SSC - Soil Formation Questions

Residual parent materials have generally been subjected to weathering for a longer period of time than have colluvial or alluvial parent materials. (True/False)?

True

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

True

The depth of a soil profile is dependent on the type of parent material. The more easily weathered the parent material, the deeper the soil profile.

False

In general, alluvium in not good for agriculture.

False. Alluvial fans are used as plots of ag land

Organic deposits are rarely found in areas of extreme wetness or extreme cold.

False. Histels are really cold and high in organic material

Till and outwash are both examples of parent materials readily found in North Carolina

False. Northeast/parts of Midwest

Organic matter accumulation is most pronounced in the ________.

O horizon

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

B horizon

Animals, microorganisms and plants contribute carbon dioxide to the soil atmosphere. Although the CO2 reacts with water to form carbonic acid, the resulting product has little effect on chemical weathering.

False

In a typical weathering sequence, rocks break down into secondary minerals which further undergo physical and chemical weathering to form primary minerals.

False

The factors of soil formation act remarkably independent, with little interaction, thus creating similar soils.

False

The parent materials for most floodplain soils are residual in nature.

False

The rate of chemical weathering is affected very little by the downward movement of water, oxygen, and organic and inorganic acids flowing through the soil profile.

False

Weathering of rocks usually is most intense in the center of a rock fragment, and gradually decreases toward the outside.

False. Think of salt dissolving in water, how it 'eats away' at it from the outside

The depth of a soil profile is dependent on the climate. Cold dry conditions promote rapid weathering and consequently soils developed under these conditions are deeper than soil developed under wet and warm conditions. (True or False?)

False. Weathering is slowed down because it's cold. For every 10 degrees increased, biochemical reactions are doubled

The reaction: mica + H2O→ K+ + OH- + acid clay is an example of ________.

Hydrolysis (take note of the water in the reactant side of the equation)

Which of the following statements is correct? A. Lacustrine parent materials have been subject to weathering for shorter periods of time than residual parent materials nearby. B. Calcium carbonate accumulation is more prominent in humid than in arid regions. C. Soils on hillsides tend to be deeper than those on level lands. D. Nutrient cycling in forested areas contributes little to soil formation. E. Limestone parent materials enhance the process of acidification.

Lacustrine parent materials have been subject to weathering for shorter periods of time than residual parent materials nearby.

Which of the following statements is not correct? A. Grasslands are found in semi-arid and sub-humid areas. B. The type of native vegetation is controlled primarily by climate. C. Coniferous forests are found mostly in cool humid areas. D. Tropical forests protect the soil from excessive weathering. E. Dense forests are found soil profiles have prominent O horizons.

Tropical forests protect the soil from excessive weathering. False.

Effective precipitation is a measure of the amount of water that flows into and through the soil profile.

True

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

ancient seas

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

clay

Glacial till is a term used to describe parent materials that ________.

contain a heterogeneous mixture of mineral debris dropped by receding glaciers

Residual parent materials are best described as ______.

materials formed by weathering of rocks and minerals in place

Which of the following is not a secondary mineral? A. silicate clay B. hematite C. calcite D. gypsum E. microcline

microline

Igneous rocks can best be characterized as ________.

rocks formed when molten magma solidifies

Alluvial fans are usually characterized by ________ soils.

sandy and gravelly (think of streams)

Exfoliation is caused by changes in ________.

temperature

Mechanical weathering processes result in ________.

the disintegration of rocks due to differential expansion of minerals

Igneous, sedimentary, and metamorphic are three ________.

types of rocks

"Biotite-->clay-->iron oxide" represents a ________.

weathering sequence