CBSE Class 11 Geography

1. Geography as a Discipline

Geography as a discipline

• Geography as a Discipline: What Geographers Study and How – Geography studies places on the Earth: what is there, where it is, why it is there and how it changes. It borrows ideas from many subjects (physics, biology, history, economics and more) and joins them for one place, so it is an integrating subject. It looks at space (where) and time (when) together. It can be studied one theme at a time across the world (systematic approach) or one region with all its themes (regional approach). Its main branches are physical geography, human geography and biogeography.

2. The Earth

Origin and evolution of the earth · Interior of the earth · Distribution of oceans and continents

• Origin and Evolution of the Earth: From Dust Cloud to Living Planet – Early thinkers said the planets formed from a spinning cloud of gas around the young Sun (nebular hypothesis) or from matter pulled out of the Sun by a passing star. Today scientists explain the universe with the Big Bang: about 13.7 billion years ago everything began from one tiny point and it is still expanding. Stars formed from clumps of gas; planets formed from dust around the Sun. The Earth, about 4.6 billion years old, was hot and molten; heavy iron sank to make the core and lighter rock formed the crust. Gases from volcanoes made the early air, water vapour rained into oceans, and life began in the oceans about 3.8 billion years ago.
• Interior of the Earth: Earthquake Waves, Layers and Volcanoes – Nobody can dig to the centre of the Earth, so we learn about the inside from direct sources (mine rocks, deep drilling, lava) and indirect sources (heat and pressure with depth, meteors, gravity, magnetism and, above all, earthquake waves). P-waves travel through solids and liquids; S-waves only through solids. Where the waves do not arrive, we get shadow zones, which prove the outer core is liquid. Earthquakes are measured by magnitude (Richter) and intensity (Mercalli). The Earth has a thin crust, a thick mantle with a soft asthenosphere, a liquid outer core and a solid inner core. Magma that reaches the surface builds volcanoes; magma that cools inside forms intrusive landforms like batholiths, sills and dykes.
• Distribution of Oceans and Continents: Drift, Spreading and Plates – In 1912 Alfred Wegener said all continents were once one landmass, Pangaea, surrounded by one ocean, Panthalassa, and that they drifted apart. Matching coastlines, rocks, fossils, glacier deposits and placer gold supported him, but he could not explain the force. Mapping the ocean floor showed ridges, plains and trenches; Harry Hess then proposed sea-floor spreading: new crust forms at mid-ocean ridges and old crust sinks at trenches. This led to plate tectonics: the lithosphere is broken into rigid plates that move on the soft asthenosphere and meet at divergent, convergent and transform boundaries. The Indian plate broke away from the south, moved north, and collided with Asia to raise the Himalayas.

3. Landforms

Geomorphic processes · Landforms and their evolution

• Geomorphic Processes: How Forces Build and Wear the Land – The Earth's surface is shaped by two sets of forces. Endogenic forces come from inside, powered by the Earth's heat: diastrophism (folding, faulting, uplift, sinking) and volcanism build up the land. Exogenic forces come from outside, powered by the Sun and gravity: weathering breaks rock where it stands, mass movements move it down slopes, and running water, wind, glaciers and waves erode and deposit it, slowly lowering high land. Weathered rock plus plants and tiny organisms over a long time becomes soil. Parent rock, climate, relief, living things and time decide what kind of soil forms.
• Landforms and their Evolution: Work of Running Water and Wind – Running water and wind are two major agents that carve and build landforms. A river cuts deep V-shaped valleys, gorges, canyons, waterfalls and potholes in its steep upper course, and it builds alluvial fans, deltas, flood plains, natural levees and point bars where it slows down. Its bends (meanders) grow and are cut off to form oxbow lakes. In deserts, wind blows away loose sand (deflation), sand-blasts rock (abrasion) into mushroom rocks, and helps sheet floods wear land into pediments, pediplains and inselbergs; it deposits sand as dunes such as barchans, parabolic, seif, longitudinal and transverse dunes. Landforms go through stages, youth, maturity and old age, like living things.

