Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GEO1111 > Weathering, Erosion, and Mass Movement > Flashcards

Weathering, Erosion, and Mass Movement Flashcards

1
Q

Define weathering

A

physical breakdown and chemical alteration of rock at or near Earth’s surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two kinds of weathering?

A

Mechanical and Chemical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Mechanical Weathering

A

physical forces breaking rock into smaller pieces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Chemical weathering

A

chemical transformation of rock into new compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

True or False: Both kinds of weathering work simultaneously and reinforce each other?

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

True or False: Mechanical weathering increases surface area?

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the relation between mechanical and chemical weathering

A

as mechanical weathering breaks rocks into smaller pieces, more surface area is exposed to chemical weathering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Types of mechanical weathering

A
  • Frost wedging
  • Sheeting/unloading
  • Biological Activity
  • Salt crystal growth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Frost wedging

A
  • water that freezes in cracks enlarges the cracks

- lenses of ice increase in size as they attract liquid water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Unloading/Sheeting

A
  • unloading leads to sheeting

- concentric slabs break loose when large masses of igneous rock are exposed due to erosion and glaciation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does an exfoliation dome form?

A

-continued weathering causes slabs to fall off and form a EXFOLIATION DOME

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are joints?

A

Joints are fractures produced by contraction during the crystallization of magma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Biological growth

A
  • PLANT ROOTS grow into fractures in rocks, expanding cracks

- BURROWING ANIMALS move fresh material to the surface, enhancing mechanical and chemical weathering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Types of Chemical Weathering

A
  • Dissolution
  • oxidation
  • hydrolysis
  • spheroidal weathering
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the most important agent in chemical wearthing?

A

Water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Three things about Dissolution

A

A small amount of acid in water is responsible for the corrosive properties

  • CO2 dissolved in rain=carbonic acid
  • Calcite (CaCO3) is particularily susceptible to weakly acidic solutoin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Three things about Oxidation

A

rust (iron oxide) forms when O2 combines with Fe

  • water catalyses the rxn
  • important in decomposing ferromagnesium minerals (olivine, pyroxene, hornblende, and biotite)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Two things Hydrolysis

A
  • any rxn with water

- silicates (clay) decompose via hydrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

True or False: Clay minerals are the most abundant product of weathering

A

true

20
Q

Spheroid weathering (3)

A

1) water penetrates jointed rocks
2) chemical waethering decomposes minerals and enlarges joints
3) rocks are attacked around the corners and edges, producing spherical shapes and fragments

21
Q

What influences the rate of weathering

A

Rock Type and Climate

  • silicate minerals weather in same order as Bowen’s rxn series (Olivine –> pyroxine –> amphibole –> biotite etc)
  • warm/moist climates enhance weathering
  • cold/dry climates inhibit
22
Q

Differential Weathering

A

uneven weathering due to different mineral composition

23
Q

Examples of differential weathering

A

Soil

-portion of regolith that supports growth of plants

24
Q

Define regolith

A

Mineral fragments that cover the surface of earth

25
Q

Impact of human activity on soil

A

soil erosion (loss of topsoil)
-enhanced by deforestation and farming
soil conservation
-planting in patterns that follow contour of landscape reduces rate of water runoff
-grassed waterways between crops prevetns formation of gullies and traps soil washed from cropland

26
Q

True or False: Weathering and erosion are slow processes (snail)

A

true

27
Q

Define Mass Movement

A

movement of bedrock, rock debris, or soil downslope due to gravity
-ie. landslide

28
Q

What is the main driving force of mass movement?

A

erosion agents (weathering, erosion etc)

29
Q

Gravitational Driving Force

A

F(drive)=ma=mg

30
Q

Friction and Cohesion RESISTING FORCE

A

F(res)= mu(fric)mgcos(theta)

F(res)=basal friction+internal strength

31
Q

Shear deformation

A

internal deformation (flow) due to gravity

32
Q

Factors that influence internal strength of rock debris, sediment, or soil

A

1) electrostatic forces (ie. clay particles)
2) friction @ grain contact=f(angularity, grain size)
3) pore pressure
4) surface tension
(wet sand–>dry sand–>damp sand) (in order of increasing cohesion)

33
Q

Define Angle of repose

A

increase with grain size

  • fine sand (round): 35 degrees
  • fine sand (angluar): 40
  • course sand: 45
34
Q

What makes a slope SUSCEPTIBLE to mass movement

A

1) slope angle
2) relief
3) bedrock type (ie. jointed, fractured, bedded)
4) thickness of debris (ie. soil cover)
5) climate
- a) ice (freeze-thaw cycle)
- b) water/moisture
- c) rain
- d) vegetation (low cover)

35
Q

What TRIGGERS mass movement

A
  • heavy rainfall/snowmelt
  • addition of buildings
  • earthquakes/explosions/eruptions
  • excavation/road construction/ river erosion
36
Q

Falls

A

Rock: rockfall, very fast
Debris: debrisfall, fast-very fast

37
Q

Slide

A

Rock: rockslide, fast
Debris:
-slump (rotational), slow-moderate
-debris slide (translational), slow-fast

38
Q

Flow:

A 
Rock: 
-creep, very slow (10 cm/yr)
Debris:
-creep, very slow (,10 cm/yr)
-Earthflow/gelifluction/debris flow/mudflow/quick clays, mod-fast
-avalanche, very fast
-
39
Q

creep

A

very slow
Mechanisms:
-wet/dry cycle
-freeze/thaw cycle

40
Q

gelifluction

A

in colder climate: H2O saturated debris moves over permafrost during warmer months

41
Q

Debris flow

A

course material (boulder/gravel) is predominant, supported by matrix of finer sediment

42
Q

mudflow

A

mix of debris and water, confined by chanel

  • faster/further than debris flow
  • high water content
43
Q

Where do mudflows occur

A

flanks of volcanoes, steep deforested mountain sides, steepened cliffs of unconsolidated fine sediment

44
Q

True or False; Pyroclastc flows (ash, hot gases, sediment) turn into mudflows (sediment and water) downstream

A

true

45
Q

Quickclays

A
  • clays deposited in laciomarine environments

- decreased stability when salt is leached out by freshwater

46
Q

Clay mineral formation

A

orthoclase feldspar + acid+ water = clay + potassium + soluble silica
(2KAlSi3O8 + 2H+ + 9H2O = Al2Si2O5(OH)4 + 2K+ + 4H4SiO4)

47
Q

What is the relative rate of weathering of common minerals?

A

most stable to least stable;
Iron oxide, aluminum hydroxides, quartz, clay minerals, musovite mica, potassium feldspar, boilite, albite, amphiboles, pyroxene, anorthite, olivine, calcite, halite.

GEO1111 (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions