Weathering

Question 1

What is weathering?

Answer 1

Processes of change of rocks, minerals, soils

Question 2

What are the types of weathering on
Earth? Give an example of each.

Answer 2

Physical-Water expanding in the cracks of a rock

Chemical-Caves or rusting

Biological-roots growing and breaking a rock

Question 3

What types of weathering occur on
Earth’s moon?

Answer 3

Physical

Question 4

Does weathering occur on Mars? Give an
example.

Answer 4

Yes; ventifacts in Gusev Crater

Question 5

What type of weathering produced Meteor
Crater?

Answer 5

Physical?

Question 6

What are ventifacts?

Answer 6

Rock that has been physically shaped by the wind and sand

Question 7

What features of basaltic flows indicate
weathering? Which type?

Answer 7

columnar basalts ; cracking ?

Question 8

What is the importance for weathering of
rock fragments?

Question 9

What is a freeze-thaw cycle? Where does
freeze-thaw weathering occur?

Answer 9

Freezing and thawing of water inside of mountains generating 2000 psi. Pikes Peak, CO

Question 10

What is a pluton? What happens during
the “unroofing” of a pluton?

Answer 10

Any crystallized mass of magma underground ; The surface has to be weathered away

Question 11

What is the “geopressure gradient”? What
is the “pressure” at a depth of about 15
km?

Answer 11

change of pressure with depth ; aproximately 4,000 psi per km of depth ; 60,000

Question 12

What are the three major categories of
weathering products?

Question 13

Which chemically reactive compounds in
Earth’s atmosphere are important
because they drive chemical weathering
processes?

Answer 13

O2, H2O, CO2 > atmospheric gases

Question 14

What is oxidation weathering? Give an
example.

Answer 14

Dissolved iron combining in streams with oxygen

Question 15

What is hydrolysis? Give an example.

Answer 15

Water breaking the bonds of an atom apart ; dissolving ; mixing salt in water

Question 16

What is carbonic acid? What feature
makes it an acidic compound?

Answer 16

When H2O picks up a CO2 and becomes H2CO3. Carbonic acid is rain

Question 17

What is the pH of natural rain?

Answer 17

5.5

Question 18

Is a sample of river water with a pH of 6.5
more or less acidic than a sample of
rainwater with a pH of 7?

Answer 18

more acidic

Question 19

How much less acidic is a sample of well
water with a pH of 6.5 more compared to
a sample of rainwater with a pH of 5.5?

Answer 19

1/10

Question 20

How much more acidic is a sample of well
water with a pH of 3.5 more compared to
a sample of rainwater with a pH of 5.5?

Answer 20

100 x

Question 21

How does the pH of groundwater
compare to the pH of rainfall? Explain.

Answer 21

pH of groundwater is lower than pH of rainwater

Question 22

What effect does groundwater have on
the mineral CaCO3 (and the rock
limestone)? Explain.

Answer 22

It weathers the rock and creates caves.

Question 23

What conditions are required for forming
caves in limestone?

Answer 23

Hydration and carbonation

Question 24

Why, and how, do sinkholes form?

Answer 24

When a caves roof collapses into the cave because it can no longer support itself.

Question 25

How does the chemical weathering of
rock affect the concentration of CO2 in
the atmosphere?

Question 26

If the chemical weathering of rock “uses
up (removes)” CO2 from the atmosphere,
where does the CO2 eventually go?

Question 27

What mineral is a major source of clay by
chemical weathering?

Answer 27

Feldspar

Question 28

What is the most, and second-most,
abundant mineral, in the sand of Alabama
beaches? Where does most of this sand
come from? How does it get to the
beach?

Answer 28

Quartz, Feldspar. Mount Cheaha. Wind and erosion.

Question 29

What is the most abundant silicate
mineral in Earth’s crust? 2nd most
abundant?

Answer 29

feldspar ; quartz

Question 30

Why is the ocean “salty”? Where does the
“salt” come from? What is “salt”, anyway?

Answer 30

• Chemically reactive water
• Dissolution of continental rock
• Transport of ions to oceans
• Evaporation of oceans leaving ions behind in the sea

Question 31

What is soil? Why is it important to
mankind?

Answer 31

Weathered rock and minerals capable of supporting plant life. It allows us to grow food.

Question 32

What major factors affect the formation of
soil?

Answer 32

Parent material, biota, climate, topography, and time

Question 33

How do temperature and rainfall,
important factors of climate, each control
the rate of soil formation?

Answer 33

Warm weather encourages plant growth and rainfall causes leeching as well as dissolving some minerals.

Question 34

What are soil horizons? In what order do
soil horizons form? What are the
characteristics and properties of these
soil horizons?

Answer 34

is a layer parallel to the soil surface, whose physical characteristics differ from the layers above and beneath.

Question 35

What are the names and characteristics
of the three major types of soils?

Answer 35

Heavy soil-Large component of clay ; heavy, sticky, and many fine particles

Medium soil-containst nutrients essential for plants, and holds water well

Light soil-drain quickly do not hold water ; sandy

Question 36

What happens during the “salinization” of
soil? Does salinization increase or
decrease agricultural production?

Answer 36

From poorly drained lands with high evaporation rate.

decrease agriculture

Question 37

What methods have been developed to
successfully farm in areas of salinized
soil? Explain.