Physical Features of India

The Himalayas are young fold mountains formed by plate collision. For exams keep them separate from the ancient plateau.

Glaciers supply water to Himalayan rivers for long periods. For exams remember the glacier and river source link.

Antecedent rivers cut their old courses even after mountain uplift. For exams remember Indus and Brahmaputra gorges.

The direct answer is B: loose sedimentary deposits and rapid erosion. The Shiwalik is the youngest and outermost Himalayan range. It was formed largely from unconsolidated or weakly consolidated sediments such as sand, gravel, clay, and pebbles brought by rivers from the higher Himalaya. Because these materials are loose, water can wash them away easily. Heavy monsoon rain cuts gullies and weakens slopes; when the slope becomes unstable, soil and rock move downward as a landslide. Option A is wrong because an extremely hard granite base generally resists weathering and is not the characteristic reason for Shiwalik instability. Option B is correct because weak material plus strong erosion makes slopes fragile. Option C is wrong: coral limestone is not the defining material of the Shiwalik range, and coral stability does not explain Himalayan landslides. Option D is wrong because black soil and its water retention are soil topics, not the principal geological explanation for this range. Remember: young outer Himalaya plus loose sediments plus monsoon erosion means greater landslide risk.

Dun valleys occur between Shiwalik and Lesser Himalaya. For exams keep Dehradun as a major example.

Coarse porous deposits in Bhabar allow water to sink. For exams distinguish Bhabar from Terai.

After Bhabar the water table rises in Terai and moisture increases. For exams remember the Bhabar Terai sequence.

Himalayan rivers form plains by depositing silt and alluvium. For exams link river deposition with plain formation.

Bhangar is the older alluvial surface of the Northern Plains. It was formed by river deposits in an earlier period and generally lies above the newer floodplain. Kankar, or concentrated calcareous nodules, is commonly found in these older deposits. Thus, the presence of kankar supports the conclusion that the area belongs to the old alluvial formation, not the recently renewed floodplain.

Khadar is the newer alluvium deposited by rivers during relatively recent floods, while Bhangar is older and often contains kankar layers. Therefore option A is correct. The other choices describe a volcanic island, a coral coast, or a different physical origin; none explains kankar in the context of the Indo-Gangetic alluvial plains.

Khadar is the lower, actively flooded part of a river’s floodplain. During floods, the river repeatedly deposits fresh alluvium such as silt and sand there, so it is called an active floodplain. Option B describes Bhangar, which consists of older alluvium and lies relatively higher. Exam tip: Khadar means new alluvium and frequent flooding; Bhangar means old alluvium and relatively higher land.

The word Doab is formed from ideas meaning two and water or river. In physical geography, it identifies the tract of land lying between two rivers, especially where river sediments have accumulated. Such land is commonly alluvial and may be fertile because the rivers deposit fine material over time. Therefore Doab describes a recognizable physical region, not merely an administrative or arbitrary place name.

The Ganga–Yamuna Doab is the familiar example: it is the land between the Ganga and Yamuna rivers. This matches option A because it includes both the position between two rivers and the alluvial character of the land. The alternatives about coral, desert salt, or glacial ice do not express the geographical meaning of Doab.

Brahmaputra brings high silt and water which can shift channels. For exams remember Majuli as a river island.

Heavy deposition in a delta divides the river into distributaries. For exams remember delta and distributary together.

Sundarbans is a mangrove area in a tidal saline delta. For exams remember the tide salinity and mangrove link.

The Peninsular Plateau is an old rocky and relatively stable landmass. For exams remember it as older than the Himalayas.

Many rivers of the Central Highlands flow north and east into the Ganga Yamuna system. For exams study slope and drainage together.

Narmada Valley between Vindhya and Satpura shows a rift valley route. For exams remember this spatial order.

The eastward slope of Deccan makes rivers like Godavari Krishna and Kaveri east flowing. For exams remember slope with river direction.

Deccan Trap is step like land formed from layers of basaltic lava. For exams link Trap with step like landform.

The direct answer is A, shrink-and-swell nature. Black soil is clay-rich. When wet, its clay particles absorb water, expand and retain moisture; when dry, they lose water, contract and produce deep cracks. Thus the two observations—holding water and cracking on drying—are linked by one property, not by two unrelated causes. A is correct. B, biological growth of coral, occurs in suitable marine environments and does not describe soil. C, glacial accumulation, is the deposition of material by ice and cannot explain the characteristic behaviour of black soil. D, tidal influence, is associated with sea-level movement in coastal areas, not ordinary Deccan black soil. The Deccan is a major region of black soil and cotton is a common crop, but the asked property is shrink-and-swell behaviour. Exam cue: wet black soil swells; dry black soil cracks.

Chotanagpur is important for industries due to minerals like coal and iron ore. For exams remember the Jharkhand region.

Meghalaya Plateau appears separated by plains and is considered an extension of the Peninsular Plateau. For exams remember Garo Khasi Jaintia.

Aravalli is among India's very old and eroded mountain ranges. For exams remember it as older than the Himalayas.

Western Ghats lift moist winds causing rainfall and a rain shadow forms on the other side. For exams remember orographic rainfall.

Rivers like Mahanadi Godavari Krishna and Kaveri cut across Eastern Ghats. For exams remember Eastern Ghats as fragmented.