Earth’s Structure, Processes, and Geological Formations

Posted on Mar 23, 2025 in Geology

Earth’s Internal Structure and Composition

  • Cortex (Outer Layer)
  • Mantle
    • Upper Mantle
    • Lower Mantle
  • Core
    • Outer Core (Iron and Nickel)
    • Inner Core (Iron)

Earth’s External Structure and Physical Behavior

  • Lithosphere – Rigid outer layer
  • Asthenosphere – Beneath the lithosphere, a plastic and deformable layer
  • Mesosphere – More rigid due to non-plastic materials
  • Outer Core
  • Inner Core

Relief Transformation Phases

  • Orogeny – Mountain-forming processes
  • Gliptogenesis – Relief wear from erosion
  • Lithogenesis – Formation of new rocks by internal and external processes

Internal Geological Processes

Deformation of rocks, earthquakes, volcanoes, shifting continents, mountain formation.

External Geological Processes

Weathering, erosion, transportation, and sedimentation.

Crustal Deformation

Three types of deformation:

  • Elastic – Material deforms but returns to its original shape.
  • Plastic – Deformation occurs, but the material does not fully recover its shape.
  • Breaking – Fracture due to exceeding the material’s internal cohesion.

Folds

Waves originating in plastic rocks. Elements of a fold:

  • Axial Plane – Divides the fold into two parts.
  • Fold Axis – Intersection line of the axial plane with the hinge.
  • Old Zone – Inner fold zone.
  • Hinge – Zone of maximum curvature.
  • Flank – Each part divided by the axial plane.

Types of Folds

  • Anticline – Curved upwards, oldest material in the core.
  • Syncline – Youngest material in the core.
  • Straight – Axial plane is perpendicular to the surface.
  • Inclined – Axial plane is inclined.
  • Lying – Parallel to the surface.
  • Inverted – Turned over 90 degrees.

Faults

Fractures in rock masses with displacement. Elements of a fault:

  • Footwall – The block below the fault plane.
  • Fault Throw – Vertical displacement between blocks.
  • Hanging Wall – The block above the fault plane.
  • Fault Plane – Surface along which displacement occurs.

Types of Faults

  • Normal Fault – Tension causes extension.
  • Reverse Fault – Compression causes shortening.
  • Strike-Slip Fault – Horizontal displacement.

Diaclases

Fractures in rock masses without displacement.

Earthquakes

Vibrations and jolts originating from a point within the lithosphere.

Elements of an Earthquake

  • Hypocenter – Point of origin inside the Earth.
  • Epicenter – Point on the surface closest to the hypocenter.
  • Seismic Waves – Originate at the hypocenter and transmit in all directions.

Seismic Waves

  • P-waves – Transmitted through solids and liquids.
  • S-waves – Transmitted only through solids.
  • L-waves – Transmitted only on the surface.

Volcanoes

Cracks in the Earth’s surface where magma erupts.

Structure of a Volcano

  • Crater – Opening for material expulsion.
  • Volcanic Cone – Mass formed by material accumulation.
  • Vent – Pipe where magma rises.
  • Magma Chamber – Cavity where magma accumulates.