Mass movements, erosion, and deposition

Correct answer: A. Main control is gravity with little transport medium

Mass movement is driven mainly by gravity on slopes, while erosion involves transport by water, wind, or ice. In exams, use gravity as the key clue.

Correct answer: B. Because added weight and pore-water pressure reduce shear strength

Saturation makes slope material heavier and weaker, so failure becomes easier. Link pore-water pressure with slope failure in exams.

Correct answer: C. Slump rotates on a curved surface, translational slide moves along a nearly planar surface

Slump is rotational, whereas translational sliding occurs along a relatively planar slip surface. In exams, curved failure surface identifies slump.

Correct answer: D. Jointed vertical cliff and ice thawing

Ice action in joints can loosen rocks on steep cliffs and cause falling. In exams, connect steep slopes and joints with rock fall.

Correct answer: A. It indicates the maximum stable slope of loose material

When the slope of loose material exceeds its stable limit, movement may begin. Link angle of repose with slope stability in exams.

Correct answer: B. It removes basal support and destabilizes the slope

Toe erosion removes support from the lower slope, allowing material to slide. Treat river undercutting as a landslide trigger in exams.

Correct answer: A. Because blocked drainage can create a slip surface

Water may accumulate above an impermeable layer and weaken regolith. Remember drainage and slip surface together in exams.

Correct answer: A. It reduces root binding and increases surface runoff

Loss of roots weakens soil, and increased runoff enhances erosion. Link deforestation with both erosion and landslides in exams.

Correct answer: B. Debris flow is water-mixed flow, rock fall is sudden falling

Debris flow moves as a water-rich flow, while rock fall is the detachment and falling of rocks. Identify movement style and material condition in exams.

Correct answer: A. Shaking can increase shear stress and initiate sliding

Seismic shaking can disturb balance along a weak plane. In exams, treat weak plane plus shaking as a combined landslide condition.

Correct answer: B. Uniform removal of a thin soil layer from the surface

Sheet erosion removes a thin layer of soil over a broad surface. In exams, treat it as an early form of water erosion.

Correct answer: A. Small channels become deeper and more permanent trenches

Rills enlarge into deeper gullies that are hard to remove by ordinary cultivation. Remember the difference in size and depth for exams.

Correct answer: B. Heaviest and coarsest sediment

When energy decreases, heavier particles settle first, while finer particles may travel farther. Link particle size with river energy in exams.

Correct answer: A. Strong vertical erosion and steep gradient

In the upper course, steep gradient helps the river cut downward strongly. Connect gorges with vertical erosion in exams.

Correct answer: B. Erosion on outer bank and deposition on inner bank

Velocity is higher on the outer bank and lower on the inner bank. Remember outer erosion and inner deposition in exams.

Correct answer: A. River cuts through the meander neck and isolates the old loop

When the meander neck is cut, the river takes a straighter course and the old loop becomes a lake. Include both erosion and deposition in exams.

Correct answer: A. A stream suddenly loses gradient and spreads coarse sediment

As a stream exits mountains onto plains, velocity drops and sediment spreads like a fan. Write gradient change as the main cause in exams.

Correct answer: A. Because heavy particles settle first as velocity drops near the bank

During floods, energy drops near the channel edge and coarse particles settle quickly. Link levees with flood deposition in exams.

Correct answer: B. Ultimate lower limit of river downcutting

Base level is the limit below which a river generally cannot erode. In exams, remember sea level as the ultimate base level.

Correct answer: A. Incised meanders or river terraces

Uplift or fall in base level can make a river cut downward again and form terraces. Link rejuvenation with renewed vertical erosion.

Correct answer: B. Dynamic balance among erosion, transport, and deposition

In a graded profile, the river adjusts between energy and load. In exams, understand it as dynamic rather than fixed balance.

Correct answer: C. Desert pavement

Deflation removes fine particles and leaves larger stones on the surface. Link desert pavement with wind erosion in exams.

Correct answer: B. Sand moving near the ground causes stronger abrasion

Wind-blown sand is more effective near the ground and cuts the base. Write it as a result of wind abrasion in exams.

Correct answer: B. Downwind direction

Barchan horns generally extend downwind in the direction of prevailing wind. Use the horns to identify wind direction in exams.

Correct answer: C. Fine dust-like particles deposited by wind

Loess is a wind-deposited fine dust that often forms fertile soil. Link it with aeolian deposition in exams.