This page consolidates all the important theories, models, books, scholars and key concepts across the entire Geography syllabus. Use it as a one-stop revision sheet for UGC NET, WB SET, and other competitive examinations.
1. Geomorphology
Origin of the Earth & Earth’s Crust
Gaseous Hypothesis
Immanuel Kant
Nebular Hypothesis
Laplace
Planetesimal Hypothesis
Chamberlin & Moulton
Tidal Hypothesis
James Jeans & Jeffreys
Binary Star Hypothesis
Russell
Big Bang Theory
Georges Lemaître
Tetrahedron Theory
Lowthian Green
Continental Drift Hypothesis
F. B. Taylor
Geo-Syncline Theory
Kober
Thermal Contraction Theory
Jeffreys
Radioactive Theory / Thermal Cycle Theory
Joly
Sliding Continent Theory
R. A. Daly
Elastic Rebound Theory
H. F. Reid
Panplain Concept
C. H. Crickmay
Primarrumpf
Walther Penck
Pleistocene Glaciation Evidence
Louis Agassiz
Theories & Models of Landscape Development
Geographical (Normal) Cycle of Erosion
W. M. Davis (1899)
Landscape evolves through Youth → Maturity → Old Age stages ending in a peneplain.
Penck’s Model of Slope Development
Walther Penck
Landscape shaped by the ratio of uplift to erosion — Aufsteigende, Gleichförmige, Absteigende Entwicklung.
Parallel Retreat of Slopes
L. C. King
Slopes retreat parallel to themselves forming pediplains (dominant in arid/semi-arid).
Dynamic Equilibrium
J. T. Hack (1960)
Landscape maintains a balance between erosional and tectonic forces.
Plate Tectonics
Hess, Wilson, Morgan
Earth’s lithosphere divided into moving plates; explains volcanism, earthquakes, mountain building.
Continental Drift
Alfred Wegener (1912)
All continents were once joined as Pangaea; moved apart over geological time.
Sea-Floor Spreading
Harry Hess (1962)
New oceanic crust forms at mid-ocean ridges and spreads outward.
Wilson Cycle
J. Tuzo Wilson
Cyclic opening and closing of ocean basins.
Isostasy — Pratt’s Hypothesis
J. H. Pratt
Crustal columns of equal depth but varying density; lighter columns stand higher.
Isostasy — Airy’s Hypothesis
G. B. Airy
Crustal columns of equal density but varying depth; mountains have deep roots.
Convection Current Theory
Arthur Holmes
Convection currents in the mantle drive plate movements.
Hypsometric Integral
Strahler
Ratio describing how much of a basin has been eroded; values near 0 = old, near 1 = young.
Horton’s Laws of Drainage
R. E. Horton
Laws of stream number, stream length, and drainage area in fluvial basins.
Strahler’s Stream Ordering
A. N. Strahler
Hierarchical ordering of streams in a drainage network.
Key Concepts
Peneplain (Davis), Pediplain (King), Panplain (Crickmay), Etchplain
Primarrumpf (Penck)
Monadnock, Inselberg, Bornhardt
Base level of erosion (local and ultimate)
Rejuvenation: Knickpoint, River terraces, Incised meanders
Superimposed and Antecedent drainage
Hydraulic geometry (Leopold & Maddock)
Thalweg, Sinuosity Index
Term “Plate” : First used by J. T. WilsonTerm “Isostasy” : First used by C. E. Dutton
2. Climatology
Theories & Models
Three-Cell Model
Hadley, Ferrel, Rossby
Global atmospheric circulation in three latitudinal cells per hemisphere.
Polar Front Theory (Cyclone Model)
Bjerknes & Solberg (1922)
Mid-latitude cyclones form along the boundary (front) between polar and tropical air masses.
Bergeron–Findeisen Process
Bergeron (1935)
Precipitation forms when ice crystals grow at the expense of supercooled water droplets.
Milankovitch Cycles
Milutin Milankovitch
Earth’s orbital variations (eccentricity, obliquity, precession) cause long-term climate change.
Walker Circulation & ENSO
Sir Gilbert Walker
East–west atmospheric circulation over the tropical Pacific; linked to El Niño / La Niña.
Rossby Waves
Carl-Gustaf Rossby
Large-scale planetary waves in the upper-atmosphere westerlies.
Köppen Climate Classification
Wladimir Köppen
Climate classified using temperature and precipitation into A, B, C, D, E groups.
Thornthwaite Climate Classification
C. W. Thornthwaite
Climate classified based on potential evapotranspiration and moisture index.
