Earth's Atmosphere, Tectonics, and Weathering

Earth's Atmosphere

The atmosphere is the gaseous layer that surrounds the Earth. It is made up of nitrogen, oxygen, and 1% argon, CO2, neon, helium, ozone, dust, and water vapor.

• Troposphere: The layer in contact with the ground, between 10 and 11 km high. It is responsible for the greenhouse effect and meteorological phenomena. The temperature decreases with height.
• Stratosphere: Extends to 45 km altitude. Its temperature increases with height. The ozone layer, which absorbs ultraviolet radiation, is located here.
• Mesosphere: Extends to approximately 80 km in height. This is where meteorites falling to Earth become incandescent and turn into shooting stars.
• Thermosphere: This layer reaches 500 km in height and contains ionized gases.
• Exosphere: The outermost layer of the atmosphere, reaching distances of over a thousand kilometers. The temperature is approximately 2400°C.

Plate Tectonics

• Mid-ocean ridges: When plates move apart, asthenosphere materials rise and become oceanic lithosphere. Oceanic ridges are ridges running through the ocean floor (e.g., the Pacific, Atlantic, and Antarctic oceans).
• Trenches: When plates move and collide, one of them, the denser one, is subducted under the other (destroyed). When two continental plates collide, their edges are deformed and folded, resulting in a mountain range.
• Transform faults: When plates slide laterally, neither is lithosphere created nor destroyed, but large fractures originate in the contact zones. These areas are called passive margins.

Weathering

• Physical Weathering: Rocks are broken down without changing their composition.
  • Gelifraction
  • Thermofraction
  • Haloclasty
• Chemical Weathering: The rock changes its chemical composition due to the action of water and atmospheric gases.
  • Oxidation
  • Dissolution
  • Hydration
  • Carbonation
• Biological Weathering: Produced by the action of living beings on the ground.
  • Certain free-living organisms release acidic substances that lead to changes in the rocks.
  • Plants break rocks due to their roots.
  • Burrowing animals, like moles, break rocks and contribute to weathering.