Weathering

Question 1

3 types of wxing

Answer 1

physical, chemical, biological

Question 2

erosion is defined as:

Answer 2

the movement of material

Question 3

2 important aids to wxing

Answer 3

1. water 2. joints

Question 4

2 cold agents of wxing

Answer 4

1. frost or ice wedging (freeze-thaw cycles) 2. Frost heave (softer materials – model: potholes)

Question 5

unloading of downward pressure on a pluton:

Answer 5

overburden release (causes parallel fx’s and sheeting/exfoliation)

combines physical and chemical wxing

Question 6

Rounding of corners & edges by phys or chem agents

Answer 6

spheroidal wxing

Question 7

small-scale exfoliation due to fire:

Answer 7

spalling

Question 8

agents of physical wxing by plants or animals

Answer 8

roots, burrows

Question 9

an agent of biochemical wxing

Answer 9

lichens

Question 10

hoodoos are an example of :

Answer 10

differential wxing

Question 11

chemical process which creates hematite:

Answer 11

oxidation

exposure to air and water speeds rate of redox

Question 12

chemical process which leads to stalactite formation:

Answer 12

solution (dissolution) – breaking of calcite’s ionic bonds due to the polarity of the water molecule

Question 13

chemical process which creates clays

Answer 13

hydrolysis of feldspar to kaolinite

Question 14

chemical process which changes anhydrite to gypsum:

Answer 14

hydration: CaSO₄ + 2H₂O ➔ CaSO₄・2H₂O

Question 15

The Equation:

Answer 15

Soil = 𝑓(Cl + O + R + P + T)

Question 16

what is calcrete/caliche/hardpan; where is it from? where does it accumulate?

Answer 16

a layer of calcite; calcium liberated from rocks by rain; accumulates in the B horizon

Question 17

what is the order of minerals’ susceptibilities to wxing, from least stable to stablest at the surface?

Answer 17

Bowen’s reaction series: [oliv & pyrox] Ca plag amphibole Na plag biotite [Kfs muscovite Qz]

Question 18

If it moves:

Answer 18

It’s erosion

Question 19

3 examples of biological wxing

Answer 19

plants – roots

animals – burrows

lichen – digest surface

Question 20

1° agent of chemical wxing:

Answer 20

water and its solutes

Question 21

3 factors governing the rate of a rock’s wxing:

Answer 21

the nature of the rock’s minerals – fs vs Qz

surface area exposed, including joints

climate – heat and water

Question 22

5 lettered soil horizons, and 2 named layers:

Answer 22

O - loose, partly decayed organic matter [topsoil 1]

A - mineral matter + some humus [topsoil 2]

E - zone of eluviation and leaching

B - zone of accumulation (clay; caliche) [subsoil]

C - partly altered parent material

regolith - broken rubble from bedrock

bedrock - unaltered parent material

Question 23

the colorant minerals of red and yellow soils:

Answer 23

hematite and limonite

Question 24

what makes clay soil a problem for plant growth?

Answer 24

clay impedes root penetration

Question 25

what are strx-conferring clumps of soil particles called?

Answer 25

peds

Question 26

4 types of peds/soil structure:

Answer 26

prismatic peds

moderate water infiltration

blocky peds

platy peds

slower rates of H₂O infiltration

spheroidal peds

Question 27

mollisols are:

Answer 27

dark and fertile; rich in organic matter

the result of glacial transport

7% of world’s ice-free surface

Question 28

entisols are:

Answer 28

young soils; little profile development 16%

Question 29

1. tropical soils are:
2. arctic soils are:

Answer 29

very thick, but orgqnic mat’ls have been washed out

a few cm thick

Question 30

Histosols and entisols

Answer 30

histosols are boggy; peat

entisols are just beginning

Question 31

flat vs steep terrain

Answer 31

flat: rock exposed over long periods; extensive, deep wxing; flood plains produce excellent soils
steep: rapid run-off; erosion

Question 32

deserts

high-nutrient forest soils

volcanic

gelisols

Answer 32

aridisols

alfisols

andisols

tundra; permafrost soils