Karnataka II PUC Geology (KSEAB) cheat sheet

Earth's internal layers by seismic evidence: crust (0–~35 km, to ~70 km under orogens), mantle to 2900 km, outer core (liquid, S-waves blocked) 2900–5150 km, inner core (solid) to 6371 km; Mohorovičić discontinuity separates crust and mantle, Gutenberg discontinuity separates mantle and core.

Isostasy: Airy model - thicker crust floats deeper (roots under mountains); Pratt model - density varies at a constant compensation depth. Post-glacial rebound of Scandinavia records elastic/viscoelastic response of the mantle.

Plate tectonics: divergent (mid-ocean ridge, new basaltic crust, normal faults), convergent (ocean–ocean → island arc; ocean–continent → Andean arc; continent–continent → Himalaya), transform (strike-slip, e.g., San Andreas). Sea-floor spreading produces symmetric magnetic stripes and age-increasing ocean floor.

Weathering: mechanical (frost wedging, exfoliation, salt crystallisation) vs chemical (hydrolysis of feldspar → clay, oxidation of Fe, carbonation of limestone). Bowen's reaction series predicts stability: quartz resists weathering; olivine and Ca-plagioclase alter fastest.

Mass wasting classification by material and motion: creep, slump, debris flow, mudflow, rockfall, rockslide. Trigger factors are slope angle, water content, vegetation removal, undercutting; angle of repose is the maximum stable slope for loose granular material.

Fluvial landforms: V-shaped valleys, gorges, waterfalls and rapids in youth; meanders, oxbow lakes, floodplains, natural levees and deltas in maturity; peneplain in old age. Stream order (Strahler) increases at confluences; drainage patterns - dendritic, radial, trellis, rectangular.

Karst: solution of limestone forms sinkholes, dolines, poljes, caves, stalactites (from roof) and stalagmites (from floor); requires jointed soluble rock, rainfall and a low water table. Karnataka examples: Yana rocks and Borra caves region (Andhra border) illustrate karst and cave development.

Coastal and arid landforms: wave-cut platforms, sea arches, sea stacks, spits and bars; desert - pediments, inselbergs, barchan and seif dunes, yardangs, zeugen. Wind erodes by deflation, abrasion and attrition.

Geomorphic cycle (Davis: youth–maturity–old age) vs Penck's morphological analysis (endogenetic vs exogenetic forces); dynamic equilibrium and grade concepts explain graded stream profiles and knickpoints.

Definition of a mineral: naturally occurring, inorganic, solid, definite chemical composition (within limits), ordered internal structure. Mohs scale: 1 talc, 2 gypsum, 3 calcite, 4 fluorite, 5 apatite, 6 orthoclase, 7 quartz, 8 topaz, 9 corundum, 10 diamond; hardness is a relative, not linear, scale.

Crystal systems (7): cubic, tetragonal, orthorhombic, monoclinic, triclinic, hexagonal, and trigonal (often grouped with hexagonal); defined by axial lengths a, b, c and interaxial angles α, β, γ. Symmetry elements: planes, axes, centre of symmetry; 32 crystal classes.

Silicate classification by SiO4 tetrahedral linkage: nesosilicates (olivine, garnet), sorosilicates (epidote), cyclosilicates (beryl, tourmaline), inosilicates single chain (pyroxene) and double chain (amphibole), phyllosilicates (mica, clay, talc), tectosilicates (quartz, feldspar, zeolite).

Feldspars: orthoclase/microcline (K), albite–anorthite plagioclase series (Na–Ca) with continuous solid solution; twinning - Carlsbad (orthoclase), polysynthetic albite twinning (plagioclase). Quartz shows conchoidal fracture, no cleavage, hardness 7, specific gravity 2.65.

Cleavage vs fracture: cleavage follows planes of weak atomic bonding - basal (mica, 1 direction), prismatic (amphibole, 2 at ~120°), cubic (galena, 3 at 90°), rhombohedral (calcite, 3 at 75°). Calcite effervesces with dilute HCl; dolomite only when powdered or warm acid.

Optical mineralogy: isotropic minerals (cubic, amorphous) are dark under crossed polars; anisotropic minerals show interference colours (birefringence = difference of refractive indices × thickness). Pleochroism, extinction angle and twinning aid identification in thin section.

Physical properties used in hand specimen identification: colour and streak (hematite red streak), lustre (metallic, vitreous, pearly, silky), specific gravity (galena ~7.5, quartz 2.65), magnetism (magnetite), taste (halite), feel (talc soapy).

Common rock-forming minerals and formulae: olivine (Mg,Fe)2SiO4; augite (Ca,Mg,Fe,Al)2(Si,Al)2O6; hornblende complex amphibole; biotite and muscovite K-Al sheet silicates; calcite CaCO3; gypsum CaSO4·2H2O; halite NaCl; magnetite Fe3O4.

