3.6

• What are sub-aerial processes?

  Sub-aerial processes include weathering and mass movement. Weathering is the gradual breakdown of rock at or near the surface, while mass movement involves the downslope movement of weathered material under gravity.
• How does weathering contribute to coastal erosion?

  Weathering breaks down rock into sediment, which can then be used by the sea to help erode the coastline.
• What is chemical weathering?

  Chemical weathering is the breakdown of rocks due to chemical reactions, such as carbonation, where weak acids dissolve calcium carbonate in rocks like limestone.
• What is carbonation in weathering?

  Carbonation occurs when rainwater absorbs carbon dioxide, forming carbonic acid that reacts with calcium carbonate in rocks, dissolving them into calcium bicarbonate.
• What is freeze-thaw weathering?

  Freeze-thaw weathering (frost-shattering) occurs when water enters cracks in rocks, freezes, expands, and exerts pressure. Repeated freezing and thawing causes rock fragments to break away, creating scree at the base of cliffs.
• What is salt-weathering?

  Salt-weathering happens when saltwater evaporates, leaving behind salt crystals that grow and exert pressure on rocks, causing them to break apart. Salt can also corrode the rock.
• What is wetting and drying in weathering?

  Wetting and drying weathering occurs in clay-rich rocks (e.g., shale) when they expand when wet and contract as they dry, causing the rock to break up.
• How does biological weathering occur?

  Biological weathering happens when plant roots grow into cracks in cliffs, widening them as the roots grow, and animals dig burrows or marine organisms secrete acids that break down rocks.
• What is soil creep?

  Soil creep is the very slow downhill movement of soil particles. It is the slowest form of mass movement and typically occurs at a rate of 5 cm to 1 meter per year.
• What is solifluction?

  Solifluction occurs mainly in tundra areas, where the top layer of soil thaws, becomes saturated, and flows over the frozen layer beneath.
• What are earth flows and mudflows?

  Earth flows and mudflows occur when an increase in water (e.g., from heavy rain) reduces friction, causing earth and mud to flow over bedrock.
• What are rock falls in mass movement?

  Rock falls occur when strong, jointed, steep rock faces are exposed to mechanical weathering (e.g., freeze-thaw). The material falls to form scree (talus) at the foot of the slope.
• What are rock debris slides?

  Rock debris slides occur when rocks with joints or bedding planes parallel to the slope become unstable due to water or mechanical weathering. The rock slides down the slope.
• What are slumps in mass movement?

  Slumps occur in saturated conditions on moderate to steep slopes, where a mass of rock or sediment moves rotationally. Common where softer materials (like clays or sands) overlie more resistant rock (e.g., limestone).
• What are the characteristics of slumped cliffs?

  Slumping causes rotational scars and terraced cliff profiles, often where softer materials overlie more resistant or impermeable rock.
• How does mass movement affect the coastline?

  Mass movement can reshape the coastline by transporting weathered material downslope, creating features like slumped cliffs and eroded rock faces.