Tamil Nadu HSE First Year Geography cheat sheet

Geography derives from Greek 'geo' (earth) and 'graphos' (description); Eratosthenes first coined the term.

Geography is an integrative, spatial science studying the earth as the home of humans - bridging physical and social sciences.

Two main branches: Physical Geography (geomorphology, climatology, hydrology, soil geography, biogeography) and Human Geography (population, settlement, economic, cultural, political).

Systematic approach studies one theme across space; regional approach studies all themes within one region.

Techniques branch includes cartography, remote sensing, GIS, quantitative methods and field survey.

Aristotle and Strabo contributed early geographic thought; Ptolemy's 'Geographia' introduced coordinates and map projection ideas.

Geography's scope spans local to global scales and links with geology, meteorology, oceanography, ecology, economics and sociology.

Key concepts: location, place, region, spatial interaction, diffusion, and human-environment relationship.

Earth's interior layers: crust (5-70 km), mantle (to ~2900 km), outer core (liquid, to ~5150 km), inner core (solid, to ~6371 km).

Discontinuities: Mohorovicic (crust-mantle), Gutenberg (mantle-core), Lehmann (outer-inner core).

Origin theories: Nebular hypothesis (Kant-Laplace), Planetesimal hypothesis (Chamberlin-Moulton), Tidal hypothesis (Jeans-Jeffreys), Big Bang for the universe.

Earth's geological history divided into eons: Hadean, Archean, Proterozoic (Precambrian) and Phanerozoic (Palaeozoic, Mesozoic, Cenozoic).

Eras of Phanerozoic: Palaeozoic (Cambrian to Permian), Mesozoic (Triassic, Jurassic, Cretaceous), Cenozoic (Tertiary, Quaternary).

Evidence for interior: seismic waves - P waves travel through solids and liquids; S waves only through solids, revealing liquid outer core.

Density and temperature increase with depth; pressure at the core is millions of atmospheres.

Age of Earth accepted as ~4.6 billion years, based on radiometric dating of meteorites and oldest rocks.

Plate tectonics: lithosphere divided into major plates (Pacific, North American, Eurasian, African, Indo-Australian, Antarctic, South American) that move over the asthenosphere.

Plate boundaries: divergent (constructive, mid-ocean ridges), convergent (destructive, trenches and fold mountains), transform (conservative, faults).

Sea-floor spreading (Hess) and palaeomagnetism support continental drift (Wegener, 1912).

Rock types: igneous (from magma - intrusive/plutonic and extrusive/volcanic), sedimentary (stratified, fossils), metamorphic (altered by heat/pressure).

Folds: anticline (upward), syncline (downward), monocline; faults: normal, reverse, strike-slip.

Endogenic forces build relief (diastrophism, volcanism); exogenic forces wear it down (weathering, erosion, deposition).

Landforms by agents: rivers (V-shaped valley, meander, delta), glaciers (cirque, moraine, U-valley), wind (barchan, yardang), waves (sea cliff, spit).

Weathering types: physical (frost, exfoliation), chemical (solution, oxidation), biological; erosion differs from weathering by transport of debris.

Composition: nitrogen ~78%, oxygen ~21%, argon ~0.93%, CO2 ~0.04%; variable gases include water vapour, ozone, dust.

Layers by temperature: troposphere (weather occurs, lapse rate 6.5°C/km), stratosphere (ozone layer), mesosphere, thermosphere, exosphere.

Insolation is maximum at the equator and decreases poleward; distribution affected by angle of sun, day length, transparency and land-water contrasts.

Temperature controls: latitude, altitude, distance from sea, ocean currents, winds, cloud cover, aspect.

Pressure belts: equatorial low (doldrums), subtropical high (horse latitudes), subpolar low, polar high.

Wind belts: trade winds (NE and SE), westerlies, polar easterlies; Coriolis force deflects winds (right in N hemisphere, left in S).

Humidity: absolute (g/m³), specific, relative (%); condensation forms dew, fog, cloud; precipitation types - convective, orographic, cyclonic.

