Earth's Internal Structure and Geological Processes

Models of the Earth's Interior

Geochemical Model

• Crust: Up to the Mohorovičić discontinuity (35 km)
  • Continental: Granite and gneiss
  • Oceanic: Basalt
• Mantle: Up to the Gutenberg discontinuity (2,900 km). Composed of peridotite.
• Core: Central sphere (up to 6,378 km). Composed of iron and nickel.

Geodynamic Model

• Lithosphere: Crust and upper mantle. Composed of solid rocks.
  • Continental: 100–200 km (less dense)
  • Oceanic: 50–100 km (more dense)
• Asthenosphere: Solid but plastic rocks. Up to 660 km.
• Mesosphere: Solid but plastic rocks. Up to 2,900 km.
• Endosphere (Core):
  • Outer core: Up to the Lehmann discontinuity (5,100 km). Molten rocks.
  • Inner core: Remainder of the core. Solid rocks.

Isostasy

The behavior of the Earth's crust, as if it were floating on denser materials in the Earth's interior. It is based on Archimedes' principle. Some continents are rising as the ice from glaciations disappears.

Magmatism

The process of magma and magmatic rock formation. The conditions for rock fusion are: temperature increase, pressure decrease, and the presence of fluids.

Volcanism

There is a direct relationship between volcanism and plate tectonics. More than 80% of volcanoes are located at mid-ocean ridges and subduction zones.

• Mid-ocean ridge: Rocks melt and magma is formed due to lower lithospheric pressure and thin lithosphere.
• Subduction zone: Rocks melt and magma is formed due to strong friction between two converging plates. Water lowers the rocks’ melting point.
• Lithospheric plate interior: Rocks melt and magma is formed at hot spots.

Metamorphism

Transformations that rocks undergo due to temperature, pressure, and chemically active fluids. The most common areas for metamorphism are subduction zones and continental collision zones.

Seismicity

Earthquakes are caused by movements between lithospheric plates; the release of energy accumulated in the rocks is transmitted as seismic waves.

Relief

A set of geographic formations that occur on the Earth's surface due to the conflict between internal and external geological processes.

Mutual Influences

• Internal processes → External processes
• External processes → Internal processes

Geological Processes

• Internal geological processes: Generated by the thermal energy of the Earth's interior and gravity. They give rise to large reliefs, such as ridges and mountain ranges.
• External geological processes: Generated by solar energy and gravity. They model the relief through erosion, transport, and sedimentation.

Topographic Maps

Methods of representing relief using various elements:

• Contour lines: Lines connecting points at the same elevation.
• Scale: The relationship between the distance on the map and the real distance.
• Equidistance: The height difference between two consecutive contour lines.