Physical Geography: Geomorphology

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Geomorphology — Key Facts for BPSC Examination

Endogenic Forces (Internal):

Force	Effect	Process
Tectonic movements	Mountain building	Folding, faulting
Volcanic activity	New landforms	Lava flows, volcanic cones
Seismic activity	Earthquakes	Fault rupture

Exogenic Forces (External):

Force	Effect	Process
Weathering	Rock breakdown	Physical, chemical, biological
Erosion	Material removal	Water, wind, ice
Transportation	Material movement	Rivers, glaciers, wind
Deposition	Material accumulation	Deltas, alluvial fans

⚡ BPSC Tip: The distinction between endogenic (building) and exogenic (wearing down) forces is frequently asked — remember that endogenic forces are generally stronger!

---

🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Geomorphology — BPSC Study Guide

Earth’s Internal Structure

Layers by Composition:

Layer	Depth	Composition
Crust	0-35 km	Silicates (SIAL/SIMA)
Mantle	35-2900 km	Iron, magnesium silicates
Outer Core	2900-5150 km	Liquid iron, nickel
Inner Core	5150-6371 km	Solid iron, nickel

Layers by Physical Properties:

Layer	Properties
Lithosphere	Rigid, broken into plates
Asthenosphere	Plastic, convective flow
Mesosphere	Stronger than asthenosphere
Outer core	Liquid, generates magnetic field

Mohorovičić Discontinuity (Moho): Boundary between crust and mantle

Plate Tectonics

Major Plates:

Plate	Type	Major Features
Eurasian	Continental	Europe, Asia, Indian subcontinent
Indo-Australian	Mixed	India, Australia, surrounding ocean
Pacific	Oceanic	Pacific Ocean floor
African	Mixed	Africa, Arabian Peninsula
North American	Continental	North America, Greenland
South American	Mixed	South America
Antarctic	Mixed	Antarctica

Plate Boundaries:

Boundary Type	Features	Example
Divergent	Mid-ocean ridges, seafloor spreading, volcanism	Mid-Atlantic Ridge
Convergent	Subduction zones, deep trenches, volcanic arcs	Himalayas, Andes
Transform	Fault lines, earthquake zones	San Andreas Fault
Collision	Mountain building, no subduction	Himalayas

Evidence for Plate Tectonics:

1. Continental drift (Alfred Wegener, 1912)
2. Seafloor spreading (Harry Hess, 1960s)
3. Paleomagnetic stripes
4. Fossil distribution patterns
5. Climate zone anomalies
6. Earthquake and volcano distribution

Landforms Created by Geomorphic Processes

Fluvial (River) Landforms:

Stage	Landforms
Youth	V-shaped valleys, waterfalls, rapids
Maturity	Meanders, oxbow lakes, natural levees
Old age	Floodplains, deltas, point bars

Erosional vs Depositional Fluvial Features:

Type	Erosional	Depositional
Youth	Gorges, canyons, waterfalls	Alluvial fans (mountain fronts)
Maturity	Meanders, oxbow lakes	Point bars, natural levees
Old age	Cut-off features	Deltas, distributaries

Glacial Landforms:

Type	Features
Erosional	Cirques, U-shaped valleys, aretes, hanging valleys
Depositional	Moraines (lateral, medial, terminal), drumlins, eskers

Wind (Aeolian) Landforms:

Type	Features
Erosional	Mushroom rocks, ventifacts, yardangs
Depositional	Sand dunes (barchan, longitudinal, transverse), loess

Coastal Landforms:

Type	Features
Erosional	Sea cliffs, wave-cut platforms, sea caves, stacks
Depositional	Beaches, spits, bars, tombolos

Weathering Types:

Type	Process	Example
Physical/Frost wedging	Water freezes, expands, splits rock	Mountain regions
Thermal expansion	Temperature changes cause expansion/contraction	Deserts
Chemical/Hydrolysis	Water + CO₂ forms carbonic acid	Feldspar → clay
Chemical/Oxidation	Iron combines with oxygen	Rust-colored rocks
Biological	Plant roots, acids from organisms	Tree roots splitting rocks

⚡ BPSC PYQ: “Explain the theory of plate tectonics with suitable examples” Answer: Earth’s lithosphere is divided into plates that move due to convection currents in the asthenosphere. At divergent boundaries, seafloor spreading occurs; at convergent boundaries, subduction or collision creates mountains and trenches; at transform boundaries, plates slide past each other causing earthquakes.