Koppen climatic types: A (tropical), B (dry), C (temperate), D (cold), E (polar); Tamil Nadu's coast is Aw (tropical savanna).

Ocean relief: continental shelf (shallow, <200 m), continental slope, continental rise, abyssal plain, mid-ocean ridge, trench (deepest, Mariana).

Salinity averages ~35 ppt; highest in subtropical seas (Red Sea ~40 ppt) due to evaporation; low near equator and river mouths.

Surface temperature decreases poleward; thermocline separates warm surface from cold deep water.

Warm currents: Gulf Stream, North Atlantic Drift, Kuroshio; cold currents: Labrador, Canary, Benguela, Humboldt.

Currents are driven by prevailing winds, Coriolis force, and differences in temperature and salinity (thermohaline circulation).

Tides: gravitational pull of Moon and Sun; spring tides at new/full moon, neap tides at quadrature.

Tidal types: semidiurnal (two high tides daily), diurnal (one), mixed; tidal range maximum in funnel-shaped estuaries.

Ocean deposits: terrigenous (from land) and pelagic (ooze, red clay); coral reefs require warm, clear, shallow water.

Soil profile horizons: O (organic), A (topsoil), B (subsoil), C (weathered parent material), R (bedrock).

Soil formation factors: parent rock, climate, relief, organisms, time (Jenny's CLORPT).

Soil types in India: alluvial, black (regur, cotton), red, laterite, desert, mountain, peaty, saline.

Biomes: tropical rainforest, savanna, desert, temperate grassland, temperate forest, taiga (boreal), tundra.

Biodiversity levels: genetic, species, ecosystem; hotspots in India include Western Ghats, Himalaya, Indo-Burma, Sundaland.

Tamil Nadu biodiversity: Gulf of Mannar Marine Biosphere Reserve, Nilgiri Biosphere Reserve, Mudumalai and Anamalai sanctuaries.

Threats: habitat loss, invasive species, pollution, climate change, overexploitation.

Conservation: in-situ (national parks, sanctuaries, biosphere reserves) and ex-situ (botanical gardens, seed banks, zoos).

Population density = population / area; India's 2011 density was 382 persons/km².

Demographic transition stages: high birth-high death, high birth-falling death, falling birth-low death, low birth-low death.

Migration push factors: poverty, unemployment, disaster; pull factors: jobs, education, better services.

Migration types: internal (rural-urban, seasonal), international (voluntary, forced); refugees differ from economic migrants.

Settlement types: rural (dispersed, nucleated, linear) and urban (conurbation, megacity, primate city).

Economic activities: primary (agriculture, mining), secondary (manufacturing), tertiary (services), quaternary (knowledge).

Population pyramid shapes indicate growth trends - broad base = high growth; narrow base = ageing population.

Urbanisation indicators include urban population share, growth rate and functional classification of towns.

Scale types: representative fraction (1:50,000), statement (1 cm = 0.5 km), graphical (bar).

Large-scale maps show small areas in detail; small-scale maps show large areas with less detail.

Latitude and longitude: latitude 0°-90° N/S, longitude 0°-180° E/W; 1° of latitude ≈ 111 km.

Contours connect equal elevation; close contours = steep slope; hachures and spot heights supplement relief.

Map projections: cylindrical (Mercator - distorts poles), conic, azimuthal; choice depends on purpose and area.

Remote sensing: passive (reflects sunlight) vs active (radar, LiDAR); resolution types - spatial, spectral, temporal, radiometric.

GIS layers: raster (grid cells) vs vector (points, lines, polygons); overlay, buffer and network analysis are common tools.

Topographic map colours: blue water, green vegetation, brown contours, black cultural features.

Tamil Nadu lies between 8°04′ and 13°35′ N latitude and 76°18′ and 80°20′ E longitude; capital Chennai.

Physiographic divisions: Coastal plains, Eastern Ghats, and the Nilgiri, Anaimalai and Palani hills of the Western Ghats.

