weathering

Weathering and Its Processes

• Definition of Weathering:

  • Weathering is the collective term for the physical and chemical processes that occur at the Earth's surface, resulting in the breakdown of rocks.

  • The end products are sediments, which are materials used to create sedimentary rocks.

• Sediments:

  • Comprise rock or mineral fragments and altered minerals such as clays and oxides, as well as elements in solution.

• Erosion:

  • After rocks are weathered and broken down into sediments, these sediments are eroded, meaning they are removed from their source.

  • Agents of Transport:

  • Wind

  • Water

  • Ice

  • Gravity

• Deposition:

  • Sediment fragments accumulate in various environments within sedimentary basins.

  • In the depositional environment, elements in solution can transform back into solid sediments through:

  • Chemical means

  • Biochemical means

• Lithification:

  • The process by which buried sediments are converted into rock.

  • Consists of two main processes:

  • Compaction: The reduction of the volume of sediment due to pressure over time.

  • Cementation: The binding together of sediments by minerals precipitating from water that occurs between the sediment grains.

• Categories of Sedimentary Rocks:

  • Based on the origins of the sediments, sedimentary rocks are classified as:

  • Detrital: Formed from the mechanical weathering debris.

  • Biochemical: Comprised of organic material and/or minerals precipitated from solution by biological processes.

  • Crystalline Chemical: Formed from the precipitation of minerals from solution.