Geomorphology Flashcards

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1
Q

Strata

A

Anotehr term for layers of rock

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2
Q

Stratified rock

A

Rock composed of layers of strata

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3
Q

Bedding plane

A

Planes separating layers of rock

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4
Q

guillies

A

Narrow, long areas of erosion on a slope

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5
Q

Plateau

A

A large, flat high lying landform

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6
Q

Sheet wash

A

Rainfall flowing over land as a sheet

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7
Q

Lava flow

A

Lava pours onto surface, cools and solidifies

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8
Q

How does horizontally layered rock form - two ways

A

1.Sediments deposited on top of each other consolidate + forms rock
2.Large scale lava flow

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9
Q

Landscapes associated with horizontal strata *4

A

*hilly landscapes
*basaltic plateaus
*canyon landscape
*karoo landscape

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10
Q

Hilly landscapes and basaltic plateaus provide…….. resistance to erosion

A

Uniform- same speed

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11
Q

Canyon landscapes provide……. resistance to erosion

A

Alternating

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12
Q

Explain how hilly landscapes are formed

A

Sedimentary strata with uniform resistance form a steep hilly landscape

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13
Q

Influence of humid areas on hilly landscapes *2

A

*rounded slopes because of sheet wash
*rainfall removes surface material on slopes

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14
Q

Influences of dry areas on hilly landscapes *

A

*steep with sharp ridges bc no sheet wash
*hills with narrow guilles form in arid climates

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15
Q

What are hilly landscapes in arid climates called

A

Badlands

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16
Q

Outburst aka

A

Successive fissure eruption

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17
Q

What do outbursts cause

A

Lava to flow on the surface

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18
Q

Explain how basaltic plateaus form *2

A

*lava flows on the surface bc of outbursts
*a layer of basalt if formed - provides uniform resistance and gives rise
Has uniform resistance

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19
Q

What does vertical erosion in basaltic plateaus cause

A

Deep, narrow gorges

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20
Q

What is tectonic uplifts due to

A

Crustal forces

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21
Q

What erosion takes place in canyons

A

Vertical

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22
Q

How does a plateau form a canyon

A

Tectonic uplifts

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23
Q

Influence of humid climate on canyons

A

*water erodes slopes - rounded and gentle

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24
Q

Influence of dry areas on canyons

A

*sharps ridges and steep uneven badlands - lack of rainfall

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25
Q

Dolerite still

A

Horizontal layer of igneous rock formed along a bedding plane

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26
Q

Where do Karoo landscapes form from

A

Canyons

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27
Q

How do Karoo landscapes form

A

Canyon floor gets wider, plateau surface gets smaller

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28
Q

Why do plateaus hold original height

A

Resistant cap rock

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29
Q

Order that plateau erodes in *4 - Karoo landscape

A

Mesa > butte > pointed butte > conical hills

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30
Q

Mesa

A

Flat topped mountain with greater width than height

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31
Q

Butte

A

Flat topped mountain with greater height than width

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32
Q

Pointed butte

A

Narrow hill with sharp peak

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33
Q

Conical hill

A

Small pointed hill

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34
Q

Conical hill

A

Small pointed hill

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35
Q

Scarp retreat

A

Erosion causing loss of width but not height

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36
Q

As plateus narrow, canyon floors become…

A

Wide

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37
Q

How are hilly landscapes utilised

A

*in humid climates slopes are steep + chemical erosion creates fertile soil - farming

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38
Q

Why can’t farming be done in high altitudes of basaltic plateaus *2

A

*cold temperatures
*rugged slopes bc vertical erosion

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39
Q

Why can farming be done in lower altitudes of basaltic plateaus *2

A

*not as cold
*basalt weathering creates fertile soil

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40
Q

Chemical weathering

A

Decomposition of rock due to chemical processes
Water, carbon dioxide, oxygen

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41
Q

Mechanical weathering

A

Decomposition of rock due to extremes in temperature

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42
Q

Utilisation of Canyon

A

Tourist attractions

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43
Q

Utilisation of Karoo *2

A

*Maybe farming, but precipitation is an issue
*Attractions

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44
Q

Inclined strata formation

A

Sedimentary layer is uplifted and tilted

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45
Q

Landscapes associated with inclined strata *

A

*homoclinical landcape
*cuestas and hogbacks

46
Q

Homoclinal landscape *2

A

Landscape formed of inclined strata* tilted by the same degree of dip in the same direction*