---

🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Geomorphology — Comprehensive BPSC Notes

Mountain Building (Orogenesis)

Fold Mountains:

Characteristic	Features
Formation	Compression, horizontal crustal shortening
Structure	Anticlines (upward folds), synclines (downward folds)
Examples	Himalayas, Alps, Andes, Rockies

Himalayan Orogeny:

• Collision between Indian and Eurasian plates (50 million years ago)
• Still rising ~1 cm per year
• Contains: Mount Everest (8849m), K2, Kangchenjunga
• Features: Nappe structures, thrust faults, deep gorges

Fault-Block Mountains:

• Due to tension or compression on fractured crust
• Uplifted blocks (horsts) and sunken blocks (grabens)
• Examples: Sierra Nevada (USA), Vosges (France), Black Forest (Germany)

Earthquakes and Volcanoes

Earthquake Properties:

Property	Description	Measurement
Focus	Origin point underground	Depth categories: shallow (<70km), intermediate (70-300km), deep (>300km)
Epicenter	Point on surface directly above focus	Located by triangulation
Seismic waves	P-waves, S-waves, Surface waves	Travel at different speeds

Richter Scale:

• Logarithmic: M = log₁₀(A/A₀)
• Each unit increase = 10× ground motion, ~31× energy
• Modified Mercalli Intensity measures shaking effects

Volcanoes:

Type	Shape	Eruption	Examples
Shield	Flat, broad	Gentle, fluid lava	Mauna Loa (Hawaii)
Composite/Stratovolcano	Steep, conical	Explosive, alternating lava/ash	Mount Fuji, Mount St. Helens
Cinder cone	Small, steep	Single vent, pyroclastic	Paricutin (Mexico)
Caldera	Large basin	Collapse after massive eruption	Crater Lake (Oregon)

Distribution of Volcanoes:

• Pacific Ring of Fire (75% of world’s volcanoes)
• Mediterranean-Himalayan belt
• Mid-Atlantic ridge

Drainage Systems and River Basins

Drainage Patterns:

Pattern	Characteristics	Example
Dendritic	Tree-like, uniform rock	Most rivers
Trellis	Rectangular, folded rocks	Appalachian rivers
Radial	Outward from central high point	Mount Vesuvius rivers
Centripetal	Inward to central basin	Inland drainage basins
Deranged	Random, youthful topography	Glaciated areas

River Basin Morphology:

Zone	Features
Upper course	Steep gradient, vertical erosion, V-shaped valleys
Middle course	Mixed erosion/deposition, meandering begins
Lower course	Gentle gradient, deposition dominates, floodplains

Delta Formation:

• Conditions: Strong deposition, weak tides/currents, subsiding coast
• Types: Arcuate (Nile), Bird’s foot (Mississippi), Estuarine (Seine)

Applications and Human Geography

Geomorphology and Human Activity:

Issue	Consideration
Settlements	Avoid earthquake zones, volcanic hazard areas, floodplains
Agriculture	Alluvial soils, terracing for slope cultivation
Transportation	Road routing around steep terrain
Mining	Resource extraction from geological formations

Bihar-specific Geomorphology:

• Part of the Indo-Gangetic Plain
• Alluvial deposits from Himalayan rivers
• Flood-prone due to multiple river systems (Ganga, Kosi, Gandak)
• Seismic vulnerability (Zone III-IV)

Important Concepts for BPSC:

1. Isostasy: Equilibrium of crust floating on mantle (post-glacial rebound)
2. Wilson Cycle: Opening and closing of ocean basins
3. Epeirogenic movements: Continental uplift/subsidence without deformation

⚡ BPSC Strategy: Map-based questions frequently combine geomorphology with Indian geography. Practice identifying mountain ranges, plate boundaries, and major river systems on blank maps.

⚡ Common BPSC Questions:

1. “Discuss the theory of plate tectonics and its supporting evidence” (10 marks)
2. “Explain the landforms produced by river erosion and deposition” (10 marks)
3. “Describe the distribution of earthquakes and volcanoes worldwide” (8 marks)
4. “Discuss the formation of the Himalayas and its significance” (15 marks)

⚡ Map Work: Be able to locate and describe: Himalayas, Indo-Gangetic Plain, Thar Desert, Western Ghats, Eastern Ghats, Deccan Plateau, major rivers (Ganga, Brahmaputra, Indus, Mahanadi, Godavari, Krishna, Kaveri)

---

Content adapted based on your selected roadmap duration. Switch tiers using the selector above.