Adiabatic Lapse Rate
—
Dry ALR ≈ 9.8°C/km; Saturated ALR ≈ 5–6°C/km.
Environmental Lapse Rate (ELR)
—
Average observed rate ≈ 6.5°C/km.
Key Concepts
Inversion of temperature, Chinook / Foehn winds
Coriolis force, Geostrophic wind, Gradient wind
ITCZ, Jet Streams, Monsoon mechanism
Cyclogenesis (tropical and extra-tropical)
Blocking anticyclone, Indian Ocean Dipole (IOD)
Greenhouse effect, Albedo, Radiation budget
3. Oceanography
Theories & Models
Thermohaline Circulation
—
Global ocean “conveyor belt” driven by differences in temperature and salinity.
Ekman Spiral & Transport
V. W. Ekman
Wind-driven surface water moves at 45° to wind; net transport is 90° to wind direction.
Rule of Constant Proportions
Dittmar (1884)
Relative proportions of major dissolved salts remain constant across oceans.
Sverdrup Balance
H. Sverdrup
Relates wind stress curl to meridional ocean transport.
CaCO₃ Compensation Depth (CCD)
—
Depth (~4,000–4,500 m) below which calcium carbonate dissolves faster than it accumulates.
Theories of Tides
Equilibrium Theory
Isaac Newton
Progressive Wave Theory
William Whewell
Canal Theory
G. B. Airy
Dynamical Theory
Laplace
Stationary Wave Theory
R. A. Harris
Key Concepts
T-S diagram, Water masses
Tides: Spring, Neap, Amphidromic points, Cotidal lines
Wave parameters: wavelength, wave base (= ½ wavelength), wave refraction
Ocean floor relief: Continental shelf, Abyssal plain, Mid-oceanic ridges, Trenches
Coral reefs: Darwin’s Paradox, Zooxanthellae
Tsunami mechanics, Upwelling and downwelling
4. Biogeography & Environment
Theories & Models
Theory of Island Biogeography
MacArthur & Wilson (1967)
Species richness on islands determined by rates of immigration and extinction.
Ecological Succession
F. E. Clements
Nudation → Invasion → Competition → Reaction → Stabilisation (Climax community).
Gaia Hypothesis
James Lovelock
Earth’s biosphere functions as a self-regulating system.
Ecosystem Concept
A. G. Tansley (1935)
Organisms and their abiotic environment form an integrated system.
Trophic Levels & Biomass Pyramid
Elton, Lindeman
Energy transfer (~10%) across successive trophic levels.
Key Concepts
Biomes: Tundra, Taiga, Tropical Rainforest, Savanna, Desert, Mediterranean
Biodiversity hotspots (Norman Myers)
Nitrogen cycle, Carbon cycle, Hydrological cycle
COP summits, UNFCCC, Kyoto Protocol, Paris Agreement
EIA (Environmental Impact Assessment)
Deep Ecology vs Shallow Ecology
Ozone depletion: Montreal Protocol
Net Zero targets
5. Population & Settlement Geography
Theories & Models
Demographic Transition Model (DTM)
Warren Thompson, Frank Notestein
Population change through 4–5 stages from high birth/death to low birth/death rates.
Malthusian Theory
Thomas Malthus (1798)
Population grows geometrically; food supply grows arithmetically → famine/checks.
Boserupian Theory
Ester Boserup
Population pressure drives agricultural innovation (inverse of Malthus).
Ravenstein’s Laws of Migration
E. G. Ravenstein (1885)
Most migrants move short distances; each current produces a counter-current.
Lee’s Push-Pull Model
Everett Lee (1966)
Migration driven by push factors (origin), pull factors (destination), intervening obstacles.
Harris–Todaro Model
Harris & Todaro
Rural–urban migration driven by expected urban wage differentials.
Lewis Model
W. Arthur Lewis
Dual-sector model: surplus labour moves from subsistence to capitalist sector.
Zelinsky’s Mobility Transition
Wilbur Zelinsky
Migration patterns change with stages of demographic transition.
Rank-Size Rule
G. K. Zipf
City population is inversely proportional to its rank.
Primate City
Mark Jefferson
The largest city is disproportionately larger than the second city.
Concentric Zone Model
E. W. Burgess (1925)
City grows outward in concentric rings from the CBD.
Sector Model
Homer Hoyt (1939)
Urban growth follows wedge-shaped sectors along transport routes.
Multiple Nuclei Model
Harris & Ullman (1945)
City develops around multiple centres, not just one CBD.
