The Solid Earth - Chapter 2: Soil Flashcards
____ and other processes create soil
Weathering
What carry out the intermediary role of assimilating the necessary elements and making them available to animals and people to support life?
Plants
The earth’s land surface is covered by ___, the layer of rock and mineral fragments produced by weathering
Regolith
Soil is a combination of ____ and ____ matter, matter, and air
Mineral
Organic
About ____ percent of the total volume of a good quality surface soil is a mixture of disintegrated and decomposed rock and humus
50
The decayed remains of animal and plant life (organic matter)
humus
The remaining half (not rock and humus) consists of ___ spaces for air and water to circulate
Pore
Humus enhances the soil’s ability to ___ ____.
Retain water
Soil water is a complex solution containing many ___ nutrients
soluble
This refers to the relative portions of different particle sizes in a soil
Soil texture
What do sandy soils do too rapidly?
Drain
The pore spaces of clay-rich soils might be too small for adequate ___
drainage
This type of soil is 10 percent silt, 40 percent clay, and 50 percent sand
Sandy clay
What are soils called that have no single particle size predominating?
Loam
Which type of soils are best suited to support plant life?
Loam
Soil particles often form clumps called
peds
Name four basic soil structures:
platy
prismatic
blocky
spheroidal
Prismatic and blocky peds usually allow for moderate ___ ____
water infiltration
Platy and spheroidal structures are characterized by slower ____ ____
infiltration rates
The source of the weathered mineral matter from which soils develop is called the ___ ___ and is a major factor influencing a newly forming soil
Parent material
When the parent material is bedrock, the soils are termed
residual
Soils developed on unconsolidated sediment are called
transported
transported soils form __ ___
in place
Transported soils form in place on parent materials that have been carried from elsewhere and ___ by gravity, water, wind, or, ice.
deposited
True or false: the parent material of the soil affects how it weathers.
True
Can the parent mineral influence the rate of chemical weathering?
yes
The chemical makeup of the parent material will affect the ___ of the soil
fertility
Name a factor that is more important than parent material in determining characteristics of a soil
climate
True or false: Regardless of time, a parent material will always have the same strong effect on soil
False
The longer a soil has been forming, the ___ it becomes and the less it resembles the parent material from which it formed
thicker
____ is considered to be the most influential control of soil formation
Climate
The chief function of plants and animals is to supply ____ _____ to the soil
organic matter
When organic matter is decomposed, it supplies important nutrients for plants, as well as food for the animals and _______ living in the soil
microorganisms
The decay of plant and animal remains causes various organic ___ to form
acids
Complex acids (quicken/slow) the weathering process
quicken
On steep slopes, soils are often ____ developed
poorly
True or false: the reason for poor soils on steep slopes is mostly because of a lack of water
true
Water logged soils in bottomlands are usually very thick and (dark/light)
dark
What makes the dark coloring in the water logged soils?
Organic matter
What is the optimum slope for soil ddevelopment?
flat to undulating upland surface
The direction the slope faces
Slope orientation
In the mid-latitudes of the northern hemisphere, a south facing slope will receive (less/more) sunlight than a north facing slope
more
Differences in the amount of solar radiation in a soil will cause difference in ___ and ___
moisture
temperature
The vertical differences in soil, which usually become more pronounced as time passes divide the soil into zones or layers … AKA ___
horizons
A vertical section through all of the soil horizons constitutes the ___ ____
soil profile
Name the horizons from top to bottom
OABC
The __ horizon consists largely of organic material
O
The name of the partly decomposed organic matter in the lower portion of the O horizon in which plant structures can no longer be identified
humus
This zone is largely mineral matter with some biological activity is high and humus is generally present
A
As water percolates downward from the surface through the __ horizon, finer particles are carried away with it.
A
The washing out of fine soil components
Eluviation
The texture of the A horizon gradually becomes ___ because a portion of the fine particles is removed
coarser
The depletion of soluble materials from the upper soil
leaching
A nickname for the B horizon
subsoil
Because much of the material is removed from the A horizon by eluviation and deposited in the B horizon, it is often referred to as the zone of ____
accumulation
True or false: the accumulation of fine clay particles from the A horizon makes it harder for the subsoil (B) to retain water
False
Sometimes clay accumulation can form an extremely dense and impermeable layer called ___
hardpan
The O, A, and B horizons constitute the “true soil” AKA the _____
solum
It is in the ____ that soil forming processes are active and that living roots and and other plant and animal life are confined
solum
Which layer is characterized by partially altered parent material and little if any organic matter?
C
A ____ _____ is easily recognized or identified in the C horizon even if it is altered in the solum
parent material
A well developed soil profile indicates that a soil is (mature/immature)
mature
Soils that lack horizons are called ____
immature
Immature soils are characteristic of steep slopes where ____ continually strips away the soil
erosion
A type of soil characterized by iron oxides and aluminum rich clays in the B horizon
Pedalfers
____ is characterized by the accumulation of calcium carbonate in the soil
Pedocal
The whitish accumulation in a soil that has an abundance of calcium carbonate
Caliche
In the hot and wet climates of the tropics, soils called ____ develop
laterites
Laterites develop with chemical weathering, so these soils are usually ____ than soils developing in the mid latitudes
deeper
What might give soil a distinctive red color?
Iron
Bacterial activity is very high in the tropics, so ____ contain practically no humus
laterites
laterites are (good/not good) for growing crops
not good
In cold or dry climates, soils are generally very ___ and poorly developed
thin
What is a climate associated with laterite?
rainforest
Water in thin sheets moving soil away is called:
sheet erosion
tiny channels formed in a soil
rills
Deeper cuts in the soil that are created as rills enlarge
gullies
What we call the soil particles once they are transported downstream and are eventually deposited
Sediment
True or false: plants have a stabilizing effect and can help stop erosion
True
Erosion caused by surface runoff may be estimated by determining the sediment loads of the ____ that drain the region
streams
When ___ conditions prevail, strong winds can remove large quantities of the soil from unprotected fields
dry
True or false: there are no concerns when soil is deposited into reservoirs
False
The contamination of soil particles with ___ can create a threat when those particles into a lake or reservoir
pesticides
Which of the following is not a technique for erosion control? A. Windbreaks B. Dunes C. Terracing D. Contour Farming Techniques
Dunes
The name of the transformation from weathering that creates mineral deposits from minor amounts of metals
secondary enrichment
the principal ore of aluminum
bauxite
Aluminum is often tied up in ___ minerals, from which it is hard to extract
silicate
Many copper and silver deposits result when weathering processes concentrate metals that are dispersed through a low-grade ____ ore
primary
____ is important because when it chemically weathers, sulfuric acid forms, which enables percolating waters to dissolve the ore materials
Pyrite
____ takes place because of changes that occur in the chemistry of the solution when it reaches the groundwater zone
Deposition
