Spain 2º Bachillerato Geology and Environmental Sciences
Chapters: 7
1. Experimentation in Geology and Environmental Sciences
Geological and environmental information sources · Instruments for geological fieldwork · Science communication and collaboration · Representing geological information · Geological and environmental heritage · Scientists and their contributions · History of geological science
- Map Skills: Reading and Using Maps – A map is a flat, scaled-down view of a place from directly above. To read one you need: the key (symbols), the scale (to measure distance), direction (compass points and bearings), grid references (to find and give a location) and contour lines (to see height and slope). Today GPS finds our position from satellites, and GIS stacks many map layers of data on a computer to answer questions about places.
- Lab Safety and Safe Experiments – Dress for safety (goggles, coat, closed shoes, hair tied). Read labels and hazard pictograms. Heat gently with the mouth of the tube pointing away. Add acid to water, waft smells, never taste. Report every accident at once. Plan experiments step by step, assess the risks first and dispose of waste correctly.
- Science Communication: Sharing and Judging Scientific Results – Science communication means sharing findings clearly and honestly, and judging what others claim. Fit the message to the audience without changing the facts. Reports and posters follow an order: question, method, results, conclusion with limits, references. Graphs need titles, labelled axes and units. In demonstrations and exhibitions, show the idea in action and invite questions. In the media, claims often grow bigger than the evidence, and everyday words like theory mean something different in science. Check the source, the evidence, the sample size and whether others confirmed it.
- Geological Maps: Reading Rocks from Above – A geological map shows which rock is found at the ground surface, using colours and symbols. Rock layers (strata) form one on top of another, so lower layers are usually older (law of superposition). Tilted layers are described by strike (the direction of a level line on the layer) and dip (the angle and direction of tilt). Faults are cracks where rock has moved. A cross-section shows the rocks as if you cut the ground like a cake, and a stratigraphic column lists the layers in order of age.
- Nature of Science: How Scientific Knowledge Is Built and Changed – Science is a way of knowing that rests on evidence anyone can check. Scientists observe, infer, test ideas that could be proved wrong, and let other experts check their work. Laws describe what happens; theories explain why. Scientific knowledge is reliable but always open to change, and sometimes a whole way of seeing (a paradigm) is replaced.
2. Plate tectonics and internal geodynamics
Internal geodynamics and plate tectonics · The Wilson cycle · Present-day internal geodynamics · Rock deformation · Internal processes and natural hazards
- 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.
- 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.
3. External geological processes
External geological processes · Landforms and their controls · External processes and natural hazards
- 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: How the Earth's Surface is Shaped – The Earth has layers: crust, mantle, outer core and inner core. The crust is broken into plates that move slowly. When plates push, pull or slide, they make mountains, valleys, earthquakes and volcanoes. On the surface, weathering breaks rocks and agents like rivers, wind, glaciers and waves carry the pieces away (erosion) and drop them (deposition). Sudden events like earthquakes, landslides, avalanches, GLOFs and duststorms are natural hazards we can prepare for.
- 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.
4. Minerals, the components of rocks
Concept of mineral · Chemical-structural classification of minerals · Identifying minerals by physical properties · Phase diagrams of minerals
- 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.
- Silicate Minerals: How One Tiny Brick Builds Most of the Earth's Crust – Silicate minerals are minerals built from silicon and oxygen. Their basic brick is the SiO₄ tetrahedron: one silicon atom with four oxygen atoms around it. Tetrahedra can stay alone or share oxygens to form chains, sheets or a 3D framework. The way they link decides the mineral's shape, cleavage and hardness. Silicates make up over 90% of the Earth's crust.
5. Igneous, sedimentary and metamorphic rocks
Concept of rock · Classifying rocks by origin · Identifying rocks · Magmas and volcanism · Diagenesis and sedimentary rocks · Metamorphic rocks · The rock cycle
- 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.
- Igneous Rocks: From Hot Magma to Solid Stone – Igneous rocks form when melted rock cools and turns solid. Melted rock underground is magma; on the surface it is lava. Magma forms where rock gets hot enough, or where pressure drops or water is added, mostly at plate boundaries and hot spots. Magma is lighter than solid rock, so it rises. If it cools slowly deep underground, crystals grow big (intrusive rocks such as granite and gabbro). If it cools fast at the surface, crystals stay tiny or glass forms (extrusive rocks such as basalt, rhyolite, obsidian and pumice). Silica content decides colour and stickiness: low-silica (mafic) magma is dark, hot and runny and erupts gently; high-silica (felsic) magma is light, cooler and sticky, traps gas and erupts explosively.
