Mass wasting factors: which option lists the controlling factors?

Mass wasting factors: which option lists the controlling factors?

• A. Slope color, wind, and humidity
• B. Plant cover, rainfall, and soil pH
• C. Slope angle, water saturation, and nature of slope material
• D. Latitude, altitude, and vegetation

Answer: (C)

Mass wasting happens when gravity pulls material downslope, and how easily that happens depends on three main factors. The slope angle sets how steep the surface is, so a steeper slope increases the gravitational component that drives motion and makes failure more likely. Water saturation matters because water adds weight and, more importantly, reduces the friction that holds materials together by increasing pore pressure; saturated conditions make it easier for a slip plane to form and for material to slide. The nature of the slope material covers how strong and cohesive the material is and how it behaves under stress—dense, cohesive clay behaves differently from loose, granular sand, and rocks with fractures or joints fail along those planes. Other options mix in factors that don’t directly control the downslope movement. Slope color, wind, and humidity don’t determine whether mass wasting will occur. Plant cover can stabilize slopes to some extent, and rainfall can trigger movement, but these are not the primary controlling factors, and soil pH is not relevant here. Latitude, altitude, and vegetation likewise don’t specify the essential mechanics of slope failure.

Mass wasting happens when gravity pulls material downslope, and how easily that happens depends on three main factors. The slope angle sets how steep the surface is, so a steeper slope increases the gravitational component that drives motion and makes failure more likely. Water saturation matters because water adds weight and, more importantly, reduces the friction that holds materials together by increasing pore pressure; saturated conditions make it easier for a slip plane to form and for material to slide. The nature of the slope material covers how strong and cohesive the material is and how it behaves under stress—dense, cohesive clay behaves differently from loose, granular sand, and rocks with fractures or joints fail along those planes.

Other options mix in factors that don’t directly control the downslope movement. Slope color, wind, and humidity don’t determine whether mass wasting will occur. Plant cover can stabilize slopes to some extent, and rainfall can trigger movement, but these are not the primary controlling factors, and soil pH is not relevant here. Latitude, altitude, and vegetation likewise don’t specify the essential mechanics of slope failure.