(a)State the difference between erosion and mass movement. (b)List four agents responsible for modifying landforms. (c)Outline three factors that influence ...

(a) Difference between erosion and mass movement

Erosion is the wearing away and removal of weathered rock and soil from one place and its transport to another by a moving agent such as running water, wind, ice or waves. It always involves a transporting medium.

Mass movement (mass wasting) is the down-slope movement of rock waste, soil and debris under the direct pull of gravity, without a transporting agent like water or wind. Examples include landslides, rock falls, soil creep and mudflows.

In short, erosion needs an agent to carry material away, while mass movement is driven mainly by gravity acting on material on a slope.

(b) Four agents responsible for modifying landforms

• Running water (rivers).
• Wind.
• Moving ice (glaciers).
• Sea waves (marine action).
• (Also gravity/mass movement and underground water.)

(c) Three factors that influence mass movement

• Gradient/steepness of slope: the steeper the slope, the greater and faster the movement.
• Water (moisture) content: water adds weight and lubricates material, making it move more easily; heavy rain triggers landslides and mudflows.
• Nature of the material and rock structure: loose, weak or unconsolidated material moves more readily; the dip of rock beds toward the slope encourages sliding.
• Vegetation cover: plant roots bind the soil and reduce movement; bare slopes move more easily.
• Earth tremors/vibrations and human activity (e.g. undercutting slopes) can also trigger movement.