Himalayas, Plains, Plateaus, Coasts & Islands (Extreme UPSC Difficulty)

A comprehensive set of flashcards on Indian geography covering the Himalayas, plains, plateaus, coasts, and islands, structured in a question and answer format for effective exam preparation.

Why is the origin of the Himalayas considered one of the most complex tectonic events?

It involves multiple uplift phases, convergence of continental plates, sediment accretion from Tethys, and successive folding episodes from Eocene to Pliocene.

How do the Himalayas defy the classic geosyncline theory in parts?

Except Kashmir, most of the ranges emerged from marginal blocks of Indian shield, not a unified geosyncline.

What tectonic evidence supports the Himalayan rise as ongoing?

The northward movement of the Indian plate and active seismic zones along HFF and MCT show continuing uplift.

How do ophiolites in Ladakh and Zaskar testify to Himalayan orogeny?

They are oceanic crust remnants thrust onto continental crust during subduction.

Why are intermontane basins like Kathmandu and Dun valleys geologically significant?

They represent synclinal depressions formed due to folding and bounded by thrusts.

Why are the Trans-Himalayas geologically older than the Greater Himalayas?

They contain marine Tethys sediments and crystalline intrusions from initial tectonic collisions.

What makes the Main Central Thrust (MCT) a key structural marker?

It separates crystalline rocks of the Greater Himalayas from metamorphosed Lesser Himalayas, indicating tectonic boundary.

How do Shiwaliks represent evidence of Himalayan denudation?

They consist of thick boulder conglomerates and molasse sediments derived from higher ranges.

Why are the Lesser Himalayas more prone to landslides?

They consist of metamorphic rocks like slate and quartzite and are tectonically compressed.

What makes the Himalayan Front Fault (HFF) the most active seismic line?

It marks the southern thrust of Himalayan orogeny where intense tectonic stress accumulates.

Why are syntaxial bends considered geological anomalies?

They exhibit sharp knee-bend folds in rock strata due to intense compressive pivoting at Indus and Brahmaputra gorges.

How do Karewas in Kashmir aid in understanding paleoclimates?

They are lacustrine deposits indicating glacial-lake phases and are agriculturally rich in saffron orchards.

Why is the Central Himalayas geomorphologically unique?

It hosts the world’s highest peaks formed by intense uplift along the Main Central Thrust.

Why is the Eastern Himalayas termed a biodiversity hotspot?

Rapid elevation change, monsoon interception, and biogeographic transitions create diverse niches.

How do Duns like Dehra Dun reflect Himalayan geomorphology?

They are synclinal valleys formed between the Lesser Himalayas and Shiwaliks due to compressive folding.

Why is the Indo-Gangetic Plain considered a foreland basin?

It formed due to downward flexing of the Indian plate under the weight of the rising Himalayas.

How do the Bhabar and Terai belts influence regional hydrology?

Bhabar absorbs river water into porous sediments; Terai sees water re-emerge, creating swamps.

Why is the Khadar-Bangar distinction significant for agriculture?

Khadar is fertile new alluvium; Bangar is older, less fertile, often with kankar nodules.

Why does the Ganga plain experience frequent avulsion and channel migration?

Low gradient, high sediment load, and tectonic tilting foster instability.

What role do mega fans play in Indo-Gangetic plain dynamics?

They are large depositional spreads formed by Himalayan rivers changing courses over time.

Why is the Deccan Trap geologically referred to as a flood basalt province?

It consists of layered basalt sheets formed by massive volcanic outflows during late Cretaceous.

How do the Vindhyas differ from Satpuras structurally?

Vindhyas are formed by sedimentation; Satpuras by faulted uplift and folding.

Why is the Malwa Plateau a dissected volcanic feature?

Erosion and uplift broke the flat Deccan lava surface into smaller tablelands.

What makes the Chota Nagpur plateau mineral-rich?

It exposes Archaean crystalline rocks with high metallic mineral concentration.

How does the Maikal range mark a transition zone?

It connects Satpura and Chhota Nagpur plateaus, influencing drainage and biodiversity.

Why are the Western Ghats not considered a true mountain range?

They are an escarpment formed by faulting along the plateau edge.

How do the Ghats influence orographic rainfall distribution?

They intercept southwest monsoon winds, causing heavy rainfall on windward side and rain-shadow on leeward.

Why is the Eastern Ghat more discontinuous than the Western Ghat?

They have been eroded by river systems flowing into the Bay of Bengal.

Why is the Nilgiri Hills a triple junction?

It connects the Western Ghats, Eastern Ghats, and southern hill chains.

Why is the Palghat Gap geostrategically important?

It is a natural pass that enables road and rail connectivity between Kerala and Tamil Nadu.

Why are the Western Coastal Plains considered emergent coasts?

They show marine erosional features and narrowness due to recent uplift.

What makes the Eastern Coastal Plains depositional in nature?

They are formed by river deltas with wider expanses and marshy zones.

Why are tidal creeks and estuaries more prominent on the west coast?

Because of submerged features, narrow shelf and strong tidal activity.

Why is the Krishna-Godavari delta region fertile yet cyclone-prone?

It has soft sediments ideal for agriculture but lies on funnel-shaped coast facing Bay of Bengal.

How does littoral drift shape Indian coastal morphology?

It moves sediments along shorelines, forming spits, bars and altering river mouths.

Why is the Thar Desert expanding eastward?

Overgrazing, wind erosion, and monsoon failure promote desertification.

How do ephemeral rivers affect Thar desert geomorphology?

They cause flash flooding, channel shifting, and local recharge.

What evidence shows that Thar was once a semi-arid savanna?

Paleoclimatic data and river paleo-channels suggest denser vegetation in Holocene.

Why does the Indira Gandhi Canal face siltation and seepage?

Arid soil lacks vegetation cover, causing erosion and poor lining.

Why are Bagar and Rohi zones important to desert ecology?

Bagar has stabilized dunes; Rohi has saline flats with occasional grazing.

Why are the Andaman and Nicobar Islands geologically active?

They lie along the subduction zone of the Indo-Burma plate boundary.

Why is the Ten Degree Channel crucial for navigation?

It separates Andaman and Nicobar groups, serving as a maritime passage.

How are coral atolls like Minicoy different from volcanic islands?

Atolls are ring-shaped structures built on submerged volcanoes with central lagoons.

Why is the Barren Island volcanically significant?

It is India’s only active volcano, part of the Sunda Arc system.

Why do the Lakshadweep islands face ecological pressure?

High population density, tourism, coral bleaching, and limited groundwater threaten sustainability.

Why is the Himalayan rivers' antecedent nature considered geomorphically rare?

They predate the Himalayan uplift and cut across ranges via deep gorges.

How does the Chambal badland topography challenge land-use planning?

Severe erosion, steep ravines, and infertility hinder cultivation and infrastructure.

What makes the Mahadeo Hills a significant orographic divide?

They mark the boundary between Narmada and Son river basins in central India.

Why is the Sunderban delta ecologically and strategically sensitive?

It is a UNESCO site with mangroves and tiger habitat, prone to cyclones and sea-level rise.

How does tectonic tilting influence the eastward flow of Indian rivers?

Slight eastward tilt of peninsular block directs most rivers into the Bay of Bengal.