Understanding Weathering, Erosion, and Deposition

Mar 18, 2025

Lecture Notes: Weathering, Erosion, and Deposition

Key Concepts

  • Weathering:

    • Definition: Breaking down and changing of rocks due to environmental exposure.
    • Example: Granite slab breaking down due to ocean waves.
    • Types of Weathering: Physical/Mechanical and Chemical.

  • Erosion:

    • Definition: Transportation of sediments broken down by weathering.
    • Example: Ocean currents carrying granite pieces.

  • Deposition:

    • Definition: Dropping off of weathered and eroded sediments.
    • Example: Granite bits deposited on a distant coastline.

Detailed Processes

Weathering

  • Physical (Mechanical) Weathering:

    • Changes in size and shape without altering composition.
    • Examples:
      • Frost Action/Ice Wedging: Water in cracks freezes/expands, breaking rocks.
      • Exfoliation: Expansion/contraction due to temperature changes causes outer layers to peel.
      • Abrasion: Rock surface worn away by wind, water, or glaciers.
      • Root Wedging: Plant roots grow in cracks, breaking rocks.

  • Chemical Weathering:

    • Rocks change chemically due to reactions with environmental substances.
    • Examples:
      • Oxidation: Iron reacts with oxygen forming rust.
      • Carbonation: Carbonic acid from water dissolves limestone, forming caves.

Factors Affecting Weathering

  • Climate:

    • Hot/dry: Minimal weathering.
    • Hot/wet: Increased chemical weathering (e.g., Florida's limestone caves).
    • Cold: Frost action prevalent.

  • Hardness:

    • Softer rocks weather faster than harder rocks.
    • Example: Shale vs. sandstone in waterfalls.

  • Surface Area:

    • More exposed surface area leads to faster weathering.

Summary

  • Weathering, erosion, and deposition are interconnected processes affecting Earth's surface.
  • Weathering is influenced by climate, rock hardness, and surface area.
  • Upcoming video will cover erosion and deposition in detail.

Additional Resources

  • Surface Process Flowchart (available on the website)

Visual Analogy

  • Weathering: Nature's hammer breaking rocks.
  • Erosion: Dump truck transporting sediments.
  • Deposition: Dump truck unloading sediments.

These notes provide an overview of weathering types and factors influencing the process, setting the stage for further exploration of erosion and deposition.