WBBSE Madhyamik Geography cheat sheet

Earth's interior is divided into crust, mantle, and core; the crust is thinner under oceans (about 5–10 km) than under continents (about 30–70 km).

Weathering is in-situ breakdown of rock; erosion involves transport of the broken material by water, wind, or ice - the two are not the same process.

River landforms: V-shaped valleys and waterfalls occur in the youthful stage, meanders and oxbow lakes in the mature stage, deltas and floodplains in the old stage.

Glacial landforms: cirque, arête, and horn are erosional; moraine, drumlin, and esker are depositional.

Wind action in deserts produces yardang and zeugen by erosion, and barchan and seif dunes by deposition.

Monsoon mechanism: differential heating of land and sea, the shift of the ITCZ, and the Himalayan barrier together reverse seasonal wind direction.

The Bay of Bengal branch and Arabian Sea branch of the southwest monsoon converge near the Himalayas; the Meghalaya plateau (Mawsynram) records the highest average rainfall.

Cyclones form over warm seas (above roughly 27°C) with Coriolis force; they weaken on landfall because moisture supply is cut off and friction increases.

India's physiographic divisions: Himalayas, Northern Plains, Peninsular Plateau, Indian Desert, Coastal Plains, and Islands.

The Western Ghats are continuous and higher (Anamudi, 2,695 m); the Eastern Ghats are discontinuous and lower, dissected by rivers such as the Mahanadi, Godavari, and Krishna.

West Bengal physiography: Darjeeling Himalaya in the north, the Terai-Duars foothills, the lateritic Rarh plain, the Ganga delta in the south, and the Sundarbans in the coastal south.

The Damodar valley is West Bengal's mineral and industrial belt (coal, iron-ore links, DVC dams at Tilaiya, Konar, Maithon, and Panchet).

The Sundarbans is a tidal halophytic mangrove forest in the Ganga-Brahmaputra delta, a UNESCO World Heritage Site and tiger reserve.

Rivers of West Bengal: the Hooghly (a distributary of the Ganga), Damodar, Teesta, and Mahananda; the Teesta causes severe floods in the Duars.

The Tropic of Cancer passes through West Bengal near Krishnanagar; the state's climate is tropical monsoon with a marked dry winter.

Laterite soil in the Rarh region forms under heavy leaching of silica in alternating wet-dry conditions; it is poor for most crops but supports tea and cashew.

Primary activities directly extract resources (farming, fishing, mining); secondary activities process them (manufacturing); tertiary activities provide services (transport, trade, banking).

Subsistence farming is for the farmer's own consumption; commercial farming is for sale, with high inputs of capital and machinery.

Plantation agriculture (tea, coffee, rubber) needs a tropical climate, abundant cheap labour, and good transport to ports.

Iron and steel plants locate near coal and iron-ore sources or along transport routes - e.g., Durgapur and Burnpur in West Bengal.

Population density = total population ÷ total area; India's 2011 Census recorded a density of about 382 persons per sq km.

Sex ratio is females per 1,000 males; Kerala records a high ratio, while Haryana and Punjab record low ratios.

Urbanisation brings slums, pressure on water and sanitation, and traffic congestion; rural push and urban pull are the main migration drivers.

Sustainable development meets present needs without compromising future generations; renewable energy and resource recycling are key strategies.

Scale types: statement (verbal), representative fraction (RF), and graphical (linear) scale; RF is unit-independent, e.g., 1:50,000.

Scale conversion: for 1:50,000, 1 cm on the map equals 0.5 km on the ground; for 1:25,000, 1 cm equals 0.25 km.

Contour lines join points of equal elevation; closely spaced contours indicate a steep slope, widely spaced contours a gentle slope.

Contour patterns: concentric closed loops with hachures or decreasing values inward mark a depression; V-shapes pointing upstream mark valleys.

A cross-section (profile) is drawn by plotting elevations along a straight line between two points against a vertical scale.

Grid references give a location by easting first, then northing; on a topographical sheet the easting is read before the northing.

Map symbols are conventional signs: blue for water bodies, green for vegetation, brown for contours, black for settlements and boundaries.

Direction is measured clockwise from north using a protractor; magnetic north differs from true north by magnetic declination.

Earthquake waves: P-waves are longitudinal and fastest, travelling through solids and liquids; S-waves are transverse and cannot pass through liquids.

Volcano types: shield volcanoes form from fluid basaltic lava with gentle slopes; composite cones form from alternating lava and ash layers.

Rock cycle: igneous rocks form from cooling magma, sedimentary from compaction of deposits, metamorphic from heat and pressure acting on either.

Latitude affects temperature (angle of insolation), altitude lowers temperature about 6.5°C per 1,000 m, and distance from the sea moderates range.

Ocean currents: warm currents raise coastal temperature and flow from low to high latitudes; cold currents flow from high to low latitudes.

Tides are caused mainly by the gravitational pull of the moon; spring tides occur at new and full moon, neap tides at the quarters.

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

India's climate is dominated by the southwest monsoon (June–September); the retreating monsoon (October–November) brings rain to Tamil Nadu's Coromandel coast.

The Ganga plain is formed of alluvium: bhangar (older, higher, calcareous) and khadar (newer, lower, renewed by floods).

West Bengal districts: Darjeeling and Kalimpong are Himalayan; Murshidabad, Nadia, and North/South 24 Parganas lie in the deltaic plain.

The Chota Nagpur plateau (bordering West Bengal) is a storehouse of minerals: coal, iron ore, mica, and bauxite.

The Farakka Barrage diverts Ganga water into the Hooghly to flush silt and maintain navigation to Kolkata port.

Kolkata's location on the Hooghly, with a hinterland covering the Ganga plain, explains its growth as eastern India's main port.

Population growth = natural increase (births minus deaths) plus net migration; India's demographic transition is in the third stage, with falling fertility.

The demographic dividend is a large working-age share of population; it yields growth only if education and jobs expand.

Industrial location factors: raw material, power, transport, labour, market, capital, and government policy.

Cottage and small-scale industries need little capital and create local employment; heavy industry needs large capital and infrastructure.

Crop-climate links: rice needs high rainfall and heat; wheat needs cool growing season and moderate rain; tea needs well-drained slopes and 150–250 cm rain.

Human Development Index combines life expectancy, education (mean and expected years of schooling), and per-capita income.

Transport modes: railways suit bulky long-distance freight, roads provide door-to-door flexibility, waterways are cheapest for heavy goods.

A topographical sheet's marginal information includes the sheet number, scale, contour interval, and magnetic declination.

Settlement patterns on maps: compact/nucleated (clustered), dispersed (scattered), and linear (along a road, river, or canal).

Drainage patterns: dendritic (tree-like, on uniform rock), trellis (parallel streams joining at right angles), radial (from a dome or volcano).

Aerial photographs are vertical or oblique; satellite images are classified by resolution - spatial, spectral, temporal, and radiometric.

Remote sensing records reflected or emitted radiation; GIS layers spatial data for analysis, and GPS fixes position by satellite signals.

To measure a straight-line map distance, multiply the measured length by the RF denominator and convert to ground units.

Slope on a map can be expressed as a gradient (vertical rise ÷ horizontal distance) or as an angle in degrees.