Q

Why do people modify river channels

A

For flood control, drainage improvement and reduction of bank erosion.

101
Q

Types of channelization

A
  1. Re-sectioning - increase width/depth to increase channel capacity
  2. Reallignment - Straightening channels to increase gradient velocity
  3. Diversions - alteration of natural course
102
Q

How do lined channels help channel velocity

A

Low roughness = less resistence = high velocity channels

103
Q

Primary source of coastal energy

A

Waves

104
Q

Components of a wave

A

Height, length, steepness, period

105
Q

Mass sediment transport in the surf zone

A
  • Swash and backwash
  • Littoral currents
  • Rip currents
106
Q

Storm surges result in

A

High tide, low atmospheric pressure, landward mass transport

107
Q

Forms of tidal coasts

A

Microtidal - wave dominant
Mesotidal - wave and tide co dominant
Macrotidal - tidal dominant

108
Q

Products of deposition at deltas

A
  • Aggradation
  • Progradation (extension of deltas)
109
Q

Hard coasts

A

Unprotected by barriers and has direct wave attack, creating seaside cliffs, arches and stacks

110
Q

Glacier types

A

Valley glaciers, ice sheets, ice shelves

111
Q

Cold vs warm vs thermally complex glaciers

A

Cold - frozen at bed
Warm - water at bed
Thermally complex = bed partially frozen

112
Q

Glacier mass balance/ inputs and outputs

A

Inputs:
Snow, rainfall, avalanching, regelation ice
Outputs:
Surface melt, basal and englacial melt, sublimation, deflation, calving, avalanching

113
Q

Glaciers can be split into two sections

A

Accumulation zone and Ablation zone with equillibrium line to sperate them

114
Q

How does the equillibrium line move in glaciers

A
  1. Positive mass balance = glacier thickens/advances and Equillibrium line moves down the glacier
  2. Negative mass balance = glacier thins/retreats and Equillibrium line moves up the glacier
115
Q

Ice flow three componenets

A

Internal deformation, Sliding, Subglacial sediment deformation

116
Q

Equation for general glacial flow

A

Glens flow law

117
Q

Glens flow law equation

A

Strain rate = constant for ice hardness x shear stress^empirical exponent

118
Q

Basal shear stress equation

A

Shear stress = ice density x gravitational acceleration x ice thickness x sin glacier surface slope

119
Q

Glacial internal deformation

A

Occurs in all glaciers where frozen bed ‘creeps’ down the valley

120
Q

Glacial sliding

A

Water acts as lubricant at glacier bed and slides glacier down valley

121
Q

Subglacial sediment deformation

A

Mobile or deforming bed moves glacier down valley

122
Q

Where is material transported through glaciers

A
  1. Supraglacial (on top)
  2. Englacial (internal, streams)
  3. Subglacial (bed erosion)
123
Q

Glacial depositional processes

A

Active deposition (lodgement)
Passive deposition (melt out, flow)
Both result in poor sorting with wide range of particle sizes

124
Q

Outcomes of milankovitch cycles

A
  1. Seasonal assymytries in annual radiation reciept, creating a variable pattern of solar radiation distribution
  2. Radiation reciept in low latitudes mainly affeced by eccentricity and procession
  3. In high latitudes, radiatio reciept is mainly affected by tilt

Geog 101 (5 decks)

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