Earth's Structure and Tectonic Activities

Earth's Layers

• Crust: The Earth's surface, similar to a peach's skin. Very thin compared to other layers.
• Mantle: Below the crust, composed of molten magma. Divided into:
  • Upper Mantle
  • Lower Mantle
• Core: Center of the Earth. Divided into:
  • Outer Core: Molten iron and nickel
  • Inner Core: Solid iron, hottest part of the Earth, temperature akin to the surface of the sun.

Tectonic Plates

• Lithosphere: Made up of the crust and the upper mantle. Divided into tectonic plates.
• Tectonic Plates:
  • There are seven large plates and several smaller ones.
  • Plates fit together like a jigsaw puzzle.

Historical Geology

• Pangaea: A supercontinent that existed 335 million years ago.
• Continental Drift: Movement of continents over millions of years due to plate tectonics. Evidence includes:
  • Continental shapes aligning (e.g., Africa and South America).
  • Fossils on different continents showing connections between them.

Plate Tectonics

• Convection Currents: Circular movements of heat and pressure within the mantle causing plates to move.
• Plate Margins: Boundaries where tectonic plates meet. Types include:
  • Constructive (Divergent) Margins: Plates move apart. Forms new geological features like volcanoes. Example: Mid-Atlantic Ridge.
  • Destructive (Convergent) Margins: Plates move towards each other. Forms fold mountains and trenches. Example: Himalayas.
  • Conservative (Transform) Margins: Plates slide past each other. Known for causing earthquakes. Example: San Andreas Fault.

Implications

• Tectonic activity: Responsible for natural disasters like volcanic eruptions, earthquakes, and tsunamis.
• Dynamic Planet: Earth's surface is always changing due to these tectonic movements.