Lithosphere
Structure and composition
The lithosphere is the rigid outer shell (crust plus uppermost mantle) broken into plates. Know the layered Earth: crust (continental, granitic and thicker; oceanic, basaltic and denser), mantle, outer core (liquid) and inner core (solid). The Mohorovičić discontinuity separates crust from mantle. Rocks fall into igneous (from magma), sedimentary (layered, from deposition) and metamorphic (altered by heat and pressure); the rock cycle links them.
Plate tectonics
Plates move on the asthenosphere. At divergent boundaries (mid-ocean ridges, rift valleys) new crust forms; at convergent boundaries you get subduction, ocean trenches, volcanic arcs and fold mountains; at transform boundaries plates slide and earthquakes occur. Minerals and fossil fuels form under specific conditions, and their distribution follows geology.
Processes and hazards
Weathering (physical, chemical, biological) breaks rock in place; erosion transports it; deposition builds landforms. Earthquakes are measured by magnitude (energy released) and intensity (effects felt), so the same quake has one magnitude but many intensities. Volcanoes range from gentle shield eruptions to explosive stratovolcanoes.
Traps
Common errors: confusing weathering with erosion; thinking the mantle is liquid (only the outer core is); mixing magnitude and intensity; and assuming all mountains are volcanic.
Worked example
A question asks why the Pacific rim has many volcanoes and deep earthquakes. Answer: it is a convergent zone where dense oceanic plates subduct, generating friction earthquakes at depth and magma that feeds volcanic arcs.