Deck 5: Weathering - the Breakdown of Rocks

Question 1

All of the following are characteristics of modern classes of soils EXCEPT:

A) paleosols are noted for their pale color, which results from the leaching of organic material.
B) entisols are noted for their lack of well- developed soil horizons.
C) vertisols are noted for the presence of clays that swell or shrink in response to fluctuations in moisture content.
D) oxisols are noted for their high concentration of insoluble iron oxides.

Answer 1

A

Question 2

In which of the following locations would a rich soil accumulate most quickly?

A) A steep topography in a moist, mid- latitude climate.
B) A steep topography in a dry, cold climate.
C) A relatively flat topography in a moist, mid- latitude climate.
D) A relatively flat topography in a dry, warm climate.

Answer 2

C

Question 3

Which of the following statements about weathering in extraterrestrial environments is NOT true?

A) Most of the weathering on Venus is chemical rather than mechanical.
B) Mechanical weathering caused by meteoritic impacts is the only discernible form of weathering on the Moon.
C) Evidence has been found showing Mars to have undergone chemical weathering in the past.
D) The Moon, Mars, and Venus have all undergone some form of mechanical weathering.

Answer 3

A

Question 4

The reason that rocks or even footprints on the Moon do not weather is that:

A) the temperatures on the Moon are so hot that all water is evaporated.
B) the temperatures on the Moon are so cold that all water at the surface exists only as ice.
C) the Moon's atmosphere is made exclusively of CO₂ and is completely lacking in water.
D) the Moon has no atmosphere, and therefore no chemical weathering can occur.

Question 5

Stability of silicate minerals follows the inverse of their order of crystallization (Bowen's Series). The correct sequence of stability for the minerals below would be (most stable- first, least stable- last):

A) pyroxene, olivine, mica, quartz.
B) olivine, pyroxene, mica, quartz.
C) quartz, mica, pyroxene, olivine.
D) mica, pyroxene, olivine, quartz.

Question 6

All of the following practices help to conserve soil EXCEPT:

A) no- tillage farming.
B) strip cropping.
C) terracing.
D) plowing fields.

Question 7

Hydrolysis refers to:

A) the removal of a mineral's ions or groups of ions by water.
B) the substitution of water molecules for silicon molecules in a mineral's internal structure.
C) the displacement of a mineral's ions by the H⁺ or OH^- ions from water.
D) the chemical combination of a mineral's ions with oxygen.

Question 8

Which of the following statements about the B horizon is NOT true?

A) The B horizon generally lies above the E horizons.
B) In arid and semi- arid climates, calcium carbonate accumulates to form a caliche layer within or below the B horizon.
C) The B horizon tends to be more fertile than the E horizon.
D) Some B horizons contain a high concentration of humus.

Question 9

Water performs all of the following functions in chemical weathering EXCEPT:

A) carries ions to reaction sites.
B) participates in the reactions.
C) carries away products of the reactions.
D) freezes in the cracks, facilitating frost wedging.

Question 10

The most distinctive feature of the E horizon is:

A) its high concentration of oxides.
B) its dark color from the accumulation of humus.
C) its mixture of both large and small rock particles.
D) its lack of both organic matter and soluble minerals.

Question 11

The type of clay developed from the chemical weathering of a given rock depends primarily on:

A) the rate and environment of deposition of the weathered clay minerals.
B) the relative percentage of feldspar within the parent rock.
C) the rate at which the rock was weathered.
D) the climatic conditions under which the chemical weathering took place.

Question 12

Weathering by thermal expansion and contraction involves all of the following factors EXCEPT:

A) the thermal expansion of air within fractures in rocks enlarges the openings.
B) the outside of a large rock experiences more temperature fluctuations than the inside of the rock.
C) the addition of water to the surface of the rock influences the rate of mechanical weathering.
D) different kinds of minerals within a rock expand at different rates when heated.

Question 13

Which of the following formulas presents an example of hydrolysis?

