Overview
This lesson discusses the different types of plate boundaries, how they interact, and the geological features they create.
Plate Boundaries: Definition and Types
- Plate boundaries are the lines at the edges of Earth's moving lithospheric plates.
- Plates move due to convection currents in Earth's interior.
- Three main types: Divergent, Convergent, and Transform boundaries.
Divergent Boundaries
- Formed when two tectonic plates move apart from each other, creating tension.
- New crust forms as magma rises and solidifies at the surface.
- Also called constructive boundaries; forms features like mid-ocean ridges and rift valleys.
- Example: Mid-Atlantic Ridge between the Eurasian Plate and North American Plate.
Convergent Boundaries
- Occur when two plates move toward each other.
- Three types: Oceanic-Continental, Oceanic-Oceanic, and Continental-Continental.
- Oceanic-Continental: Oceanic plate subducts under continental plate (subduction); causes volcanic activity.
- Oceanic-Oceanic: One oceanic plate subducts, forming a trench and island volcanic chain.
- Continental-Continental: Plates crumple, forming mountain ranges like the Himalayas.
Transform Boundaries
- Formed when two plates slide past each other horizontally.
- Also called strike-slip faults; causes cracks and linear valleys.
- Example: San Andreas Fault between the Pacific Plate and North American Plate.
Key Terms & Definitions
- Plate Boundaries — Edges where two lithospheric plates meet and interact.
- Divergent Boundary — Plates move apart, forming new crust.
- Convergent Boundary — Plates move toward each other; can result in subduction or mountain formation.
- Subduction — Process where one plate is forced beneath another into the mantle.
- Transform Boundary — Plates slide past each other, causing faults and earthquakes.
- Mid-Ocean Ridge — Undersea mountain range formed at divergent boundaries.
- Subduction Zone — Area where subduction occurs, marked by trenches and volcanic activity.
Action Items / Next Steps
- Review types of plate boundaries and their examples.
- Practice identifying boundary types in diagrams or maps.
- Prepare for activities and quizzes on plate tectonics.