Polymorphism: same composition, different structure - diamond/graphite (C), calcite/aragonite (CaCO3), quartz/tridymite/cristobalite (SiO2), kyanite/andalusite/sillimanite (Al2SiO5, pressure–temperature indicators).

Igneous classification by silica: ultrabasic <45% SiO2 (dunite, peridotite), basic 45–52% (gabbro/basalt), intermediate 52–66% (diorite/andesite), acid >66% (granite/rhyolite). Plutonic = coarse-grained (slow cooling), volcanic = fine-grained or glassy (rapid cooling).

Bowen's reaction series (cooling order): discontinuous - olivine → pyroxene → amphibole → biotite; continuous - Ca-plagioclase → Na-plagioclase; both converge to orthoclase, muscovite, then quartz. Explains mineral assemblages and crystallisation from a cooling melt.

Igneous textures: phaneritic (coarse), aphanitic (fine), porphyritic (two-stage cooling), glassy (obsidian), vesicular (pumice, scoria), pyroclastic (tuff, agglomerate), pegmatitic (very coarse). Magma types: basaltic (low viscosity, quiet eruptions), andesitic, rhyolitic (high viscosity, explosive).

Sedimentary rock classification: clastic by grain size - conglomerate/breccia (>2 mm), sandstone (2–0.0625 mm), siltstone, shale (<0.004 mm); chemical - limestone, dolomite, chert, rock salt, gypsum; organic - coal, oil shale. Rounding and sorting indicate transport distance and energy.

Sedimentary structures: bedding, cross-bedding (current direction), graded bedding (turbidites, fining upward), ripple marks (symmetrical = wave, asymmetrical = current), mud cracks (desiccation), sole marks, bioturbation, and fossils. These record palaeoenvironment and palaeocurrent.

Diagenesis: compaction, cementation (calcite, silica, iron oxide), recrystallisation and lithification convert sediment to rock. Porosity and permeability in sandstones and limestones control groundwater and hydrocarbon storage.

Metamorphism types: thermal/contact (around intrusions, non-foliated hornfels), regional/dynamothermal (foliated schists, gneisses), dynamic/cataclastic (mylonite, fault zones), hydrothermal (metasomatism). Agents: heat, pressure (confining and directed), chemically active fluids.

Metamorphic textures and grades: slate → phyllite → schist → gneiss (increasing grade, foliation coarsening); non-foliated - quartzite (from sandstone), marble (from limestone), hornfels. Index minerals: chlorite, biotite, garnet, staurolite, kyanite, sillimanite define zones.

Protolith–product pairs: limestone → marble; sandstone → quartzite; shale → slate → phyllite → schist → gneiss; basalt → greenschist/amphibolite/eclogite; coal → anthracite → graphite. Migmatite marks partial melting at high grade.

Strike and dip define planar orientation: strike is the compass direction of a horizontal line on the plane; dip is the angle of steepest descent measured perpendicular to strike, with dip direction. Apparent dip is always less than true dip except when measured perpendicular to strike.

Folds: anticline (strata arch upward, oldest in core), syncline (youngest in core), monocline (single bend), symmetrical/asymmetrical/overturned/recumbent/isoclinal by axial plane attitude. Plunge is the angle of the fold axis; hinge line, limb, axial plane and crest are key terms.

Fault classification by slip: normal (hanging wall down, extension), reverse/thrust (hanging wall up, compression; thrust has dip <45°), strike-slip (dextral/sinistral), oblique. Recognition criteria: displaced beds, slickensides, drag folds, fault breccia/mylonite, fault scarps, offset streams.

Joints are fractures with no visible displacement; columnar joints in basalt (cooling contraction), sheet joints in granite (unloading). Unconformities: angular (folded then eroded), nonconformity (over igneous/metamorphic), disconformity (parallel erosion surface).

Stress and strain: compressional, tensional, shear stress; elastic, plastic and rupture stages. Strain ellipsoid (X > Y > Z) explains boudinage, foliation and lineation; Mohr circle and Byerlee's law describe failure conditions.

Plate boundaries and structures: divergent → normal faults and rift valleys (East African Rift); convergent → thrusts and folds (Himalaya, subduction zones); transform → strike-slip (San Andreas). Hotspots produce intraplate volcanic chains (Hawaii, Deccan Traps).

Wilson cycle: continental rifting → ocean opening → subduction → continental collision → suturing. Ophiolite sequences (peridotite, gabbro, sheeted dykes, pillow basalt, sediments) mark obducted oceanic crust.

Indian plate tectonics: northward movement at ~5 cm/yr, collision with Eurasia since ~50 Ma, forming the Himalaya; intraplate seismicity along Narmada–Son and other lineaments; Karnataka's Closepet granite and Dharwar schist belts record Archaean crustal processes.

Fossil preservation types: petrifaction/permineralisation, mould (external), cast (internal fill), impression, carbonisation (compression), recrystallisation, replacement (pyrite, silica), trace fossils (footprints, burrows, coprolites). Index fossils are abundant, widely distributed, short-ranging.

