Weathering and soils

What is by far the most important agent of chemical weathering, and why?

Water: It is a good solvent and carrier of acids. Exfoliation: New cracks give chemical reactions the chance to operate. The Sun: It drives all external processes on Earth. Soil: Moisture in soil is the carrier of acids and drives chemical weathering.

Which types of soils are rich in iron aluminum oxides, are heavily leached, and are considered poor for agricultural use?

spodosols alfisols ultisols oxisols

Which horizon is typically a light-colored layer containing little organic matter and fine soil components, and what process or processes are responsible?

the A horizon; thermal expansion and root uptake the B horizon; accumulation of clay the O (organic) horizon; bacterial activity the E horizon; leaching and eluviation

The process of weathering is best described as __________.

the physical removal of materials by water, wind, or ice the persistence of resistant materials at Earth's surface the transfer of rock and soil downslope under the influence of gravity the physical breakdown and chemical alteration of rocks at or near Earth's surface

At what point does soil become sediment?

when soil makes it to the ocean or a lake when soil is on the bottom of a slope when soil is produced and water is expelled when soil makes it down slope and enters into a stream

Which of the following statements is true about the relationship between a mineral's temperature of crystallization and resistance to weathering?

Bowen's reaction series describes a specific order of mineral crystallization as a magma cools. Minerals crystallizing at higher temperatures will be more resistant to weathering than those crystallizing at lower temperatures. Bowen's reaction series describes a specific order of mineral crystallization as a magma cools. Once these minerals crystallize, they are stable at the Earth's surface and do not weather. Bowen's reaction series describes a specific order of mineral crystallization as a magma cools; however, there is no relationship observed between a mineral's temperature of crystallization and resistance to weathering. Bowen's reaction series describes a specific order of mineral crystallization as a magma cools. Minerals crystallizing at lower temperatures will be more resistant to weathering than those crystallizing at higher temperatures.

Why would the presence of earthworms aid soil production?

Earthworms add water to the soil formation site. Earthworms secrete enzymes that chemically alter the soil. Earthworms cause the area to become warmer and moist, thus producing soil. Earthworms effectively mix organic and inorganic matter.

Select the correct statement regarding soil erosion.

Excessive soil erosion and subsequent sediment deposition can lead to other environmental problems. Soil erosion is part of the rock cycle; when soil erosion becomes excessive, the rate of soil formation increases to keep the system in equilibrium. Soil conservation measures have been successfully applied globally and have significantly reduced unnecessary soil erosion. Soil erosion is mainly an issue confined to tropical areas where rainforests are being destroyed; it is not typically an issue in temperate areas such as the United States.

Which of the following best describes frost wedging?

Frost wedging is a momentary process by which water freezes inside the pore spaces in rocks and explodes the rocks catastrophically. Frost wedging is a gradual process by which roots from trees wedge rocks apart as they grow larger. Once the rocks break and fall, new roots form in new cracks. Frost wedging is a cyclic process by which water in fractures freezes at night, expanding the space between blocks of rock. During daytime, the ice melts, and the process begins again.

Why is humus an essential component of soil?

It is an important source of plant nutrients and improves soil drainage. It provides structure for plant support and improves soil drainage. It is an important source of plant nutrients and enhances the soil's ability to retain water. It is an important source of plant nutrients and neutralizes many soil acids.

Which of the following is the correct order of the soil horizons found in a temperate region, from top to bottom?

O, A, E, B, C, unweathered unweathered, A, B, C, O, E unweathered, O, A, E, C, B O, B, C, E, A, unweathered

Which of the following statements best describes the soil profile and its relevance to weathering?

Soil-forming processes occur from the bottom up. This causes vertical variations in soil composition, texture, structure, and color. Soil-forming processes occur from the top down. This causes vertical variations in soil composition, texture, structure, and color. Soil-forming processes occur in single layers at a time. This causes each layer to appear different in composition, texture, structure, and color. Soil-forming processes occur laterally in the same layer. As a result, different vertical profiles allow geologists to determine that variation from place to place.

Why are weathering, mass wasting, and erosion considered external processes?

These processes affect only the surface of the rock. These processes occur at Earth's surface and are powered by energy from the Sun. These processes require an external source of oxygen and can occur only at Earth's surface. These processes occur at Earth's surface but are considered external because they require no additional energy.

Select the correct statement regarding the parent material its influence on soil formation.

The soil's fertility is independent of the parent material. Soil development will progress more rapidly when unconsolidated material is the parent material. Each type of soil can be linked to a specific parent material. Soil development will progress more slowly when unconsolidated material is the parent material.

The chemical weathering of silicate minerals frequently produces __________.

clay minerals soluble iron oxides feldspars soluble iron oxides and feldspars clay minerals and feldspars

What are the significant factors controlling the rate of soil erosion?

climate, slope, type of soil type of vegetation, slope, presence of water, aridity slope, type of vegetation, type of soil climate, slope, type of vegetation

In which of the following climates is chemical weathering most effective?

dry areas with low temperatures moist areas with warm temperatures snowy areas with warm temperatures wet areas with low temperatures

The physical removal of material by mobile agents such as water, wind, or ice is referred to as __________.

erosion mass wasting weathering diagenesis

Of the two types of weathering, ______________ weathering is accomplished by physical forces that break rock into smaller and smaller pieces without changing the rock's mineral composition.

mechanical

What is the most influential factor controlling soil formation?

plants and animals time parent material climate slope

The layer of rock and mineral fragments produced by weathering is referred to as __________.

regolith soil subsoil zone of leaching humus

Which of the following best describes a vertisol?

soils that contain a large amount of clay, which causes them to shrink and swell according to the amount of water they contain soils that represent the products of long periods of weathering young soils characterized by little profile development that occur in areas of permafrost dark, soft soils that have developed under grass vegetation