Landforms — Set 3

Correct Answer: D. River (Running Water)

• **River (Running Water)** = V-shaped valleys are formed by vertical erosion of fast-flowing rivers in mountain areas, where steep gradients cause rapid downcutting through rock. • **Youthful stage** — the phase of river development associated with V-valley formation, characterized by steep gradients, waterfalls, and rapids. • 💡 Wrong-option analysis: Glacier: creates U-shaped valleys with flat floors and steep sides, not V-shaped; Wind: creates dunes, yardangs, and mushroom rocks in deserts; Underground Water: creates karst features like sinkholes, stalactites, and caves.

Correct Answer: D. Alluvial Fan

• **Alluvial Fan** = a fan-shaped sediment deposit formed where a stream exits a steep mountain canyon onto a flat plain, as sudden velocity drop causes the river to release its load. • **Piedmont plains** — wide plains like those bordering the Himalayas in India, formed by the coalescence of many alluvial fans into continuous bajadas. • 💡 Wrong-option analysis: Water-gap: a notch in a ridge through which a river passes, an erosional feature; Pothole: a cylindrical hole drilled in river bedrock by eddy currents, an erosional feature; Gorge: a deep narrow valley with steep walls, formed by intense river erosion.

Correct Answer: D. Wind

• **Wind** = loess is fine wind-blown silt deposited over vast areas, creating very fertile agricultural land with a distinctive uniform, unstratified structure. • **Yellow River (Huang He)** — flows through the massive Loess Plateau of China, where deposits up to 300 metres thick were carried from Central Asian deserts by wind. • 💡 Wrong-option analysis: Volcanic eruptions: deposit volcanic ash which can be fertile but has a different origin and structure than loess; River floods: deposit alluvium in flood plains, which is layered and water-sorted unlike loess; Glacial retreat: leaves behind glacial till and outwash, not uniform wind-blown silt.

Correct Answer: B. Drumlin

• **Drumlin** = a depositional landform, not erosional — it is an elongated teardrop-shaped hill made of glacial till, with the tapered end pointing in the direction of ice movement. • **Stoss end and Lee end** — the two parts of a drumlin; the stoss end faces the direction of ice flow (blunt), and the lee end is the tapered tail pointing downflow. • 💡 Wrong-option analysis: Cirque: an erosional bowl-shaped basin carved by glacier at the valley head; Hanging Valley: formed by differential erosion between a main glacier and a tributary glacier; Arete: a sharp knife-like ridge formed by erosion of two parallel glaciers.

Correct Answer: C. Lagoon

• **Lagoon** = a shallow body of water separated from a larger ocean by barrier islands or reefs, typically protected from high waves and ocean currents. • **Chilika Lake, India** — Asia's largest coastal lagoon in Odisha, separated from the Bay of Bengal by a narrow strip of land, a Ramsar wetland site. • 💡 Wrong-option analysis: Atoll: a ring-shaped coral reef enclosing a lagoon, the entire structure not just the water body; Estuary: where a river meets the sea with tidal influence, not separated by a sandbar; Fjord: a deep glacially-carved inlet, much deeper and narrower than a lagoon.

Correct Answer: D. Ox-bow Lake

• **Ox-bow Lake** = forms in the old/mature stage when a meander loop is cut off from the main channel during floods, leaving a curved lake behind as the river takes a shorter path. • **Crescent shape** — the characteristic shape of an ox-bow lake, named after the U-shaped collar of an ox, visible from aerial photographs in floodplains. • 💡 Wrong-option analysis: Waterfalls: associated with the youthful stage where rivers cascade over hard rock ledges; Gorges: deep narrow valleys typical of the youthful vigorous river stage; V-shaped valley: the primary landform of the youthful/upper river stage.

Correct Answer: B. Stalactite

• **Stalactite** = an iconic karst feature formed by dissolution of limestone — calcium carbonate-rich water drips from cave ceilings and deposits calcite as it evaporates. • **Karst regions** — named after the Kras Plateau in Slovenia, typically lacking surface drainage because water drains underground through dissolved limestone channels. • 💡 Wrong-option analysis: Mushroom Rock: a wind erosion feature from desert environments; Barkhan: a crescent-shaped sand dune formed by wind, not limestone dissolution; Moraine: a glacial depositional feature of rocks and debris carried by ice.

Correct Answer: B. River erosion

• **River erosion** = a gorge is a narrow valley with steep rocky walls formed where a river cuts through hard rock layers, similar to a canyon but usually smaller and steeper. • **Zanskar Gorge, India** — one of the world's deepest river gorges in Ladakh, where the Zanskar River cuts through the Himalayan ranges. • 💡 Wrong-option analysis: Coastal deposition: creates beaches, spits, and barrier islands, not gorges; Wind erosion: creates yardangs, ventifacts, and mushroom rocks in deserts; Glacial deposition: creates moraines, drumlins, and eskers, not deep river gorges.

Correct Answer: B. Wind

• **Wind** = yardangs are elongated ridges and ventifacts are rocks with smooth flat faces cut by wind-driven sand abrasion in desert environments, indicating prevailing wind direction. • **Yardangs up to 200 metres high** — the scale of large yardangs, found especially in the Sahara Desert and central Asia, showing the power of long-term wind abrasion. • 💡 Wrong-option analysis: Sea Waves: form sea cliffs, sea arches, sea stacks, and wave-cut platforms through hydraulic action; Rivers: form V-shaped valleys, gorges, meanders, and deltas; Glaciers: form U-shaped valleys, cirques, aretes, and hanging valleys.

Correct Answer: D. Bajada

• **Bajada** = a broad slope of alluvial debris at the foot of a mountain range formed by coalescing multiple alluvial fans, typical of dry climates where flash floods transport sediment. • **Himalayan foothills, India** — where numerous streams flowing from the Shivaliks form a continuous bajada (Bhabar zone), a classic example of this landform. • 💡 Wrong-option analysis: Canyon: a deep river-carved valley, an erosional feature not a coalescence of fans; Delta: a fan-shaped deposit at a river mouth where it meets standing water, not at mountain bases; Peneplain: a nearly flat plain from long-term erosion of an entire landscape.