Geological time scale eras and periods: Palaeozoic (Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian); Mesozoic (Triassic, Jurassic, Cretaceous); Cenozoic (Palaeogene, Neogene, Quaternary). Major boundaries: 541 Ma, 252 Ma (end-Permian), 66 Ma (K–T).

Key fossil groups and ages: trilobites (Cambrian–Permian), graptolites (Ordovician–Silurian), ammonites (Mesozoic), brachiopods, corals, crinoids, foraminifera (Cretaceous–Recent), stromatolites (Precambrian), Glossopteris flora (Gondwana, Permian), dinosaurs (Mesozoic).

Stratigraphic principles: superposition, original horizontality, lateral continuity, cross-cutting relationships, inclusion, faunal succession. Lithostratigraphy (formation, member, group) vs biostratigraphy (zones) vs chronostratigraphy (system, series, stage).

Correlation tools: index fossils, lithological markers, radiometric dating (U–Pb, K–Ar, Rb–Sr, 14C for <50 ka), magnetostratigraphy, chemostratigraphy (δ13C, δ18O), sequence stratigraphy. Unconformities mark gaps in the stratigraphic record.

Indian stratigraphy: Archaean Dharwar Supergroup (Karnataka), Cuddapah and Vindhyan Supergroups (Proterozoic), Gondwana Supergroup (Carboniferous–Jurassic, coal), Deccan Traps (Cretaceous–Palaeocene), Siwalik Group (Neogene), alluvium (Quaternary).

Palaeoclimate and evolution: mass extinctions at end-Ordovician, end-Devonian, end-Permian (~90% species), end-Triassic and end-Cretaceous (asteroid impact, Chicxulub). Gondwana glaciation (~300 Ma) recorded by tillites and striated pavements.

Fossil record and taphonomy: burial, decay, transport and diagenesis determine preservation. Microfossils (foraminifera, ostracods, diatoms, pollen) are key for biostratigraphy, palaeoenvironment and palaeoclimate reconstruction.

Ore deposit types: magmatic (chromite in Bushveld, Ni–Cu sulphides, diamond in kimberlite), hydrothermal (veins, porphyry Cu, epithermal Au), sedimentary (banded iron formation, coal, phosphorite), residual (bauxite, laterite), placer (gold, diamond, monazite), evaporite (halite, gypsum).

Karnataka mineral wealth: Kolar Gold Fields (gold in Dharwar schist belts), Hutti and Chitradurga gold, Bellary–Hospet iron ore, Sandur manganese, Koppal and Bellary iron, chromite in Hassan and Mysore, magnesite in Mysore, bauxite in Belgaum, limestone for cement, granite and ornamental stone.

Ore genesis processes: magmatic segregation, hydrothermal replacement and cavity filling, metasomatism, supergene enrichment, residual concentration, placer concentration, sedimentary precipitation, metamorphism of pre-existing deposits (e.g., graphite from coal).

Gangue vs ore: gangue is waste mineral (quartz, calcite); ore grade is metal content, cut-off grade determines economic viability. Concentration methods: gravity (jig, table), magnetic, electrostatic, froth flotation, leaching, cyanidation for gold.

Banded iron formations (BIF) host most iron ore; in Karnataka the Bababudan and Sandur groups contain hematite–magnetite ores. Bauxite forms by lateritic weathering of aluminous rocks under tropical climate; India's deposits in Belgaum and coastal Karnataka.

Coal and hydrocarbons: coal rank - peat → lignite → sub-bituminous → bituminous → anthracite (increasing carbon, decreasing volatiles). India's coal is mostly Gondwana (Permian) and Tertiary (NE). Oil and gas occur in structural traps and stratigraphic traps.

Mineral economics and law: reserves vs resources; MMDR Act governs mineral concessions in India; National Mineral Policy; sustainable mining, mine closure plans and environmental clearance are statutory requirements.

Exploration methods: geological mapping, geochemical sampling (soil, stream sediment), geophysical (gravity, magnetic, electrical, seismic), remote sensing, drilling and assay. Ore reserve estimation via block modelling and grade–tonnage curves.

Hydrological cycle and groundwater: infiltration, percolation, recharge, discharge, evapotranspiration. Aquifer types - unconfined (water table), confined (artesian, potentiometric surface), perched. Aquiclude, aquifuge, aquitard are relative terms of permeability.

Porosity (n) = volume of voids / total volume × 100; specific yield (Sy) = drainable water; specific retention = water held. Permeability (hydraulic conductivity K) measured by Darcy's law: Q = K·A·(dh/dL). Transmissivity T = K × saturated thickness b.

Pumping test analysis: Theis (unsteady) and Jacob's straight-line (steady, late time) methods give T and storativity S. Well yield, drawdown, cone of depression, radius of influence, specific capacity = yield/drawdown.

