Test: Landforms And Their Evolution - UPSC MCQ

1. Youth Stage of Landform - Initial Stage of Development
This is correctly matched. In the youth stage, the landform is in its initial stage of development.

2. Mature Stage of Landform - Peak of Erosional Activities
This is correctly matched. In the mature stage, erosional activities are at their peak, and the landscape is more defined with valleys and hills.

3. Old Stage of Landform - Formation of New Landforms
This is incorrectly matched. The old stage is characterized by reduced erosion and more deposition leading to flatter terrains, not the formation of new landforms.

4. Running Water - Primary Agent in Arid Regions
This is incorrectly matched. Running water is a primary agent in regions with high humidity and heavy rainfall, not in arid regions where wind is more dominant.

Thus, only the first and second pairs are correctly matched, making the answer Option A: Only one pair.

Answer: d.Rills, gullies, valleys, canyons 

Explanation: Valleys start as small rills which develop into gullies, then deeper valleys, and in certain geological settings, they can further evolve into canyons.

Statement-I correctly defines river terraces as surfaces indicating old valley floor or floodplain levels resulting from erosion caused by vertical erosion by the stream into its own depositional floodplain. This aligns with the information provided in the text about river terraces. On the other hand, Statement-II describes alluvial fans as deposits formed when streams carrying coarse load break into low-gradient foot slope plains and deposit materials as broad cone-shaped deposits. Although alluvial fans are discussed in the text, the specific details mentioned in Statement-II are not entirely accurate, as alluvial fans are not necessarily solely about the stream carrying coarse load but rather about the deposition on foot slope plains. Therefore, Statement-II is incorrect in its description of alluvial fans, making the correct answer (C) Statement-I is correct, but Statement-II is incorrect.

1. Incorrect: River terraces are not always formed due to tectonic uplift of land. They can also occur due to receding water after a peak flow, change in hydrological regime due to climatic changes, or sea level changes in case of rivers closer to the sea.

2. Correct: Paired terraces do occur at the same elevation on either side of the river. These terraces are formed when the river downcuts its own floodplain at a uniform rate on both sides.

3. Correct: Unpaired terraces are indeed typical in areas of slow uplift of land or where the water column changes are not uniform along both the banks. This results in terraces forming at different elevations on either side of the river.

Thus, the correct statements are 2 and 3. Therefore, the correct option is Option D: 2 and 3 Only.

1. Statement 1 is correct. During the youth stage of landscape development in running water regimes, streams do indeed have poor integration and flow over original slopes. This stage typically features shallow V-shaped valleys and minimal floodplains.
2. Statement 2 is incorrect. In the mature stage, the stream divides are sharp and not broad and flat. Broad and flat stream divides with marshes, swamps, and lakes are characteristics of the youth stage, not mature.
3. Statement 3 is correct. The old stage of landscape development is indeed characterized by streams meandering freely over vast floodplains, creating features such as natural levees and oxbow lakes. At this stage, the landscape is mostly at or slightly above sea level.
Thus, the correct statements are 1 and 3, making Option C: 1 and 3 Only the correct answer.

Answer: c. Running water

Explanation: In regions with high humidity and heavy rainfall, running water is the primary agent responsible for the erosion and shaping of land surfaces through processes like overland flow and stream erosion.

Statement-I correctly describes the process of valley formation through the progression from small rills to wide valleys. Statement-II also accurately highlights the pattern of erosion in streams with steep gradients, emphasizing erosion concentration at the channel bottom. However, Statement-II does not directly explain the sequence outlined in Statement-I but rather provides additional information on erosion patterns in specific stream conditions. Hence, both statements are correct, but Statement-II does not directly elucidate Statement-I's content, making option (b) the correct choice.

Statement 1: Stalactites are indeed icicle-shaped formations that hang from the ceilings of limestone caves. When carbonated water, rich in dissolved calcium carbonate, seeps through the ceiling of a cave and evaporates, it leaves behind calcium carbonate deposits that form stalactites. This statement is correct.

Statement 2: Stalagmites are formations that rise from the floor of a cave, typically forming directly beneath stalactites. They are created by the dripping of water from the ceiling, which deposits calcium carbonate as it evaporates on the ground. This statement is correct.

Statement 3: While glaciers do experience some melting at their bases, their primary movement is due to the force of gravity acting on the mass of ice, causing it to flow slowly downhill. This statement oversimplifies the process and is not entirely accurate. Therefore, this statement is incorrect.

Thus, the correct answer is Option B: 1 and 2 Only.

1. Peneplain : Incorrect. A peneplain is a nearly level plain formed by extensive stream erosion, not wind erosion.

2. Gorge : Correct. A gorge is a deep valley with very steep to straight sides, often formed by a river.

3. Plunge Pool : Correct. A plunge pool is a deep hole at the base of a waterfall, formed by the impact of water and the rotation of boulders.

4. Canyon : Correct. A canyon is a narrow valley with steep, step-like sides, which is wider at the top than at the bottom, typically formed by a river cutting through horizontal bedded sedimentary rocks.

Thus, three pairs are correctly matched, making Option C the correct answer.

1. Correct - Landforms indeed undergo three stages: youth, mature, and old stages. This is a standard concept in geomorphology.

2. Correct - Running water is considered the primary geomorphic agent in regions with high humidity and heavy rainfall, due to overland flow and linear flow in valleys.

3. Incorrect - Erosional landforms created by running water are predominantly associated with youthful rivers flowing over steep gradients, not mature rivers flowing over gentle gradients. Mature rivers are more associated with deposition rather than erosion.

Thus, statements 1 and 2 are correct, while statement 3 is incorrect. Hence, the correct answer is Option B: 1 and 2 Only.