Weathering Processes and Types

Study Notes

Weathering

Weathering is the process by which rocks break down into smaller pieces in place, without movement.
Three main types of weathering:
- Mechanical weathering: Breaks down rocks physically without changing their chemistry. Examples:
  - Frost wedging: Water expands in cracks when freezing, fracturing rock.
  - Exfoliation: Rock layers peel off due to pressure release from uplift or erosion.
  - Abrasion: Rocks rubbing against each other.
  - Animal actions: Burrowing animals loosen and break up ground.
  - Plant growth: Roots growing in cracks can wedge and break rocks.
- Chemical weathering: Changes the chemical makeup of rocks through reactions with water, air, or other substances. Examples:
  - Oxidation: Reaction with oxygen, often leading to rust in iron-rich rocks.
  - Hydrolysis: Reaction with water, breaking down minerals.
  - Carbonation: Reaction with carbon dioxide, dissolving minerals like calcite.
  - Acid rain: Rainwater containing dissolved acids.
- Biological weathering: Breakdown of rocks by living organisms, often involving chemical reactions. Examples:
  - Plant roots: Roots exert pressure cracking rocks.
  - Lichens: Lichens produce acids that chemically weather rocks.
  - Burrowing animals: Animals loosen and break up rock and soil.

Erosion

Erosion moves weathered rock and soil from one place to another due to wind, water, ice, or gravity.
Agents of erosion:
- Water: Rivers, streams, rain, waves, ocean currents.
- Wind: Transports smaller particles like sand and dust.
- Glaciers: Move large amounts of rock and sediment.
- Gravity: Causes sediment movement downslope, alone or supporting other processes.
Features of erosion:
- Valleys: Formed by rivers carving through rock.
- Canyons: Deep, V-shaped valleys carved by rivers in hard rock.
- Deltas: Triangular sediment deposits at river mouths.
- Alluvial fans: Cone-shaped deposits at mountain bases.
Factors influencing erosion rate:
- Climate: Rainfall, temperature, and wind speed affect weathering and transport.
- Topography: Steeper slopes erode faster.
- Type of rock: Hard rocks erode slower; soft rocks faster.
- Vegetation: Plants anchor soil, reducing erosion.
Erosion and Deposition: Erosion moves material; deposition drops it elsewhere. It's a cyclical process, interdependent.
Sediment Load: Eroded material, characterized by size and composition, is transported.
Sedimentary rocks: Compressed and cemented sediment forms sedimentary rocks.

Description

Explore the fascinating processes of weathering, including mechanical and chemical types. This quiz examines how various natural forces break down rocks without movement. Test your knowledge of frost wedging, exfoliation, and oxidation among other weathering processes.