4. Climate

Composition and structure of atmosphere · Solar radiation, heat balance and temperature · Atmospheric circulation and weather systems · Water in the atmosphere · World climate and climate change

• Composition and Structure of the Atmosphere – The atmosphere is a thick blanket of air held to the Earth by gravity. It is mostly nitrogen (78%) and oxygen (21%), with small amounts of argon, carbon dioxide, ozone, water vapour and dust. It has five layers: troposphere (where weather happens), stratosphere (ozone layer), mesosphere (coldest), thermosphere (ionosphere, very hot) and exosphere (the outer edge). Weather is the state of air for a short time; climate is the average over about 30 years. Both are described by the same elements: temperature, pressure, wind, humidity, clouds and precipitation.
• Climate of India: How the Monsoon Shapes Our Year – India has a tropical monsoon climate. Its climate depends on latitude, the Himalayas, distance from the sea, height, and winds. The monsoon is a wind that turns around with the season. In summer the land gets hotter than the sea, so wet wind blows from the sea to the land and brings rain. In winter dry wind blows from the land to the sea. India has four seasons: cold, hot, south-west monsoon and retreating monsoon. Rain is uneven: over 400 cm on the Western Ghats and in the north-east, under 60 cm in the Thar and Ladakh. Farming, food prices and jobs depend on the monsoon. Global warming is making heat waves stronger and rain less regular.
• Solar Radiation, Heat Balance and Temperature – The Earth gets its energy from the Sun as short waves; the energy received is called insolation. It is strongest where the Sun's rays fall straight (near the equator) and weakest where they are slanting (near the poles). Air is heated mostly from below: the ground warms first, then passes heat to air by conduction, convection and advection, and by terrestrial radiation (long waves) that greenhouse gases absorb. Out of 100 units of sunlight, 35 are reflected (albedo), 14 are absorbed by air and 51 by the ground; all 65 absorbed units are sent back to space, so the Earth keeps a steady heat budget. Temperature falls from the equator to the poles and with height, and is changed by land–sea contrast and ocean currents. Sometimes cold air lies under warm air: this is a temperature inversion.
• Atmospheric Circulation and Weather Systems – Air has weight, so it presses down: this is air pressure (about 1013 mb at sea level). Wind blows from high pressure to low pressure, pushed by the pressure gradient force, turned by the Coriolis force (right in the north, left in the south) and slowed by friction near the ground. Uneven heating makes pressure belts (equatorial low, subtropical highs, subpolar lows, polar highs) and three circulation cells, giving planetary winds: trade winds, westerlies and polar easterlies. Belts shift with the seasons, giving seasonal winds like the monsoon; local winds include land and sea breezes and mountain and valley winds. Big bodies of air with the same temperature and moisture are air masses; where two meet is a front. Cyclones are low-pressure storms: tropical cyclones form over warm seas; extratropical ones form along fronts. Thunderstorms and tornadoes are small but violent storms.
• Water in the Atmosphere – Air always holds some water as invisible vapour; the amount is called humidity. Absolute humidity is the actual mass of vapour in a volume of air; relative humidity is how full the air is compared with the most it could hold at that temperature. Water becomes vapour by evaporation (taking heat) and turns back to water by condensation (giving heat) when air cools to its dew point. Condensation near the ground gives dew, frost, mist and fog; higher up it gives clouds: cirrus, cumulus, stratus and nimbus. When drops or crystals grow heavy they fall as precipitation: rain, snow, sleet or hail. Rain forms in three main ways: convectional, orographic (relief) and cyclonic (frontal). Rainfall is heaviest near the equator and on windward coasts, and least in subtropical deserts, continental interiors and polar lands.
• Climate Change and the Greenhouse Effect – Climate is the average weather of a place over about 30 years. Greenhouse gases like carbon dioxide and methane trap some of the heat the Earth gives off. Humans have added a lot more of these gases by burning fossil fuels and cutting forests, so the Earth is warming. This causes melting ice, rising seas and more extreme weather. We can cut emissions (mitigation) and prepare for changes (adaptation).

5. Water (Oceans)

Water (oceans) · Movements of ocean water

• Water (Oceans): Hydrological Cycle, Ocean Floor, Temperature and Salinity – The Earth's water keeps moving between oceans, air, land and living things in the hydrological (water) cycle; about 97% of it is in the oceans. The ocean floor has major divisions — continental shelf, continental slope, deep sea plain and ocean deeps (trenches) — and minor features like mid-ocean ridges, seamounts, guyots, submarine canyons, atolls and banks. Ocean surface water is warmest near the equator and colder towards the poles; with depth it falls sharply through a layer called the thermocline, below which the water is near 0–4 °C. Salinity is the salt in sea water, about 35 grams per 1,000 grams (35‰). It rises with evaporation and falls with rain, rivers and melting ice, so it is high in the subtropics and enclosed hot seas and low near the equator, poles and river mouths.
• Movements of Ocean Water: Waves, Tides and Currents – Ocean water moves in three ways. Waves are made mostly by wind: the energy moves forward while each bit of water goes round in a small circle; waves slow down and break in shallow water. Tides are the regular rise and fall of the sea, usually twice a day, caused by the Moon's (and Sun's) pull and the Earth–Moon spin. When Sun, Moon and Earth line up (new and full moon) we get very high spring tides; when they are at right angles (quarter moons) we get weak neap tides. Ocean currents are huge rivers of water flowing in fixed directions, pushed by winds, heating, gravity, salinity and density differences, and turned by the Coriolis force. Warm currents flow from the equator towards the poles; cold currents flow from the poles towards the equator. Currents change coastal climates, fishing, fog and shipping.

