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🌍 Earth’s Structure
Q: What are the four main layers of the Earth? A: Crust, mantle, outer core, inner core. Q: What is the lithosphere? A: The rigid outer layer of the Earth, made up of the crust and uppermost mantle. Q: What is the asthenosphere? A: A semi-molten, “plastic-like” layer of the mantle beneath the lithosphere, where convection currents occur.
🌍 Plate Movement
Q: What drives tectonic plate movement? A: Convection currents in the mantle. Q: How do convection currents cause plate movement? A: Hot magma rises, spreads, cools, and sinks, dragging plates with it.
🌍 Types of Plates
Q: What are the two types of tectonic plates? A: Oceanic plates and continental plates. Q: What is oceanic crust made of? A: Dense rock rich in silicon and magnesium (basalt). Q: What is continental crust made of? A: Less dense rock rich in silicon and aluminum (granite).
⚡ Plate Boundaries
Q: What happens at a constructive plate boundary? A: Plates move apart, magma rises, and new crust forms (e.g., Mid-Atlantic Ridge). Q: What happens at a destructive plate boundary? A: Oceanic plate subducts beneath a continental plate, forming trenches and volcanoes (e.g., Nazca–South American plate boundary).
Q: What happens at a conservative plate boundary? A: Plates slide past each other, causing earthquakes (e.g., San Andreas Fault). Q: What happens at a collision plate boundary? A: Two continental plates collide, forming fold mountains (e.g., Himalayas).
Geological Features
Q: What features form at constructive boundaries? A: Mid-ocean ridges, volcanic islands, rift valleys. Q: What features form at destructive boundaries? A: Volcanoes, oceanic trenches, fold mountains, island arcs. Q: What features form at conservative boundaries? A: Earthquake fault lines (no volcanoes). Q: What features form at collision boundaries? A: Fold mountains, e.g. the Himalayas.
🌍 Plate Tectonic Theory
Q: Who proposed the idea of continental drift? A: Alfred Wegener. Q: What was Wegener’s supercontinent called? A: Pangaea. Q: What evidence supports plate tectonics? A: Fossil distribution, matching rock formations, paleomagnetism, and fitting coastlines.
🌍 Hazards
Q: What natural hazards are linked to tectonic activity? A: Earthquakes, volcanic eruptions, tsunamis, pyroclastic flows, and landslides. Q: Why do earthquakes occur at plate boundaries? A: Stress builds up as plates move, then releases as seismic energy. Q: Why do volcanoes form at destructive boundaries? A: Subducting plates melt into magma, which rises to the surface.