47
Q

Undercutting

A

Erosion at the base of a slope with the collapse of overhang

48
Q

Homoclinal shifting

A

Movement of Homoclinal ridge towards dip slope

49
Q

Homoclinal shifting

A

Movement of Homoclinal ridge towards dip slope

50
Q

Mass wasting

A

Movement of eroded material downhill due to gravity

51
Q

Scarp slope

A

Steep slope of Homoclinal ridge

52
Q

Dip slope

A

Gentler slope of Homoclinal ridge

53
Q

Why is erosion less on dip slope

A

Resistant rock strata

54
Q

What is erosion on scarp slope due to

A

Sheet wash and mass wasting

55
Q

How does scarp retreat take place

A

undertaking takes place and collapses the scarp slope

56
Q

Homoclinal displacement

A

Erosion of ridge:
Moves in direction of dip slope, not getting lower

57
Q

How are cuestas, Homoclinal ridges and hogsback differentiated *1+3

A

Angle of resistant strata
Cuesta - 10-25*
Homoclinal ridge - 25 - 45*
Hogsback 45*

58
Q

Cuesta

A

Ridge with gentle dip slop and scarp slope

59
Q

Hogsback

A

Ridge with steep dip slope and scarp slope

60
Q

What are Cuesta basins and domes a result of

A

Folding

61
Q

Cuesta dome *2

A

*Circular landform as a result of erosion of anticline
*Folded strata raised into a dome

62
Q

Cuesta basin *2

A

*Circular landform as a result of erosion of syncline
*Folded strata bent into a basin

63
Q

Folding

A

Rocks are bent when pressed from both sides

64
Q

Characteristics of Cuesta dome *3

A

*strata pushed into shape
*scarp slope points inwards
*dip slope points outwards

65
Q

Characteristics of Cuesta basin *3

A

*strata folded into shape
*scarp slope points outwards
*dipslope points inwards

66
Q

Magma extrusion *2

A

Magma forces itself through weak spots in the surface*
Comes to land as lava and cools and solidifies*

67
Q

Magma intrusion *2

A

Magma flows as reaches the crust*
Moves existing rock to the side forming new rock*

68
Q

Utilisation of dip slope of Cuesta

A

Course + infertile slope - forestry

69
Q

Utilisation of scarp slope of Cuesta

A

Too steep, can’t be used

70
Q

Utilisation of Homoclinal ridges

A

Doesn’t have barriers between them - transport routes

71
Q

Utilisation of poort between Homoclinal ridges

A

Good for dam wall

72
Q

Utilisation of Cuesta basin

A

Yields artisian water

73
Q

Utilisation of Cuesta dome

A

Yields oil and gas

74
Q

Poort

A

Gap between two mountains created by river erosion

75
Q

How are intrusions formed

A

Magma flows through crust, cools and solidifies

76
Q

Batholith characteristics *1+3

A

*large magma dome shaped intrusion
*magma cools slowly to form large rock mass
*usually granite
*no bedding planes

77
Q

Laccolith definition and characteristics *1+4

A

*small mushroom shaped magma intrusion
*connected by pipe to intrusion source
*magma intruding strata causes them to dome
*dolerite is formed if magma cooled closer to the surface
*granite is formed if magma cooled deeper in the crust

78
Q

Lopolith definition and characteristics *1+2

A

*pan shaped intrusion found deeper in crust
*bend downwards
*usually granite

79
Q

Dyke definition and characteristics *1+1

A

*vertical dolerite sheets
*form when magma intrudes into vertical cracks

80
Q

Sill definition and characteristics *1+2

A

*horizontal dolerite layer
*fluid magma intruded between bedding planes
*stratified rock rather than massive

