Catalonia PAU Geology & Env Sci cheat sheet

Earth's layers by composition: crust (oceanic ~7 km, continental ~35 km), mantle, core; by rheology: lithosphere (rigid, ~100 km), asthenosphere (ductile, ~100–350 km), mesosphere, outer core (liquid), inner core (solid).

Discontinuities: Mohorovičić (crust–mantle), Gutenberg (~2900 km, mantle–core), Lehmann (~5150 km, outer–inner core).

Isostasy: Airy model - thicker crust floats higher; Pratt model - density differences at equal depth. Post-glacial rebound is isostatic readjustment.

Divergent boundaries: normal faults, shallow seismicity, basaltic magmatism (MORB), rift valleys, mid-ocean ridges, high heat flow.

Convergent boundaries: reverse/thrust faults, Benioff–Wadati deep seismicity, calc-alkaline magmatism, andesitic stratovolcanoes, trenches, accretionary prisms.

Transform boundaries: strike-slip faults, shallow seismicity, no magmatism (e.g., San Andreas).

Hotspots: intraplate volcanism (Hawaii, Iceland); seamount chains record plate motion direction and rate.

Metamorphism types: regional (pressure–temperature, orogenic), contact (thermal aureole), dynamic (cataclastic), hydrothermal; index minerals mark grade (chlorite→biotite→garnet→sillimanite).

Deformation: brittle (faults, joints) vs ductile (folds); anticline limbs dip away from axis, syncline toward; dip and strike define planar orientation.

Weathering: physical (frost wedging, thermal, salt, biological) vs chemical (hydrolysis, oxidation, carbonation, dissolution). Silicate hydrolysis is the dominant chemical process.

Bowen's stability series is the reverse of crystallisation order: olivine weathers fastest, quartz slowest.

Erosion agents: water (dominant), wind, ice, gravity. Transport mode depends on grain size and flow competence.

Fluvial transport: bedload (traction, saltation), suspended load, dissolved load. Hjulström curve links velocity to erosion/deposition of clasts.

Rounding and sorting indicate transport distance and agent: well rounded + well sorted = long water transport; angular + poorly sorted = short distance or glacial till.

Karst: dissolution of limestone by carbonic acid; features include dolines, poljes, caves, stalactites, and disappearing streams.

Mass movements classified by material (rock/soil) and motion (fall, slide, flow, creep); triggered by water saturation, undercutting, seismic shaking.

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

Coastal processes: longshore drift, wave refraction, erosional (cliff, stack, arch) and depositional (beach, spit, tombolo) landforms.

Principles: superposition, original horizontality, lateral continuity, cross-cutting relationships, inclusion, faunal succession.

Unconformities: angular (tilted then eroded), nonconformity (sediment over igneous/metamorphic), disconformity (parallel erosion surface).

Relative dating uses stratigraphic principles and fossils; absolute dating uses radiometric isotopes with known half-lives (e.g., ¹⁴C for ~50 ka, U–Pb for billions of years).

Geological time scale eras: Palaeozoic (541–252 Ma), Mesozoic (252–66 Ma), Cenozoic (66 Ma–present); Precambrian covers ~88% of Earth history.

Major extinctions: end-Ordovician, Late Devonian, end-Permian (~252 Ma, largest, ~90% species), end-Triassic, end-Cretaceous (~66 Ma, Chicxulub impact).

Fossils as indicators: index fossils are short-ranging and widespread (ammonites, graptolites, trilobites); facies fossils indicate environment.

Evolution evidence in the record: transitional forms (Tiktaalik), adaptive radiation, punctuated equilibrium vs gradualism.

Key events: Great Oxidation Event (~2.4 Ga), Cambrian explosion (~541 Ma), colonisation of land in the Ordovician–Silurian.

Mineral identification: hardness (Mohs 1 talc–10 diamond), cleavage vs fracture, lustre, streak, colour, specific gravity, acid reaction (calcite).

Silicate structures: isolated tetrahedra (olivine) → chains (pyroxene, amphibole) → sheets (mica, clay) → frameworks (quartz, feldspar).

Igneous classification: plutonic vs volcanic, and by silica content - felsic (granite/rhyolite), intermediate (diorite/andesite), mafic (gabbro/basalt), ultramafic (peridotite).