Question 14

Living organisms influence the rate at which chemical weathering takes place primarily by:

A) grinding rocks and minerals into smaller pieces.
B) increasing the exposure of rocks and minerals to weathering agents.
C) secreting acid that dissolves rocks and minerals.
D) ingesting the minerals that are necessary for nutrition.

Question 15

Which of the following statements about the rounding of boulders by chemical weathering is NOT true?

A) Chemical exfoliation, the weathering of rocks in concentric layers, occurs because chemical weathering attacks the outside of the rock before attacking the inside.
B) Rounding occurs because rock edges and corners offer more surface area than its planar faces.
C) The rounding of angular rocks by chemical weathering is termed spheroidal weathering.
D) Rounding occurs because the portions of a rock on the edges and corners are less stable than portions in the interior of the rock.

Question 16

Nutrient- poor soils are derived from a parent material that resists chemical weathering, such as:

A) limestone.
B) sandstone.
C) basalt.
D) granite.

Question 17

Which of the following statements about soil horizons is NOT true?

A) The A horizon consists of a mixture of inorganic minerals and decayed organic matter.
B) The B horizon is a zone of illuviation that contains soluble materials derived from overlying horizons.
C) The C horizon consists mostly of rock chunks that differ little from the underlying bedrock.
D) The color of the E horizon results from humus that has leached downward from the A horizon.

Question 18

Which of the following chemical effects is not a consequence of acid rain?

A) Corrosion of paint and steel in bridges.
B) Dissolution of concrete buildings and marble statues.
C) Dissolution of soil nutrients^.
D) Precipitation of calcium carbonate.

Question 19

A mineral's stability, or resistance to chemical change, is primarily a result of:

A) the amount of silica within the mineral.
B) the mineral's hardness.
C) the strength of a mineral's chemical bonds.
D) the color and streak of a mineral.

Question 20

A metal ore is:

A) any naturally occurring concentration of valuable metals that can be profitably extracted.
B) any naturally occurring concentration of valuable metals.
C) any naturally occurring concentration of metals.
D) any naturally occurring body of pure metal.

Question 21

All of the following are true regarding metal ore EXCEPT:

A) many deposits of minable ore were formed by ancient weathering processes.
B) understanding weathering conditions under which mineral deposits form gives insights into ancient climates.
C) the weathering processes that formed valuable mineral deposits in ancient times no longer operate today.
D) most valuable minerals are abundant in the Earth's crust but are rarely found in their pure form.

Question 22

What is the primary difference between weathering and erosion?

A) Weathering and erosion are synonymous and may be used interchangeably.
B) Weathering is the breakdown of rocks by mechanical means; erosion occurs by chemical means.
C) Weathering is the breaking down of minerals; erosion is the breaking down of rocks.
D) Weathering is the breaking down of rocks; erosion is the transporting of rock fragments.

Question 23

Vegetation promotes chemical weathering by:

A) shading the ground surface from intense sunlight.
B) producing organic acids upon decay.
C) consuming carbon dioxide in photosynthesis.
D) shading the ground surface from rainfall.

Question 24

Clay minerals are formed predominately from the hydrolysis of:

A) quartz.
B) nonsilicate minerals.
C) metal ores.
D) feldspars.

Question 25

The single most important factor controlling the rate of chemical weathering is:

A) living organisms.
B) water.
C) temperature.
D) carbonic acid.

Question 26

In a temperate region, the most distinctive feature of the O horizon of a soil is:

A) its inability to maintain fertility because of constant leaching of materials to lower soil horizons.
B) the mixture of mostly inorganic matter and humus.
C) the abundance of finely ground rock particles.
D) the abundance of both organic matter and living organisms.

Question 27

Which of the following statements about weathering and erosion is NOT true?

A) Weathering and erosion are predominately detrimental to humanity.
B) Without weathering and erosion we would have no soil.
C) Weathering and erosion can deteriorate buildings and statues.
D) Products of erosion can be found in both our food and water.

Question 28

All of the following deposits represent paleosols EXCEPT:

A) Australian ultisols.
B) Connecticut caliches.
C) Georgia bauxites.
D) New England forest soils.