Groundwater quality: TDS, hardness (as CaCO3), pH, chloride, fluoride (excess causes fluorosis in Karnataka's granitic terrain), nitrate, arsenic, iron. Piper and Wilcox diagrams classify water for irrigation (SAR, RSC).

Water harvesting and management: recharge wells, percolation tanks, check dams, contour bunds, watershed development; Karnataka's tank irrigation tradition and borewell dependence; over-exploitation causes falling water table and saline intrusion in coastal belts.

Environmental geology hazards: earthquakes (Karnataka in seismic zone II–III), landslides in Western Ghats (heavy rainfall, deforestation), soil erosion, laterite formation, mine spoil degradation, groundwater contamination from tanning and industries.

Environmental impact assessment (EIA) steps: screening, scoping, baseline study, impact prediction, mitigation, EMP, public hearing and clearance. Pollution types: air (SPM, SO2, NOx), water (BOD, COD), soil (heavy metals), noise.

Waste management and remediation: sanitary landfill, leachate control, bioremediation, phytoremediation, permeable reactive barriers. Sustainable development and carrying capacity underpin environmental geology practice.

Engineering geology: rock mass classification (RMR, Q-system), rock strength, weathering grade, joint spacing and orientation determine foundation and slope stability. Bearing capacity and settlement govern foundation design; site investigation uses boreholes, SPT, plate load and geophysical tests.

Tunnels and dams: alignment should cross strata at right angles, avoid fault zones and shear zones; tunnel support depends on rock mass quality. Dam site selection needs impermeable foundation, sound abutments, low permeability and adequate reservoir catchment.

Landslide analysis: factor of safety = resisting forces / driving forces; slope stability improved by benching, drainage, retaining walls, rock bolts, shotcrete and vegetation. Landslide hazard zonation maps classify risk in Western Ghats.

Geophysical methods: seismic refraction (depth to bedrock), electrical resistivity (groundwater, ore), gravity (density contrasts), magnetic (ore bodies, basement), GPR (shallow), well logging. Each method maps a physical property contrast, not direct geology.

Remote sensing and GIS: satellite data (LANDSAT, IRS, Sentinel) for lithological mapping, lineament analysis, land use, mineral exploration and groundwater potential zonation; GIS overlays thematic layers with weighted index methods.

Geological mapping scale and methods: reconnaissance, detailed and subsurface mapping; field tools - Brunton compass/clinometer, GPS, hand lens, hammer, acid bottle, tape; recording strike/dip, lithology, structures and sample locations in a field notebook.

Construction materials: aggregate quality (soundness, grading, alkali–silica reactivity), cement raw materials (limestone, shale, gypsum), brick clay, dimension stone. Testing: crushing strength, Los Angeles abrasion, water absorption.

Mining geology applications: orebody modelling, grade control, pit slope design, dilution control, mine water management, and exploration drilling with core logging and assay.

Field methods: traverse mapping, outcrop description (lithology, colour, texture, structure, weathering), sampling with proper labelling, structural measurements with Brunton compass (strike, dip, plunge, trend), and sketch/photograph documentation.

Karnataka geology at a glance: Dharwar Craton (Archaean), Western Dharwar Craton (older, 3.0–3.4 Ga gneisses and greenstone belts) vs Eastern Dharwar Craton (younger, 2.5–2.7 Ga, Closepet granite, Kolar and Hutti schist belts), Deccan Traps in northern Karnataka, Proterozoic Kaladgi and Bhima basins, and laterite/Quaternary cover.

Dharwar Supergroup divisions: Bababudan Group (base - quartzite, BIF, metabasalt) and Chitradurga Group (greywacke, phyllite, limestone, BIF), with younger Kaladgi and Bhima Supergroups on the craton margin. Sargur Group (older, ~3.3 Ga) hosts ultramafic and BIF sequences.

Closepet Granite (~2.5 Ga) is a N–S linear belt of granite and migmatite marking a suture/thermal boundary within the Dharwar Craton; its emplacement relates to late Archaean cratonisation.

Greenstone belts of Karnataka: Kolar (gold, amphibolite, BIF), Hutti (gold), Sandur (iron and manganese), Chitradurga (copper, BIF), Bababudan (iron ore), Nuggehalli and Holenarsipur schist belts. They are Archaean volcano-sedimentary sequences in a granite–greenstone terrain.

Deccan Traps: ~66 Ma flood basalts covering parts of northern Karnataka (Bidar, Gulbarga), with intertrappean beds and laterite caps; associated with the Réunion hotspot and K–Pg boundary events.

Geological Survey of India and state agencies: GSI mapping, Department of Mines and Geology (Karnataka), and DMG mineral exploration; field visits to Kolar, Hutti, Sandur and Closepet provide type examples for exams.

Field safety and ethics: carry helmet, boots, first aid, maps and compass; obtain permission for mine and quarry visits; record GPS coordinates and never remove protected specimens from reserved areas.

