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Geog375Gmphlgy > Intro > Flashcards

Intro Flashcards

1
Q

Geomorphology is the science of what?

A

Science of Scenery

  • Study of Earth surface materials, processes and resulting landforms
  • Interactions between Earth’s spheres at a variety of temporal and spacial scales
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2
Q

What are the spheres of interaction that geomorphology studies?

A

Atmosphere, Lithosphere, Hydrosphere, Cryosphere, Biosphere

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3
Q

What is involved in an empirical science?

A

Observation, measurement, description

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4
Q

Relevance of Geomorphology?

A
  • Land use and planning
  • Agriculture, forestry, mining, parks
  • Stream/watershed management
  • hydrology, flood control, water resources
    Geological hazards
  • Volcanic hazards
  • Resources for construction or mineral exploration
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5
Q

Geomorphology pre - 1850

- Leonardo da Vinci

A
  • Studied topography of Arno River Northern Italy
  • Drew 1st contour map of a whole river basin
  • Believed rivers carved valleys and shaped topo
  • Wanted to regulate river for agriculture and transport
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6
Q

Nicholas Steno

A
  • Principle of original horizontality
  • Law of superposition
  • found shark teeth on mountains indicated SL originally higher
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7
Q

Law of Superposition

A
  • Oldest at the bottom
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8
Q

James Hutton

A
  • Theory of the Earth
  • Uplift, erosion, consolidation of rock
  • Had a lot of jobs (lawyer, chemist, physician, farming)
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9
Q

Sir Charles Lyell

A
  • Uniformitarianism
  • Principles of Geology in 3 volumes (1830)
  • Stratigraphic principle that rock layers correlate according to fossils
  • Glaciers not icebergs transport erratics
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10
Q

Uniformitarianism

A
  • slow geological processes have occurred throughout history and are still occurring today
  • present is the key to the past
  • contrasted to accepted theory of catastrophism
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11
Q

Catastrophism

A
  • theory that Earth’s features formed in a single catastrophic event and remained unchanged thereafter
  • Accepted theory for a long time
  • Contrasted to Lyell’s uniformitarianism
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12
Q

Two main geomorphic principles of Hutton and Lyell

A
  • Landforms and landscapes evolve

- Event frequency and magnitude control landscape development

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13
Q

Modern Geomorphology from 1850 - 1950

A
  • Uniformitarianism accepted but the gradualism was overstated (some events catastrophic)
  • expansion of knowledge of Earth history and processes
  • descriptive studies of landforms emerged (drainage basins)
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14
Q

Powell (1870s)

A
  • USGS
  • Colorado river exploration
  • Base level of river systems
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15
Q

Gilbert (1878)

A
  • Dynamic equilibrium
  • Henry Mountains Utah
  • Weathering, erosion, debris transport mechanisms, graded streams
  • dynamic adjustment between form and process
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16
Q

Davis (1909), Penck (1924), King (1953)

A
  • Cycle of Erosion

- Theories of Landscape Evolution

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17
Q

Cycle of Erosion

A
  • youthful (Downcutting)
  • mature (Very topographic)
  • old (Eroded to bedrock, flatter)
  • youthful
  • Universal down-wearing to peneplain
  • Increase in entropy of the system (toward equilibrium)
  • uplift occurs rapidly, continuous landscape evolution through stages of erosion and decreasing slope gradients
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18
Q

Concept of Base Level

A
  • The lowest elevation to which a stream can erode

- Usually coincident with sea level

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19
Q

Graded Stream

A
  • over a period of years a slope is adjusted to yield the velocity required for transportation of the load supplied from the drainage basin
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20
Q

What were Penck and King’s contributions to the Cycle of Erosion?

A
  • Uplift occurs gradually and continuously, not only at end of a cycle
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21
Q

Peneplain

A

final stage once base level of erosion has been reached

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22
Q

What was the knowledge shift in the 1950’s to present?

A

Shift to Process geomorphology

  • Measurement based research and theory development
  • Realized uniformitarianism was overstated
  • understanding of processes with physics
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23
Q

What was the overstated uniformitarianism replaced with?

A
  • Frequency and magnitude relations
  • Equilibrium
  • Thresholds
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24
Q

What are landforms viewed as in process geomorphology?

