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Erosion is defined as the process by which surface materials are removed and transported from one location to another.
Answer: True
Explanation: The provided text defines erosion as the action of surface processes that remove and transport material from one location to another.
Physical erosion involves the removal of rock or soil as clastic sediment, not through dissolution.
Answer: True
Explanation: Physical erosion refers to the removal of rock or soil as clastic sediment, whereas dissolution is characteristic of chemical erosion.
Following their removal by erosional processes, eroded materials undergo transport and subsequent deposition in a new location.
Answer: True
Explanation: The cycle of erosion involves the detachment and transport of material, which is eventually deposited elsewhere.
What is the fundamental definition of erosion as presented in the text?
Answer: The action of surface processes that remove soil, rock, or dissolved material from one location and transport it to another.
Explanation: The source identifies erosion as the process by which surface materials are detached and transported from one location to another by natural agents.
How does the text distinguish between physical and chemical erosion?
Answer: Physical erosion involves clastic sediment removal, while chemical erosion involves dissolution.
Explanation: Physical erosion entails the detachment and transport of rock or soil as solid particles, whereas chemical erosion involves the removal of material through dissolution by chemical reactions.
What is the fate of materials after they are removed by erosional processes?
Answer: They are transported, potentially over long distances, and then deposited in a new location.
Explanation: Once detached and removed by erosion, materials are transported by various agents and eventually deposited in new environments, forming sediments.
What is the key difference between weathering and erosion according to the text?
Answer: Weathering breaks down rocks and soil, while erosion involves the movement of these materials.
Explanation: Weathering is the process of rock and soil disintegration, whereas erosion encompasses the subsequent detachment and transport of these weathered materials.
Splash erosion is the initial and least severe form of soil erosion caused by rainfall and surface runoff.
Answer: True
Explanation: Splash erosion, caused by the impact of raindrops, is the initial stage and generally the least severe form of soil erosion, preceding sheet, rill, and gully erosion.
Sheet erosion is characterized by the uniform removal of soil particles by overland flow across the landscape.
Answer: True
Explanation: Sheet erosion involves the transport of detached soil particles by shallow, broad surface runoff, resulting in the uniform removal of a thin soil layer.
Rill erosion is characterized by the formation of small, temporary channels resulting from concentrated water flow.
Answer: True
Explanation: Rill erosion occurs when surface runoff concentrates into small channels, which are typically temporary and can be removed by tillage.
A gully is defined as a channel with a cross-sectional area of at least one square foot, distinguishing it from rills.
Answer: True
Explanation: Gully erosion forms larger channels than rills; specifically, a gully is defined by a cross-sectional area of at least one square foot, making it too substantial for normal tillage.
Badlands are landscapes characterized by extensive gully erosion, typically forming on easily eroded bedrock with limited vegetation.
Answer: True
Explanation: Badlands develop on bedrock that is highly susceptible to erosion, particularly in arid or semi-arid climates where vegetation cover is sparse, leading to extensive dissection by gullies.
Valley erosion initially involves vertical deepening before lateral widening occurs.
Answer: True
Explanation: The initial phase of valley erosion by streams is primarily vertical, carving downwards to create V-shaped valleys, before lateral erosion begins to widen the valley floor.
Scour in a river context refers to erosion of the stream's bed, not its banks.
Answer: True
Explanation: Bank erosion affects the lateral boundaries of a river channel, whereas scour is the erosive action concentrated on the channel bed.
Submarine canyons are primarily formed by the rapid downslope movement of sediment via turbidity currents.
Answer: True
Explanation: Submarine canyons are carved into the continental slope by powerful underwater sediment flows known as turbidity currents, which are a form of rapid mass movement.
Which type of soil erosion, caused by rainfall and surface runoff, is considered the initial and least severe?
Answer: Splash erosion
Explanation: Splash erosion, initiated by raindrop impact, is the first stage and generally the least severe form of soil erosion.
What characterizes rill erosion?
Answer: The formation of small, temporary channels created by concentrated water flow.
Explanation: Rill erosion is defined by the development of small, ephemeral channels formed by concentrated surface runoff, which can transport significant amounts of soil.
How is gully erosion distinguished from rill erosion?
Answer: Gullies are channels with a cross-sectional area of at least one square foot, too large for normal tillage.
Explanation: Gully erosion is differentiated from rill erosion by its scale; gullies are channels with a cross-sectional area of at least one square foot, rendering them unmanageable by standard tillage equipment.
Badlands, landscapes known for extreme gully erosion, typically form on:
Answer: Easily eroded bedrock in climates favorable to erosion, often with limited vegetation.
Explanation: Badlands develop on bedrock that is highly susceptible to erosion, particularly in arid or semi-arid climates where vegetation cover is sparse, leading to extensive dissection by gullies.
In valley or stream erosion, what is the initial process described?
Answer: Initially primarily vertical erosion, creating V-shaped valleys.
Explanation: The initial stage of valley erosion by streams involves vertical downcutting, which carves V-shaped profiles into the landscape.