- Sedimentary Rocks: Layer by Layer into Stone – Sedimentary rocks form at Earth's surface from bits of older rock, minerals that come out of water, or remains of living things. Weathering breaks rock into sediment; erosion and transport by rivers, wind, ice and waves carry it; when the flow slows, sediment is deposited in layers (strata), usually in seas, lakes, rivers and deserts. The oldest layer is at the bottom (law of superposition). Diagenesis turns loose sediment into rock: compaction (the weight of layers above squeezes grains and pushes water out) and cementation (minerals such as calcite, silica and iron oxide crystallise between grains and glue them). Clastic rocks are named by grain size: conglomerate and breccia (gravel), sandstone (sand), siltstone, and shale or mudstone (clay). Chemical rocks form from minerals that precipitate from water: rock salt, gypsum, some limestone, chert. Organic (biogenic) rocks form from remains of living things: coal, chalk and shelly limestone. Sedimentary rocks cover about 75% of the land surface, hold almost all fossils, oil, gas, coal and groundwater, and their structures (bedding, cross-bedding, ripple marks, mud cracks, graded bedding) tell us about past environments.
- Metamorphic Rocks and Metamorphism – Metamorphic rocks form when an existing rock (the parent rock) is changed by high temperature, high pressure and hot fluids while staying solid. Minerals grow, change and line up. Directed pressure makes foliated rocks (slate, phyllite, schist, gneiss); heat without squeezing makes non-foliated rocks (marble, quartzite, hornfels). Regional metamorphism happens where plates collide; contact metamorphism happens next to hot magma.
6. The fluid layers of the Earth
Atmosphere and hydrosphere · Air and water pollution
- 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.
- Pollution: Air, Water, Land and Noise – Pollution is the release of harmful substances or energy into air, water or land faster than nature can remove them. Main air pollutants are particulates, carbon monoxide, sulfur dioxide, nitrogen oxides and ozone; they cause acid rain and smog. Water pollution by nutrients, sewage and toxins causes eutrophication and biomagnification. We reduce pollution by cutting emissions at the source, cleaning waste before release, and the 3Rs.
7. Resources and their sustainable management
Geological and biological resources · Resource, deposit and reserve · Impacts of resource exploitation · Water resources · Soil properties and importance · Soil and water degradation · Exploiting rocks, minerals and energy · Waste prevention and management · Measures against resource impacts
- Resources and Development – A resource is anything in nature that people can use with the help of technology. Resources can be grouped by origin, by how long they last, by who owns them and by how much we have developed them. India must plan how it uses resources, look after its land, and protect its soils from erosion.
- Mineral and Energy Resources of India (Class 12) – Minerals are natural substances with a fixed make-up. Most of India's minerals lie in old plateau rocks, in three belts: the north-eastern plateau, the south-western plateau and the north-western belt. Metallic minerals include iron ore, manganese, bauxite and copper; mica is a non-metallic mineral. Coal, petroleum and natural gas are conventional energy that will run out. Nuclear, solar, wind, tidal, geothermal and bio-energy are non-conventional and cleaner. Because minerals are non-renewable, we must use less, recycle scrap and use substitutes.
- Water Resources – Almost all water on Earth is salty sea water; only a tiny part is usable fresh water. Growing population, farming, industry and pollution cause water scarcity. Multipurpose dams store water for many uses but also create problems. Rainwater harvesting is an old and simple way to save water.
- Soil: How It Forms, Its Layers and How to Protect It – Soil is the thin, loose top layer of the land where plants grow. It is a mix of rock grains (about 45%), organic matter or humus (about 5%), water (about 25%) and air (about 25%). Soil forms very slowly when weathering breaks parent rock and living things add humus. Five factors control it: parent rock, climate, living things, relief (slope) and time. A cut through the ground shows layers called horizons: O (litter and humus), A (topsoil), B (subsoil, where washed-down minerals collect), C (broken rock) and R (bedrock). Soil texture depends on the share of sand, silt and clay. Soil feeds plants, stores and cleans water, stores carbon and is home to countless organisms, but erosion, salt and pollution can destroy it far faster than it forms.
- Ozone Layer Depletion and Waste Management – High above us, ozone (O₃) blocks harmful UV rays, but CFCs thin it; on the ground, biodegradable waste breaks down naturally while non-biodegradable waste stays for years, so we must reduce, reuse, recycle and segregate.