Earth's internal layers by seismic evidence: crust (0–~35 km, to ~70 km under orogens), mantle to 2900 km, outer core (liquid, S-waves blocked) 2900–5150 km, inner core (solid) to 6371 km; Mohorovičić discontinuity separates crust and mantle, Gutenberg discontinuity separates mantle and core.

Isostasy: Airy model - thicker crust floats deeper (roots under mountains); Pratt model - density varies at a constant compensation depth. Post-glacial rebound of Scandinavia records elastic/viscoelastic response of the mantle.

Plate tectonics: divergent (mid-ocean ridge, new basaltic crust, normal faults), convergent (ocean–ocean → island arc; ocean–continent → Andean arc; continent–continent → Himalaya), transform (strike-slip, e.g., San Andreas). Sea-floor spreading produces symmetric magnetic stripes and age-increasing ocean floor.

Weathering: mechanical (frost wedging, exfoliation, salt crystallisation) vs chemical (hydrolysis of feldspar → clay, oxidation of Fe, carbonation of limestone). Bowen's reaction series predicts stability: quartz resists weathering; olivine and Ca-plagioclase alter fastest.

Mass wasting classification by material and motion: creep, slump, debris flow, mudflow, rockfall, rockslide. Trigger factors are slope angle, water content, vegetation removal, undercutting; angle of repose is the maximum stable slope for loose granular material.

Fluvial landforms: V-shaped valleys, gorges, waterfalls and rapids in youth; meanders, oxbow lakes, floodplains, natural levees and deltas in maturity; peneplain in old age. Stream order (Strahler) increases at confluences; drainage patterns - dendritic, radial, trellis, rectangular.

Karst: solution of limestone forms sinkholes, dolines, poljes, caves, stalactites (from roof) and stalagmites (from floor); requires jointed soluble rock, rainfall and a low water table. Karnataka examples: Yana rocks and Borra caves region (Andhra border) illustrate karst and cave development.

Coastal and arid landforms: wave-cut platforms, sea arches, sea stacks, spits and bars; desert - pediments, inselbergs, barchan and seif dunes, yardangs, zeugen. Wind erodes by deflation, abrasion and attrition.

Geomorphic cycle (Davis: youth–maturity–old age) vs Penck's morphological analysis (endogenetic vs exogenetic forces); dynamic equilibrium and grade concepts explain graded stream profiles and knickpoints.

Definition of a mineral: naturally occurring, inorganic, solid, definite chemical composition (within limits), ordered internal structure. Mohs scale: 1 talc, 2 gypsum, 3 calcite, 4 fluorite, 5 apatite, 6 orthoclase, 7 quartz, 8 topaz, 9 corundum, 10 diamond; hardness is a relative, not linear, scale.

Crystal systems (7): cubic, tetragonal, orthorhombic, monoclinic, triclinic, hexagonal, and trigonal (often grouped with hexagonal); defined by axial lengths a, b, c and interaxial angles α, β, γ. Symmetry elements: planes, axes, centre of symmetry; 32 crystal classes.

Silicate classification by SiO4 tetrahedral linkage: nesosilicates (olivine, garnet), sorosilicates (epidote), cyclosilicates (beryl, tourmaline), inosilicates single chain (pyroxene) and double chain (amphibole), phyllosilicates (mica, clay, talc), tectosilicates (quartz, feldspar, zeolite).

Feldspars: orthoclase/microcline (K), albite–anorthite plagioclase series (Na–Ca) with continuous solid solution; twinning - Carlsbad (orthoclase), polysynthetic albite twinning (plagioclase). Quartz shows conchoidal fracture, no cleavage, hardness 7, specific gravity 2.65.

Cleavage vs fracture: cleavage follows planes of weak atomic bonding - basal (mica, 1 direction), prismatic (amphibole, 2 at ~120°), cubic (galena, 3 at 90°), rhombohedral (calcite, 3 at 75°). Calcite effervesces with dilute HCl; dolomite only when powdered or warm acid.

Optical mineralogy: isotropic minerals (cubic, amorphous) are dark under crossed polars; anisotropic minerals show interference colours (birefringence = difference of refractive indices × thickness). Pleochroism, extinction angle and twinning aid identification in thin section.

Physical properties used in hand specimen identification: colour and streak (hematite red streak), lustre (metallic, vitreous, pearly, silky), specific gravity (galena ~7.5, quartz 2.65), magnetism (magnetite), taste (halite), feel (talc soapy).

Common rock-forming minerals and formulae: olivine (Mg,Fe)2SiO4; augite (Ca,Mg,Fe,Al)2(Si,Al)2O6; hornblende complex amphibole; biotite and muscovite K-Al sheet silicates; calcite CaCO3; gypsum CaSO4·2H2O; halite NaCl; magnetite Fe3O4.

