PLATE TECTONICS & HISTORY OF THE EARTH

Tectonic Plates Overview

  • Tectonic plates form the outer shell of the Earth and are constantly shifting.

Major Tectonic Plates

  • Pacific Plate

  • North American Plate

  • Eurasian Plate

  • African Plate

  • South American Plate

  • Antarctic Plate

  • Indo-Australian Plate

  • Indian Plate

  • Australian Plate

  • Nazca Plate

  • Philippine Sea Plate

  • Arabian Plate

Types of Plate Boundaries

Divergent Boundaries

  • Occur when tectonic plates move away from each other.

  • As plates separate, a gap is created, which can fill with water or magma, forming new land.

  • Rift Valley: Formed when the East African Rift Zone widens, indicating significant tectonic activity.

  • Mid-Oceanic Ridge: A mountain system formed in oceanic plates at divergent boundaries.

Convergent Boundaries

  • Occur when two tectonic plates slide towards each other.

  • Can form various geological features:

    • Subduction Zone: One plate moves underneath another.

    • Orogenic Belt: A region of mountains formed from colliding plates.

Types of Convergence

  1. Oceanic-Oceanic Convergence

    • Forms a subduction zone that creates a chain of volcanoes.

    • Example: Mariana Trench - A long, narrow depression in the ocean floor.

  2. Oceanic-Continental Convergence

    • The denser oceanic plate subducts beneath the continental plate.

    • Produces volcanic activity above subduction zones (e.g., Andes Mountains, Cascade Range).

  3. Continental-Continental Convergence

    • Two continental plates collide without subduction, leading to suture.

    • Results in the formation of mountain ranges due to crust buckling (e.g., Himalayas, Alps).