(MODULE 6) WEATHERING & SOIL FORMATION

Question 1

the physical breakdown and chemical alteration of rock

Answer 1

weathering

Question 2

the physical removal of rock particles by mobile agents (water, wind, ice, gravity)

Answer 2

erosion

Question 3

movement of eroded particles by agents (rivers, waves, glaciers, wind)

Answer 3

transportation

Question 4

weathering which breaks up rock but doesn’t change composition

Answer 4

mechanical weathering

Question 5

decomposition of rock from exposure to water and atmospheric gases; as rock is decomposed by these agents, new chemical compounds form

Answer 5

chemical weathering

Question 6

reduction of pressure on a body of rock; can cause rock to crack as it expands

Answer 6

pressure release

Question 7

how does pressure release happen and how do sheet joints form?

Answer 7

the pressure on top of the deep pluton is released through unloading, causing an uplift on the plutonic rock which expands and develops cracks called sheet joints which develop parallel to the outer surface of the rock.

Question 8

why can’t sheet joints exist without clay?

Answer 8

the sheet joints contain cleavage surfaces between the slabs, hence the name. when the sheet joints form, they become weak surfaces which flake off.

Question 9

on slopes, gravity may cause the rock between the joints to break loose in concentric slabs from the underlying granite mass. this process of spalling off of rock layers is called ___.

Answer 9

exfoliation

Question 10

the mechanical effect of freezing water on rocks

Answer 10

frost action

Question 11

the expansion of freezing water pushes rock apart

Answer 11

frost wedging

Question 12

the expansion of freezing water pushes rock apart

Answer 12

frost wedging

Question 13

vertical expansion of rock and soil due to water freezing underneath the surface

Answer 13

frost heaving

Question 14

particularly roots growing in cracks can break up rocks

Answer 14

plant growth

Question 15

___ can cause a rock to expand until it breaks.

Answer 15

extreme changes in temperature

Question 16

mechanical weathering can ___, accelerating the rate of chemical weathering

Answer 16

increase the surface area of a rock

Question 17

the decomposition of rock from exposure to water at atmospheric gases

Answer 17

chemical weathering

Question 18

chemical weathering changes the ___ of rocks

Answer 18

composition

Question 19

chemical weathering is a ___ process, as the mineralogy of the rock adjusts to the near surface environment

Answer 19

gradual and ongoing

Question 20

chemical weathering is ___ such as the presence of water and oxygen

Answer 20

enhanced by geological agents

Question 21

major processes of chemical weathering:
1.
2.
3.

Answer 21

1. dissolution
2. oxidation
3. hydrolysis

Question 22

major processes of mechanical weathering
1.
2.
3.
4.

Answer 22

1. pressure release
2. frost action
3. plant growth
4. extreme temperature change

Question 23

aided by small amounts of acid in the water

Answer 23

dissolution

Question 24

the most important natural source of acid for rock weathering at earth’s surface is ___ in water.

Answer 24

carbon dioxide

Question 25

water and carbon dioxide form ___, the acid featured in dissolution.

Answer 25

carbonic acid

Question 26

the decomposition of rock through dissolution is ___.

Answer 26

gradual and subtle

Question 27

___ are processed because they are acidic and cause changes in the surroundings; they originate from mines and its draining processes

Answer 27

mine tailings

Question 28

any reaction when electrons are lost form one element

Answer 28

oxidation

Question 29

oxygen from the atmosphere combines with the iron to form iron oxide. iron oxide formed through oxidation is a weathering product of numerous minerals containing iron, such as the ___ group.

Answer 29

ferromagnesian

Question 30

___ is a good indication of oxidation.

Answer 30

color

Question 31

resulting mineral when oxygen combines with iron to form iron oxide through oxidation.

Answer 31

hematite

Question 32

the reaction of any substance with water

Answer 32

hydrolysis

Question 33

how does hydrolysis occur?

Answer 33

hydrogen ions destroy the arrangement of the rocks’ atoms and create new minerals in its place

Question 34

factors affecting weathering
1.
2.
3.
4.

Answer 34

1. availability of water
2. climate
3. temperature
4. steep slopes, precipitation, freezing/thawing, flowing glacial ice

Question 35

rock chemically weathers much faster in ___ than in arid climates.

Answer 35

humid climates

Question 36

the most intense chemical weathering occurs in ___.

Answer 36

the tropics

Question 37

a natural process; it is part of the constant recycling of earth materials that we call the rock cycle

Answer 37

soil erosion

Question 38

types of soil erosion
1.
2.

Answer 38

1. splash erosion
2. sheet erosion

Question 39

splash erosion requires ___, whereas sheet erosion requires ___.

Answer 39

1. water
2. movement of sediments

Question 40

the rate of soil erosion is influenced by several factors:
1.
2.
3.
4.

Answer 40

1. soil characteristics
2. climate
3. slope
4. vegetation

Question 41

course-grained soils tend to have ___ and can ___ than fine-grained soils (clay)

Answer 41

1. larger pore spaces
2. absorb more water

Question 42

a gentle rain over a long period of time produces ___ than a short, heavy rain storm.

Answer 42

less splash erosion

Question 43

___ can infiltrate the soil during gentle rainfall and there is ___ of sheet erosion occurring.

Answer 43

1. more water
2. less likelihood

Question 44

water moves more slowly on ___ and is more likely to percolate down into the soil.

Answer 44

gentle slopes

Question 45

the faster-moving water on ___ does not infiltrate and has greater ability to dislodge and transport soil particles down from the slope.

Answer 45

steeper slopes