Polymorphism: same composition, different structure - diamond/graphite (C), calcite/aragonite (CaCO3), quartz/tridymite/cristobalite (SiO2), kyanite/andalusite/sillimanite (Al2SiO5, pressure–temperature indicators).

Igneous classification by silica: ultrabasic <45% SiO2 (dunite, peridotite), basic 45–52% (gabbro/basalt), intermediate 52–66% (diorite/andesite), acid >66% (granite/rhyolite). Plutonic = coarse-grained (slow cooling), volcanic = fine-grained or glassy (rapid cooling).

Bowen's reaction series (cooling order): discontinuous - olivine → pyroxene → amphibole → biotite; continuous - Ca-plagioclase → Na-plagioclase; both converge to orthoclase, muscovite, then quartz. Explains mineral assemblages and crystallisation from a cooling melt.

Igneous textures: phaneritic (coarse), aphanitic (fine), porphyritic (two-stage cooling), glassy (obsidian), vesicular (pumice, scoria), pyroclastic (tuff, agglomerate), pegmatitic (very coarse). Magma types: basaltic (low viscosity, quiet eruptions), andesitic, rhyolitic (high viscosity, explosive).

Sedimentary rock classification: clastic by grain size - conglomerate/breccia (>2 mm), sandstone (2–0.0625 mm), siltstone, shale (<0.004 mm); chemical - limestone, dolomite, chert, rock salt, gypsum; organic - coal, oil shale. Rounding and sorting indicate transport distance and energy.

Sedimentary structures: bedding, cross-bedding (current direction), graded bedding (turbidites, fining upward), ripple marks (symmetrical = wave, asymmetrical = current), mud cracks (desiccation), sole marks, bioturbation, and fossils. These record palaeoenvironment and palaeocurrent.

Diagenesis: compaction, cementation (calcite, silica, iron oxide), recrystallisation and lithification convert sediment to rock. Porosity and permeability in sandstones and limestones control groundwater and hydrocarbon storage.

Metamorphism types: thermal/contact (around intrusions, non-foliated hornfels), regional/dynamothermal (foliated schists, gneisses), dynamic/cataclastic (mylonite, fault zones), hydrothermal (metasomatism). Agents: heat, pressure (confining and directed), chemically active fluids.

Metamorphic textures and grades: slate → phyllite → schist → gneiss (increasing grade, foliation coarsening); non-foliated - quartzite (from sandstone), marble (from limestone), hornfels. Index minerals: chlorite, biotite, garnet, staurolite, kyanite, sillimanite define zones.

Protolith–product pairs: limestone → marble; sandstone → quartzite; shale → slate → phyllite → schist → gneiss; basalt → greenschist/amphibolite/eclogite; coal → anthracite → graphite. Migmatite marks partial melting at high grade.

Strike and dip define planar orientation: strike is the compass direction of a horizontal line on the plane; dip is the angle of steepest descent measured perpendicular to strike, with dip direction. Apparent dip is always less than true dip except when measured perpendicular to strike.

Folds: anticline (strata arch upward, oldest in core), syncline (youngest in core), monocline (single bend), symmetrical/asymmetrical/overturned/recumbent/isoclinal by axial plane attitude. Plunge is the angle of the fold axis; hinge line, limb, axial plane and crest are key terms.

Fault classification by slip: normal (hanging wall down, extension), reverse/thrust (hanging wall up, compression; thrust has dip <45°), strike-slip (dextral/sinistral), oblique. Recognition criteria: displaced beds, slickensides, drag folds, fault breccia/mylonite, fault scarps, offset streams.

Joints are fractures with no visible displacement; columnar joints in basalt (cooling contraction), sheet joints in granite (unloading). Unconformities: angular (folded then eroded), nonconformity (over igneous/metamorphic), disconformity (parallel erosion surface).

Stress and strain: compressional, tensional, shear stress; elastic, plastic and rupture stages. Strain ellipsoid (X > Y > Z) explains boudinage, foliation and lineation; Mohr circle and Byerlee's law describe failure conditions.

Plate boundaries and structures: divergent → normal faults and rift valleys (East African Rift); convergent → thrusts and folds (Himalaya, subduction zones); transform → strike-slip (San Andreas). Hotspots produce intraplate volcanic chains (Hawaii, Deccan Traps).

Wilson cycle: continental rifting → ocean opening → subduction → continental collision → suturing. Ophiolite sequences (peridotite, gabbro, sheeted dykes, pillow basalt, sediments) mark obducted oceanic crust.

Indian plate tectonics: northward movement at ~5 cm/yr, collision with Eurasia since ~50 Ma, forming the Himalaya; intraplate seismicity along Narmada–Son and other lineaments; Karnataka's Closepet granite and Dharwar schist belts record Archaean crustal processes.

Fossil preservation types: petrifaction/permineralisation, mould (external), cast (internal fill), impression, carbonisation (compression), recrystallisation, replacement (pyrite, silica), trace fossils (footprints, burrows, coprolites). Index fossils are abundant, widely distributed, short-ranging.