Question 29

The primary cause of mechanical exfoliation is:

A) the removal of shrubs, grasses, and other plants from the rock's surface.
B) the thermal expansion of water contained within fractures in the rock.
C) the removal by erosion of overlying rock and soil.
D) abrasion by rock particles contained in streams, wind, or glaciers.

Question 30

Mechanical weathering can:

A) change the internal composition of minerals.
B) change the size and shape of rock structures.
C) convert particular minerals into more stable forms.
D) transport rock and mineral fragments to different locations.

Question 31

Frost wedging would be most prominent in:

A) mid- latitude regions where temperatures hover around 0^°C (32^°F) during certain seasons.
B) desert regions where day and night temperatures fluctuate radically for much of the year.
C) low- latitude rainforests where there is abundant moisture to enter fractures and pores in rocks.
D) polar regions where temperatures remain below 0^°C (32^°F) most of the year.

Question 32

In geology, the term "oxidation" often refers to:

A) the chemical combination of a mineral's ions with oxygen.
B) the removal of a mineral's ions or groups of ions by water.
C) the substitution of water molecules for silicon molecules in a mineral's internal structure.
D) displacement of a mineral's ions by H⁺ or OH^- from water.

Question 33

Which of the following formulas presents an example of oxidation?

Question 34

The dissolution of limestone to form caves results from water combining with:

A) carbon dioxide to form carbonic acid.
B) sulfur to form sulfuric acid.
C) carbon to form bicarbonate.
D) calcium to form calcite.

Question 35

Chemical exfoliation requires the presence of feldspars because:

A) they shield the boulder from water absorption.
B) they weather to clays, which expand upon absorbing water.
C) they weather quickly, offering more surface area to chemical weathering.
D) they expand outward from water absorption.

Question 36

Acid rain has a pH value of approximately:

A) 5.5.
B) 7.
C) less than 5.
D) 1- 2.

Question 37

Rocks that are carried along at the base of a glacier scrape against underlying rocks. This form of mechanical weathering is called:

A) dissolution.
B) expansion.
C) abrasion.
D) exfoliation.

Question 38

The process of dissolution occurs because:

A) the heat energy within water is sufficient to break the bonds of crystalline structures.
B) the atoms of water molecules wedge themselves between the atoms of a mineral's crystalline structure.
C) water molecules are less stable, and therefore bond more readily with other elements than do the molecules of most minerals.
D) the oppositely charged sides of water molecules attract and separate ions from mineral crystals.

Question 39

Carbon dioxide is added to the atmosphere by all of the following processes EXCEPT:

A) lava flows.
B) animal respiration.
C) chemical weathering of silicate minerals.
D) volcanic eruptions.

Question 40

The main difference between regolith and soil is:

A) soil is the upper few meters of regolith, containing both minerals and organic matter.
B) regolith is equivalent to soil, but is on the ocean floor.
C) regolith includes only the inorganic portion of soil.
D) regolith refers to blocks and chunks of rocks, while soil refers to finer rock particles.

Question 41

Why are some minerals more resistant to chemical weathering than others?

Question 42

In which type of climate would mechanical weathering occur most quickly, and in which type would it occur most slowly? Explain.

Question 43

In general, chemical weathering would occur most rapidly in a:

A) cool, dry climate.
B) warm, dry climate.
C) warm, moist climate.
D) cool, moist climate.

Question 44

What is the difference between dissolution and hydrolysis?

Question 45

Explain how parent material, climate, topography, vegetation, and time influence soil formation.

Question 46

How do clays form? Explain, with two examples, how different environments produce clays with different compositions.

Question 47

What are the most important characteristics of soils used in modern soil classification schemes?

Question 48

In what way are mechanical and chemical weathering related?

Question 49

Explain how levels of carbon dioxide may be related to global chemical weathering.

Question 50

In what ways is the process of weathering detrimental to humanity? In what ways is it beneficial?

Question 51

Why are paleosols not considered one of the soil orders in the classification of soils?