SS 121 Will (poly) 1st Midterm Study KEY

Glacial till is deposited by melt waters flowing out from the front of glaciers.

F

Igneous rocks can best be characterized as:

Rocks formed from magma

Which of the following describes the relationship between particle size and soil permeability?

The finer the texture, the smaller the pore size and the lower the permeability

Which of the following would be the last horizon to form as a soil profile develops is the:

B. B

Silicate clay accumulation is most common in the ____.

B. B horizon

Granite tends to weather to soils that are

B. Infertile and coarse textured

process by which earthworms, ants move soil up and down in the soil profile is called

B. Pedoturbation

Calculate the porosity of the soil in questions 135 and 136 using your calculated bulk density and particle density values.

D. 45%

In a load of 10 cubic meters of ideal topsoil, approximately how many cubic meters of the volume would be solid material?

D. 5

The element most often involved in oxidation reactions as minerals weather is _____.

E. iron

An eolian deposit of silt-sized materials is called:

E. loess

Among the following weathering processes which one is most likely to produce iron oxide minerals?

E. reduction and oxidation of augite

A soil developed in transported parent materials will likely have properties related to the properties of the bedrock located below the C horizon.

F

A, B, C, and E horizons are found in all soils.

F

oxygen found in minerals is:

chemically bound to other elements

Among the following processes of weathering which one is a physical weathering process?

disintegration of feldpars due to rapid temperature changes

Secondary minerals are not found in:

igneous rocks and the atmosphere

Calculate the bulk density of a 100 cm3 soil sample containing 150 grams of oven dry soil.

1.50 g/cm3

In a floodplain deposit, the coarser textured soils are found developing in the material deposited at which location (A, B, or C)?

A, The deepest Portion of the river

The total volume of solid particles in the soil in question 135 was 55 cm3. Calculate the particle density of the soil in question 135.

A. 2.73 g/cm3

Which of the following soil horizons would likely have the highest percentage of organic matter?

A. A

Functions of soil include

A. Filtering rain and other water that passes through it B. Recycling of organic wastes C. Supporting bridges and other manmade structures D. Providing habitat for microorganisms that help provide plant nutrients E. All of the above

Calcium carbonate (CaCO3) in a soil horizon dissolves in the rain water passing through the soil, moves down through the soil profile into the groundwater. This is an example of which soil forming process?

A. Loss

In the Northern Hemisphere, soil development is most likely greatest on slopes which are:

A. North Facing

The two soil horizons common in humid, forested areas derived from sandy granitic alluvium are:

A. O and E horizons

Organic matter accumulation is most pronounced in the ____.

A. O horizon

Which of the following plant essential elements is made available to plants in significant quantities by the weathering of quartz?

A. Si D. Ca B. O = E. none of the above is correct C. Mg

Which of the following soil properties has the greatest influence on soil infiltration rate?

A. Texture

Which of the following is true about the hydrolysis reaction

A. Water changes the chemical composition of minerals, making them less resistant to further weathering and releasing elements to soil solution

Percent porosity and soil bulk density are related. An increase in porosity results in:

A. a decrease in bulk density

If you wanted to find a soil where physical weathering dominated over chemical breakdown you would be most apt to find it in ______.

A. a desert region of Arizona

Argillic horizons are characterized by

A. accumulation of silicate clays

Because of their greater surface area per unit of soil mass, silt loams soils generally have a greater capacity than loamy sand soils to

A. adsorb water B. adsorb gases C. release nutrients by mineral weathering D. support bacterial growth 13 E. all of the above=

Material deposited by moving fresh water is called:

A. alluvium

Eolian parent materials are transported:

A. by atmospheric winds from their points of origin

Which of the following conditions would result in the least soil development and weathering; assuming that all other soil forming factors are equal:

A. cold, dry climate with tundra vegetation

Formation of granular aggregates is aided by

A. fungal hyphae B. fine roots C. microbial and plant exudates D. all of the above

Compared to silt, clay-sized soil particles are characterized by

A. greater attraction for water

Information about conditions at 2 to 4 meters deep in a soil is most helpful for understanding _______.

A. how best to design a building foundation

Among the following processes of weathering which one is not a physical weathering process?

A. hydrolysis

The reaction: orthoclase + HOH → K+ + OH- + kaolinite clay is an example of ________.

A. hydrolysis

Soils on south aspects in the Northern Hemisphere generally have ________ than the soils on adjacent north aspects.

A. less vegetative cover and warmer temperatures

The ease with which air, water, and plant roots pass through the soil is called

A. permeability

The most widely distributed and extensive of all parent materials is

A. residuum

Which of the following conditions would result in the greatest soil development, assuming that all other soil forming factors are equal:

A. temperate, moist climate with forest vegetation

Igneous, sedimentary, and metamorphic are three _________.

A. types of rocks

"Topsoil" is generally equivalent to which soil horizon?

A.A

Which graph most correctly portrays the relationship between humus content and soil depth in a grassland soil?

