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mechanical weathering
breaking down of rocks into smaller particles without altering their chemical composition
climate influence
typically occurs in regions with extreme climates and little vegetation - deserts and mountainous areas
main types
freeze thaw action
exfoliation
freeze thaw action
most common type of physical weathering and is especially active in mountainous regions
temperature fluctuation
freeze thaw action occurs where daytime temperatures rise above freezing and nightime temperatures fall below freezing
role of rainfall
rainwater seeps into cracks and rocks and freezes at night - expanding and widening the cracks
when water freezes it expands by 10%, putting pressure on the rock
repetition effect
repeated cycles of freezing and thawing eventually causes the rock to break apart
exfoliation
causes layers of rock to peel off resembling onion layers shed.
it affects rocks with alternating hard and soft layers - which respond differently to temperature changes
temperature extremes
in desert climates -rocks expand in extreme daytime heat (up to 50 degrees celsius) and contract during cold nights (below 0 degrees)
expansion vs contraction
outer rock layers expand more than inner ones during the day making them more prone ot peeling.
formation of scree
broken outer layers collect at the base of the rock forming loose debris known as scree.
environmental impact
exfoliation contributes to soil formation and changes in slope stability
engineering relevance
physical weathering has practical implications for constructions and infrastructure projects in affected regions