Physical Weathering

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Weathering Noun

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[weth-er-ing]

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Weathering

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The mechanical and chemical processes that change objects on Earth's surface over time by wearing, breaking, and abrading them.

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Example: This image shows water on a rock, which is the first step of frost wedging, a type of physical weathering where water freezes and expands.

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Mechanical Weathering Noun

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[muh-kan-i-kuhl weth-er-ing]

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Mechanical Weathering

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The physical process that breaks down rocks into smaller pieces without altering their original chemical composition or mineral content.

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Example: Water seeps into a rock crack, freezes and expands as ice, and eventually breaks the rock apart. This process is a type of mechanical weathering.

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Frost Wedging Noun

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[frost wej-ing]

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Frost Wedging

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A weathering process caused by the repeated freezing and thawing of water inside rock cracks, causing expansion and breakage.

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Example: Water enters a crack in a rock, freezes into ice, and expands, forcing the crack to get wider and deeper over time.

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Root Wedging Noun

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[root wej-ing]

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Root Wedging

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The physical weathering of rocks caused by the progressive growth of plant roots within existing cracks, forcing them apart.

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Example: This diagram shows how a tree's roots grow into cracks in rock, and as the roots get bigger, they force the cracks to widen, breaking the rock apart.

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Salt Wedging Noun

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[sawlt wej-ing]

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Salt Wedging

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The process where salt crystals grow from evaporated water in rock pores, exerting pressure that breaks the rock apart.

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Example: This image shows water entering a rock crack and then freezing into ice, which expands and forces the crack to widen.

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Abrasion Noun

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[uh-brey-zhuhn]

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Abrasion

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The mechanical grinding, scraping, or wearing away of rock surfaces by friction from particles carried by water, ice, or wind.

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Example: As a glacier moves, rocks embedded in its base scrape and wear away the bedrock underneath, which is a form of physical weathering.

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Exfoliation Noun

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[eks-foh-lee-ey-shuhn]

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Exfoliation

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A mechanical weathering process in which curved plates or thin sheets of rock are stripped from a larger rock mass.

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Example: The image shows large, thin sheets of rock peeling off a larger rock mass, which is the process of exfoliation in physical weathering.

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Thermal Expansion Noun

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[thur-muhl ik-span-shuhn]

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Thermal Expansion

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The breaking of rocks over time resulting from repeated heating and cooling, which causes expansion and contraction stresses.

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Example: This diagram shows a metal ball passing through a ring when cold, but not after being heated, demonstrating that materials expand when their temperature increases.