What is the distinction between bank erosion and scour in a river context?
Answer: Bank erosion refers to the wearing away of the sides of a stream, while scour refers to erosion on the bed.
Explanation: Bank erosion affects the lateral boundaries of a river channel, whereas scour is the erosive action concentrated on the channel bed.
What are kolks, and how do they contribute to erosion?
Answer: Kolks are swirling masses of water that cause intense localized erosion by scouring bedrock.
Explanation: Kolks, or vortices, are powerful swirling water masses that create intense localized erosion, particularly by scouring bedrock in river channels.
Hydraulic action, wave pounding, and abrasion are key processes involved in coastal erosion.
Answer: True
Explanation: Coastal erosion is driven by wave action, including hydraulic action (air compression in joints), wave pounding (direct force), and abrasion (sediment grinding against the coast).
Longshore drift contributes to coastal erosion when the transport capacity of the current exceeds the available sediment supply from upstream sources.
Answer: True
Explanation: When longshore drift currents are strong enough to transport more sediment than is supplied, they erode material from the coastline.
Deflation and abrasion are identified as the two primary types of wind erosion.
Answer: True
Explanation: Wind erosion primarily manifests as deflation, the removal of loose particles, and abrasion, the wearing down of surfaces by particle impact.
Saltation is the most significant category of deflation, accounting for 50-70% of its total.
Answer: True
Explanation: Saltation, the bouncing movement of particles along the surface, is the most significant mode of deflation, responsible for the majority of wind erosion.
Which of the following is a key process involved in coastal erosion driven by waves?
Answer: Abrasion, where waves carrying sediment grind against the coastline.
Explanation: Abrasion, the grinding action of waves laden with sediment against the shore, is a significant mechanism of coastal erosion.
How does longshore drift contribute to coastal erosion?
Answer: By moving sediment along the coast when the transport capacity exceeds the supply, causing the current to pick up more material from the shore.
Explanation: Longshore drift contributes to erosion when the sediment transport capacity of the current surpasses the available sediment supply, leading to the removal of material from the shore.
What are the two main types of wind erosion?
Answer: Deflation and abrasion.
Explanation: Wind erosion primarily manifests as deflation, the removal of loose particles, and abrasion, the wearing down of surfaces by particle impact.
Which category of deflation is the most significant contributor to wind erosion, accounting for 50-70% of its total?
Answer: Saltation
Explanation: Saltation, the process of particles bouncing along the surface, is the most significant component of deflation, responsible for the majority of wind erosion.
Thermal erosion is primarily caused by the melting and weakening of permafrost due to the action of moving water.
Answer: True
Explanation: Thermal erosion occurs in permafrost regions when warming temperatures or moving water cause ice-rich ground to thaw and erode, rather than by the physical impact of ice.
Glaciers primarily erode land through abrasion, plucking, and ice thrusting.
Answer: True
Explanation: These three processes—abrasion (scouring by debris), plucking (removal of bedrock fragments), and ice thrusting (incorporation of sediment)—are the principal mechanisms by which glaciers shape landscapes.
The 'glacial buzzsaw' concept describes how glaciers limit the maximum height of mountain ranges by increasing erosion.
Answer: True
Explanation: The 'glacial buzzsaw' refers to the phenomenon where glaciers, by increasing erosion rates, counteract tectonic uplift, thereby capping the maximum height that mountain ranges can achieve.
Mass wasting, or mass movement, is driven primarily by gravitational forces acting on slopes.
Answer: True
Explanation: Mass wasting is fundamentally driven by gravity, which pulls materials downslope. While factors like water saturation can destabilize slopes, wind is not the primary driver.
Slumping typically occurs on steep slopes and involves movement along distinct fracture zones.
Answer: True
Explanation: Slumping is a form of mass movement characteristic of steeper slopes, where material moves downslope along a curved rupture surface, often resulting in a spoon-shaped depression.
Thermal erosion is commonly observed in permafrost regions and is caused by:
Answer: The melting and weakening of permafrost due to the action of moving water.
Explanation: In permafrost environments, thermal erosion is driven by the thawing and destabilization of ice-rich ground, often facilitated by the presence of moving water.
What are the primary processes by which glaciers erode the land?
Answer: Plucking, abrasion, and ice thrusting.
Explanation: Glacial erosion is primarily accomplished through abrasion (scouring), plucking (removal of bedrock fragments), and ice thrusting (incorporation of sediment).
The 'glacial buzzsaw' phenomenon describes how glaciers:
Answer: Limit the maximum height of mountain ranges by increasing erosion that counteracts uplift.
Explanation: The 'glacial buzzsaw' effect explains how glaciers can cap mountain heights by accelerating erosion, counteracting tectonic uplift processes.
What is the primary driving force behind mass wasting (mass movement)?
Answer: Gravity
Explanation: Mass wasting is fundamentally driven by gravity, which causes the downslope movement of soil, rock, and debris.
Which of the following is a landform created or modified by glacial erosion?
