Mass movements, erosion, and deposition

On the outer bank, water speed is higher and cutting occurs. In river bends, the outer bank is linked with erosion.

Direct answer: A, deposition. In a meandering river, the inner side of a bend usually has slower water, while the outer side usually has faster water and greater erosion. Step by step: water follows a curved channel; velocity is generally greater near the outer bank; the outer bank is cut, while flow on the inner bank loses energy; sand, silt, and gravel settle there. Option A is correct because settling of transported sediment is deposition. Option B, volcanic eruption, is caused by magma and is unrelated to the ordinary inner bank of a river bend. Option C, earthquake, is sudden movement in Earth’s crust, not the normal process at a bend. Option D, evaporation, is liquid water becoming vapour and does not explain the accumulation of river sediment. The exact local pattern can vary, but this is the standard school-level rule. Memory cue: outer bend cuts, inner bend deposits.

Correct answer: A, an alluvial fan. When a stream carrying sand, gravel, and other sediment leaves a steep mountain valley and reaches flatter land, its speed decreases. Because the water loses carrying power, it deposits the material near the mountain front. The deposits spread outward in a broad, fan-like shape, so the landform is called an alluvial fan. B is wrong because a sea cave is cut into a coastal cliff by waves. C is wrong because a glacial trough is a broad valley carved by moving ice, often with a U-shaped cross-section. D is wrong because a volcanic crater is an opening or depression around a volcano, not a sediment deposit. Memory cue: water leaves a steep slope, slows down, and spreads deposits like a fan.

These agents erode, transport, and deposit materials. In exams, treat rivers, wind, and glaciers as agents.

Gravity is the main force in mass movement, and running water is not always required. This separates it from river erosion.

When soil becomes water-saturated, the bonding between soil particles weakens and the soil mass becomes heavier. On a slope, this can cause the soil to move downhill as a landslide. Soil erosion mainly refers to the removal of particles by agents such as water or wind, whereas this question describes the downslope movement of a large mass of soil. Exam tip: Connect steep slopes, heavy rainfall, and saturated soil with landslide risk.

A delta is formed when a river deposits sediments such as silt and sand near its mouth, so it is a depositional landform. An erosional valley, sea cliff, and gorge are formed mainly by erosion. Exam tip: Landforms created by the accumulation of sediments are generally depositional landforms.

A gorge is a deep, narrow valley formed mainly by vigorous vertical erosion by a river. Therefore, it is an erosional landform. A delta and a floodplain are formed by river deposition, while a sand dune is formed by wind deposition. Exam tip: Deep valleys, gorges, and canyons are generally associated with erosion.

In mass movement, rock, soil, or weathered material moves downslope under the force of gravity. Therefore, steep mountainous slopes commonly experience landslides, rockfalls, and soil creep. Nearly level plains and stable flat plateaus have much less slope, so mass movement is less common there. Exam tip: Gravity is the main driving force of mass movement, while a steep slope increases its likelihood and speed.

When a flowing river carries pebbles, sand, and other sediments from one place to another, the process is called transportation. Erosion is the wearing away and removal of material, whereas deposition occurs when the river loses carrying capacity and lays the material down. Exam tip: wearing away = erosion, carrying = transportation, and laying down = deposition.

In weathering, rocks and other materials break down or decompose at their original location through physical, chemical, or biological processes. Therefore, weathering is correct. Erosion is the closest distractor, but it involves the removal and transport of material by agents such as water, wind, glaciers, or waves. Exam tip: ‘Breakdown in place’ indicates weathering, whereas ‘removal or transport’ indicates erosion.

The rapid downslope movement of water-saturated debris, soil, and rock fragments under gravity is called a debris flow. Since it is the collective downslope transfer of slope material, it is classified as mass movement. Fluvial erosion is caused mainly by flowing river water, whereas gravity is the primary driving force here. Exam tip: When material moves downslope due to gravity, identify it as mass movement.

When the river’s velocity decreases, the silt it carries settles and accumulates on the river bed; this is deposition. Erosion involves the removal and transport of material, whereas this example describes its accumulation. Exam tip: Examples involving the settling or building up of material usually indicate deposition.

Strong wind can pick up loose sand particles and carry them from one place to another. This is wind erosion and transport, especially common in desert regions. River deposition is different because it involves water laying down the material it carries. Exam tip: If particles are removed or blown away by wind, link the process to wind erosion.

