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Geomorphology > Weathering and Erosion > Flashcards

Weathering and Erosion Flashcards

1
Q

weathering vs erosion

A

weathering
- process at or near earth’s surface that causes rocks and minerals to break down

erosion-
process of removing rocks/minerals/
sediments from their original sites through weathering and transport

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2
Q

does weathering happen in situ or ex situ

A

IN SITU

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3
Q

does weathering involve sediment transport

A

NO

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4
Q

does erosion take place before or after weathering

A

AFTER

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5
Q

are particles transported in erosion

A

yes

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6
Q

what process does 1 represent

A

deposition

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7
Q

what process does 2 represent

A

weathering

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8
Q

what process does 3 represent

A

erosion

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9
Q

three types of weathering

A
  • mechanical/physical
  • chemical
  • biological
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10
Q

physical/mechanical weathering

A

processes that break rock or mineral into smaller pieces WITHOUT altering the composition

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11
Q

does mechanical weathering involve chemical changes

A

NO - just breaks the rock into smaller pieces

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12
Q

chemical weathering

A

processes that change the chemical composition of rocks and minerals

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13
Q

biological weathering

A

process of breaking down rocks by biological agents (plants, animals, humans, secretions)

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14
Q

what are agents of mechanical weathering

A
  • frost wedging
  • abrasion by wind, water or gravity
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15
Q

what are agents of biological weathering

A

plant growth

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16
Q

what type of weathering is this

A

mechanical - wind abrasion

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17
Q

what type of weathering is this

A

mechanical - splitting

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18
Q

what type of weathering is this

A

biological - plant growth

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19
Q

what is the process of mechanical weathering

A

actions or things that break down earth materials WITHOUT changing composition

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20
Q

describe frost wedging

A

the cracking of rock mass by the expansion of water as it freezes in crevices and cracks (think of the freeze thaw cycle)

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21
Q

what is abrasion

A

sediments transported in or that broke off from the rock’s surface that can be moved along the rock’s surface (grating the larger section of rock) by wind or water

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22
Q

what type of weathering is this

A

mechanical weathering - wave abrasion

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23
Q

what type of weathering is this

A

mechanical - ice abrasion

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24
Q

how does plant growth cause weathering

A
  • their root systems find their way into existing cracks in rocks
  • as the roots increase in size they force the cracks apart which increases separation and weathering
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25
Q

what are three examples of chemical weathering

A
  • dissolution (dissolving)
  • oxidation
  • hydrolysis
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26
Q

do the different types of weathering work isolated from each other

A

NO - often the different processes work in tandem (biological weathering opens the door for chemical weathering)

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27
Q

describe the process of dissolution

A

water contains acids from dissolved CO2

  • these acids will dissolve minerals from the rock and leave large cavities behind
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28
Q

what is the main agent of dissolution

A

water

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29
Q

what are possible outcomes from dissolution

A

giant cavities leading to sinkholes or caves

  • building of materials forming stalactites and stalagmites
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30
Q

what is the equation for the production of carbonic acid leading to bicarbonate

A

CO2 + H2O —> H2CO3 —–> HCO3- + H+

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31
Q

what is the equation for the dissolution of calcite (CaCO3)

A

CaCO3 + H2CO3 —–> 2HCO3- + Ca2+

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32
Q

what type of weathering causes sink holes

A

chemical - dissolution

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33
Q

what type of weathering is this

A

chemical —> dissolution

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34
Q

what type of weathering is this

A

chemical - dissolution

35
Q

describe how acid rain forms

A

by burning fossil fuels we release sulfuric dioxide and nitrogen dioxide which react with water (in clouds) and precipitate back to the ground as sulfuric acid and nitric acid

36
Q

describe oxidation

A

minerals that combine with oxygen to form new minerals that are NOT AS HARD

37
Q

are the product of oxidation resistant to weathering

A

NO- are softer

38
Q

what type of weathering is this

A

chemical - oxidation

39
Q

describe hydrolysis

A

minerals combine chemically with water to form new minerals NOT as strong as the original material

40
Q

what form of weathering gives clay materials

A

chemical weathering - hydrolysis

41
Q

what type of weathering is this

A

chemical - hydrolysis

42
Q

what are four factors that determine rates of chemical weathering

A

climate
plants/animals
time
mineral composition

43
Q

how does climate affect chemical weathering

A

warm and wet climates maximize chemical reactions = more weathering

44
Q

how do plants/animals affect chemical weathering

A

they secrete substances that reach with rock which aids weathering agents and increase weathering

