UPSC Static Quiz – Geography : 7 November 2024

Solution: d)

Deposition marks the end of the erosion process and occurs when the energy of the transporting agent (such as wind, water, or ice) diminishes to a point where it can no longer hold or move the sediment. This leads to the settling and accumulation of sediment in areas like riverbeds, lakes, coastlines, and valleys. This concept is essential in understanding sedimentary landscapes and features such as deltas, sand dunes, and alluvial fans, where sediment deposited over time creates new landforms.

Solution: c)

The transition from a V-shaped to a U-shaped valley typically occurs as the river reaches maturity, not during the youthful stage, making statement 1 incorrect.

Statement 2 is also incorrect because the transition to a U-shaped valley is primarily due to lateral erosion, not vertical erosion, which widens the valley floor rather than deepening it.

Statement 3 is correct; as the river matures, lateral erosion becomes more prominent, causing the valley walls to recede and the valley to broaden into a U shape.

Statement 4 is incorrect because U-shaped valleys, once formed, do not revert to V-shaped profiles.

The U-shaped profile is common in mature rivers and glacial valleys where lateral erosion reshapes the valley, forming a broad base with a gentle, concave slope.

Solution: b)

Statement 2 is correct as hailstones form in layers of clear and cloudy ice through the freezing of super-cooled droplets within strong updrafts.

Statement 3 is also correct; hailstones can indeed be much larger than sleet, with sizes ranging from a pea to larger than a grapefruit.

Statement 1 is incorrect because hailstones require specific conditions, including strong thunderstorms with updrafts and are not common in mild weather conditions.

Solution: b)

The Indo-Gangetic plains have several oxbow lakes, especially to the north of the present Ganga River course, resulting from the southward shifting of the river over time, making statement 1 correct.

These oxbow lakes provide significant evidence of past river courses and meandering patterns, confirming statement 3 as correct.

However, statement 2 is incorrect, as the formation of oxbow lakes in the plains is due to fluvial processes—particularly river meandering and lateral shifting—rather than glacial activity.

The presence of oxbow lakes helps geologists trace historical patterns of river movement and changes in the river’s dynamics over time.

Solution: c)

Snow generally forms in sub-freezing temperatures and often accompanies high, thin cirrus clouds, which are typical in colder atmospheric conditions. When the temperature is below freezing, water vapor directly crystallizes into ice, forming snowflakes. These ice crystals often fall as snow if the air near the surface is also cold, but they may partially melt if they pass through warmer layers, sometimes resulting in mixed precipitation. Snow can fall even at slightly above-freezing temperatures if rapid cooling around the flakes prevents full melting. This cooling is achieved through immediate evaporation, which temporarily cools the air around the snowflakes, allowing them to reach the ground as snow.