A
  • Interacting Systems
  • Dynamic processes of mass and energy exchange over space and time
  • Landforms strive to attain equilibrium in form/function over time
  • Landforms linked to larger landscape changes
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25
Q

Unit of measurement for frequency

A

Hertz, s^-1

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26
Q

Unit of measurement for Force

A

Newton, kg m s^-2

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27
Q

Unit of measurement for pressure, stress, momentum flux

A

Pascal, kg m^-1 S^-1, N m^-2

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28
Q

Unit of measurement for work, energy

A

Joule, kg m^2 s^-2, N m

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29
Q

Unit of measurement for power

A

Watt, kg m^2 s^-3, J s^-1

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30
Q

Force

A

Phenomenon causing motion of mass with both magnitude and direction

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31
Q

What is the driving force

vs resisting force?

A

moving vs keeping in place

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32
Q

What is an example of resisting force?

A

friction

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33
Q

What is an example of driving force?

A

Pressure

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34
Q

Newtons 2nd Law

A

F = m x a = Newton

  • Force required to move and accelerate 1kg to 1ms^-2
  • All motion results from force
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35
Q

Gravitational acceleration

A

9.81 m s^-2

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36
Q

Gravitational Force

A

9.81 kg m s^-2

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37
Q

Work

A
  • Force moving mass over a certain distance in direction of applied force
  • w = F x d = m x a x d
  • Requires E in Joules (N m)
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38
Q

What are the 5 fundamental considerations of process geomorphology?

A
  • Time
  • Space
  • Process
  • Morphology
  • Composition
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39
Q

Space/scale considerations

A
  • micrometer to sub-continental scale (<10km)
  • spatial distribution and morphology of features
  • Temporally limited to human timescales while most large events are outside of human record
  • Rely on theory and interpretation
  • artificial entry point, must use care in interpreting given limited spatio-temporal perspective
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40
Q

What is a major limit to scale for geomorphic studies?

A
  • Understanding complexities is difficult, especially rare events
  • Many large events (EQ’s and floods happen outside of human timescale
  • ex. 2013 Calgary flood had no historical record to predict severity
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41
Q

Time considerations

A
  • Landforms develop over longer timespans than human
  • Often focused on human timescales
  • Not all are active
  • Study models of present or past
  • define relevant timescales
  • extrapolate short records over long spans
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42
Q

Process considerations

A
  • Mass and Energy drive morphodynamics
  • relate form to process to explain landform dynamics and change
  • But erosion eliminates past forms/processes, records discontinuous
  • Rely’s on fundamental principles (uniformitarianism, stratigraphy, fluid dynamics)
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43
Q

Morphology considerations

A
  • Describe, measure, model
  • Link process to form using theoretical or conceptual frameworks (facies models, class schemes)
  • Hypothesis then test with evidence
  • Theory plus observation plus pre-existing evidence
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44
Q

Composition considerations

A
  • Controlled by what is inside (Sedimentology)
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45
Q

Critical concepts in modern geomorph

A
  • Delicate balance between process and landform
  • Balance of driving and resisting forces
  • Change in driving force can push past threshold and change landform
  • Balance and thresholds are all scale dependent
46
Q

What are the 2 types of temporal scales?

A
  • Time dependent

- Time independent

47
Q

Spatial and Temporal scale graph

A
  • y-axis = increasing length (m)
  • x-axis = increasing time scale (yrs)
  • sand-bed streams to increased channel width and depth to gravel-bed streams to increased meander wavelength to increased reach gradient to increased profile concavity and gradient
48
Q

Time-independent

A
  • landforms are open systems constantly adjusting to inputs and outputs of matter and energy striving to attain equilibrium
  • Characteristic-form models are used to describe landform states after some period of adjustment (b/c steady state is never reached)
  • Gilbert’s dynamic graded stream concept
49
Q

Time-dependent

A
  • landforms adjust in response to initial disturbance or change input (climate change, tectonism)
  • landforms reflect a developmental stage in a gradual evolution at increasingly slower rates (entropic)
  • Davis’ cycle of erosion
50
Q

Davis (1909)

A

“sudden” uplift then erosion

51
Q

Penck (1924)

A

Gradual uplift then erosion

52
Q

King (1953)

A

dominant lateral erosion not uplift

53
Q

Frequency

A

occurrences per unit time

54
Q

Magnitude

A

Energy used or Mass moved per unit time by a geomorphic process

  • level a river reaches each year
  • (rate of movement?)
55
Q

how is how often an event of a certain magnitude expressed?

A
  • Recurrence interval R = (n + 1)/m (n = # records, m = magnitude ranking, 100 yr flood)
  • Probability P = (R - 1) x 100
56
Q

How are magnitude and frequency related?

