GEOLOGIC PROCESSES

• Geological processes


  The natural forces that shape the physical makeup of a planet
• Plate tectonics, erosion, chemical weathering and sedimentation are all examples of forces that significantly affect the Earth's surface and account for its major features
• Why geologists and earth scientists need to improve their knowledge on the planet's history

  • To help locate useful resources
  • To aid the prediction of potentially disastrous events, such as earthquakes, tsunamis and volcanic eruptions
• Categories of Earth processes

  • Exogenous (External)
  • Endogenous (Internal)
• Exogenous processes


  Occur on or near the surface of the Earth, usually influenced or driven by gravity, water, wind, and organisms. Can be destructive and leave significant changes on the landscape and ecosystem
• Types of exogenous processes

  • Weathering (Physical And Chemical)
  • Erosion
  • Mass Wasting
  • Sedimentation
• Physical weathering


  Breakdown of rocks by mechanical forces concentrated along rock fractures, due to changes in temperature, pressure, etc.
• Physical weathering


  • Soil cracks because of extreme heat and drought
  • Water, wind or ice may abrade or scrape rocks or soil
• Chemical weathering


  The process by which rocks breakdown by chemical reaction, resulting in new or secondary minerals developing and sometimes replacing the original properties
• Types of chemical weathering


  • Oxidation
  • Hydrolysis
• Acid rain

  • another contributor to chemical weathering
  • causing metal or stone to corrode or deteriorate due to reaction with acids in the minerals
• Erosion

  • process by which Earth's surface is worn away by wind, water, or ice
  • moving rock debris or soil from one place to another
• Erosion takes place, when there is:

  • rainfall, surface runoff, flowing rivers, sea water intrusion, flooding, freezing and thawing, hurricanes, winds, etc.
• Movement of land animals during migration or stampede can also cause erosion
• Human activities such as deforestation, overgrazing, and mining also cause erosion, leading to deterioration and destruction of infrastructure
• Mass wasting


  • Movement of large masses of materials down a slope or steep-sided hill or mountain due to the pull of gravity
  • very destructive in areas with increased waterflow, steep slopes, scarce or no vegetation, or vibrating or moving grounds
• Types of mass wasting


  • Debris flow: large amount of sediments, usually rocks of various sizes, falling down the slope without needing water to flow
  • Slump: slow movement of soil along a curved surface, forming a depression
• Sedimentation


  The deposition of rock fragments, soil, organic matter, or dissolved material that has been eroded and transported by water, wind, ice, or gravity
• Endogenous processes


  • take place within or in the interior of the Earth
  • driven by the thermal energy of the mantle
  • mostly from the decay and disintegration of radioactive elements in the Earth's core
• Types of endogenous processes


  • Magmatism
  • Volcanism or Plutonism
  • Metamorphism
• Magmatism


  The process of magma being generated and developing into igneous (magmatic) rocks, either under the surface or on the surface of Earth
• Volcanism or Plutonism


  The process where magma tries to escape from the source through openings such as volcanoes or existing cracks on the ground, coming out with extreme heat and pressure and causing destructive explosions.
• Metamorphism


  The process of changing the materials that makeup a rock, where the chemical components and geologic characteristics of the rock change due to heat and pressure, even if the rock does not melt
• Types of stresses that influence rock behavior


  • Compressional
  • Tensional
  • Shear
  • Confining
• Compressional stress


  Rocks push or squeeze against one another, with the stress directed toward the center, leading to thickening, shortening or breaking of the crust, often resulting in mountain building
• Tensional stress


  Rocks are pulled apart, separating in opposite directions or moving farther away from one another, speculated to be the cause of the breaking away of the supercontinent Pangaea
• Shear stress


  Portions of a plate at the edges may break away in different directions, eventually making the plate smaller in size. The friction can cause earthquakes
• Confining stress


  The crust becomes compact, making it look smaller, without the edges breaking away. Changes occur inside the crust without visible external changes
• Weathering

  • disintegration of rocks, soil, and minerals together with other materials through contact with earth's subsystems
• Weathering

  • The breaking down of soil and rocks happen on the spot due to exposure to weather conditions such as rain, wind, temperature changes, and biological activity.
• Oxidation

  • reaction of a substance with oxygen
• Hydrolysis

  • chemical breakdown of a substance when combined with water
• Sedimentation

  • process of settling down of heavier insoluble particles at the bottom of a liquid
• Sediments

  • heavier insoluble particles that settle down at the bottom of the liquid
• Insoluble

  • cannot combined with the solvent to form a homogeneous solution
• Endogenous Process

  • responsible for earthquakes, development of continents, mountain building, volcanic activities and other movements related to Earth's crust
• Lava

  • magma on the surface of the earth
• Volcanism or Plutonism

  • process that usually happens after magma is formed
• Geological Stress

  • force (from the pushing and pulling of plates) that acts on the rocks thereby creating different behavior or characteristics