Plate Tectonics Overview

Introduction to Plate Tectonics

• The Earth's surface is made up of rigid plates.
• These plates move relative to each other, carrying everything on them, including continents.

Types of Plates

• Pacific Plate
• Nazca Plate
• South American Plate
• Antarctic Plate
• North American Plate
• Plates are depicted in a 2D projection, leading to size distortions, especially at the poles.

Plate Movement

• Plates are moving relative to one another, which can create new land.
• Examples of plate interactions:
  • Nazca Plate and Pacific Plate are moving apart, leading to new land formation.
  • In the Atlantic Ocean, the African Plate and the South American Plate are also moving apart, creating more plate material.

Terminology of Plate Tectonics

• Clarification on the term crustal plates vs. lithospheric plates.

Layers of the Earth

• Chemical Layers:
  • Crust: The outermost and thinnest layer.
  • Mantle: Located below the crust.
  • Core: Innermost layer.

Mechanical Properties

• Solid: The crust is solid and rigid.
• Magma/Plastic Solid: Parts of the mantle are hot enough to behave like a plastic solid or magma.
• Fluid State: The outer core is liquid, while the inner core is solid due to high pressure.

Mechanical vs. Chemical Properties

• The crust is solid.
• The upper mantle has solid parts; deeper sections have magma-like properties.
• The core has both liquid and solid states based on temperature and pressure.

Lithosphere and Asthenosphere

• Lithosphere: The outer solid layer, including the crust and the upper solid part of the mantle.
• Asthenosphere: The layer below the lithosphere, characterized by more fluid properties but still viscous.

Summary of Definitions

• Lithospheric Plates: The correct term for the plates involved in plate tectonics, combining crust and solid upper mantle.
• Asthenosphere: The more fluid layer beneath the lithosphere.