Landforms — Set 4

Correct Answer: C. Bay

• **Bay** = a recessed coastal body of water that directly connects to a larger main water body, smaller and less enclosed than a gulf. • **Bay of Bengal** — the world's largest bay, covering about 2.17 million km², bounded by India, Sri Lanka, Bangladesh, and Myanmar. • 💡 Wrong-option analysis: Cape: a narrow headland of land jutting into the sea, the opposite — land projecting into water; Strait: a narrow body of water connecting two larger seas, not land; Isthmus: a narrow strip of land connecting two larger landmasses, not water.

Correct Answer: C. Colorado

• **Colorado River** = carved the Grand Canyon over millions of years through the Colorado Plateau, creating one of the world's most spectacular river erosion landforms. • **1.6 km deep, 446 km long** — the dimensions of the Grand Canyon in Arizona, which exposes nearly 2 billion years of Earth's geological history. • 💡 Wrong-option analysis: Amazon: drains South America, forms the world's largest river delta and floodplain, not in USA; Nile: flows through Africa, known for its delta and Nile Valley civilization; Mississippi: drains central USA, known for its delta and floodplains, not the Grand Canyon.

Correct Answer: C. Spit

• **Spit** = a narrow coastal landform extending from shore into the sea, created by longshore drift depositing sand and sediment in a line beyond a headland. • **Chesil Beach, England** — a famous 29 km long spit in Dorset, demonstrating how longshore drift can create substantial depositional features. • 💡 Wrong-option analysis: Sea Arch: formed when wave erosion cuts through a headland, an erosional feature; Sea Cave: forms where waves erode weak rock in a cliff face, an erosional feature; Sea Stack: an isolated pillar of rock left when a sea arch collapses, an erosional feature.

Correct Answer: B. A sharp, narrow mountain ridge

• **Arete** = a thin, knife-like ridge of rock formed when two glaciers erode parallel U-shaped valleys on either side of a mountain, sharpening the dividing ridge. • **Matterhorn, Alps** — the world's most famous arete-shaped peak, its pyramid form resulting from glacial erosion on all sides creating multiple intersecting aretes. • 💡 Wrong-option analysis: A winding river of ice: describes a valley glacier itself, not an erosional landform; A lake formed by melting ice: describes a tarn (in a cirque) or proglacial lake; A large rock moved by ice: describes an erratic, a boulder transported far from its origin by glacial ice.

Correct Answer: B. Ox-bow Lake

• **Ox-bow Lake** = a U-shaped water body formed when a wide meander loop is cut off from the main river channel during flooding, leaving a crescent-shaped lake. • **Loktak Lake, Manipur** — India's largest freshwater lake contains many ox-bow-like features formed by the Manipur River's course changes over time. • 💡 Wrong-option analysis: Glacial Lake: formed in hollows left by retreating glaciers or blocked by moraines; Volcanic Lake: forms in a caldera or crater after volcanic activity; Tectonic Lake: forms in depressions created by faulting or rifting of Earth's crust.

Correct Answer: D. A flat-bottomed basin that temporarily fills with water

• **Playa** = a dry, flat lake bed in an undrained desert basin that periodically fills with water after heavy rain; when water evaporates, it leaves salt or clay layers. • **Sambhar Salt Lake, India** — India's largest inland salt lake in Rajasthan, an example of a playa where evaporation leaves salt deposits used commercially. • 💡 Wrong-option analysis: A narrow pass between mountains: describes a col or mountain pass; A dense oasis: a water-fed vegetation area in a desert, not a dry flat basin; A high sand dune: describes a seif dune or barkhan, not a flat basin feature.

Correct Answer: A. Caldera

• **Caldera** = a large cauldron-like depression formed when a magma chamber empties and the volcanic cone collapses inward, much larger than a typical crater. • **Yellowstone Caldera, USA** — the world's largest supervolcanic caldera, measuring 72 km by 55 km, formed about 640,000 years ago. • 💡 Wrong-option analysis: Atoll: a ring-shaped coral reef enclosing a lagoon, formed by coral growth around a subsiding volcanic island; Delta: a river depositional landform at a river mouth, not volcanic; Cirque: a glacial erosional bowl-shaped hollow carved by glacier action.

Correct Answer: C. Corrasion

• **Corrasion** = mechanical erosion where rocks and sediment carried by a river grind against the riverbed (also called abrasion), deepening and widening the valley. • **4 processes of river erosion** — corrasion (abrasion), hydraulic action, attrition, and corrosion/solution, all working together to shape river valleys. • 💡 Wrong-option analysis: Exfoliation: the peeling off of rock surfaces due to heating and cooling cycles, a type of physical weathering; Carbonation: a chemical weathering process where CO₂ dissolved in water reacts with limestone; Deflation: the removal of loose particles by wind in desert environments.

Correct Answer: A. A sandbar or spit

• **A sandbar or spit** = a tombolo is formed when wave refraction around an island causes sediment deposition in the sheltered water between the island and mainland, creating a narrow land bridge. • **Mont Saint-Michel, France** — a famous tombolo where a tidal causeway of sand connects the island abbey to the mainland, covered by tides twice daily. • 💡 Wrong-option analysis: A coral reef: connects islands through biological growth, not wave-deposited sediment; A bridge built by humans: a man-made structure, not a natural geomorphological landform; A narrow mountain ridge: describes an arete or col, a subaerial erosional feature.

Correct Answer: C. Intermontane Plateau

• **Intermontane Plateau** = the Tibetan Plateau is enclosed by mountain ranges (Himalayas to the south, Kunlun to the north), making it the world's highest and largest such plateau. • **4,500 metres average elevation** — the Tibetan Plateau's average height, earning it the name 'Roof of the World', formed during India-Eurasia continental collision. • 💡 Wrong-option analysis: Piedmont Plateau: found at the foot of mountains, not enclosed by them (e.g., Piedmont Plateau, USA); Continental Plateau: a large, elevated flat area not surrounded by mountains (e.g., Arabian Plateau); Volcanic Plateau: formed by lava flows, not by mountain-building collision (e.g., Deccan Plateau).