Romania Clasa a IX-a Geography
Chapters: 8
1. Geography – the science of Earth's space
Geography today and mapping space · GIS, satellite images and GPS
- 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).
- Spatial Information Technology: GIS (Class 12 Geography Practical) – A Geographical Information System (GIS) is a computer system that stores, links, analyses and shows data about places. It keeps the world in layers. It needs hardware, software, data, people and methods. Spatial data come in raster (grid of cells) and vector (points, lines, polygons) formats. Data are entered by digitising, scanning, GPS or satellite images and linked to attribute tables. Overlay combines layers to find where conditions meet; buffer draws a zone of fixed distance around a feature.
2. Earth as a cosmic body
Earth in the Universe · Earth's motions and their effects
- The Sun–Earth–Moon System – The Sun is a star; Earth orbits it once in about 365¼ days while spinning once a day, and the Moon orbits Earth once in 27.3 days. The Sun always lights half of the Moon. As the Moon goes round, we see changing amounts of that lit half: the phases, which repeat every 29.5 days. The Moon spins once per orbit, so the same face always points at us. Its gravity (with the Sun's) raises two tidal bulges, giving two high tides a day; spring tides come at New and Full Moon, neap tides at the quarters. A solar eclipse happens when the Moon's shadow falls on Earth (New Moon); a lunar eclipse when the Moon enters Earth's shadow (Full Moon). The Moon's 5° tilted orbit means eclipses do not happen every month. Earth's distance from the Sun, liquid water, atmosphere and magnetic field make it fit for life.
- Rotation and Revolution of the Earth – Earth has two main motions. Rotation: it spins on its axis from west to east once in about 24 hours, giving day and night, the daily path of the Sun, local time (15° of longitude per hour) and the bending of winds and currents (Coriolis effect). Revolution: it travels round the Sun on an elliptical orbit once in about 365¼ days. Because the axis is tilted 23.5° from the perpendicular to the orbit plane (the ecliptic) and always points the same way, the overhead Sun moves between the Tropics of Cancer and Capricorn, day length changes, and we get seasons, solstices and equinoxes.
3. Geology: internal dynamics, resources and risks
Earth's interior, minerals and rocks · Internal dynamics and geological time · Endogenous hazards
- 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.
4. Relief – support for human society
Major landforms and shaping processes · Relief types and habitability
- 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.
5. Atmosphere and climate change
Atmosphere and climate · Climate change and climate hazards
- 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 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).
6. Hydrosphere – a dynamic system
World ocean and inland waters
- 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.
7. Biosphere and soils – geographic diversity
Biosphere and soils
- Biodiversity and its Conservation – Biodiversity is the variety of life at three levels: genetic, species and ecological. It is highest near the equator and grows with area (log S = log C + Z log A). Every species matters, like rivets on a plane. We are losing species fast because of the 'evil quartet': habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinction. The IUCN Red List (Red Data Book) ranks species from Least Concern to Extinct. We protect life in situ (hotspots, national parks, sanctuaries, biosphere reserves, sacred groves, Ramsar wetlands) and ex situ (zoos, botanical gardens, seed and gene banks).
- Diversity and Classification of Living Organisms – Earth has millions of kinds of living things, and India is one of the richest places. To study them, we sort them into groups by asking simple questions about their bodies: Is there a nucleus? One cell or many? Can it make its own food? This gives five kingdoms: Monera, Protista, Fungi, Plantae and Animalia. Animals split into invertebrates and vertebrates. Every species gets a two-part scientific name. Viruses are not cells, so they fit in no kingdom.
8. Natural environments of the Earth
Natural environments and their degradation
- Biomes and Forests: Life on Earth – A biome is a large region with a similar climate, plants and animals, like tundra, taiga, grassland, desert, savanna and tropical rainforest. Rain and temperature decide which biome forms. India protects special areas as biosphere reserves, which have a core, buffer and transition zone. Forest dwellers depend on forests and know how to use them without harming them; ecotourism can give them income. We conserve forests and wildlife through national parks, sanctuaries, laws and people's movements like Chipko, and we must prevent forest fires.