Central Place Theory
Walter Christaller (1933)
Settlements arranged hierarchically based on market (k=3), transport (k=4), administrative (k=7) principles.
Bylund’s Colonisation Theory
Erik Bylund
Rural settlement expansion through “clone” and “daughter” colonisation.
Mumford’s Theory of Town Origin
Lewis Mumford
Social evolution: Eotechnic → Paleotechnic → Neotechnic → Biotechnic.
Urban Economic Base Theory
—
Cities grow by expanding their “basic” (export) sector relative to “non-basic” (local) sector.
Fused Growth Theory
Garrison
Rank-Size Rule (Initial idea)
Felix Auerbach (1913)
First to observe the relationship between city rank and size.
Key Concepts
Fertility: CBR, TFR, GRR, NRR
Mortality: CDR, IMR, Life expectancy
Sex ratio, Dependency ratio
Census methods: de facto vs de jure
Ecumene and non-ecumene
Rural–urban fringe, Exurb, Ethnoburb
Nearest Neighbour Analysis (settlement pattern)
Term “Umland” : First used by Andre Allix
6. Economic Geography & Regional Development
Theories & Models
Von Thünen’s Agricultural Location
J. H. von Thünen (1826)
Concentric rings of land use around a central market based on transport cost and rent.
Weber’s Industrial Location
Alfred Weber (1909)
Industry locates at point of least transport cost; Locational Triangle.
Lösch’s Market Area Theory
August Lösch
Hexagonal market areas maximising profit rather than minimising cost.
Rostow’s Stages of Growth
W. W. Rostow (1960)
Economic growth in 5 stages: Traditional → Preconditions → Take-off → Drive to Maturity → High Mass Consumption.
Dependency Theory
A. G. Frank, Paul Baran
Underdevelopment of periphery caused by exploitation from core nations.
Core-Periphery Model
John Friedmann
Spatial inequality: Core regions dominate while periphery remains underdeveloped.
Growth Pole Theory
François Perroux
Development radiates from key industrial centres (“growth poles”).
Cumulative Causation
Gunnar Myrdal
Initial advantage leads to cumulative growth (spread effects vs backwash effects).
Hirschman’s Unbalanced Growth
Albert Hirschman
Deliberate investment in strategic sectors creates forward/backward linkages. Trickling down vs polarization effects.
Gravity Model
—
Interaction between two places is proportional to their sizes and inversely proportional to distance.
Ullman’s Spatial Interaction
Edward Ullman
Three bases: Complementarity, Intervening Opportunity, Transferability.
Fordism / Post-Fordism
—
Mass production (Fordism) vs flexible specialisation (Post-Fordism).
Market Competition Theory
Fetter & Hotelling
Least Cost Theory
E. M. Hoover
Maximum Profit Theory
August Losch / D. M. Smith
Key Concepts
Basic vs Non-basic activities
Agglomeration economies, Footloose industries
Quaternary and Quinary sectors
WTO, ASEAN, OPEC
Economic integration and globalisation
Smart Cities Mission (India)
7. Social, Cultural & Political Geography
Theories & Models
Heartland Theory
Halford Mackinder (1904)
Who controls East Europe commands the Heartland → commands the World Island → commands the world.
Rimland Theory
Nicholas Spykman (1944)
The coastal “Rimland” is the key to world power, not the Heartland.
Sea Power Concept
A. T. Mahan
Emphasizes naval dominance for global hegemony.
Air Power Theory
Seversky
Highlights the strategic importance of air superiority.
Heart of Heartland Concept
David Hooson
Refinement of Mackinder’s Heartland focused on internal resource nodes.
Geo-Strategic Concept
Saul Cohen
Division of the world into geostrategic and geopolitical regions.
Geopolitical Concept
Karl Haushofer
Influence of geography on state policy and expansion.
Lebensraum (Living Space)
Friedrich Ratzel
States need expanding territory to sustain growing populations (influenced geopolitics).
Unified Field Theory of Political Geography
S. B. Jones
Political territory develops through: Idea → Decision → Movement → Field.
Cultural Landscape
Carl O. Sauer
Landscapes are shaped by human cultural imprint on the natural environment.
Cultural Ecology
Julian Steward
Study of how cultures adapt to their environment.
Social Area Analysis
Shevky & Bell
Urban areas differentiated by social rank, urbanisation, and segregation.