Geological time scale eras and periods: Palaeozoic (Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian); Mesozoic (Triassic, Jurassic, Cretaceous); Cenozoic (Palaeogene, Neogene, Quaternary). Major boundaries: 541 Ma, 252 Ma (end-Permian), 66 Ma (K–T).

Key fossil groups and ages: trilobites (Cambrian–Permian), graptolites (Ordovician–Silurian), ammonites (Mesozoic), brachiopods, corals, crinoids, foraminifera (Cretaceous–Recent), stromatolites (Precambrian), Glossopteris flora (Gondwana, Permian), dinosaurs (Mesozoic).

Stratigraphic principles: superposition, original horizontality, lateral continuity, cross-cutting relationships, inclusion, faunal succession. Lithostratigraphy (formation, member, group) vs biostratigraphy (zones) vs chronostratigraphy (system, series, stage).

Correlation tools: index fossils, lithological markers, radiometric dating (U–Pb, K–Ar, Rb–Sr, 14C for <50 ka), magnetostratigraphy, chemostratigraphy (δ13C, δ18O), sequence stratigraphy. Unconformities mark gaps in the stratigraphic record.

Indian stratigraphy: Archaean Dharwar Supergroup (Karnataka), Cuddapah and Vindhyan Supergroups (Proterozoic), Gondwana Supergroup (Carboniferous–Jurassic, coal), Deccan Traps (Cretaceous–Palaeocene), Siwalik Group (Neogene), alluvium (Quaternary).

Palaeoclimate and evolution: mass extinctions at end-Ordovician, end-Devonian, end-Permian (~90% species), end-Triassic and end-Cretaceous (asteroid impact, Chicxulub). Gondwana glaciation (~300 Ma) recorded by tillites and striated pavements.

Fossil record and taphonomy: burial, decay, transport and diagenesis determine preservation. Microfossils (foraminifera, ostracods, diatoms, pollen) are key for biostratigraphy, palaeoenvironment and palaeoclimate reconstruction.

Ore deposit types: magmatic (chromite in Bushveld, Ni–Cu sulphides, diamond in kimberlite), hydrothermal (veins, porphyry Cu, epithermal Au), sedimentary (banded iron formation, coal, phosphorite), residual (bauxite, laterite), placer (gold, diamond, monazite), evaporite (halite, gypsum).

Karnataka mineral wealth: Kolar Gold Fields (gold in Dharwar schist belts), Hutti and Chitradurga gold, Bellary–Hospet iron ore, Sandur manganese, Koppal and Bellary iron, chromite in Hassan and Mysore, magnesite in Mysore, bauxite in Belgaum, limestone for cement, granite and ornamental stone.

Ore genesis processes: magmatic segregation, hydrothermal replacement and cavity filling, metasomatism, supergene enrichment, residual concentration, placer concentration, sedimentary precipitation, metamorphism of pre-existing deposits (e.g., graphite from coal).

Gangue vs ore: gangue is waste mineral (quartz, calcite); ore grade is metal content, cut-off grade determines economic viability. Concentration methods: gravity (jig, table), magnetic, electrostatic, froth flotation, leaching, cyanidation for gold.

Banded iron formations (BIF) host most iron ore; in Karnataka the Bababudan and Sandur groups contain hematite–magnetite ores. Bauxite forms by lateritic weathering of aluminous rocks under tropical climate; India's deposits in Belgaum and coastal Karnataka.

Coal and hydrocarbons: coal rank - peat → lignite → sub-bituminous → bituminous → anthracite (increasing carbon, decreasing volatiles). India's coal is mostly Gondwana (Permian) and Tertiary (NE). Oil and gas occur in structural traps and stratigraphic traps.

Mineral economics and law: reserves vs resources; MMDR Act governs mineral concessions in India; National Mineral Policy; sustainable mining, mine closure plans and environmental clearance are statutory requirements.

Exploration methods: geological mapping, geochemical sampling (soil, stream sediment), geophysical (gravity, magnetic, electrical, seismic), remote sensing, drilling and assay. Ore reserve estimation via block modelling and grade–tonnage curves.

Hydrological cycle and groundwater: infiltration, percolation, recharge, discharge, evapotranspiration. Aquifer types - unconfined (water table), confined (artesian, potentiometric surface), perched. Aquiclude, aquifuge, aquitard are relative terms of permeability.

Porosity (n) = volume of voids / total volume × 100; specific yield (Sy) = drainable water; specific retention = water held. Permeability (hydraulic conductivity K) measured by Darcy's law: Q = K·A·(dh/dL). Transmissivity T = K × saturated thickness b.

Pumping test analysis: Theis (unsteady) and Jacob's straight-line (steady, late time) methods give T and storativity S. Well yield, drawdown, cone of depression, radius of influence, specific capacity = yield/drawdown.

