SS 121 Exam One

"Subsoil" is generally equivalent to which soil horizon?

B

Which of the following statements is correct?

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

The loss of calcium carbonate in soils is accomplished by:

Carbonation and solution

Most chemical weathering processes are promoted by the presence of

Carbonic acid

The oxygen found in minerals is:

Chemically bound to other elements.

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

Clay generally promotes free water movement.

Soils developed from colluvial parent material are usually

Coarse, stony, with fast drainage.

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

False

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

Higher carbonic acid levels

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

Higher carbonic acid levels in the topsoil.

Residual parent materials are best described as ______.

Materials formed by weathering of rocks and minerals in place

Alluvial deposits are usually characterized by ______ soils.

Nearly level

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

None of the above is correct

With regards to topography, where would cool moist soil with an E horizon be found?

North-facing slope

Typically, the older the soil, the greater the:

Number of different soil horizons.

Typically, the younger the soil, the fewer the:

Number of different soil horizons.

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

Nutrients in solution and secondary minerals.

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

O and B horizons

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

O and E horizons

Organic matter accumulation is most pronounced in the ________.

O horizon

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

Organic matter content is higher in the mountains.

Rock exfoliation is caused by changes in _______.

Oxidation

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

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

Particle density

Physical weathering of rock causes:

Particle size breakdown

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

Pedoturbation

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

Permeability

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

True

Glacial till is deposited by melt waters over the soil surface is restricted and where wetlands form.

True

Igneous rocks are formed when molten magma cools and solidifies.

True

Secondary minerals are most prominent in the _____ fraction of soils.

Clay

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

True

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

True

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

True

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

True

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

True

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

True

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

True

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

False

Subsoil is typically equivalent to the O horizon.

False

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.

False

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

True

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

True

Match the subordinate horizon designation shown below with the appropriate soil description: 1. Illuvial accumulation of clay 2. Farming disturbance of the topsoil 3. Illuvial accumulation of carbonates 4. Illuvial concentration of humus 5. Prolonged wetness A. p B. t C. h D. k E. g

1. t 2. p 3. k 4. h 5. g

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

2.0mm to 0.05mm

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

5 cubic meters

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?

50% water and 50% air

"Topsoil" is generally equivalent to which soil horizon?

A

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

A

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

A

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

A

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

Are a heterogeneous mixture of mineral debris dropped by receding glaciers.

Soil iron-bearing minerals may be chemically reduced by:

A permanently high water table at the soil surface.

Complete oxidation of iron in soils can result in:

A red, orange, or brown soil color.

A soil is developing on a floodplain area of Brizzolara Creek 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?

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?

A, C

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

Absorb water, absorb gases, release nutrients by mineral weathering, support bacterial growth (All of the above).

Argillic horizons are characterized by

Accumulation of silicate clays

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?

Addition

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

Aeolian dune sand

Material deposited by moving fresh water is called:

Alluvium

The most widely distributed and extensive of all parent material is

Alluvium

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

Alluvium and glacial

If you were to choose the MOST FAVORABLE location for agriculture, which of the following sites would you choose?

An old river channel

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

Ancient seas

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

B

In which of the following horizons has the process of illuviation most likely occurred?

B horizon

Silicate clay accumulation is most common in the _______.

B horizon

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

Bk

Eolian parent materials are transported:

By atmospheric winds from their points of origin.

The most common mineral in limestone is:

Calcite

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

CO2

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

Cold, dry climate with tundra vegetation.

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

Colluvial

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

Columnar

Primary minerals in igneous rocks from during the:

Cooling and solidification of magma.

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

Decrease in bulk density

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

Deep residual soils

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

Disintegration of feldspar due to rapid temperature changes.

The downward movement of material out of the soil surface horizon is called:

Eluvation

E soil horizons are defined as zones of:

Eluviation

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

False

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

False

Sandstones are examples of metamorphic rocks.

False

Functions of soil include

Filtering rain and other water that passes through it, recycling of organic wastes, supporting bridges and other man-made structures, providing habitat for microorganisms that help provide plant nutrients.

Parent materials derived from weathered basalt results in

Fine textured soils containing K, Mg, and Fe

Formation of granular aggregates is aided by

Fungal hyphae, fine roots, and microbial and plant exudates (All of the above).

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

Granular

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.

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

Greater attraction for water.

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

Horizons

Relationship between humus content and soil depth in a grassland soil?

Humus content decreases with soil depth.

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

Hydrolysis

The reaction: orthoclase+HOH--> K^++OH^- +kaolinite clay is an example of _______.

Hydrolysis

An example of chemical weathering of minerals is:

Hydrolysis of orthoclase and olivine.

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

Hydrolysis, oxidation, carbonation, plant roots.

Granite is an example of a(n) _______.

Igneous rock

Secondary minerals are not found in:

Igneous rocks and the atmosphere

B horizons are defined as zone of:

Illuviation

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

Increase in mineral material and decrease in air-filled pore space.

Granite tends to weather to soils that are _____.

Infertile and coarse textured

The ease with which water enters the soil is called

Infiltration rate

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

Iron

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

Light porous and productive.

An eolian deposit of silt-sized materials is called:

Loess

Eolian parent materials would be mainly located on:

Loess plains and sand dunes

Soil organic matter

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

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

Rain water

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

Reduction and oxidation of augite.

Climate is a soil-forming factor that results in:

Regional soil differences.

Shale tends to weather to soils that are

Relatively fertile and fine textured

Metamorphic rocks can best be characterized as:

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

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

Sand, silt and clay

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

Sandstone, shale, limestone

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

Sedimentary

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

Soil horizon

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

South-facing

Two land forms upon which one would expect to find alluvium include:

Stream terraces and flood plains.

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

Surface runoff

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

Taken up plants or leeched.

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

Temperate, moist climate with forest vegetation.

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

Texture

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

Texture

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

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

With regards to topography, where would shallow soil with little horizon development be found?

The middle of a south facing slope

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

The proper classification of the soil.

A soil profile consists of ________.

The set of layers seen in a vertical cross section of a soil.

Aspect is a component of which soil forming factor?

Topography

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 example of what soil forming processes?

Transformation/Translocation

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?

Translocation

(T/F) Most of the water in our freshwater rivers has come in contact with and has been affected by soils.

True

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

Upper Peninsula Michigan

Which of the following is NOT considered one of the five major factors influencing soil formations?

Valence state

With regards to topography, where would flat soil rich in organic matter with potential for a high water table be found?

Valley

With regards to topography, where would relatively deep well drained soil be found?

Very top mesa

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

Volcanic activity

Which of the following is true about the hydrolysis reaction?

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

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

Well-structured garden soil.

The steeper the topography, usually the ______ the soil.

Younger and shallower

Soils formed on landslide deposits have parent materials which are:

colluvial

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

desert region of Arizona.

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

g

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

less vegetative cover and warmer temperatures

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

north-facing

Igneous rocks can best be characterized as:

rocks formed when molten magma solidifies.

Igneous, sedimentary, and metamorphic are three ________.

types of rocks.