Weathering, Erosion and Soil Study Guide

First Name:

Modified True/False

Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the sentence or statement true.

Frost wedging is an example of erosion. _________________________

Water, carbon dioxide, and acids are significant agents of physical weathering. _________________________

To some extent, the density of rocks determines the effects that chemical weathering will have on them. _________________________

Without gravity, glaciers would not move downslope and streams would not flow. _________________________

The parent bedrock determines what kinds of minerals a soil will contain. _________________________

The addition of compost, organic mulch, and peat moss to soil helps to maintain its acidity. _________________________

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

Most of the weathering of Cleopatra’s Needle is caused by ____.

a.	hydrolysis	c.	oxidation
b.	chemical weathering	d.	frost wedging

In which of the following climates would chemical weathering most readily occur?

a.	wet and warm	c.	wet and cool
b.	dry and warm	d.	dry and cool

Barrier islands are formed when ____.

a.	the ocean floor is uplifted
b.	the wind continuously blows sand out to sea
c.	sand is repeatedly picked up, moved, and deposited by ocean currents
d.	sand bars are worn away

10.

Which of the following has the potential for the most erosion?

a.	water flowing across a flatland
b.	wind blowing materials in the air, against the force of gravity
c.	wind blowing materials down a slope
d.	water flowing down a steep slope

11.

What is one source of organic matter in soil?

a.	acid precipitation	c.	weathered topsoil
b.	dead fungi, bacteria, and protozoa	d.	eroding bedrock

12.

Of the three soil samples shown below, Sample 1, the darkest and richest, would be found in ____ of a typical soil profile.

a.	horizon A	c.	horizon C
b.	horizon B	d.	the hardpan

13.

Which of the following characteristics of water can be responsible for mechanical weathering?

a.	Water flows downstream under gravity.
b.	Water expands when it freezes.
c.	Water combines with atmospheric gases to form acid rain.
d.	Water reacts with and can dissolve many kinds of minerals.

14.

In which of the following areas is wind a major erosional agent?

a.	grasslands	c.	deserts
b.	temperate forests	d.	tropical rain forests

15.

Which of the following statements is NOT true of soil?

a.	It is a loose covering of broken rock particles and decaying organic matter.
b.	There is one kind of soil in the United States.
c.	Living organisms add nutrients to it.
d.	It takes a long time to form.

16.

Which of the following could increase the rate of chemical weathering of a rock?

a.	moving it to a location with few plants and animals
b.	moving it to a drier climate
c.	increasing its total surface area
d.	moving it to a colder climate

17.

Which of the following happens when a river enters a large body of water?

a.	The river water slows down and deposits large amounts of sediments.
b.	The river water increases its speed and carries out gully erosion.
c.	The river water flows over the delta, causing exfoliation.
d.	The river water erodes the shoreline and deposits barrier islands.

18.

The color of a soil ____.

a.	is a reliable indicator of its fertility
b.	is always dark brown or black
c.	is not dependent on the amount of humus
d.	is determined by its composition and climate

19.

Which of the following statements is NOT true about the deposition of eroded materials in bodies of water?

a.	It improves the quality of ecosystems.
b.	It limits the availability of water for hydroelectric energy.
c.	It reduces water supplies for personal consumption.
d.	It can restrict navigation through the water bodies.

20.

Which of the following statements is NOT true of soils in sloped areas?

a.	Smaller particles remain on the slopes, while coarser particles move downslope.
b.	Soils on slopes tend to be infertile.
c.	Valley soils are usually thick.
d.	South-facing slopes have somewhat thicker soils than slopes facing other directions.

21.

There can be no stream erosion or glacial erosion without ____.

a.	gravity	c.	wind
b.	hydrolysis	d.	deposition

Completion

Complete each sentence or statement.

22.

In a process known as ____________________, eroded materials are dropped in another location.

23.

A major problem in farming areas is _________________________, which is the deepening and widening of rill channels.

24.

A(n) _________________________ is a distinct layer, or zone, within a soil profile.

25.

____________________ is the removal and transportation of weathered material from one location to another.

26.

The process by which rocks on or near Earth’s surface break down and change is ____________________.

27.

_________________________ is the erosion by running water of a small channel on the side of a slope.

Matching

Match each item with the correct statement below.

a.	temperate soils	c.	polar soils
b.	tropical soils	d.	desert soils

28.

These soils form at high latitudes and high elevations and have good drainage but no distinct horizons.

29.

With rainfall greater than 50 – 60 cm per year, these soils vary greatly and may contain large amounts of humus.

