Landforms — Set 2

Correct Answer: A. Meanders

• **Meanders** = loop-like bends in a river's course that develop on gentle slopes through erosion on the outer bank and deposition on the inner bank. • **Ox-bow lake** — the lake formed when a meander loop is completely cut off from the main river channel, a feature of the river's old age stage. • 💡 Wrong-option analysis: Levees: raised river banks formed by silt deposition during floods; Gorges: deep narrow valleys with steep walls, formed by vertical river erosion; Cataracts: large powerful waterfalls or rapids, an erosional feature.

Correct Answer: C. Arid and semi-arid regions

• **Arid and semi-arid regions** = inselbergs are isolated, steep-sided hills of resistant rock rising abruptly from a surrounding plain, remnants of extensive erosion in dry climates. • **Ayers Rock (Uluru)** — one of the world's most famous inselbergs in Australia, a 348-metre-high sandstone rock rising from the desert plain. • 💡 Wrong-option analysis: Tropical rainforests: support lush vegetation, not the dry exposed rock terrain required for inselberg formation; Deep ocean floors: host seamounts and mid-ocean ridges, not inselbergs; Glacial plains: characterized by drumlins, moraines, and eskers, not isolated rock outcrops.

Correct Answer: C. Stalactite

• **Stalactite** = an icicle-like mineral formation hanging from cave ceilings, built up by calcium carbonate-rich water that drips and evaporates, leaving calcite deposits. • **Stalagmite** — the corresponding formation rising from the cave floor; when stalactite and stalagmite meet, they form a column. • 💡 Wrong-option analysis: Sinkhole: an erosional collapse feature, not depositional; Polje: a large flat-floored depression in karst, formed by dissolution/erosion; Lapies: grooved rock surface formed by dissolution of limestone, an erosional feature.

Correct Answer: C. Wind

• **Wind** = saltation is the process where sand grains are lifted and bounce along the ground surface, transporting sand to eventually form dunes, a key desert geomorphology process. • **70-80%** — the estimated proportion of sand transported by saltation in desert environments, making it the dominant mode of wind sediment transport. • 💡 Wrong-option analysis: Biotic factors: plant roots, burrowing animals, contribute to soil mixing, not saltation; Ocean currents: transport sediment in water via suspension and traction, not saltation; Glaciers: transport sediment by plucking and abrasion, not by bouncing particles.

Correct Answer: A. A deep glacial trough submerged by the sea

• **Fjord** = a long, narrow inlet with steep sides created by a glacier that has retreated, leaving a U-shaped valley that was subsequently flooded by rising sea levels. • **Sognefjord, Norway** — the world's deepest fjord at 1,308 metres, and the world's longest at 205 km, exemplifying this glacial landform. • 💡 Wrong-option analysis: A steep mountain peak in the desert: describes a yardang or rocky pinnacle, not a fjord; A volcanic crater filled with water: describes a crater lake or caldera lake; A seasonal river in a limestone region: describes a stream in karst topography.

Correct Answer: B. Mesa

• **Mesa** = an isolated, flat-topped hill with steep sides, from the Spanish word for 'table', larger than a butte but smaller than a plateau, typically formed by erosion in arid climates. • **Mesa Verde, USA** — famous mesa in Colorado, site of ancient cliff dwellings, demonstrating the characteristic flat top and steep sides of this landform. • 💡 Wrong-option analysis: Valley: a low area between hills or mountains, the opposite of an elevated flat-top feature; Ridge: a long narrow elevated landform, not flat-topped; Moraine: a glacial depositional landform made of debris, not an erosional flat-topped hill.

Correct Answer: A. A bowl-shaped erosional depression

• **Cirque** = an amphitheater-like, bowl-shaped basin carved into a mountainside by glacier erosion, found at the head of a glacial valley. • **Tarn lake** — the lake that often forms in a cirque when ice melts, filling the bowl-shaped depression with water. • 💡 Wrong-option analysis: A long ridge of sand: describes a sand bar or spit, coastal depositional features; A deep crack in the ice: describes a crevasse, a feature within a glacier itself; A delta formed by melting ice: describes outwash plain deposits, not an erosional bowl.

Correct Answer: B. It is formed by the erosion of a young river

• **Formed by erosion of a young river** = V-shaped valleys are created by vertical downcutting of fast-flowing rivers in their youthful stage on steep gradients. • **Himalayan gorges** — some of the world's deepest V-shaped valleys, where rivers like the Indus and Kali Gandaki cut deeply through the mountains. • 💡 Wrong-option analysis: Found only on the ocean floor: V-shapes exist on land in mountainous river regions; Formed by glacial action: glaciers create U-shaped valleys with flat wide bottoms; Wide, flat floor: characteristic of U-shaped glacial valleys, not young river V-valleys.

Correct Answer: B. Isthmus

• **Isthmus** = a narrow neck of land with sea on either side, forming a link between two larger landmasses, contrasted with a strait which is a narrow body of water. • **Isthmus of Panama** — the classic example connecting North and South America, through which the Panama Canal was built in 1914. • 💡 Wrong-option analysis: Peninsula: a piece of land almost surrounded by water on three sides but still connected to the mainland; Lagoon: a shallow body of water separated from the ocean by sandbars or reefs; Strait: a narrow body of water connecting two larger seas, the opposite of an isthmus.

Correct Answer: D. Extensive and prolonged erosion

• **Extensive and prolonged erosion** = peneplains are low-relief plains representing the final stage of the erosion cycle, where mountains and hills are worn down to a nearly level surface. • **Monadnock** — an isolated resistant hill left standing on a peneplain, the last remnant of pre-existing terrain (named after Mount Monadnock in New Hampshire, USA). • 💡 Wrong-option analysis: Rapid glacial deposition: creates outwash plains and till plains, not peneplains; Sudden tectonic uplift: elevates land to create plateaus and mountains, opposite of peneplain formation; Long-term volcanic activity: creates volcanic plateaus and lava plains, not peneplains from erosion.