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Erosion and Deposition: Wind, Gravity, and Living Things — Quiz Answers

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1
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Vegetation can reduce erosion and stabilize slopes through physical and hydrological processes. However, some landscape observations may result from other factors not related to vegetation cover. Classify each statement based on whether it describes a condition influenced by vegetation presence or a condition unrelated to vegetation.

Answer:

A thick forest canopy reduces the direct impact of raindrops on soil.,Slopes with dense root systems have lower sediment loss after heavy rain.|Landslide frequency increases during prolonged drought.,Rockslides are triggered by seismic activity

2
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Match each vegetation-related condition to the type of surface change or erosion pattern it is most likely to create.

Answer:

top layer dries unevenly and cracks under temperature shifts|fine particles are lifted, breaking down topsoil texture|raindrop impact fragments surface and initiates splash erosion|surface channels deepen and expand after repeated rainfall

3

In a semi-arid region, vegetation was removed from slopes that had historically absorbed occasional rainfall through grass and shrub systems. Several months later, storms resulted in rapid landscape change. Which process most likely contributed to the change?

A
With no root systems in place, water infiltrated too quickly and caused slope collapse.
B
Intermittent wetting and drying cycles caused surface breakdown, making it easier for soil to erode.
C
Loss of canopy exposure caused the soil to harden, protecting it from further erosion.
D
Vegetation removal led to improved soil cohesion due to reduced biological disturbance.
4

A team modeled how vegetation placement affects the direction and concentration of runoff and sediment build-up on a slope. In one model, curved rows of shrubs were planted to follow the slope's contours. This arrangement slowed runoff and caused sediment to accumulate in patches behind the shrub rows, often in stable zones upslope. In the other model, shrub rows were planted directly downslope. This arrangement channeled runoff straight downhill, and sediment collected more evenly at the base of the slope. Which explanation best supports how vegetation influenced deposition in this case?

A
Shrubs arranged across slope contours prevented all soil loss by blocking flow at the top of the model.
B
Vegetation placed along slope contours redirected flow laterally, concentrating sediment in stable, elevated zones.
C
Vegetation rows in both models affected runoff flow, but neither changed where sediment was most likely to collect.
D
Shrubs placed in straight lines downslope created turbulence that reduced erosion but evenly spread sediment.
5

After large tracts of mangrove forest were removed along a tropical coastline, researchers observed measurable shoreline retreat within five years. Which statement best explains this outcome?

A
The removal of vegetation increased direct exposure of coastal sediment to water’s forces.
B
Reduced canopy cover altered surface temperature but had limited effect on sediment displacement.
C
Vegetation loss interfered with microclimate balance but did not significantly affect sediment transport.
D
The loss of root systems reduced soil cohesion but did not directly increase shoreline erosion.
6

Match each vegetation-based mitigation strategy to the hazard-prevention function it supports.

Answer:

intercepts surface water flow and disperses runoff energy before it reaches the base of the slope|reinforces unstable slopes and slows the initiation of slope failures|reduces raindrop impact and delays soil saturation that can trigger erosion or landslides

7

A steep hillside above a rural village had remained stable for years. After a week of intense rainfall, the slope gave way, triggering a landslide that blocked nearby roads and damaged part of the landscape. Which condition most likely contributed to slope failure by altering the balance between resisting and driving forces?

A
Evaporation removed excess water and increased soil cohesion.
B
Tree roots stabilized the slope by anchoring surface soil.
C
Surface compaction reduced the likelihood of water penetration.
D
Water infiltration weakened internal friction and increased downslope force.
9

A coastal highway was built on a bluff overlooking the ocean in a region with frequent tectonic activity. The bluff sits above a fault line that shifts slightly, even during minor earthquakes. Recently, inspectors observed widening cracks along the road, and residents reported loud popping sounds from the slope during a storm. Which explanation best describes what is happening and what may occur next?

A
Tectonic stress is causing thermal expansion along the roadbed, creating minor surface changes only.
B
Wave action is carving out the bluff from below, but the fault line makes no contribution to slope instability.
C
Cracks are likely from salt crystal growth in coastal rock, not related to gravity-driven processes.
D
The combination of fault movement and water infiltration is increasing stress in the slope, likely leading to a sudden landslide.
10

A conservation team is studying a wetland that has recently expanded due to a large beaver dam. Nearby, they notice new plants growing along the water’s edge and fewer signs of erosion on the banks. The team wants to understand whether the beavers are playing a role in reducing erosion in the area. Which explanation best connects the beavers’ actions to reduced erosion in this environment?

A
The beaver dam slows water flow, allowing soil to settle and vegetation to grow.
B
The beaver dam increases water speed, which clears out sediment.
C
The dam fully blocks water movement, eliminating erosion entirely.
D
The beavers remove plants, which causes sediment to move downstream.

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