Answer: U-shaped valleys
Explanation: Glacial erosion is responsible for shaping distinctive landforms, including U-shaped valleys, which are characteristic of valleys that have been carved by glaciers.
The provided text identifies wind, rainfall, and glacial processes as key agents of erosion.
Answer: True
Explanation: The text explicitly lists wind, rainfall, and glacial processes among the various agents responsible for erosion.
Precipitation amount and intensity are key climatic factors influencing water erosion.
Answer: True
Explanation: The volume and intensity of rainfall are critical climatic determinants for the rate and type of water erosion, particularly when soil infiltration capacity is exceeded.
Vegetative cover decreases erosion by increasing soil permeability and reducing runoff.
Answer: True
Explanation: Vegetative cover plays a crucial role in mitigating erosion by enhancing soil infiltration, reducing surface runoff, and stabilizing soil particles with root systems.
Topography influences erosion by affecting the velocity and volume of surface runoff.
Answer: True
Explanation: Topographical features, such as slope gradient and length, directly influence the velocity and volume of surface runoff, thereby modulating erosion rates.
Which of the following is NOT identified as a primary agent of erosion in the provided text?
Answer: Volcanic activity causing lava flows
Explanation: While volcanic activity can reshape landscapes, the text specifically lists rainfall, rivers, glaciers, wind, and the sea as primary agents of erosion.
How does vegetative cover influence erosion?
Answer: It significantly reduces erosion by increasing soil permeability, decreasing runoff, and binding soil with roots.
Explanation: Vegetative cover plays a crucial role in mitigating erosion by enhancing soil infiltration, reducing surface runoff, and stabilizing soil particles with root systems.
How does topography affect erosion rates?
Answer: Topography influences erosion by affecting the velocity of surface runoff; longer and steeper slopes increase erosion.
Explanation: Topographical features, such as slope gradient and length, directly influence the velocity and volume of surface runoff, thereby modulating erosion rates.
Human activities have significantly increased the global rate of soil erosion compared to natural geological rates.
Answer: True
Explanation: The source indicates that human activities have substantially accelerated soil erosion rates, often exceeding natural geological rates by a considerable margin.
Reduced agricultural productivity is identified as an 'on-site' problem resulting from excessive erosion.
Answer: True
Explanation: Reduced agricultural productivity is classified as an 'on-site' consequence of erosion, stemming from the loss of fertile topsoil, while 'off-site' problems typically involve impacts on water bodies or infrastructure.
Water erosion and wind erosion are together responsible for the majority of the world's land degradation attributed to erosion.
Answer: True
Explanation: The text states that water and wind erosion combined account for approximately 84% of the global extent of land degradation caused by erosion.
Deforestation and intensive agriculture are identified as major contributors to increased erosion rates.
Answer: True
Explanation: The source explicitly identifies deforestation and intensive agriculture as significant drivers that substantially increase erosion rates.
The extent of chemical erosion is generally measured by analyzing the solutes present in streams.
Answer: True
Explanation: Analyzing the dissolved mineral content (solutes) in water bodies, such as streams, is a primary method for quantifying the rate of chemical erosion.
Erosion can influence tectonic processes by removing surface mass, potentially leading to isostatic uplift.
Answer: True
Explanation: The removal of significant mass from the Earth's crust through erosion can cause the underlying lithosphere to rebound isostatically, demonstrating a feedback loop between surface processes and tectonic activity.
According to the text, how have human activities impacted the global rate of soil erosion?
Answer: Increasing it, with estimates suggesting it occurs 10 to 40 times faster than natural rates.
Explanation: Human activities such as intensive agriculture and deforestation have significantly accelerated soil erosion, with estimates suggesting rates are 10 to 40 times higher than natural geological rates.
Which of the following is identified as an 'on-site' problem resulting from excessive erosion?
Answer: Reduced agricultural productivity
Explanation: Reduced agricultural productivity is an on-site consequence of erosion, directly impacting land use and food production due to topsoil loss.
What proportion of global land degradation due to erosion is attributed to water and wind erosion combined?
Answer: Approximately 84%
Explanation: Water and wind erosion are the predominant causes of land degradation globally, accounting for approximately 84% of the total extent.
Which human activity is identified as a significant contributor to accelerated erosion rates?
Answer: Deforestation
Explanation: Deforestation is cited as a major human activity that significantly increases erosion rates by removing protective vegetation cover and destabilizing soil.
How is the extent of chemical erosion generally measured?
Answer: The solutes present in streams.
Explanation: The concentration of dissolved substances (solutes) in water bodies serves as a primary indicator for quantifying chemical erosion.
What is 'lisasion' in the context of human land development and erosion?
Answer: The intentional removal of soil and rock by human activities like construction.
Explanation: Lisasion refers to the deliberate removal of soil and rock by human activities, such as construction and mining, which constitutes a significant form of accelerated erosion.
What is the estimated timescale for the significant erosion of a major mountain range like the Himalayas?
Answer: Over 450 million years
Explanation: The geological timescale for the significant erosion of large mountain ranges, such as the Himalayas, is estimated to be in the hundreds of millions of years.