Playbook
Earth's Structure, Landforms and Geological Time
74 q · 20% HARD. Earth's Interior, Crust and Plate Tectonics (18 · 28% HARD — densest HARD subtopic, plate-boundary types, seismic-wave layering), Landforms and Mass Movements (15 · 13% HARD), Rocks, Minerals and Geological Time (14 · 29% HARD — igneous/sedimentary/metamorphic identification), Weathering and Denudation (9 · 0% HARD — guaranteed marks pocket), Earthquakes (8 · 37% HARD), plus Volcanoes + Soils. Apply strand because mechanism-tracing dominates: tectonic processes, rock-cycle classification, weathering chemistry.
- questions in the bank
- 74
- tagged HARD
- 20%
- subtopic(s)
- 7
- worked examples
- 2
When you’ll see it
A plate-tectonics or earthquake question (plate-boundary type, seismic-wave behaviour), a rock-type identification (igneous/sedimentary/metamorphic), a landform question (folding/faulting/erosion features), a weathering-process question (mechanical vs chemical vs biological), or a soil/volcano question.
How this chapter is tested
74 q in 10 years, 20% HARD. The Apply strand workhorse for solid-earth geography — every subtopic requires tracing a process, not just naming a feature. Earth's Interior, Crust and Plate Tectonics (18 q · 28% HARD) is the chapter's densest HARD subtopic. Earth's layers: inner core (solid iron-nickel, 5100–6371 km depth, ~5500°C), outer core (LIQUID iron-nickel, 2900–5100 km, generates magnetic field via geodynamo), mantle (silicate rocks, 30–2900 km; upper mantle includes asthenosphere = partial melt, drives convection currents that move plates), crust (5–10 km oceanic = basalt-dense; 30–70 km continental = granite-light). Discontinuities: Moho (crust-mantle), Gutenberg (mantle-outer core), Lehmann (outer-inner core). Plate boundaries: CONVERGENT (collide — oceanic-continental = subduction + volcanic arc + deep trenches, e.g. Andes; continental-continental = mountain folding, e.g. Himalayas; oceanic-oceanic = island arcs, e.g. Japan), DIVERGENT (separate — mid-oceanic ridges = seafloor spreading, e.g. Mid-Atlantic Ridge), TRANSFORM (slide past — strike-slip faults, e.g. San Andreas California).
Landforms and Mass Movements (15 q · 13% HARD) tests landform genesis. Fold mountains (Himalayas, Andes, Alps, Rockies) — formed by compression at convergent boundaries; block mountains (Sierra Nevada, Vosges, Black Forest) — formed by faulting; volcanic mountains (Mauna Loa Hawaii, Mount Fuji, Mount Vesuvius) — formed by magma eruption; residual mountains (Aravalli — among oldest in world) — what's left after erosion. Plateaus: intermontane (Tibet, Bolivian) — between mountain ranges; piedmont (Patagonia) — at mountain base; volcanic (Deccan, Columbia) — lava flows. Erosion features by agent: river — V-shaped valleys, waterfalls, ox-bow lakes, deltas; glacier — U-shaped valleys, cirques, moraines, fjords; wind — yardangs, sand dunes, mushroom rocks; sea — sea cliffs, sea caves, stacks, beaches; underground water — caves, sinkholes, stalactites, stalagmites. Mass movements: landslides, avalanches, rockfalls, mudflows, soil creep.
Rocks, Minerals and Geological Time (14 q · 29% HARD): Igneous rocks form from COOLED MAGMA — intrusive/plutonic (cooled SLOWLY underground → coarse-grained → granite, gabbro), extrusive/volcanic (cooled FAST at surface → fine-grained → basalt, rhyolite, obsidian, pumice). Sedimentary rocks form from compacted sediments — mechanically formed (sandstone, shale, conglomerate), CHEMICALLY formed (chert, halite/rock salt, gypsum), organically formed (limestone, coal, chalk). The 2025 HARD PYQ tests sedimentary classification — chert is chemically formed (silica precipitates), shale is mechanical. Metamorphic rocks form from heat/pressure transformation: limestone → MARBLE, sandstone → QUARTZITE, shale → SLATE → schist → gneiss, granite → gneiss, basalt → schist, coal → anthracite. The 2026 EASY PYQ tests quartzite genesis — metamorphosed from sandstone. Rock cycle: igneous ↔ sedimentary ↔ metamorphic. Earthquakes and Seismic Waves (8 q · 37% HARD): P-waves (Primary, longitudinal/compressional, fastest at 5–8 km/s, travel through solid + liquid + gas — through everything); S-waves (Secondary, transverse/shear, ~3–4 km/s, CAN'T travel through liquid — that's how we know outer core is liquid because S-waves don't pass through it); L-waves (surface, slowest, most destructive, travel along Earth's surface). Magnitude: Richter (logarithmic, each unit = 10× amplitude), Moment Magnitude (modern). Volcanoes: shield (low slope, basaltic, effusive — Hawaii), composite/stratovolcano (steep, andesitic, EXPLOSIVE eruptions with pyroclastic flows — Fuji, Vesuvius), cinder cone (small, mafic). The 2026 MOD PYQ tests composite volcanoes — explosive + pyroclastic + steep.
