Overview
This lecture covers the movement of tectonic plates, comparing continental and oceanic plates, explaining the different types of plate boundaries, and how these movements form geological features like folds and faults.
Introduction to Tectonic Plates
- The Earth's lithosphere is divided into tectonic plates that move over the asthenosphere.
- Plate movement shapes the Earth's surface and causes geological events.
Continental Plates vs. Oceanic Plates
- Continental plates are thicker but less dense than oceanic plates.
- Oceanic plates are thinner, denser, and mostly found under oceans.
Types of Plate Boundaries
- Three main plate boundaries: Convergent, Divergent, and Transform.
- Each type of boundary is associated with distinct geological processes and landforms.
Convergent Boundaries
- Plates move towards each other, often causing subduction (one plate moves under another).
- Subduction can create volcanic arcs, mountain ranges, and folds.
- Example landforms: mountains, volcanic arcs.
Divergent Boundaries
- Plates move apart from each other, allowing magma to rise and create new crust.
- Commonly seen at mid-ocean ridges and continental rift valleys.
- Example landforms: rift valleys, mid-ocean ridges.
Transform Boundaries (Strike-Slip Boundaries)
- Plates slide horizontally past each other with little vertical movement.
- These boundaries often result in faults and earthquakes.
- Example: San Andreas Fault.
Key Terms & Definitions
- Tectonic Plate — Large rigid piece of Earth's lithosphere that moves over the asthenosphere.
- Continental Plate — Thick, less dense tectonic plate mostly under continents.
- Oceanic Plate — Thin, dense tectonic plate mostly under oceans.
- Convergent Boundary — Plate boundary where two plates move towards each other.
- Subduction — Process where one plate moves beneath another.
- Volcanic Arc — Curved line of volcanoes above a subduction zone.
- Mountain — Landform created by tectonic plate collisions.
- Fold — Bend in rock layers caused by compression.
- Divergent Boundary — Plate boundary where plates move apart.
- Rift Valley — Lowland formed by divergent plate movement on land.
- Mid-Ocean Ridge — Undersea mountain range formed at divergent boundaries.
- Transform Boundary — Plate boundary where plates slide past one another.
- Fault — Crack in Earth's crust from plate movement.
Action Items / Next Steps
- Review types of plate boundaries and their effects on Earth's surface.
- Study examples of landforms created by each type of boundary.
- Prepare for quiz on key terms and definitions.