Sedimentary rocks: clastic (conglomerate, sandstone, shale), chemical (limestone, gypsum, halite), organic (coal, chert).

Metamorphic rocks: foliated (slate→phyllite→schist→gneiss) and non-foliated (marble, quartzite, hornfels).

Energy resources: fossil fuels (coal, oil, gas), nuclear (uranium), geothermal, and critical minerals for renewables (lithium, cobalt, rare earths).

Mining methods: open-pit vs underground; environmental impacts include acid mine drainage, tailings, subsidence, and land degradation.

Sustainability: resource depletion, recycling, circular economy, and restoration obligations after mine closure.

Atmospheric composition (dry air): N₂ ~78%, O₂ ~21%, Ar ~0.93%, CO₂ ~0.04%; variable water vapour up to ~4%.

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

Pressure systems: cyclones (low pressure, convergence, rising air, precipitation) vs anticyclones (high pressure, subsidence, clear skies).

Global circulation: Hadley, Ferrel, and Polar cells; trade winds, westerlies, polar easterlies; Coriolis deflection.

Climate controls: latitude, altitude, distance from sea, ocean currents, prevailing winds, relief.

Greenhouse gases: CO₂, CH₄, N₂O, water vapour, CFCs; enhanced greenhouse effect drives anthropogenic warming.

Feedback loops: ice–albedo (positive), water vapour (positive), cloud cover (mixed), carbon uptake by oceans (negative).

Climate proxies: ice cores, tree rings, sediment cores, corals, historical records; Milankovitch cycles drive glacial–interglacial cycles.

Water cycle: evaporation, transpiration, condensation, precipitation, infiltration, runoff, groundwater flow, discharge.

Global water distribution: ~97% saline, ~2.5% freshwater (mostly ice caps and glaciers); accessible freshwater is a small fraction.

Watershed (basin): area drained by a river system; divides separate basins; hydrograph shows discharge response to rainfall.

Groundwater: water table, aquifer (confined vs unconfined), porosity vs permeability, recharge and discharge zones.

Water quality indicators: BOD, COD, dissolved oxygen, nitrates, phosphates, turbidity, pH, heavy metals, coliform bacteria.

Pollution sources: point (industrial discharge, sewage) vs diffuse (agricultural runoff, fertilisers, pesticides).

Eutrophication: nutrient enrichment → algal bloom → oxygen depletion → fish kills; mitigation includes buffer strips and wastewater treatment.

Water management: dams, reservoirs, desalination, irrigation efficiency, pricing, and integrated river basin management.

Ecosystem components: abiotic (light, temperature, water, soil) and biotic (producers, consumers, decomposers).

Energy flow: unidirectional through trophic levels; ~10% transferred between levels (Lindeman's rule); pyramids of numbers, biomass, energy.

Biogeochemical cycles: carbon (photosynthesis, respiration, combustion, dissolution), nitrogen (fixation, nitrification, denitrification), phosphorus (sedimentary, no gaseous phase), water.

Population dynamics: exponential growth vs logistic growth (carrying capacity K); r- vs K-strategists.

Species interactions: competition, predation, mutualism, parasitism, commensalism; competitive exclusion principle.

Biodiversity levels: genetic, species, ecosystem; hotspots and endemism; keystone and indicator species.

Succession: primary vs secondary; pioneer species → climax community; resilience and stability.

Human impacts: habitat fragmentation, invasive species, overexploitation, pollution, climate change.

EIA process: screening, scoping, baseline study, impact prediction, mitigation, reporting, public consultation, decision, monitoring.

Risk = hazard × exposure × vulnerability; risk management reduces any of these components.

Natural hazards: earthquakes, volcanic eruptions, landslides, floods, droughts, storms, coastal erosion, wildfires.

Seismic risk: hazard maps, building codes, retrofitting, early-warning systems, land-use zoning.

Flood mitigation: dams, levees, retention basins, reforestation of catchments, floodplain zoning, insurance.

Land-use planning: restrict development in high-risk zones (floodplains, steep slopes, volcanic flanks); buffer zones.

Sustainability principles: precautionary principle, polluter pays, prevention over remediation, Agenda 2030 SDGs.

Environmental management tools: environmental audits, ISO 14001, life-cycle assessment, carrying capacity assessment.