Earth’s Dynamic Processes and Atmospheric Phenomena

Posted on Dec 4, 2024 in Geology

Unit 7: Earth’s Structure and Processes

Earth’s Layers

Core: The inner zone of higher temperature and density, occupying 17% of Earth’s volume. The high temperature is due to the disintegration of uranium and other radioactive elements.

Mantle: Occupies 82% of Earth’s volume with a density slightly lower than the core. Mostly solid except for the asthenosphere, located between the mantle and crust. Convection currents within the asthenosphere move the tectonic plates of the lithosphere.

Lithosphere and Crust: The Earth’s outer, less dense, and colder layer. Largely submerged under the ocean, forming the oceanic crust, which is much thinner than the continental crust.

Geosphere

The solid portion of the planet, primarily composed of rocks made up of one or more minerals. These minerals form large, homogeneous units that divide the Earth’s crust.

Convection Currents

Density variations in the asthenosphere drive convection currents. Heat from the mantle makes the molten rock material (magma) less dense, causing it to rise. The upper layers, in contact with the cooled crust, become denser and sink. These convection currents in the asthenosphere push the tectonic plates of the lithosphere, causing them to move in different directions—a phenomenon called continental drift.

Tectonic Plates

Tectonic plates constantly move due to the energy of convection currents. Initially, there was a single continent called Pangea, which later divided into Gondwana and Laurasia.

The theory of plate tectonics explains that earthquakes and volcanic activities are caused by the movement and collision of tectonic plates.

Landscape Formation

  • Internal Processes: Triggered by energy inside the planet, bringing new materials to the existing crust or deforming it.
  • External Processes: Modify the main features of the landscape and constantly reshape the land’s relief.

Factors Influencing Landscape

  • Lithological Factors: The rocks that make up the ground in a particular place.
  • Structural Factors: The characteristics of the initial geological structures.
  • Dynamic Factors: The processes that construct the landscape.
  • Climatic Factors: Climatic differences create different reliefs.
  • Human Factors: Human activities that produce local changes.

Atmosphere

The layer of gases surrounding any celestial body. Approximately 90% of the atmosphere’s mass is within 15 km of the ground.

Origin and Evolution of the Atmosphere

  • Release of Gases: Volcanic eruptions released gases from inside Earth.
  • Prebiotic Stage: Water vapor condensed, forming oceans and dissolving compounds.
  • Microbiological Stage: Anaerobic bacteria originated, and photosynthetic organisms began to consume carbon dioxide, which was approximately 95% of the atmosphere.
  • Biological Stage: Eukaryotic organisms developed more efficient photosynthetic processes.

Structure of the Current Atmosphere

  • Ionosphere: Reflects radio waves.
  • Thermosphere: Temperature increases, allowing ionization (loss of an electron).
  • Mesosphere: Temperature drops to as low as -100°C.
  • Stratosphere: Contains the ozone layer, formed by the interaction of solar rays with oxygen molecules.
  • Troposphere: Contains approximately 90% of the atmosphere’s air.

Weathering

The process of rocks breaking down. Can be physical (changes in pressure, temperature, etc.) or chemical.

Minerals and Rocks

Rocks can contain essential (primary) minerals, which define the rock’s nature, and ancillary (secondary) minerals, formed from alterations of primary minerals. Some rocks are formed by various minerals, while others (monomineralic rocks) are formed by a single material, like gypsum.

  • Magmatic (Igneous) Rocks: Formed by the cooling and solidification of molten geological material.
  • Sedimentary Rocks: Formed by the erosion, accumulation, and compaction of geological materials.
  • Metamorphic Rocks: Formed by the transformation of existing rocks due to variations in temperature and pressure.

The Rock Cycle

Encompasses all rock types and has played a role in the evolution of our planet. Sedimentary rocks have the potential to contain fossils.

Unit 8: Natural Disasters

The movement of tectonic plates causes seismic and volcanic phenomena, releasing large amounts of energy. Hurricanes and tropical storms are high-energy phenomena that occur in areas where water absorbs and releases large amounts of heat into the atmosphere.

Eruptions and Earthquakes

  • Explosive Eruption: Magma finds a break to reach the surface, throwing rocks, dust, and gases from the crater.
  • Effusive Eruption: Fluid magma with few gases causes a quiet eruption with multiple outputs, not just from the crater.
  • Hypocenter: The point where colliding plates break, releasing mechanical energy.
  • Epicenter: The point on the surface directly above the hypocenter.

Water on Earth

  • Tides: Changes in sea level caused by the gravitational forces of the Sun and Moon.
    • Sun and Moon aligned = Spring tide (high high tides, low low tides).
    • Sun and Moon at 90° = Neap tide (low high tides, high low tides).
  • Tsunamis: Walls of water caused by violent eruptions and earthquakes near sea areas.

Storms and Hurricanes

  • Thunderstorm: Strong winds and/or heavy rain.
  • Hurricane: A tropical storm.