45
Q

how does time affect chemical weathering

A

the longer the rock is exposed to the elements/weathering agents the more it will be weathered

46
Q

how does regolith form

A

by weathering

47
Q

what is regolith

A

a rock blanket composed of small rock and mineral fragments

48
Q

when does soil officially form

A

when organic matter is mixed with regolith

49
Q

is soil formed in situ or ex situ

A

in situ

50
Q

what is soil NOT

A

dirt, sediments, rocks or regolith

51
Q

what is soil formed from

A

rock/mineral particles weathered from parent material mix with organic material, air and water

52
Q

what are the five soil forming factors

A
  1. parent material
  2. living organisms
  3. climate
  4. topography
  5. time
53
Q

how does the parent material affect soil formation

A

determines the sediments mixing to form soil will be (different parent materials weather different sediments which form different soil compositions)

54
Q

how does the local organism life affect soil formation

A

flora, fauna and people living in the area all affect the composition of soil (based on how they interact with it, build homes in it, the presence of micro-organisms…)

55
Q

how does the climate affect soil formation

A

hot and wet climates have a more rich soil profile (based on having more weathering) where a dry and cold climate has a less rich profile

56
Q

how does the topography affect soil formation

A

deep basins that can hold soil and prevent weathering away of loose top soil will have a richer and deeper soil profile where steep slopes that don’t have the protections against loosing the soil will have a less rich soil profile (smaller in depth)

57
Q

how does time affect soil formation

A

more soil will form over long periods of time and will build up more the longer it can be undisturbed

58
Q

how are soils structures organized

A

vertically into layers

59
Q

what are soil layers called

A

horizons

60
Q

what are horizons based on

A
  • colour
  • structure
  • chemistry
  • texture
  • organic content
61
Q

are transitions between soil horizons always clear

A

NO

62
Q

describe the different layers of a soil profile

A

O - humus layer

A- topsoil (high organic content)

B - subsoil (illuviation or accumulation layer)

C - regolith

R- bedrock

63
Q

what are agents of erosion

A
  • water
    (rain, streams/rivers, oceans, ice)
  • wind
  • gravity
64
Q

is wind just an erosion agent

A

NO - also a weathering agent (mechanical)

65
Q

how is gravity an agent of erosion

A

when slopes are weakened by weathering they are less resistant to the force of gravity on them and result in failures where particles will fall (leave their in situ placements)

66
Q

how are streams an agent of erosion

A

flowing water will lift and carry small sediments away and deposit them elsewhere on the river course

67
Q

describe how streams move sediments

A

water moves faster along the outside of a curve which causes more erosion and sediments to enter the moving water

water moves slower on the inside of a bend and will deposit the sediments in the water

68
Q

how do glaciers transport sediments

A

they are large slow downhill moving ice fields that drag rocky material over the surface and deposit it in gouges in the earth as it melts

69
Q

how is wind an erosion agent

A

it will carry fine and dry sediments over long distances

70
Q

what is the term for transport by gravity

A

mass movements

71
Q

what are examples of transport by gravity

A

slumps

scree (loose sediments transported by gravity caused by frost wedging)

72
Q

what type of erosion by gravity is this

A

scree fields

73
Q

what type of erosion by gravity is this

A

slump

74
Q

what is the final step after erosion and weathering

A

deposition

75
Q

what is deposition

A

when the transported sediments are deposited in layers and generate strata

76
Q

what are different forms of weathering

A
  • granular disintegration
  • crumbly disintegration
  • flaking
  • exfoliation (like onion peels)
  • spherodial
  • blocky (right angle breakage)
77
Q

permeability vs porosity

A

permeability
- how readily a liquid can move THROUGH a substance (holes are interconnected)

porosity
- the capacity (like for soils) to hold water so wholes are NOT interconnected

78
Q

what facilitates weathering

A

exposed surface area (allow weathering agents inside rock)

high permeability (water is efficiently moved through)

high porosity (high capacity to hold water)

climate (freeze cycles, wet/dry)

the mineral being more susceptible to weathering

79
Q

where does weathering occur

A

at the outer layer of the rock OR the top layer of soils (earth surface to water table)

80
Q

what is the weathering rate a function of

A

surface area

81
Q

the larger the relative surface area/exposed sediments

A

the faster weathering process

82
Q

how does grain sizes affect weathering rates

A

smaller grain sizes = more exposed surface area = more weathering

larger grain sizes = less exposed surface area = less weathering

83
Q

what is soil formation a result of

A

weathering

Geomorphology (4 decks)

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