The Solid Earth - Chapter 2: Weathering

Question 1

Disintegration and decomposition of rock or near the surface of the earth

Answer 1

Weathering

Question 2

transfer of rock material downslope under the influence of gravity

Answer 2

Mass wasting

Question 3

incorporation and transportation of material by a mobile agent, usually water, wind, or ice

Answer 3

erosion

Question 4

As _____ breaks rock apart, it facilitates the movement of rock debris by erosion and mass wasting

Answer 4

Weathering

Question 5

True or false: the natural processes that break apart a concrete sidewalk are different in nature from those that disintegrate rock

Answer 5

False

Question 6

After millions of years of ___ and erosion, the rocks overlying a large intrusive igneous body may be removed, exposing it at the surface

Answer 6

uplift

Question 7

Rocks will change gradually until they are once again in equilibrium with their new ____

Answer 7

environment

Question 8

Mechanical and chemical weathering (do/do not) often work together

Answer 8

Do

Question 9

When a rock undergoes this type of weathering it is broken into smaller and smaller pieces, each retaining the characteristics of the original material

Answer 9

mechanical

Question 10

By breaking rocks into small pieces, mechanical weathering (increases/decreases) the amount of surface area available for chemical weathering

Answer 10

increases

Question 11

What are the four important physical processes that lead to the fragmentation of rock?

Answer 11

Expulsion from unloading
Frost wedging
Organic activity
Thermal expansion

Question 12

One of the most important processes of mechanical weathering is alternate freezing and ___

Answer 12

thawing

Question 13

Water expands about ___ percent when it expands

Answer 13

9

Question 14

The increase in volume in frozen water occurs because the molecules arrange themselves into a (straight line/open crystalline structure)

Answer 14

open crystalline structure

Question 15

True or false: when water freezes it can exert a tremendous outward force

Answer 15

true

Question 16

What is it called when rocks break into pieces after many freeze-thaw cycles?

Answer 16

frost wedging

Question 17

Where is frost wedging most pronounced:? (Hint: this area goes through a daily freeze-thaw cycle)

Answer 17

mountainous regions

Question 18

Large piles formed from sections of rocks that are wedged loose after frost wedging

Answer 18

talus slopes

Question 19

When large masses of igneous rock are exposed by erosion, concentric slabs begin to (break loose/cool)

Answer 19

break loose

Question 20

The process that produces the onion like layers that strip away in slabs in unloading

Answer 20

sheeting

Question 21

In unloading, sheets begin to strip away because the pressure has (decreased/increased)

Answer 21

decreased

Question 22

Fractures from unloading tend to develop (parallel/perpendicular) to the surface topography and give the exhumed igneous body a domed shape

Answer 22

parallel

Question 23

Continued weathering eventually causes the slabs produced by sheeting to separate and spall off these large structures known as ______ domes

Answer 23

exfoliation

Question 24

True or false: large rock slabs have been known to explode off the walls of newly cut mine shafts because of the reduced pressure

Answer 24

true

Question 25

Fractures produced by contraction during the crystallization of magma and tectonic forces are known as ___

Answer 25

joints

Question 26

Joints are important rock structures that allow ____ to penetrate to depth and start the process of weathering before the rock is exposed at the surface

Answer 26

water

Question 27

The daily cycle of temperature change is thought to (weaken/strengthen) rocks

Answer 27

weaken

Question 28

Which is true?
A. Heating a rock causes it to contract, and freezing a rock causes it to expand
B. Heating a rock causes it to expand, and freezing a rock causes it to contract

Answer 28

B

Question 29

Which part of the shell is withstanding stress as the rocks expand and contract?

Answer 29

Shell

Question 30

Scientists have debated the veracity of the thermal expansion explanation, and the plausible response they concluded is that rocks must be weakened by ____ _____ before they are broken down by thermal activity

Answer 30

chemical weathering

Question 31

Plant roots in search of _____ and _____ grow into fractures, and as the roots grow they wedge the rock apart

Answer 31

Minerals

Water

Question 32

This group of organisms further break down rock by moving fresh material to the surface where physical and chemical processes can more effectively attack it

Answer 32

burrowing animals

Question 33

Decaying organisms produce ____ which contribute to chemical weathering

Answer 33

acid

Question 34

This type of weathering involves the complex processes that alter the internal structures of minerals by removing or adding elements

Answer 34

chemical

Question 35

___ is by far the most important agent of chemical weathering

Answer 35

water

Question 36

Oxygen dissolved in water will ____ some materials

Answer 36

oxidize

Question 37

When rocks containing iron-rich minerals _____, a yellow to reddish brown rust will appear on the surface

Answer 37

oxidize

Question 38

Carbon dioxide (CO2) dissolved in water (H2O) forms ____ ____ (_____)

Answer 38

carbonic acid (H2CO3)

Question 39

Rain dissolves some carbon dioxide as it falls through the ______, and additional amounts released by decaying organic matter are acquired as the water percolates through the soil

Answer 39

atmosphere

Question 40

What very reactive hydrogen ion does Carbonic acid ionize to form?

Answer 40

H+

Question 41

What is the very reactive bicarbonate ion formed when carbonic acid ionizes?

Answer 41

(HCO3-)

Question 42

Because ____ ____ are the end product of weathering, they are very stable under surface conditions

Answer 42

clay materials

Question 43

Clay materials make up a (high/low) percentage of the inorganic material in soil.

Answer 43

high

Question 44

The abundant sedimentary rock ___ contains a high level of clay materials

Answer 44

shale

Question 45

In the formation of clay minerals, some ____ is removed from the feldspar structure and carried away by groundwater

Answer 45

silica

Question 46

Dissolved silica will eventually ____ to produce nodules of chert or flint, fill in the pore spaces between sediment grains, or be carried to the ocean, where microscopic animals will remove it to build hard shells

Answer 46

precipitate

Question 47

The weathering of potassium feldspar generates a residual clay mineral, a soluble salt (potassium bicarbonate) and some _____ which enters into solution

Answer 47

silica

Question 48

Quartz is very resistant to ____ weathering

Answer 48

chemical

Question 49

Name the four ions silicate minerals yield when chemically weathered

Answer 49

Calcium
Potassium
Magnesium
Sodium

Question 50

When angular rock masses are attacked by water that enters along joints, the rocks tend to take on a ____ shape

Answer 50

spherical

Question 51

The process in which edges of rocks become more rounded

Answer 51

Spheroidal weathering

Question 52

The addition of what increases size in spherical scaling?

Answer 52

water

Question 53

The ____ weather in essentially the same order as their order of crystallization

Answer 53

Silicates

Question 54

The optimum environment for chemical weathering is a combination of ___ temperatures and abundant ____

Answer 54

warm

moisture

Question 55

This phrase means that rocks exposed do not weather at the same rate

Answer 55

Differential weathering