A

Inversely

57
Q

Which types of events do the most Work in geomorphic systems?

A

Moderate does the most Work b/c HighMag-LowFreq aren’t frequent enough for long-term transport rates and LowMag-HighFreq don’t do enough Work.

58
Q

Steady Time

A
  • Engineering Time
  • mins-yrs
  • Time- independent, some components unchanging
  • Steady base flow in a river
59
Q

Graded Time

A

10^2 years

  • Time-dependent and independent
  • Sediment load and channel gradient over hundreds of yrs and discharge over a year
  • Fluctuating dynamic equilibrium as system approaches some steady state
60
Q

Cyclic (Geologic) Time

A

10^3 - 10^6

  • Time-dependent
  • Time is independent variable (also climate, initial relief and geology)
  • All landform responses depend on these
61
Q

Equilibrium in Geomorph

- Static

A

Stationary or unchanging

62
Q

Equilibrium in Geomorph

- Stable

A

Revert to previous state after disturbance (feedback)

63
Q

Equilibrium in Geomorph

- Unstable

A

Small disturbance causes movement away from equilibrium toward a new (stable?) state

64
Q

Equilibrium in Geomorph

- Metastable

A

Incremental change from one to another state of equilibrium (threshold)

65
Q

Equilibrium in Geomorph

- Steady State

A
  • Fluctuation about an average
  • No obvious trend
  • Caused by numerous small-scale disturbances
  • Long-term
  • ex. Weather
66
Q

Equilibrium in Geomorph

- Thermodynamic

A
  • tend toward max entropy

- Long-term

67
Q

Equilibrium in Geomorph

- Dynamic-Metastable

A
  • Fluctuation about a trending mean with abrupt shifts to new equilibrium states (threshold)
  • system jumps after threshold
  • Very common
68
Q

Equilibrium in Geomorph

- Dynamic

A
  • Fluctuation about a trending, non-repetitive mean

- Quasi-equilibrium

69
Q

Threshold

A
  • Limit w/in a landform or process beyond which equilibrium cannot be maintained
  • Defines ability to respond and adjust to changing Mass or Energy conditions
  • Natural part of most geomorphic systems
70
Q

What are the 2 types of thresholds

A
  • Intrinsic

- Extrinsic

71
Q

Intrinsic Threshold

A
  • No external
  • Changes occur w/o a change in, or influence from, an external variable
  • ex. Slope angle
72
Q

Extrinsic Threshold

A
  • Respond to external
  • Response of a system to external influence
  • Ex. rain or landslides
73
Q

Reaction and Relaxation times

A

Response to a threshold often lags behind initial disturbance or change in process

74
Q

Reaction Time

A

Lag from disturbance (change in Energy) to morphological response (change in Mass)

75
Q

Relaxation Time

A

Adjustment time of landform/process to new equilibrium or another threshold

76
Q

Feedbacks and 2 types

A
  • Response to change in M and/or E causing shift from (+) or back (-) to equilibrium
  • Processes affect the landscape, but through feedback, the landscape also affects those processes
  • Positive
  • Negative
77
Q

Positive Feedback

A
  • Self-amplifying
  • Increases trend away from equilibrium
  • Landslide continuing
  • Faulting increases stream slope, increases erosion, reduces slope
78
Q

Negative Feedback

A
  • Self-regulating
  • Decreases trend away from equilibrium
  • Landslide stabilizing to new slope
79
Q

Over long time periods, what type of feedback do most geomorphic systems experience?

A
  • Negative feedback

- Changes are resisted and tendency towards equilibrium is maintained

80
Q

General Systems Theory

A
  • Framework for conceptualizing and modelling complex phenomena
  • inputs, throughputs and outputs matter and/or energy
  • ex. Hydrological cycle is conceptual framework using systems approach
81
Q

System

A
  • Set of objects, attributes, and processes that form a functioning whole
  • A model, simplification of a very complex reality
  • Components operate together as a functioning whole
82
Q

System Objects

A

Landform elements, defined spatially (drainage basin, mountain slope etc.)

83
Q

System Attributes

A

Physical properties, measurable (slope gradient, soil texture, etc.)

84
Q

System Processes

A

Functional relationships between elements that affect or control attributes (water flow, exertion of wind stress, land sliding etc.)

85
Q

When is a system positive or negative?

