Question 1

Which of the following is not a significant factor triggering mass wasting events?

Accepted Answer

Mine tailings filling a valley would not be a significant factor triggering mass wasting events as it is a man-made activity and not a natural process like the other options. Forest fires, heavy rainfall, and earthquakes can all contribute to mass wasting events by altering the stability of the ground and creating changes in the slope angle or surface water flow.

Question 2

Which soil horizon represents the lowest part of the zone of accumulation, also referred to as the subsoil?

Accepted Answer

Sol is the correct answer as it represents the subsoil, which is the lower part of the zone of accumulation. None of the other options specifically refer to this soil horizon.

Question 3

A mass wasting process that involves slip of solid rock above a distinct sliding surface is called______ .

Accepted Answer

A rock slide involves the slip of solid rock above a distinct sliding surface.

Question 4

Most insurance companies will not insure property with a known landslide hazard. Why?

Accepted Answer

Most insurance companies will not insure property with a known landslide hazard because the risk is high on human life time scales, and the hazard is difficult to assess. Landslides can occur due to a variety of factors, including long-term weather patterns and changes in land use, and can be difficult to predict. As a result, insurance companies may be reluctant to take on the risk associated with insuring property located in areas with a known landslide hazard.

Question 5

Consider a weathered rock or soil particle lying on a slope. How will the gravitational force pulling the particle downward along the land surface vary with the inclination of the slope?

Accepted Answer

The gravitational force pulling a particle downward along the slope decreases as the slope angle is lessened because the component of gravitational force acting along the slope is directly related to the sine of the slope angle. As the angle decreases, the sine of the angle decreases, thus reducing the force component acting along the slope.

Question 6

Deforestation of rain forests exposes tropical soils that are famous for their low fertility, despite the fact that they had previously hosted a lush tropical forest. Which soil type would describe these soils?

Accepted Answer

Oxisols are known for their low fertility due to heavy leaching and high levels of iron and aluminum oxides, making them unsuitable for agricultural activity. These soils are common in areas where tropical rain forests have been deforested.

Question 7

After the drought of the 1930's farmers in the Great Plains were encouraged to plant rows of trees across fields to decrease soil erosion. How would this reduce soil erosion?

Accepted Answer

The answer of After the drought of the 1930's farmers...

Question 8

As an erosional process, how is mass wasting unique compared to wind, water, and ice?

Accepted Answer

Mass wasting does not require a transporting medium like wind, water, and ice do, making it unique among erosional processes.

Question 9

What type of sand holds its shape the best?

Accepted Answer

Moist sand holds its shape the best because the water creates cohesive forces between the sand particles, allowing them to stick together without being too wet or too dry.

Question 10

Most stream valleys have a V shaped cross section because______ .

Accepted Answer

The V-shaped cross section is maintained because of mass wasting of weathered rocks on the slope, which maintains an angle of repose slope. This means that any loose material on the slopes will come down and maintain the angle of the slope, resulting in a V-shaped valley. The other choices are not correct because water washing down the slope can result in different types of channels, and vegetation on the slopes does not necessarily force a V-shaped profile.

Question 11

You buy land in the tropics on steep mountain slopes covered by large trees and deep soil. You want to build a house on the land. Which of the following building plans is a not adviseable because of the danger of triggering mass wasting?

Accepted Answer

Excavating a flat bench and pushing debris down the slope can destabilize the slope further, increasing the risk of mass wasting. Planting grass on a steep slope is insufficient to prevent erosion or stabilize the soil.

Question 12

In terrain with steep hill slopes, which crop and cultivation technique will minimize soil erosion?

Accepted Answer

Planting apples and leaving the land between the trees in grass rather than cultivating helps to minimize soil erosion in terrain with steep hill slopes. The grass cover helps to hold the soil in place and prevent it from being washed away by rainwater. Additionally, the trees themselves can also help to anchor the soil and protect it from erosion. Meanwhile, the wider spacing of rows (B), leaving the field idle (C), or straight rows and frequent cultivation (D) can all contribute to increased soil erosion in steep terrain.

Question 13

Climate change and human activity like overgrazing of grasslands is leading to large areas subject to "desertification" where native grass cover dies out during drought periods, exposing soil to erosion. What is potentially the greatest initial soil erosion potential during this type of an event?

Accepted Answer

During a drought when grass cover dies out, the soil is left exposed to strong winds which can cause large-scale wind erosion and loss of topsoil. This can have a devastating impact on the ecosystem, making it difficult for new plants to establish and increasing the risk of desertification. Local gullying produced by intermittent rainstorms and the growth of shrubs shading the ground are also concerns, but they are not as significant as the potential for topsoil loss through wind erosion. Sand blown in from adjacent deserts is not a factor in this scenario as the desertification is caused by the loss of native grass cover.