81
Q

What do massive rocks have rather than bedding planes

A

Joints and cracks

82
Q

Contractual joint

A

Joint formed when magma cooled

83
Q

Off-loading joint

A

Joint formed when the weight of overlying material was removed

84
Q

Granite dome

A

Landform caused by erosion of overlying strata to expose a batholith

85
Q

Exfoliation

A

Peeling of rock layers due to expansion and contraction

86
Q

Tor

A

Exposed granite blocks made from core stones -
Mass of loose core stones surrounded by weathered debris

87
Q

Why can’t tors form if joints are very close

A

Granite is mass weathered underground

88
Q

Explain the theory of slope decline by W.M Davis *2

A

*Steep slopes are created by rivers eroding vertically into uplifted landmass
*Slopes are less steep to the point where peneplain is formed

89
Q

Peneplain

A

Nearly flat plain formed from erosion of slopes

90
Q

Down wasting

A

Erosion of land mass where it flattens over time

91
Q

Pediplain

A

Nearly flat plane formed as canyons widen

92
Q

Back wasting

A

Erosion of land mass when it gets narrower

93
Q

Scarp/parallel retreat

A

Erosion of scarp slope - loss of ground but not height

94
Q

Explain scarp retreatment theory *3

A

*landscape started as uniform slope with equal weathering
*scree accumulates at base
*scree replaces gentler slope - doesn’t get lower

95
Q

🏔️Mass movement

A

Downward movement of weathered material as a result of gravity

96
Q

Factors that can influence mass movement *min 4 max 7

A

*slope gradient
*rock structure
*vegetation
*soil
*climate
*people
*earthquakes

97
Q

How does vegetation prevent erosion and downward movement *2

A

*roots bound soil
*vegetation provides resistance

98
Q

Three categories for mass movement

A

Flow
Slide
Fall

99
Q

Types of flow mass movement *4

A

*soil creep
*soilfluction
*earthflow
*mudflow

100
Q

🏔️Soil creep definition and characteristics *1+4

A

*slow continuous movement of soil down a slope
*less than 1cm per year
*expansion (soil and water) then contraction after soil dries
*forms small steps - teracettes
*indicated by bent landforms - accumulation of soil against them

101
Q

🏔️Solifluction definition and characteristics *1+2

A

*top soil is saturated, slides off frozen ground beneath
*terrace-like landforms, destroyed OG soil stratification
*5cm - 1m per year

102
Q

🏔️Earthflow definition and characteristics *1+2

A

*clay soil particles are saturated with water - move down a gentle slope
*5cm - 15km per year
*sediments deposited in river systems, damage roads

103
Q

🏔️Mudflow definition and characteristics *1+3

A

*streams of mud flows down a steep slope in definite channels
*1km per hour
*running water collects clay and ash - moved rapidly
*damages property

104
Q

Slide mass movement types *2

A

Landslides
Slumps

105
Q

🏔️Landslides and slumps definition *1+2

A

*sudden movement after a large mass of land breaks and plunged down a slope
*50km per hour
*impacts are more severe - property damage, death, loss of crops

106
Q

Fall mass movement type

A

Rockfalls

107
Q

🏔️Rockfall definition and characteristics *1+3

A

*rock fragments break off parent mass bc of weathering
collected as bottom as scree
*most rapid form - 100km p.h
slopes 40 or steeper
Just know impact is the worst

108
Q

Impact of mass movement on people *4

A

*Death and injury
*Damage to infrastructure
*Property damage
*Damage to agricultural land

109
Q

Why do people clear vegetation *5

A

*settlement
*transport routes
*dumping
*recreation
*quarrying

110
Q

Quarrying

A

Removing material from bottom or side of hill

111
Q

🏔️What needs to be implemented to minimise mass movement effects *5

A

*research on geology, ecology and rainfall in that area
*vegetation must be maintained
*drainage measures
*landslide areas must be restricted
*risk assessments must be conducted

112
Q

🏔️Factors that increase the risk of mass movement *5

A

*saturated pore water
*layered rock
*downslope
*extensive development- little vegetation
*steep slope angle