6. Life on the Earth

Biodiversity and conservation

Coming soon

7. Map Work: Physical Geography

World map work

• Introduction to Maps – A map is a small, flat drawing of all or part of the Earth, seen from above and drawn to a scale. Every map needs a title, scale, direction (north arrow), legend with symbols, and a grid based on a projection. Maps are grouped by scale (large or small) and by what they show (physical or cultural).
• World Map Work (Physical Geography): Oceans, Plates, Deserts, Seas, Currents and Hotspots – In map work you find physical features on an outline map of the world. Five oceans join into one world ocean. The crust is split into seven major and many minor plates; the Ring of Fire circles the Pacific and the mid-Atlantic ridge runs down the Atlantic. Hot deserts lie near 15°–30° on the west side of continents. Seas are smaller, partly closed parts of oceans. Warm currents flow towards the poles, cold currents towards the equator. Biodiversity hotspots are rich but threatened areas; four touch India.

8. India: Location

India: location

• India: Location, Size, Latitude–Longitude Extent and Standard Time – India covers about 3.28 million km², about 2.4% of the world's land, and is the 7th largest country. The mainland stretches from 8°4′N to 37°6′N and from 68°7′E to 97°25′E, about 29° each way. The Tropic of Cancer (23°30′N) cuts it into a tropical south and a sub-tropical north. Because the east–west spread gives about a 2-hour difference in sun time, India uses one standard meridian, 82°30′E (near Mirzapur), so IST = GMT + 5 h 30 min.

9. Physiography

Structure and physiography · Drainage system

• Structure and Physiography of India: Mountains, Plains, Plateau, Desert, Coasts and Islands – India's land has three structural parts: the old, hard Peninsular block, the young fold mountains of the Himalaya, and the Indo-Ganga-Brahmaputra plain between them. On this base there are six physiographic divisions: northern and north-eastern mountains (Himadri, Himachal, Shiwalik, Purvanchal), the northern plain (bhabar, terai, bhangar, khadar), the peninsular plateau (Deccan, Western and Eastern Ghats), the Indian desert, the coastal plains (narrow west, wide east) and the island groups (Andaman & Nicobar, Lakshadweep).
• Drainage System of India: Patterns, Basins, Himalayan and Peninsular Rivers, River Linking and Pollution – Drainage means the flow of water through well-defined channels, and a network of such channels is a drainage system. Rivers make patterns (dendritic, radial, trellis, centripetal) decided by rock and slope. The land that drains into one river is its catchment or basin, and the high line between two basins is the water divide (watershed). Himalayan rivers are perennial, fed by snow and rain, and cut deep gorges; peninsular rivers are older, rain-fed and seasonal, most flowing east to deltas while the Narmada and Tapi flow west through rift valleys. River linking, wise water use and cleaning rivers are key challenges.

10. Climate, Vegetation and Soil

Climate · Natural vegetation

• Climate of India: How the Monsoon Shapes Our Year – India has a tropical monsoon climate. Its climate depends on latitude, the Himalayas, distance from the sea, height, and winds. The monsoon is a wind that turns around with the season. In summer the land gets hotter than the sea, so wet wind blows from the sea to the land and brings rain. In winter dry wind blows from the land to the sea. India has four seasons: cold, hot, south-west monsoon and retreating monsoon. Rain is uneven: over 400 cm on the Western Ghats and in the north-east, under 60 cm in the Thar and Ladakh. Farming, food prices and jobs depend on the monsoon. Global warming is making heat waves stronger and rain less regular.
• Natural Vegetation of India: Forests, Wildlife and Biosphere Reserves – Natural vegetation is the plant cover that grows on its own, without people planting it. In India, rainfall and temperature decide which forest grows where. Very wet places have tall tropical evergreen forests. Places with moderate rain have deciduous forests, which drop their leaves in the dry season; these are the most common. Dry places have thorny bushes. Mountains have forests that change with height, and river mouths by the sea have mangroves. Forests give us wood, food, medicine and clean air, and they are home to wildlife. India protects them with laws, national parks, wildlife sanctuaries, special projects and biosphere reserves, which have a strictly protected core, a buffer and an outer transition zone.

11. Natural Hazards and Disasters

Natural hazards and disasters

• Natural Hazards – A natural hazard is a natural event that can harm people and property, such as an earthquake, volcano, landslide, flood, drought or cyclone. It becomes a disaster when it hits people who are not ready. Geological hazards come from inside the Earth; meteorological (weather) hazards come from the air and water. Risk = hazard × vulnerability ÷ capacity to cope, so warning systems, strong buildings and trained people cut the damage.