A= larger A horizon

Which horizon of a soil profile is most changed from the parent material?

B. A

"Subsoil" is generally equivalent to which soil horizon?

B. B

Effect of climate on soil formation. Select the set of profiles that best shows the effect of climate on soil development as one moves from west to east across the U.S.

B. W- A Bt Ck. E-O A Bt C

The presence of rocks such as shale and sandstone indicate the existence of _______.

B. ancient seas

The mixed angular gravel, rock, and soil found at the foot of a slope is typical of what type of parent material?

B. colluvial

Primary minerals in igneous rocks form during the:

B. cooling and solidification of magma

B horizons are defined as zones of:

B. illuviation

Compacting a soil results in which set of changes in percent by volume of its constituents?

B. increase in mineral material and decrease in air-filled pore space

Residual parent materials are best described as __________.

B. materials formed by weathering of rocks and minerals in place

106. Typically, the younger the soil, the fewer the:

B. number of different soil horizons

Typically, the older the soil, the greater the:

B. number of different soil horizons

Physical weathering of rock causes:

B. particle size breakdown

The percentages of which soil components represent the minimum information necessary in order to determine the textural class of a soil?

B. silt and sand

Most of the different nutrients essential for growth are supplied to plants directly from the ______.

B. soil solution

In the Northern Hemisphere, soil development is most likely the least on slopes which are:

B. south-facing

The amount of different sizes of mineral particles in a soil defines the soil ________.

B. texture

The presence of basalt indicates the existence of _______ in the past.

B. volcanic activity

Which of the soil horizons would more likely be found in a desert than under a rainforest?

Bk

In many soil profiles, the subsoil is high in clay, but is also moderately permeable to percolating water. Why?

Blocky structure may be well developed

Which of the following horizon sequences would be most characteristic of an "old" soil?

C = A E Bh Bt C

In the USDA classification system, the size range of sand is:

C. 2.0 mm to 0.05 mm

Material was transported by wind from the receding glaciers and deposited on developing soils in the Great Plains. What type of process is this with regard to the soils developing on the Great Plains?

C. Addition

Soils developed from accumulated organic material have which of the following characteristics

C. Light porous and productive

Which of the following soil horizons would likely be found in a densely vegetated, redwood forest?

C. O and B horizons

Shale tends to weather to soils that are

C. Relatively fertile and fine textured

During the development of a soil from loess parent material, rainwater containing organic acids dissolves carbonates from the loess and moves them down to a zone of accumulation. In order of their occurrence, the two processes described are examples of what soil forming processes?

C. Transformation / Translocation

Most chemical weathering processes are promoted by the presence of

C. carbonic acid

The downward movement of material (e.g., humus, iron oxide, clay) out of the soil surface horizon is called:

C. eluviation

Physical weathering processes result in:

C. the disintegration of rocks due to differential expansion of minerals.

Aspect is a component of which soil forming factor?

C. topography

The steeper the topography, usually the ______ the soil.

C. younger and shallower

Which of the following statements is correct?

Calcium carbonate accumulation is more prominent in arid than in humid regions

Secondary minerals are most prominent in the fraction of soils.

Clay

Soils developed from colluvial parent material are usually

Coarse, stony, with fast drainage

Soils formed on landslide deposits have parent materials which are:

Colluvial

In a typical mineral soil in optimal condition for plant growth, approximately what percentage of the pore space would be filled with water and what percentage filled with air?

D. 50% water and 50% air

A soil is developing on a floodplain area of Brizzolara Creek on the Cal Poly campus that is still occasionally flooded. Although the climate is warm here, there is not much rainfall. The vegetative cover is sparse grasses and small forbs. Which of the following is the most likely horizon scenario?

D. A, C

A soil is developing on the steep south-facing slope of Bishop Peak. The native vegetation of this semi-arid location is annual grasses. The parent material is residuum weathered from the underlying igneous rock. Which of the following is the most likely horizon scenario?

D. A, C

Which of the following gases tends to be about ten times more concentrated in the soil atmosphere than in the above-ground atmosphere?

D. CO2

Parent materials derived from weathered basalt results in

D. Fine textured soils containing K, Mg, and Fe

Where in the U.S. would you expect peat deposits to be located?

D. Upper Peninsula Michigan

Complete oxidation of iron in soils can result in:

D. a red, orange, or brown soil color

Transported soil parent materials moved by water and ice, respectively, are called:

D. alluvium and glacial

Which type of structure is typically found in sodium-rich sub-surface horizons?

D. columnar

Loess is a wind deposited soil parent material. The material originally was:

D. fine material deposited when the last glaciers retreated

The A horizon of a limestone-derived soil is more acid than the parent material due to:

D. higher carbonic acid levels

The layers of contrasting material found when one digs a hole in a soil are called _______.

