EXOGENIC PROCESSE

• EXOGENIC PROCESSES

  • take place at or near the earth’ s surface that makes the surface wear away

  • Exogenic processes are very destructive.

  • responsible for degradation and sculpting the earth’ s surface
• EXOGENIC PROCESSES

  1. weathering
  2. erosion
  3. sedimentation/deposition
  4. mass wasting
• 1. weathering - process that breaks down rock into smaller pieces
• physical weathering

  • rock is physically broken down into smaller pieces
• chemical weathering

  • breaking down rock through chemical changes
• biological weathering

  • caused by movements of plants and animals
• Physical Weathering

  1. disintegration
  2. granular disintegration
  3. exfoliation
• Disintegration and decay of rocks via weather elements:

  high temperatures, extreme cold and freeze-thaw cycles

  No change in chemical composition of rock
• Granular disintegration happens when the grains of a rock become loosened and fall out, leaving a pitted, uneven surface due to changing temperatures
• Exfoliation mechanism in which large flat or curved sheets of rock are broken and separated from the outcrop due to the release of pressure
• Chemical Weathering

  • Oxidation

  • Hydrolysis

  • Carbonation and Solution
• Oxidation – important in iron-rich rocks – reddish coloration like rust
• Hydrolysis – igneous rocks have much silica which readily combines with water
• Carbonation and Solution – carbon dioxide dissolved in water reacts with carbonate rocks to create a soluble product (calcium bicarbonate
• Biological Weathering

  Roots

  Lichens

  Burrowing animals
• Roots physically break or wedge rock
• Lichens (algae and fungi living as single unit), remove minerals and weaken rock by releasing acids
• Burrowing animals can increase weatherin
• b. erosion

  • rock particles are carried away by wind, ice, and gravity.

  • Weathering causes the rocks to break down. Erosion (water) or transportation moves the sediments downhill to other places
• erosion

  • Flowing Water
  • wind
  • tides and waves
  • moving ice
• •Flowing Water – Fluvial Morphology
• Wind – Aeolian Landscapes deflation hollows, ventifacts, Yardang, etc
• Tides and Waves – Coastal Morphology Sea cliffs, sea caves, sea arches, sea stacks, wave-cut beaches, etc..
• Moving Ice – Glacial Morphology glacial troughs (U-shaped valleys), hanging valleys, glacial lakes
• Types of glaciers • ice shelves • ice • valley or alpine
• sedimentation/deposition

  a natural process in which a material is carried to the bottom of bodies of water and forms to solid
• stream loads

  1. suspended load
  2. bed load
  3. dissolved load
• 1. suspended load - particles are carried at the main parts of the stream
• bed load- coarser and denser particles that remain on the stream bed, but moves when particles collide
• dissolved load- ions that have been dissolved into the water by chemical weathering of rocks
• mass wasting

  • the downward movement of a rock, soil and regolith due to the action of gravity

  • triggered by the following factors: over-steepened slope, water, earthquake, and vegetation removal.
• Solifluction

  • slow, downward movement of water-saturated soil and sediment, often occurring in areas with permafrost

  • characterized by the flow of soil down a slope, typically in a saturated condition.
• Where does Earth’ s Internal Heat come from? 1

  1. Primordial heat of the planet remains from early stage
  2. Heat from decay of radioactive elements
  3. Gravitational pressure
  4. Dense core material in the center of the planet
• Primordial heat of the planet remains from early stage

  1. Accretion
  2. masses compacted and formed planetisimals
  3. heat was generated from the collision of masses
  4. Earth’ s heat remain from its early stages of deveopment
• 2. Heat from decay of radioactive elements

  • main source of internal heat come from the produced decay of naturally occuring isotopes from its interior
  • radioactive decay
• • radioactive decay - spontaneous breakdown of atomic nucleus causes the release of energy and matter
• Accretion - gases and dust of clouds are attracted by gravitational energy
• • Isotopes

  • Potassium-40
  • Uranium-235
  • Uranium-238
  • Thorium-232
• 3. Gravitational Pressure

  • pressure near the center of the Earth is considered to be 3 - 4 million times the pressure in the atmosphere at sea level
  • the escape of heat from Earth' s surface is less than the heat generated from internal gravitational attraction or squeezing of rocks, so heat builds up withi
• 4. Dense Core Materials in the Center of the Planet

  • due to increase in pressure and presence of heavier materials, density also increases
  • the intense pressure and density present iron and other elements to be in liquid state that conserve heat in the Earth' s inner core