Groundwater quality: TDS, hardness (as CaCO3), pH, chloride, fluoride (excess causes fluorosis in Karnataka's granitic terrain), nitrate, arsenic, iron. Piper and Wilcox diagrams classify water for irrigation (SAR, RSC).

Water harvesting and management: recharge wells, percolation tanks, check dams, contour bunds, watershed development; Karnataka's tank irrigation tradition and borewell dependence; over-exploitation causes falling water table and saline intrusion in coastal belts.

Environmental geology hazards: earthquakes (Karnataka in seismic zone II–III), landslides in Western Ghats (heavy rainfall, deforestation), soil erosion, laterite formation, mine spoil degradation, groundwater contamination from tanning and industries.

Environmental impact assessment (EIA) steps: screening, scoping, baseline study, impact prediction, mitigation, EMP, public hearing and clearance. Pollution types: air (SPM, SO2, NOx), water (BOD, COD), soil (heavy metals), noise.

Waste management and remediation: sanitary landfill, leachate control, bioremediation, phytoremediation, permeable reactive barriers. Sustainable development and carrying capacity underpin environmental geology practice.

Engineering geology: rock mass classification (RMR, Q-system), rock strength, weathering grade, joint spacing and orientation determine foundation and slope stability. Bearing capacity and settlement govern foundation design; site investigation uses boreholes, SPT, plate load and geophysical tests.

Tunnels and dams: alignment should cross strata at right angles, avoid fault zones and shear zones; tunnel support depends on rock mass quality. Dam site selection needs impermeable foundation, sound abutments, low permeability and adequate reservoir catchment.

Landslide analysis: factor of safety = resisting forces / driving forces; slope stability improved by benching, drainage, retaining walls, rock bolts, shotcrete and vegetation. Landslide hazard zonation maps classify risk in Western Ghats.

Geophysical methods: seismic refraction (depth to bedrock), electrical resistivity (groundwater, ore), gravity (density contrasts), magnetic (ore bodies, basement), GPR (shallow), well logging. Each method maps a physical property contrast, not direct geology.

Remote sensing and GIS: satellite data (LANDSAT, IRS, Sentinel) for lithological mapping, lineament analysis, land use, mineral exploration and groundwater potential zonation; GIS overlays thematic layers with weighted index methods.

Geological mapping scale and methods: reconnaissance, detailed and subsurface mapping; field tools - Brunton compass/clinometer, GPS, hand lens, hammer, acid bottle, tape; recording strike/dip, lithology, structures and sample locations in a field notebook.

Construction materials: aggregate quality (soundness, grading, alkali–silica reactivity), cement raw materials (limestone, shale, gypsum), brick clay, dimension stone. Testing: crushing strength, Los Angeles abrasion, water absorption.

Mining geology applications: orebody modelling, grade control, pit slope design, dilution control, mine water management, and exploration drilling with core logging and assay.

Field methods: traverse mapping, outcrop description (lithology, colour, texture, structure, weathering), sampling with proper labelling, structural measurements with Brunton compass (strike, dip, plunge, trend), and sketch/photograph documentation.

Karnataka geology at a glance: Dharwar Craton (Archaean), Western Dharwar Craton (older, 3.0–3.4 Ga gneisses and greenstone belts) vs Eastern Dharwar Craton (younger, 2.5–2.7 Ga, Closepet granite, Kolar and Hutti schist belts), Deccan Traps in northern Karnataka, Proterozoic Kaladgi and Bhima basins, and laterite/Quaternary cover.

Dharwar Supergroup divisions: Bababudan Group (base - quartzite, BIF, metabasalt) and Chitradurga Group (greywacke, phyllite, limestone, BIF), with younger Kaladgi and Bhima Supergroups on the craton margin. Sargur Group (older, ~3.3 Ga) hosts ultramafic and BIF sequences.

Closepet Granite (~2.5 Ga) is a N–S linear belt of granite and migmatite marking a suture/thermal boundary within the Dharwar Craton; its emplacement relates to late Archaean cratonisation.

Greenstone belts of Karnataka: Kolar (gold, amphibolite, BIF), Hutti (gold), Sandur (iron and manganese), Chitradurga (copper, BIF), Bababudan (iron ore), Nuggehalli and Holenarsipur schist belts. They are Archaean volcano-sedimentary sequences in a granite–greenstone terrain.

Deccan Traps: ~66 Ma flood basalts covering parts of northern Karnataka (Bidar, Gulbarga), with intertrappean beds and laterite caps; associated with the Réunion hotspot and K–Pg boundary events.

Geological Survey of India and state agencies: GSI mapping, Department of Mines and Geology (Karnataka), and DMG mineral exploration; field visits to Kolar, Hutti, Sandur and Closepet provide type examples for exams.

Field safety and ethics: carry helmet, boots, first aid, maps and compass; obtain permission for mine and quarry visits; record GPS coordinates and never remove protected specimens from reserved areas.