D. horizons

Which set of weathering mechanisms would you expect to be at work in the tropical rainforest of Brazil

D. hydrolysis, oxidation, carbonation, plant roots

Granite is an example of a(n) ________.

D. igneous rock

The ease with which water enters the soil is called

D. infiltration rate

Alluvial deposits are usually characterized by ______ soils.

D. nearly level

The two common products of hydrolysis weathering of a primary mineral are:

D. nutrients in solution and secondary minerals

As one travels from the Mojave Desert into the Sierra Nevada mountains, precipitation increases. One can expect that soil:

D. organic matter content is higher in the mountains

Two landforms upon which one would expect to find alluvium include:

D. stream terraces and floodplains

Precipitation falling in excess of the soil infiltration rate is lost by:

D. surface runoff

A soil profile consists of _________.

D. the set of layers seen in a vertical cross section of a soil

Which of the following is not considered one of the five major factors influencing soil formation?

D. valence state

On a stable upland landscape with little erosion or deposition, one would expect to find:

Deep residual Soils

In a given soil, the horizon with the highest organic matter content is generally the _____ horizon.

E. A

soil with a bulk density equal to 0.55 g/cm3 is most likely what type of soil?

E. an organic soil

Glacial till is a term used to describe parent materials that:

E. are a heterogenous mixture of mineral debris dropped by receding glaciers.

The most common mineral in limestone is:

E. calcite

The loss of calcium carbonate in soils is accomplished by:

E. carbonation and solution

Structure that resembles cookie crumbs and is commonly found in surface horizons is

E. granular

Sandstones are examples of metamorphic rocks.

F

Soils developed in wind-blown parent materials such as loess are generally of poor agricultural value.

F

Subsoil is typically equivalent to the O horizon.

F

The dark brown and black humus found in many soils does not mix well with clay minerals so there is very little contact between these two soil components.

F

The topmost horizon in most humid region forest soils is the A horizon

F

Which of the following statements is true about the relationship between soil structure and soil permeability

Granular structure in an A horizon results in rapid permeability due to the dominance of macropores

Soil organic matter

Makes up approximately 5% of the volume and 1-6% of the weight of a surface soil Is a major source of N, P and S for plants

Cool moist soil with an E horizon

Mildly sloping north side (B)

Rock exfoliation is caused by changes in _________.

Overburdened pressure

The most common rock type presently on surface of the land is

Sedimentary

Shallow soil with little horizon development

Steep hill facing south (C)

Relatively deep well-drained soil

Summit (A)

Chemical weathering is accelerated by water, oxygen, and organic and inorganic acids moving down through decomposed rock.

T

Climate influences not only the rate of weathering but the type of native vegetation in an area.

T

Eluviation of clay, iron, and other materials is the principal process responsible for the formation of an E horizon.

T

Igneous rocks are formed when molten magma cools and solidifies.

T

Most of the water flowing in rivers passed through a soil profile or over soil surfaces before reaching the flowing river waters.

T

Most of the water in our freshwater rivers has come in contact with and has been affected by soils.

T

Organic deposits are most common in areas where water flow over the soil surface is restricted and where wetlands form.

T

Residual parent materials have formed in place and have not been transported from one area to another.

T

Secondary clay-size minerals are recrystallized products of the chemical breakdown and/or alteration of primary minerals.

T

Soil air usually has a higher carbon dioxide content than the air in the atmosphere.

T

The O horizons of a soil are dominantly organic horizons occurring above mineral horizons.

T

The soil A horizons are more apt to be cultivated during agriculture than the E horizons.

T

Flat soil rich in organic matter with potential for a high water table

Valley (D)

Soil iron-bearing minerals may be chemically reduced by:

a permanently high water table at the soil surface

If you were to choose the most favorable location for agriculture, which of the following sites would you choose? 10

an old stream floodplain

E soil horizons are defined as zones of:

eluviation

The lower case letter used to designate a B horizon with evidence of prolonged periods of water saturation is _____.

g

prolonged wetness

g

illuvial concentration of humus

h

An example of chemical weathering of minerals is:

hydrolysis of orthoclase and olivine

illuvial accumulation of carbonates

k

Eolian parent materials would be mainly located on:

loess plains and sand dunes

farming disturbance of the topsoil

p

The unconsolidated and chemically weathered mineral or organic matter from which the solum of soils is developed by natural processes of soil development is called:

parent material

61. Climate is a soil-forming factor that results in:

regional soil differences

Metamorphic rocks can best be characterized as:

rocks formed by heat and pressure alterations of pre-existing rocks.

Which of the following is a list of common sedimentary rock types?

sandstone, shale, limestone

A layer of soil formed by natural processes of soil development is called a:

soil horizon

illuvial accumulation of clay

t

elements added to the soil solution by mineral weathering can be:

taken up by plants or leached

percentages of sand, silt and clay in a soil define the soil's:

texture

Bk horizon of a calcareous shale-derived soil has a higher pH than its parent material due to:

the presence of abundant illuvial calcium carbonate