30.

These soils experience high temperatures and heavy rainfall, which leads them to become weathered and often infertile.

31.

These soils generally get less than 25 cm of rain per year, which results in high levels of accumulated salts.

Match each item with the correct definition below.

a.	residual soil	f.	soil
b.	transported soil	g.	soil profile
c.	exfoliation	h.	chemical weathering
d.	oxidation	i.	frost wedging
e.	hydrolysis

32.

The loose covering of broken rock particles and decaying organic matter overlying the bedrock of Earth’s surface

33.

The repeated thawing and freezing of water in the cracks of rocks

34.

A vertical sequence of soil layers

35.

The process by which rocks and minerals undergo changes in their composition as the result of chemical reactions

36.

The chemical reaction of oxygen with other substances

37.

Soil that has been moved to a location away from its parent bedrock

38.

The reaction of water with other substances

39.

Soil located above its parent material

40.

The process by which outer layers of a rock are stripped away

Short Answer

41.

What is the difference between weathering and erosion?

42.

What is acid precipitation and how does it affect the weathering process?

43.

Give an example of how animals, including humans, affect the erosional process.

44.

Describe how soils form layers.

45.

Below is a picture of a soil profile. Compare the characteristics of soil in Horizon A with soil in Horizon B.

46.

How does climate influence the rate of weathering of earth materials?

47.

Describe how soil forms.

48.

How do living things impact weathering and erosion?

49.

Contrast mechanical and chemical weathering, and give examples of each.

Study the diagram. Then answer the following questions.

50.

What property of soil does the diagram illustrate?

51.

Name the three sizes of soil particles, from largest to smallest.

52.

How would you classify a soil that contains 60 percent sand, 30 percent silt, and 10 percent clay?

53.

How would you classify a soil that contains equal percentages of all three sizes of soil particles?

54.

About what proportion of sand/silt/clay makes up sandy clay?

55.

In general, soil drainage is determined by particle size: the larger the particle size, the better the drainage. Compare the drainage of sand, sandy clay, and clay soils.

Problem

A golf course designer, who is about to build a championship golf course, has come to you with a problem. He tells you that parts of his developing course cannot grow grass and tend to flood. After testing the soil, you decide that the reason it drains poorly and doesn’t retain adequate moisture is because it has too much nonporous clay. You tell him that by adding soil conditioners, the new soil will improve its drainage and retain more water. You mention that water retention is important because water supplies are low in the hot summer months, and grasses need water to stay green. Improved drainage will also allow more rainfall to be soaked into the soil, thus lessening runoff and water erosion.

You develop a simple setup to test various soil combinations for drainage and water retention. You will add dry soil, which was heated to expel all moisture, to a beaker. The beaker has a drain hole in the bottom to allow the drainage of excess water to a measuring cylinder. You add 200 ml of water to the beakers with the various soil combinations. After one hour, you then reweigh the soil and measure the drainage water.

The clay is the unsuitable soil from the golf course. Humus and sand were picked up from a local nursery, and soils A and B are higher priced synthetic soils produced by a chemical company. Most of the soil combinations drained in less than 30 minutes. When the drain time is greater than 60 minutes, this indicates poor drainage and some of the water will remain on top of the soil, where it either evaporates or runs off. All water weights are given in grams. One gram of water is approximately equal to one milliliter.

	Clay	Clay + Humus	Clay + Sand	Clay + Soil A	Clay + Soil B
Dry soil weight	600 g	600 g	600 g	600 g	600 g
Water added	200 g	200 g	200 g	200 g	200 g
Wet soil weight	690 g	730 g	640 g	730 g	760 g
Water drainage	20 g	70 g	160 g	70 g	35 g
Time to drain	>60 min	30 min	20 min	30 min	>60 min

56.

The water added to the dry soil should equal the weight of the wet soil plus the drainage weight. If it doesn’t, it’s because some of the water evaporated or ran off. Using the data from the chart provided above, complete the table below by indicating the amount of water that either evaporated or ran off.

	Clay	Clay + Humus	Clay + Sand	Clay + Soil A	Clay + Soil B
Water evaporated/runoff

57.

Compare the use of sand and humus as far as their ability to retain water and improve drainage.

58.

How does Soil A and B compare to humus as far as their ability to retain water and improve drainage.

59.

Why do you suppose clay has such a high evaporation rate?

60.

Why is sand not a good soil conditioner?

61.

What soil combination would you recommend to the golf course designer? What are some other factors that might influence the selection of the best soil conditioner?