The sub-skills
The rules and habits that decide whether you get a question right.
Earth's interior layer + composition
Inner core: solid iron-nickel (5100–6371 km, 5500°C, density 13). Outer core: LIQUID iron-nickel (2900–5100 km, generates magnetic field via geodynamo). Mantle: silicate rocks (30–2900 km); asthenosphere = upper mantle partial-melt (drives plate convection). Crust: oceanic basalt-dense (5–10 km, 3.0 g/cm³); continental granite-light (30–70 km, 2.7 g/cm³). Discontinuities: Moho (crust-mantle), Gutenberg (mantle-outer core), Lehmann (outer-inner core).
Plate boundary type → resulting feature
Convergent oceanic-continental → SUBDUCTION + volcanic arc + deep trench + earthquakes (Andes, Cascades). Convergent continental-continental → MOUNTAIN FOLDING + earthquakes (Himalayas, Alps). Convergent oceanic-oceanic → ISLAND ARC + trench (Japan, Aleutians, Mariana). Divergent → MID-OCEANIC RIDGE + seafloor spreading + volcanic activity (Mid-Atlantic Ridge, East Pacific Rise). Transform → STRIKE-SLIP FAULT + shallow earthquakes (San Andreas, Anatolian).
Rock-type identification by formation process
IGNEOUS: cooled magma. Intrusive (slow, deep, coarse) = granite, gabbro. Extrusive (fast, surface, fine) = basalt, rhyolite, obsidian, pumice. SEDIMENTARY: compacted sediments. Mechanical = sandstone, shale, conglomerate. Chemical = chert, halite/rock salt, gypsum. Organic = limestone, coal, chalk. METAMORPHIC: heat/pressure. Limestone → marble. Sandstone → quartzite. Shale → slate → schist → gneiss. Granite → gneiss. Basalt → schist. Coal → anthracite.
Seismic-wave behaviour + Earth-interior inference
P-waves: Primary, longitudinal/compressional, fastest (5–8 km/s), travel through solid + liquid + gas. S-waves: Secondary, transverse/shear (3–4 km/s), CAN'T travel through liquid — that's why S-wave SHADOW ZONE behind outer core tells us outer core is LIQUID. L-waves: surface (Love + Rayleigh), slowest, most destructive (cause building damage). Magnitude: Richter scale logarithmic (each unit = 10× amplitude, 32× energy). Modern: Moment Magnitude scale.
Volcano type + eruption character
Shield volcano: low slope, basaltic lava, EFFUSIVE eruptions (smooth, low silica, runny lava), Hawaii (Mauna Loa, Mauna Kea), Iceland. Composite/stratovolcano: steep, andesitic lava, EXPLOSIVE eruptions, pyroclastic flows + ash columns, Mount Fuji, Mount Vesuvius, Krakatoa, Mount St. Helens. Cinder cone: small, mafic, fragmented ejecta. Caldera: collapsed magma chamber, very large (Yellowstone, Toba).
2 worked examples from the bank
Real past-year questions illustrating the playbook. Click to reveal options + solution.
[Q113 · Sep · 2025]
[Q105 · Apr · 2026]
Traps to expect
Distractor shapes specific to this chapter. The page-wide Traps section covers the bank-level patterns.
S-waves travel through liquid
S-waves CAN'T travel through liquid (transverse waves need shear strength, which liquids lack). Distractor says S-waves travel through outer core or all Earth's layers. The S-wave SHADOW ZONE (104°–140° from epicenter) is the direct evidence that outer core is liquid. P-waves travel through everything (solid + liquid + gas), but slow down through liquid. Memorise: P = Pass through everything; S = Stops at liquid.
Marble is sedimentary (or limestone is metamorphic)
Marble is METAMORPHIC (formed from limestone under heat/pressure). Limestone is SEDIMENTARY (organically formed, mostly calcium carbonate from marine organism shells). Distractor swaps the categories. Other swap-prone pairs: quartzite (metamorphic, FROM sandstone-sedimentary), slate (metamorphic, FROM shale-sedimentary), gneiss (metamorphic, FROM granite-igneous OR shale path).
Convergent boundaries always form mountains
Convergent boundaries can form mountains (continental-continental → Himalayas) OR subduction zones with volcanic arcs (oceanic-continental → Andes) OR island arcs (oceanic-oceanic → Japan). The outcome depends on the type of crust colliding. Distractor says 'all convergent boundaries form mountain ranges' — wrong, oceanic-oceanic forms island arcs + trenches, not large mountain ranges.
Chert is mechanically formed
Chert is a CHEMICALLY formed sedimentary rock — silica (SiO₂) precipitates out of solution to form chert, flint, jasper. Distractor labels chert as mechanically formed. Mechanical sedimentary rocks: sandstone, shale, conglomerate, breccia (compacted from rock fragments). Chemical: chert, halite, gypsum, dolomite. Organic: limestone, coal, chalk. The 2025 HARD PYQ tests this exact distinction.
Drill every earth's structure, landforms and geological time question
74 questions from the bank, scoped to 7 bundled subtopics.
Related playbooks
Often paired with this one — drill these next if you found the worked examples above tractable.