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Ecology 228 > Chapeter 2 > Flashcards

Chapeter 2 Flashcards

1
Q

Weathering

A

In-situ breakdown and alteration of earth forming materials (physical or chemical)

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2
Q

Why does weathering happen

A

Rocks are formed within the crust: higher P,T
Unstable under surface conditions
Products of weathering are more stable

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3
Q

Controls on weathering rate

A

Mineralogy
Petrology
Climate
Vegetation

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4
Q

Main control on weathering

A

Climate

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5
Q

Most active part of the weathering zone

A

soils

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6
Q

Active process on soil weathering

A 
Organic accumulation and decay
Oxidation
Reduction
Ground water movement
Bioturbation
Microbial activity
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7
Q

Soil O

A

Organics

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8
Q

Soil A

A

Surface soil layer (top soil)

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9
Q

Soil E

A

Zone of eluvation

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10
Q

Soil B

A

Zone of Accumulation

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11
Q

Soil C

A

Realtively unalterd parent material

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12
Q

Types of Physical weathering

A 
Unloading
Thermal expansion
Frost action
Wetting and drying
Salt crystal growth
Root action
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13
Q

Unloading

A

(pressure release)
Erosion removes overburden–> rocks expand
Rocks split into sheets parallel to the topography

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14
Q

Thermal expansion

A

Rocks and minerals expand/ contract in respoince to heating and cooling
Need frequent, extreme fluctuations

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15
Q

Frost action

A

Repeated formation and melting of ice in pore

Water expands 9% upon freezinf

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16
Q

Wetting and drying

A

Materials swell when wet and shrink. crack when dry

Most effective in clay-rich rocks and sediment

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17
Q

Salt crystal growth

A

Precipitation of salt crystals in rock pores/ cracks

Typical of dry climate and coasts

18
Q

Root action

A

Plant roots grow into joints, force rock apart

19
Q

Chemical weathering

A

AKA Decomposition

Secondary minerals are produced (clays)

20
Q

Types of Chemical Weathering

A

Hydrolysis
Oxidation
Solution
Carbonation

21
Q

Hydrolysis

A 
Breakdown of water into H+ and OH- ions
H ions replace metal cations in rock
Freed cations form soluble oxides
Accelerated if there is CO2 in the water
Dominant process in igneous rocks
22
Q

Oxidation

A

Addition of oxygen to minerals- forms oxides

Most effective in aerated zone: presence of air and water

23
Q

Solution

A 
Dissociation of minerals in water
Ions lost to ground water
Most effective in acidic water 
Forms karst like features
Salts, gypsum, carbonate are especially prone
24
Q

Carbonation

A

So;ution of minerals in carbonic acid
CO2 from atmosphere, decaying organic matter
Prevalent in limestone bedrock, dolomite and marble

25
Q

Weathering landscapes

A

High rates of weathering no other dominant processes

26
Q

Types of weathering land scapes

A

Felsenmeer

Karst

27
Q

Felsenmeer

A

Block feild topography
Dominated by frost action
Alpine areas, artic, antartic

28
Q

karst

A

Landscapes formed by carbonation
Limestone or dolomite bedrock
Humid clomate

29
Q

Sediment

A

Fragments of rock that have moved from their orignal position
Requires weathering

30
Q

Three phases to sediment movement

A

Erosion
Transport
Deposition

31
Q

Slopes may be

A

Weathering limited
Erosion limited
Equilibrium

32
Q

Erosional slope is

A

Convex upper slope , Possible ‘ free face’

33
Q

Transport slope

A

Straight mid slope

34
Q

Depositional

A

Concave lower slope

35
Q

Rain splash

A

Impact of raindrops—> particles ‘ jump away
Effective in areas with sparse vegetation cover
Main outcome: pores sealed by fine material—> more surface run off’

36
Q

Sheet erosion

A

Result of sheet flow: Overland flow as a shallow layer

removes particles in thin layers

37
Q

Rilling

A

Sheet flow concentrates into rivulets

Cut small parallel channels called rills

38
Q

Gully erosion

A

rills may join to form gullies: deeper v shaped channels carved by concentrated run off

39
Q

causes for more intence run off

A

land clearing, roads

40
Q

Causes for less permeable soil

A

Land clearing farm equipment, ranging live stock

41
Q

Causes for steeper slopes

A

Roads

Ecology 228 (4 decks)

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