A
  • Based on the # of Negatives in system
  • Odd # = Negative
  • Even # = Positive
86
Q

Qualitative/Conceptual Models

A
  • Descriptive models of key components in a land system
  • Based on observed data, graphs, maps, hypotheses
  • Qualitative
  • Useful for generalizing observations and applying elsewhere
87
Q

Morphological Models

A
  • Forms, attributes, patterns

- Little quantification of process or Matter and/or E exchange

88
Q

Cascading Model

A
  • M and/or E transfer btwn components via directional pathways
  • Little consideration of morphological implications
  • Doesn’t really loop back on itself
  • Atm moisture to precipitation to surface water to infiltration to soil water
89
Q

Process-response Model

A
  • Integrate characteristics of both morphological and cascading systems
  • Form & process interactions
  • Useful for modelling responses to changing events over time
  • Feedback between components
  • Most common approach
90
Q

Positive feedback =

A

Amplification

91
Q

Negative feedback =

A

Regulation

92
Q

Process-Control Models

A
  • Deliberate human control/replication of geo processes to better understand key forces, responses, M and E exchanges
  • Scientific research, engineering, management or planning
93
Q

Analogue Models

A
  • Physical scaled models of forms and/or processes

- Geometric (form) scaling is easy while dynamic (process) scaling is very difficult

94
Q

Geometric (form) scaling is easy while dynamic (process) scaling is very difficult.
Why?

A
  • Need big labs to mimic nature for process
95
Q

Mathematical Models

A
  • Model complex phenomenon using # and eqn’s
  • Quantitative
  • Great precision
  • Accuracy depends on knowledge of phenomenon
96
Q

Advantages of Systems approaches

A

1) Recognize relations btwn form and process (encourages process-based study where records lack)
2) Logical framework and wholistic view for study of complex, multivariate systems (allows for dynamic variations in response to changing processes over time)
3) Application/linkage to broader geographic study (Climate change)

97
Q

What are the disadvantages of Systems approaches ?

A
  • Models are abstractions, not reality
  • Simplified
  • Ground in theory/frameworks
    So:
  • Recognize simplifications/limitations
  • verify/validate
98
Q

Landforms as process-response geological systems

A
  • Matter Exchange/ Rock Cycle to
  • Energy Exchange/ Geomorphic Process to
  • Morphological Response (Landforms)
99
Q

Matter Exchange/Rock Cycle

A
  • Magma
  • Lithification
  • Rocks
  • Weathering
  • Debris
  • Erosion/Transport
  • Load
  • Deposition
100
Q

Energy Exchange/ Geomorphic Process

A
  • Tectonics (Folding, faulting, uplift, subsidence)
  • Physical Disintegration/ Chemical decomposition
  • Entrainment and Transport by wind, water, ice
  • Deposition by wind, water, ice
101
Q

Structural Landforms

A

Mountains, faults, rift valleys

102
Q

Weathering landforms

A

Karst topo, talus cones

103
Q

Erosional Landforms

A

River/glacial valleys, Gullies

104
Q

Depositional Landforms

A

Sand dunes, bars, deltas, floodplains

105
Q

Two fundamental types of geomorphic processes

A
  • Endogenic

- Exogenic

106
Q

Endogenic geomorphic process

A
  • Energy from inside the Earth
  • Landforms built by tectonic/volcanic processes
  • Intrusive landforms (batholiths)
  • Extrusive (volcanic) landforms
  • Tectonic landforms (folded and faulted mountains)
107
Q

Exogenic geomorphic process

A
  • Process driving by gravity and atmospheric forces
  • Landforms modified by sedimentary forces
  • Colluvial, fluvial, glacial, eolian, coastal processes
  • Resultant landforms are relatively small scale but widespread
108
Q

Batholiths

A
  • Roots of continents
  • form from intrusive rocks, coarse crystalline, magma derived
  • Exposed by later erosion
  • Solid, well jointed rocks
109
Q

Structural Landforms

A
  • Folding (Plastic deformation of rocks under compressional stress)
  • Most common/obvious in sed rocks at convergent margins
  • Faulting (brittle fracture, normal, reverse, overthrust, strike slip)
  • Used in tectonic geomorphology, assess tectonic activity
110
Q

Volcanic Landforms

A
  • Built by magma extrusion
  • Lava and tephra
  • Occur at divergent/convergent boundaries and hotspots
111
Q

Related landforms in Convergent margins

A

Calderas, cinder cones, lava domes

Geog375Gmphlgy (9 decks)

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