A river’s carrying capacity is the largest amount or size of sediment that its flow can transport. When discharge, velocity, or stream energy decreases, the river can no longer keep all of its load moving. The heaviest and largest particles need the greatest force to remain suspended or rolling, so they settle first on the bed. Finer particles can often remain in transport for a longer distance before being deposited.

Option A is correct because reduced flow energy causes heavy particles to lose support and begin deposition. They do not become clouds, light, or invisible; they simply settle where the river’s ability to carry them is insufficient. This process can build bars, floodplains, or other depositional features, depending on the location. The exact order can vary with shape and density, but the general school-level principle is that heavier particles are deposited before finer ones.

Afforestation on slopes helps because plant roots bind soil and loose weathered material. This reduces erosion during rainfall and improves slope stability, lowering the chance of landslides. In contrast, leaving slopes bare or carrying out uncontrolled cutting removes root support and increases landslide risk. Exam tip: Link vegetation cover with slope stability.

Sea waves move sand and other sediments from one place to another along the shoreline. This is called coastal transport; longshore drift is a common example. Weathering breaks down or alters rocks in place, whereas this question describes movement of sand. Exam tip: When material is carried from one location to another, identify it as transport.

The direct answer is A: layers of accumulated material indicate deposition. Deposition occurs when sediment carried by water, wind, ice, or gravity is dropped and builds up. Repeated episodes can place one layer over another, so visible layers are evidence of successive accumulation. Step by step: an agent erodes or collects particles; it transports them; its energy decreases or conditions change; particles settle; later material forms another layer. Option A is correct because layered accumulation is a typical depositional feature. Option B, magnetism, is a physical property or force and does not explain sediment layers. Option C, transpiration, is the release of water vapour from plant leaves and does not create deposited layers. Option D, an earthquake wave, is a vibration travelling through Earth; it may disturb deposits but is not the process that accumulates them. Rivers and wind can both create layered deposits. Memory cue: layer by layer means material was laid down.

In erosion, running water, wind, glaciers, or sea waves cut and carry away rock and soil. This can lower the land surface and produce dissected landforms such as valleys and gullies. Weathering breaks rocks down in place, whereas erosion is mainly responsible for removing the material. Exam tip: choose erosion when the clue is ‘cutting and carrying away’.

Deposition is the process in which sand, silt, pebbles, or debris carried by water, wind, glaciers, or gravity is laid down at a place. Therefore, it adds material to the land surface. Erosion removes material, whereas abrasion and solution help in wearing away or dissolving rocks. Exam tip: remember that deposition adds material, while erosion removes it.

Heavy rainfall fills pore spaces in soil and weathered rock, increasing their weight and reducing friction and cohesion between particles. This can destabilise a slope and trigger mass movements such as landslides or soil creep. Increased vegetation usually helps bind the slope through roots and improves stability. Exam tip: water saturation of a slope after rainfall is a major trigger of mass movement.

The direct answer is A, Transportation. In geography, rivers, wind, glaciers, waves, and gravity act as geomorphic agents. First, weathering or erosion loosens and removes rock, soil, or sediment. Next, the moving agent carries that material away; this carrying stage is called transportation. Finally, when the agent loses energy, the material is laid down, which is deposition. Option A is correct because it exactly means moving removed material from one place to another. Option B, condensation, means water vapour changes into liquid water, so it is a change of state, not the movement of sediment. Option C, precipitation, means rain, snow, or hail falling from the atmosphere. Option D, photosynthesis, is the process by which green plants make food using light, carbon dioxide, and water. Thus only A fits the definition. Remember the sequence: erosion removes, transportation carries, and deposition settles.

Soil creep is the very slow downhill movement of soil caused by gravity. Over a long period, it can make field surfaces uneven or tilted downslope and can gradually lean walls, poles, and fences. It does not instantly level soil because its movement is slow and downslope. Exam tip: Leaning walls or poles on a slope are common indicators of soil creep.

Repeated wave impact breaks, abrades, and removes material from coastal rocks. This is marine erosion, so option A is correct. Delta deposition is the settling of sediments carried mainly by rivers; it is not caused by wave attack on a cliff. Exam tip: If waves are described as cutting or wearing away rocks, identify marine erosion.

Eroded material can be transported and deposited elsewhere. Remember the order as erosion, transportation, and deposition.