12. Map Work: India

India map work

• India Map Work: Finding Physical Features by Latitude and Longitude – Map work asks you to find and mark physical features of India on an outline map. The trick is to use latitude and longitude lines as an address. India's mainland lies between 8°4′N and 37°6′N and between 68°7′E and 97°25′E. The standard meridian 82°30′E, near Mirzapur, sets Indian Standard Time. On the map you should know the mountain ranges, high peaks, passes, plateaus, coastal plains, island groups, rivers, lakes and gulfs, places with extreme heat, cold and rain, forest types, and national parks. Learn each one with its grid address and a nearby clue, like a river or a coast.
• Introduction to Maps – A map is a small, flat drawing of all or part of the Earth, seen from above and drawn to a scale. Every map needs a title, scale, direction (north arrow), legend with symbols, and a grid based on a projection. Maps are grouped by scale (large or small) and by what they show (physical or cultural).
• World Map Work (Physical Geography): Oceans, Plates, Deserts, Seas, Currents and Hotspots – In map work you find physical features on an outline map of the world. Five oceans join into one world ocean. The crust is split into seven major and many minor plates; the Ring of Fire circles the Pacific and the mid-Atlantic ridge runs down the Atlantic. Hot deserts lie near 15°–30° on the west side of continents. Seas are smaller, partly closed parts of oceans. Warm currents flow towards the poles, cold currents towards the equator. Biodiversity hotspots are rich but threatened areas; four touch India.

13. Practical Work in Geography Part I

Introduction to maps · Map scale · Latitude, longitude and time · Map projections · Topographical maps · Introduction to remote sensing

• Introduction to Maps – A map is a small, flat drawing of all or part of the Earth, seen from above and drawn to a scale. Every map needs a title, scale, direction (north arrow), legend with symbols, and a grid based on a projection. Maps are grouped by scale (large or small) and by what they show (physical or cultural).
• World Map Work (Physical Geography): Oceans, Plates, Deserts, Seas, Currents and Hotspots – In map work you find physical features on an outline map of the world. Five oceans join into one world ocean. The crust is split into seven major and many minor plates; the Ring of Fire circles the Pacific and the mid-Atlantic ridge runs down the Atlantic. Hot deserts lie near 15°–30° on the west side of continents. Seas are smaller, partly closed parts of oceans. Warm currents flow towards the poles, cold currents towards the equator. Biodiversity hotspots are rich but threatened areas; four touch India.
• Map Scale – Scale is the ratio between a distance on the map and the same distance on the ground. It is shown in three ways: statement ("1 cm represents 5 km"), representative fraction (1 : 500,000) and graphical (bar) scale. We can construct a bar scale for any RF and convert statement ↔ RF in metric and English units.
• Latitude, Longitude and Time – Parallels of latitude are east–west circles measured north or south of the Equator (0° to 90°). Meridians of longitude are pole-to-pole half-circles measured east or west of the Prime Meridian (0° to 180°). The Earth turns 15° every hour, so each degree of longitude equals 4 minutes of time. Countries use a standard meridian (India: 82°30′E, 5 h 30 min ahead of GMT), and the calendar date changes at the International Date Line (180°).
• Map Projections – A map projection is a method of drawing the globe's network of parallels and meridians (the graticule) on a flat surface. No projection keeps area, shape, direction and distance all correct. Projections are grouped by the surface used (cylindrical, conical, zenithal), by method, and by the property kept. The conical projection with one standard parallel suits narrow mid-latitude areas; Mercator's cylindrical projection keeps shape and direction and is used for navigation.
• Topographical Maps – Topographical maps are large-scale maps that show both natural and human features of a small area in detail, using agreed signs and colours. In India they are made by the Survey of India in a nested sheet series (1:1,000,000 → 1:250,000 → 1:50,000 → 1:25,000). Relief is shown by contours; their spacing and shape tell slope and landform, and a cross-section turns them into a side view.
• Introduction to Remote Sensing – Remote sensing is collecting information about the Earth's surface without touching it, by recording the energy that objects reflect or emit. It works in stages from an energy source to the user. Sensors ride on platforms (ground, aircraft, satellites) and give photographic or digital products. Different objects have different spectral signatures, which is how we tell water, plants and soil apart.

14. Formative-only topic

Minerals and rocks

• Rocks and Minerals – A mineral is a natural, non-living solid with a fixed chemical make-up and a regular crystal shape, like quartz or halite. A rock is a mixture of one or more minerals. Rocks are of three types: igneous (from cooled magma or lava), sedimentary (from layers of pressed bits) and metamorphic (changed by heat and pressure). The rock cycle slowly turns each type into the others over millions of years.