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
2
Q
does weathering happen in situ or ex situ
A
IN SITU
3
Q
does weathering involve sediment transport
A
NO
4
Q
does erosion take place before or after weathering
A
AFTER
5
Q
are particles transported in erosion
A
yes
6
Q
what process does 1 represent
A
deposition
7
Q
what process does 2 represent
A
weathering
8
Q
what process does 3 represent
A
erosion
9
Q
three types of weathering
A
- mechanical/physical
- chemical
- biological
10
Q
physical/mechanical weathering
A
processes that break rock or mineral into smaller pieces WITHOUT altering the composition
11
Q
does mechanical weathering involve chemical changes
A
NO - just breaks the rock into smaller pieces
12
Q
chemical weathering
A
processes that change the chemical composition of rocks and minerals
13
Q
biological weathering
A
process of breaking down rocks by biological agents (plants, animals, humans, secretions)
14
Q
what are agents of mechanical weathering
A
- frost wedging
- abrasion by wind, water or gravity
15
Q
what are agents of biological weathering
A
plant growth
16
Q
what type of weathering is this
A
mechanical - wind abrasion
17
Q
what type of weathering is this
A
mechanical - splitting
18
Q
what type of weathering is this
A
biological - plant growth
19
Q
what is the process of mechanical weathering
A
actions or things that break down earth materials WITHOUT changing composition
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)
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
22
Q
what type of weathering is this
A
mechanical weathering - wave abrasion
23
Q
what type of weathering is this
A
mechanical - ice abrasion
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
25
what are three examples of chemical weathering
- dissolution (dissolving)
- oxidation
- hydrolysis
26
do the different types of weathering work isolated from each other
NO - often the different processes work in tandem (biological weathering opens the door for chemical weathering)
27
describe the process of dissolution
water contains acids from dissolved CO2
- these acids will dissolve minerals from the rock and leave large cavities behind
28
what is the main agent of dissolution
water
29
what are possible outcomes from dissolution
giant cavities leading to sinkholes or caves
- building of materials forming stalactites and stalagmites
30
what is the equation for the production of carbonic acid leading to bicarbonate
CO2 + H2O ---> H2CO3 -----> HCO3- + H+
31
what is the equation for the dissolution of calcite (CaCO3)
CaCO3 + H2CO3 -----> 2HCO3- + Ca2+
32
what type of weathering causes sink holes
chemical - dissolution
33
what type of weathering is this
chemical ---> dissolution
34
what type of weathering is this
chemical - dissolution
35
describe how acid rain forms
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
describe oxidation
minerals that combine with oxygen to form new minerals that are NOT AS HARD
37
are the product of oxidation resistant to weathering
NO- are softer
38
what type of weathering is this
chemical - oxidation
39
describe hydrolysis
minerals combine chemically with water to form new minerals NOT as strong as the original material
40
what form of weathering gives clay materials
chemical weathering - hydrolysis
41
what type of weathering is this
chemical - hydrolysis
42
what are four factors that determine rates of chemical weathering
climate
plants/animals
time
mineral composition
43
how does climate affect chemical weathering
warm and wet climates maximize chemical reactions = more weathering
44
how do plants/animals affect chemical weathering
they secrete substances that reach with rock which aids weathering agents and increase weathering
45
how does time affect chemical weathering
the longer the rock is exposed to the elements/weathering agents the more it will be weathered
46
how does regolith form
by weathering
47
what is regolith
a rock blanket composed of small rock and mineral fragments
48
when does soil officially form
when organic matter is mixed with regolith
49
is soil formed in situ or ex situ
in situ
50
what is soil NOT
dirt, sediments, rocks or regolith
51
what is soil formed from
rock/mineral particles weathered from parent material mix with organic material, air and water
52
what are the five soil forming factors
1. parent material
2. living organisms
3. climate
4. topography
5. time
53
how does the parent material affect soil formation
determines the sediments mixing to form soil will be (different parent materials weather different sediments which form different soil compositions)
54
how does the local organism life affect soil formation
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
how does the climate affect soil formation
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
how does the topography affect soil formation
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
how does time affect soil formation
more soil will form over long periods of time and will build up more the longer it can be undisturbed
58
how are soils structures organized
vertically into layers
59
what are soil layers called
horizons
60
what are horizons based on
- colour
- structure
- chemistry
- texture
- organic content
61
are transitions between soil horizons always clear
NO
62
describe the different layers of a soil profile
O - humus layer
A- topsoil (high organic content)
B - subsoil (illuviation or accumulation layer)
C - regolith
R- bedrock
63
what are agents of erosion
- water
(rain, streams/rivers, oceans, ice)
- wind
- gravity
64
is wind just an erosion agent
NO - also a weathering agent (mechanical)
65
how is gravity an agent of erosion
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
how are streams an agent of erosion
flowing water will lift and carry small sediments away and deposit them elsewhere on the river course
67
describe how streams move sediments
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
how do glaciers transport sediments
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
how is wind an erosion agent
it will carry fine and dry sediments over long distances
70
what is the term for transport by gravity
mass movements
71
what are examples of transport by gravity
slumps
scree (loose sediments transported by gravity caused by frost wedging)
72
what type of erosion by gravity is this
scree fields
73
what type of erosion by gravity is this
slump
74
what is the final step after erosion and weathering
deposition
75
what is deposition
when the transported sediments are deposited in layers and generate strata
76
what are different forms of weathering
- granular disintegration
- crumbly disintegration
- flaking
- exfoliation (like onion peels)
- spherodial
- blocky (right angle breakage)
77
permeability vs porosity
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
what facilitates weathering
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
where does weathering occur
at the outer layer of the rock OR the top layer of soils (earth surface to water table)
80
what is the weathering rate a function of
surface area
81
the larger the relative surface area/exposed sediments
the faster weathering process
82
how does grain sizes affect weathering rates
smaller grain sizes = more exposed surface area = more weathering
larger grain sizes = less exposed surface area = less weathering
83
what is soil formation a result of
weathering
