Freeze Thaw
What is freeze thaw?
This process occurs when water enters cracks in rocks, freezes, expands, and eventually breaks the rock apart.
What is heating and cooling (thermal expansion)?
Rocks expand when heated and contract when cooled, eventually causing them to crack.
What is salt crystallisation?
This process occurs when salt crystals grow in rock pores, causing the rock to break apart.
What is pressure release (dilatation)?
Rocks fracture and peel off in layers when overlying material is removed.
What is vegetation root action?
Roots growing into cracks in rocks can physically split them apart.
Explain why freeze-thaw weathering is more common in temperate or polar climates than in tropical climates.
because these regions experience frequent cycles of freezing and thawing, whereas tropical climates remain too warm for water to freeze
Why is heating and cooling weathering particularly common in deserts?
deserts experience large diurnal temperature ranges, causing frequent expansion and contraction of rock surfaces?
Identify the environments where salt crystallisation is most effective.
arid or coastal regions with high evaporation rates, where salts accumulate in rock pores?
Explain how unloading of overlying rock layers can lead to pressure release weathering
removal of overlying rock reduces pressure, causing underlying rock to expand and fracture parallel to the surface?
Explain why root action is more pronounced in tropical forests than deserts.
dense vegetation in tropical forests produces extensive root systems, whereas deserts have limited plant growth
Describe how freeze-thaw weathering can contribute to the formation of scree at the base of a cliff.
repeated freezing and thawing causes rock fragments to break off and accumulate at the base of the slope, forming scree
Explain how heating and cooling can lead to exfoliation of rock layers.
repeated expansion and contraction causes outer layers of rock to peel away in thin sheets?
Explain why salt crystallisation can cause rock surfaces to flake or crumble.
as salt crystals grow, they exert pressure on the rock’s internal structure, forcing fragments to break off?
Describe the role of pressure release in shaping granite landscapes.
it leads to domed shapes and exfoliation sheets commonly seen in granite outcrops
Describe how vegetation root action can contribute to both mechanical and chemical weathering.
What is roots can exert physical pressure to split rocks and release organic acids that chemically break down minerals
Evaluate the potential impact of freeze-thaw weathering on human-built structures in cold regions.
it can crack pavements, damage buildings, and weaken roads over time due to repeated expansion and contraction of water in cracks?
Compare the effects of heating and cooling weathering with freeze-thaw weathering on rock breakdown.
heating and cooling acts mainly on surface layers in hot climates, causing gradual exfoliation, while freeze-thaw breaks rocks apart more rapidly along existing cracks in cold climates
Assess the potential damage caused by salt crystallisation on historical monuments near coastal areas.
continuous salt growth can erode stone carvings and structural features, especially in porous rocks like limestone or sandstone
Evaluate the significance of pressure release compared with other mechanical weathering processes in shaping large landforms.
pressure release is important in exposing and shaping massive rock formations, while other processes like freeze-thaw and salt crystallisation act on smaller fragments
Assess the long-term impact of vegetation root action on soil formation in mountainous regions.
root action accelerates rock breakdown, producing mineral particles that mix with organic matter, contributing to soil development over time
Explain why the size of rock fragments produced by freeze-thaw weathering might vary depending on the rock type and structure.
harder, less fractured rocks produce larger fragments because fewer initial weaknesses exist, whereas softer or heavily jointed rocks break into smaller pieces more easily
Discuss the limitations of heating and cooling as a weathering process in regions with moderate temperatures.
limited temperature variation reduces expansion/contraction cycles, so rock breakdown is slower and less pronounced than in deserts?
Evaluate how human activities, such as road salting, could accelerate salt crystallisation in urban environments.
salts used for de-icing penetrate building materials and pavements, accelerating mechanical breakdown and increasing maintenance needs?
Discuss how climate and vegetation cover might influence the rate of pressure release weathering.
areas with rapid erosion and little vegetation experience faster unloading and sheet formation, whereas vegetated or stable slopes slow down the process
Evaluate the role of vegetation root action in preventing landslides compared with its role in promoting rock breakdown.
roots stabilize soil and slope materials, reducing landslide risk, while still mechanically breaking rock, showing a balance between constructive and destructive effects