Key Concepts
Culture trait, Culture complex, Culture realm, Culture hearth
Acculturation, Assimilation, Syncretism
Cultural convergence vs divergence
Boundary types: Antecedent, Subsequent, Superimposed, Relict
Buffer zones, Frontiers vs Boundaries
Gerrymandering
Scheduled Tribes and Castes distribution in India
Language families: Indo-Aryan, Dravidian, Austro-Asiatic, Sino-Tibetan
Religion-based demography
8. Geographical Thought & Philosophy
Theories & Paradigms
Environmental Determinism
Ratzel, Semple, Huntington
Physical environment controls human activity and cultural development.
Possibilism
Vidal de la Blache
Environment offers possibilities; humans choose based on culture (genres de vie ).
Neo-Determinism / Stop-and-Go Determinism
Griffith Taylor
Nature sets limits; within those, humans have choice.
Regional Geography (Chorology)
Hettner, Hartshorne
Geography as the study of areal differentiation.
Quantitative Revolution
Schaefer, Berry, Bunge, Hägerstrand
Geography as spatial science using statistical and mathematical methods.
Behaviouralism
—
Focus on perception, mental maps, and decision-making.
Radicalism / Marxist Geography
David Harvey, Richard Peet
Geography of social justice, inequality, and capitalist spatial structures.
Humanistic Geography
Yi-Fu Tuan, Anne Buttimer
Emphasis on human experience, sense of place, and meaning (Topophilia ).
Feminism in Geography
Doreen Massey et al.
Gender shapes spatial experiences; challenges male-centric perspectives.
Postmodernism
Michael Foucault, Soja
Rejects grand narratives; emphasises plurality, spatiality, and deconstruction.
Structuralism
—
Deep structures (economic, social) shape surface-level phenomena.
Post-Structuralism
—
Challenges fixed structures; focus on discourse, power, and knowledge.
Key Books
Cosmos Alexander von Humboldt
Erdkunde Carl Ritter
Anthropogeographie Friedrich Ratzel
The Nature of Geography Richard Hartshorne
Perspectives on the Nature of Geography Richard Hartshorne
Explanation in Geography David Harvey
Social Justice and the City David Harvey
Geography: A Global Synthesis Peter Haggett
Geography and Geographers R. J. Johnston
Locational Analysis in Human Geography Peter Haggett
Topophilia Yi-Fu Tuan
La Terre Elisée Réclus
Physische Geographie Immanuel Kant
The Structure of Scientific Revolutions Thomas Kuhn
Key Concepts
Idiographic vs Nomothetic approaches
Paradigm shifts (Kuhn’s model): Pre-paradigm → Normal science → Crisis → Revolution
Comte’s stages: Theological → Metaphysical → Positive
Teleology vs Causality
Geopiety (J. K. Wright)
Darwinism in geography: evolution, ecology, organism analogy
Place–Work–Folk (Le Play / Vidal)
9. Cartography, Statistics & Remote Sensing
Key Concepts & Techniques
Map Projections
Zenithal, Conical, Cylindrical; properties — Equal Area, Orthomorphic (Conformal), Equidistant.
Mercator’s Projection
Conformal (orthomorphic) cylindrical projection; used for navigation.
UTM (Universal Transverse Mercator)
60 zones worldwide, each 6° wide. West Bengal = Zone 45.
Toposheet Reading
SOI topographic maps at 1:50,000 and 1:250,000 scales.
NDVI
(NIR − Red) / (NIR + Red); measures vegetation health.
FCC (False Colour Composite)
NIR → Red, Red → Green, Green → Blue; vegetation appears red.
Spatial Resolution
LISS-III: 23.5 m; AWiFS: 56 m; CartoDEM: 30 m.
Resampling Methods
Nearest Neighbour, Bilinear Interpolation, Cubic Convolution.
Radiometric Resolution
Number of grey values (e.g., 8-bit = 256 levels).
GIS Data Models
Vector (Points, Lines, Polygons) vs Raster (Grid cells).
Overlay Operations
Intersection, Union, Identity, Clip, Erase.
Chi-Square Test
Tests goodness of fit / independence; χ² = 0 means perfect fit (null hypothesis accepted).
ANOVA
Preferred over multiple t-tests for comparing ≥3 group means (controls Type I error).
Correlation (r)
Ranges from −1.0 to +1.0.
Coefficient of Variation
(SD / Mean) × 100; measures relative dispersion.
p-value ≤ 0.05
Strong evidence against null hypothesis.
PCA (Principal Component Analysis)
Orthogonal transformation converting correlated variables to uncorrelated.
Random Forest
Machine learning algorithm based on bagging (Bootstrap Aggregation).
Nearest Neighbour Statistic
R = 0 (clustered), 1 (random), 2.15 (dispersed).