Question 14

In North America "no till farming" has become a widespread practice made possible by genetically modified GM. crops that can be sprayed with herbicide that kills everything but the GM plant. Evaluate the following statements on the role of GM crops on soil conservation issues?

Accepted Answer

No till farming with GM crops allows for a loose organic matter cover on the soil surface, which acts as a barrier to wind and runoff, thereby reducing rates of soil erosion. This is a positive effect on soil conservation.

Question 15

A mass wasting process that involves rotational motion of material sliding above a distinct slip surface is called ______.

Accepted Answer

A slump is a type of mass wasting where the material moves along a curved surface in a rotational motion. This occurs when a weakened or saturated layer of soil or rock slides downwards and rotates along the slip surface. A rock avalanche, rock fall, and rock slide all typically have a more linear motion rather than a rotational one.

Question 16

Water runoff is a major factor in soil erosion, what is a common land use practice on slopes to minimize soil erosion?

Accepted Answer

Terracing slopes to stop downslope runoff and rill formation is the most effective and common land use practice to minimize soil erosion on slopes. Terracing involves building a series of level platforms, or terraces, on the slope, which help to slow down water runoff and trap sediment, preventing it from being carried away by the flowing water. This method also helps to stabilize the soil, making it less prone to erosion, and is often used in areas where row cropping or other land use practices are not practical. Planting trees and adding a rock mulch layer can also help to reduce erosion, but are less effective than terracing, particularly on steep slopes. Planting row crops with rows running downhill can actually increase channelization of flow, accelerating erosion, and is not a recommended practice for erosion control on slopes.

Question 17

Which soil horizon represents the lowest part of the zone of accumulation, also referred to as the subsoil?

Accepted Answer

The B horizon represents the subsoil layer, which is the layer beneath the topsoil (A horizon) where minerals and nutrients accumulate. It is also known as the zone of accumulation. The C and E horizons are deeper layers of soil that have not undergone significant weathering and do not contain organic material or nutrient accumulation.

Question 18

Which of the following mass movements is most likely to occur in a geologic setting where the rock strata are inclined?

Accepted Answer

Rockslides are most likely to occur in areas where rock strata are inclined, as the layers can slide down along the planes of weakness.

Question 19

Landslides commonly occur when hurricanes hit steep terrain. Why?

Accepted Answer

Heavy rainfall from a hurricane can saturate steep slopes, triggering mass wasting events like landslides and mudslides.

Question 20

How does deforestation by fire or human activity contribute to mass wasting?

Accepted Answer

Deforestation by fire or human activity can kill tree roots that help hold the slopes in place. This can weaken the stability of the slopes and allow mass movement to occur.

Quiz 8: Weathering, Soil, and Mass Movement

Which of the following is not a significant factor triggering mass wasting events?

Which soil horizon represents the lowest part of the zone of accumulation, also referred to as the subsoil?

A mass wasting process that involves slip of solid rock above a distinct sliding surface is called______ .

Most insurance companies will not insure property with a known landslide hazard. Why?

Consider a weathered rock or soil particle lying on a slope. How will the gravitational force pulling the particle downward along the land surface vary with the inclination of the slope?

Deforestation of rain forests exposes tropical soils that are famous for their low fertility, despite the fact that they had previously hosted a lush tropical forest. Which soil type would describe these soils?

After the drought of the 1930's farmers in the Great Plains were encouraged to plant rows of trees across fields to decrease soil erosion. How would this reduce soil erosion?

As an erosional process, how is mass wasting unique compared to wind, water, and ice?

What type of sand holds its shape the best?

Most stream valleys have a V shaped cross section because______ .

You buy land in the tropics on steep mountain slopes covered by large trees and deep soil. You want to build a house on the land. Which of the following building plans is a not adviseable because of the danger of triggering mass wasting?

In terrain with steep hill slopes, which crop and cultivation technique will minimize soil erosion?

Climate change and human activity like overgrazing of grasslands is leading to large areas subject to "desertification" where native grass cover dies out during drought periods, exposing soil to erosion. What is potentially the greatest initial soil erosion potential during this type of an event?

In North America "no till farming" has become a widespread practice made possible by genetically modified GM. crops that can be sprayed with herbicide that kills everything but the GM plant. Evaluate the following statements on the role of GM crops on soil conservation issues?

A mass wasting process that involves rotational motion of material sliding above a distinct slip surface is called ______.

Water runoff is a major factor in soil erosion, what is a common land use practice on slopes to minimize soil erosion?

Which soil horizon represents the lowest part of the zone of accumulation, also referred to as the subsoil?

Which of the following mass movements is most likely to occur in a geologic setting where the rock strata are inclined?

Landslides commonly occur when hurricanes hit steep terrain. Why?

How does deforestation by fire or human activity contribute to mass wasting?