Major rivers: Cauvery, Vaigai, Tamiraparani, Palar, Pennar; Cauvery delta is the 'granary' of Tamil Nadu.

Climate: tropical monsoon; NE monsoon (Oct-Dec) brings most rain; SW monsoon rain shadow over interior.

Crops: rice, sugarcane, cotton, groundnut, millets; Tamil Nadu leads in banana and coconut production.

Field study steps: define objective, select site, prepare questionnaire/observation sheet, collect data, tabulate, analyse, report.

India's physiographic divisions: Himalaya, Northern Plains, Peninsular Plateau, Coastal Plains, Islands.

Tamil Nadu minerals and industries: lignite at Neyveli, cement, textiles at Coimbatore, automobiles at Chennai.

Cartography is the art and science of making maps; it includes data collection, design, reproduction and interpretation.

Map elements: title, scale, legend, direction (north arrow), grid, source and projection note.

Distance measurement: use scale to convert map length to ground length; string method for curved routes.

Bearing measured clockwise from north; prismatic compass and clinometer are field instruments.

Remote sensing platforms: satellites (Landsat, Sentinel, IRS), aircraft, drones; sensors include optical and microwave.

GIS software examples: QGIS, ArcGIS; data models include shapefile, GeoJSON, GeoTIFF.

GPS uses ≥4 satellites for 3-D position fix; accuracy depends on geometry and atmospheric correction.

Applications: land-use mapping, disaster management, urban planning, agriculture and forestry monitoring.

India's location: 8°4′ to 37°6′ N latitude, 68°7′ to 97°25′ E longitude; Tropic of Cancer crosses 8 states.

India's area is 3.28 million km² (2.4% of world land); coastline ~7,516 km including islands.

Himalayan rivers: Indus, Ganga, Brahmaputra - perennial, snow-fed; peninsular rivers seasonal.

Tamil Nadu districts: 38; major cities Chennai, Coimbatore, Madurai, Tiruchirappalli, Salem, Tirunelveli.

Field study observation checklist: land use, vegetation, soil, water bodies, settlement pattern, transport.

Data presentation: tables, bar charts, pie charts, line graphs, sketch maps, transects.

Tamil Nadu's Nilgiri Biosphere Reserve was India's first (1986), shared with Karnataka and Kerala.

India's climate influenced by monsoon, jet stream, ENSO and Himalayan barrier; Tamil Nadu is largely rain-shadow in SW monsoon.

Map reading sequence: identify title, orientation, scale, legend, then interpret features.

Contour interval is constant on a map; index contours are thickened and labelled for orientation.

Slope calculation: gradient = vertical rise / horizontal distance, expressed as ratio or percent.

Cross-section (profile) drawn from contour map reveals valley and ridge shapes.

GIS geoprocessing: clip, intersect, union, dissolve, spatial join, buffer.

Remote sensing image interpretation elements: tone, texture, pattern, shape, size, shadow, association.

Coordinate systems: geographic (lat/long) vs projected (UTM, Lambert); datum examples WGS84.

Field survey instruments: tape, chain, GPS receiver, compass, clinometer, camera, questionnaire.

Tamil Nadu soil types: red loam, black, laterite, alluvial, coastal sandy; red soils dominate interior.

Forest types in Tamil Nadu: tropical evergreen (Western Ghats), deciduous, thorn scrub, mangrove (Pichavaram).

Major irrigation: Cauvery delta canals, Mettur Dam, Vaigai Dam, Lower Bhavani project.

Population (2011): Tamil Nadu ~72 million; literacy ~80%; urbanisation above national average.

Field study sampling: random, systematic, stratified; choose based on site and objective.

Report structure: title, introduction, aim, methodology, observations, analysis, conclusion, references.

India's physiographic regions: Himalaya, Northern Plains, Peninsular Plateau, Coastal Plains, Islands.

Tamil Nadu borders: Andhra Pradesh (N), Karnataka (NW), Kerala (W), Bay of Bengal (E), Indian Ocean (S).