Hypsometric Integral
Low value → old/eroded basin; High value → young/uneroded basin.
10. Geography of India
Key Facts & Concepts
Tropic of Cancer states
Rajasthan, Gujarat, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, Mizoram
Green Revolution Phase I
Wheat — Punjab, Haryana, Western UP
Green Revolution Phase II
Rice — Andhra Pradesh, Tamil Nadu
“Ruhr of India”
Damodar Valley (Chhotanagpur Plateau)
Major coalfields
Jharia (largest), Raniganj (WB), Bokaro
Chromite
Odisha — largest producer
Palghat Gap
Connects Kerala and Tamil Nadu through the Western Ghats
Thalghat
Maharashtra
Bhorghat
Maharashtra
National Waterways
NW-1: Ganga (Allahabad–Haldia); NW-2: Brahmaputra (Sadiya–Dhubri); NW-3: Kerala (Kollam–Kottapuram)
Biogeographic zones
Largest: Trans-Himalayan; largest biosphere reserve network varies by criteria
North-Eastern Region (DoNER)
8 states including Sikkim (not WB)
Area rank of states
Rajasthan > Madhya Pradesh > Maharashtra > Uttar Pradesh
Mawsynram
Wettest place; ~1,187 cm annual rainfall
NE Monsoon
Winter rainfall in Tamil Nadu coast
Quick Revision: Scholar → Contribution
Humboldt
Cosmos ; Unity of Nature; scientific exploration
Ritter
Erdkunde ; teleological approach; regional geography
Ratzel
Anthropogeographie; Lebensraum; environmental determinism
Vidal de la Blache
Possibilism; genres de vie ; regional monographs
W. M. Davis
Geographical Cycle of Erosion
Walther Penck
Morphological analysis of slopes
L. C. King
Pediplain concept; parallel slope retreat
Christaller
Central Place Theory (1933)
Von Thünen
Agricultural Location Theory (1826)
Weber
Industrial Location Theory (1909)
Wegener
Continental Drift (1912)
Hess
Sea-Floor Spreading
Hartshorne
The Nature of Geography ; areal differentiation
Sauer
Cultural landscape; Berkeley School
Hägerstrand
Spatial diffusion; Time-Geography
Harvey
Explanation in Geography ; Social Justice and the City
Yi-Fu Tuan
Topophilia ; humanistic geography
Mackinder
Heartland Theory
Spykman
Rimland Theory
Myrdal
Cumulative Causation; spread vs backwash
Rostow
Stages of Economic Growth
Burgess
Concentric Zone Model
Hoyt
Sector Model
Harris & Ullman
Multiple Nuclei Model
Friedmann
Core-Periphery Model
Perroux
Growth Pole Theory
Malthus
Population–Food supply imbalance
Boserup
Population drives agricultural change
Ravenstein
Laws of Migration
Zelinsky
Mobility Transition Model
Kant
Gaseous Hypothesis
Laplace
Nebular Hypothesis; Dynamical Theory of Tides
Chamberlin & Moulton
Planetesimal Hypothesis
James Jeans & Jeffreys
Tidal Hypothesis
Russell
Binary Star Hypothesis
Georges Lemaître
Big Bang Theory
Lowthian Green
Tetrahedron Theory
F. B. Taylor
Continental Drift Hypothesis
Kober
Geo-Syncline Theory
Jeffreys
Thermal Contraction Theory
Joly
Radioactive Theory
R. A. Daly
Sliding Continent Theory
Isaac Newton
Equilibrium Theory of Tides
William Whewell
Progressive Wave Theory
G. B. Airy
Canal Theory; Isostasy (Airy’s Hypothesis)
R. A. Harris
Stationary Wave Theory
A. T. Mahan
Sea Power Concept
Seversky
Air Power Theory
David Hooson
Heart of Heartland Concept
Saul Cohen
Geo-Strategic Concept
Karl Haushofer
Geopolitical Concept
H. F. Reid
Elastic Rebound Theory
C. H. Crickmay
Panplain Concept
Louis Agassiz
Pleistocene Glaciation Evidence
J. T. Wilson
Coined the term “Plate”
C. E. Dutton
Coined the term “Isostasy”
Felix Auerbach
Initial observer of Rank-Size Rule
Andre Allix
Coined the term “Umland”
Fetter & Hotelling
Market Competition Theory
E. M. Hoover
Least Cost Theory
D. M. Smith
Maximum Profit Theory
Garrison
Fused Growth Theory
Last updated: April 2026
7. Social, Cultural & Political Geography
Theories & Models
Key Concepts