Summary
Understanding the Earth's structure and the movement of tectonic plates helps explain the distribution of natural hazards like earthquakes and volcanoes.
- Inner Core — The solid innermost layer made of iron and nickel. Example: Despite high temperatures, immense pressure keeps it solid.
- Outer Core — The liquid layer of iron and nickel surrounding the inner core. Example: It generates Earth's magnetic field.
- Mantle — A thick layer of semi-molten rock that moves slowly. Example: Convection currents here drive plate movement.
- Crust — The thin, solid outer layer where we live. Example: Oceanic crust is denser than continental crust.
- Lithosphere — The rigid outer layer made of the crust and upper mantle. Example: It breaks into tectonic plates.
- Asthenosphere — The semi-molten layer beneath the lithosphere. Example: It allows tectonic plates to move.
- Tectonic Plates — Large slabs of the Earth's lithosphere. Example: They fit together like a jigsaw puzzle.
- Convection Currents — Circular movements in the mantle caused by heat. Example: They drag tectonic plates along.
- Divergent Boundary — Where two plates move apart, creating new crust. Example: Mid-ocean ridges form here.
- Convergent Boundary — Where two plates move toward each other. Example: Subduction zones create trenches and volcanoes.
- Conservative Boundary — Where two plates slide past each other. Example: Causes earthquakes but no new crust.
- Ring of Fire — A zone of high tectonic activity around the Pacific Ocean. Example: Contains 75% of the world's volcanoes.
Exam Tips
Key Definitions to Remember
- Tectonic Plates
- Convection Currents
- Lithosphere
- Asthenosphere
- Subduction
- Divergent Boundary
- Convergent Boundary
- Conservative Boundary
Common Confusions
- Confusing Earth's layers with lithosphere and asthenosphere
- Mixing up types of plate boundaries
Typical Exam Questions
- What is the layer of the Earth that is liquid? Outer Core
- Explain why convection currents occur in the mantle. Heat from the core warms mantle rock, making it less dense. The hot rock rises, cools, and sinks, creating a circular current.
- Name the type of plate boundary where new crust is formed. Divergent (or Constructive) boundary
What Examiners Usually Test
- Understanding of Earth's structure and layers
- Explanation of how convection currents drive plate movement
- Knowledge of different plate boundaries and their features
- Ability to describe global distribution patterns of tectonic hazards