Q:

What is frost wedging?

A:

Quick Answer

Frost wedging is a type of mechanical weathering caused by frost and ice. Water expands when it freezes, and repeated cycles of freezing and thawing slowly weaken the structural integrity of porous and cracked rocks. Over time, frost wedging enlarges tiny cracks into huge fissures. The fissures eventually split the rock completely.

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Full Answer

Frost wedging is a slow, cyclical process. During the day, liquid water warmed by the sun trickles into microscopic pores, cracks and spaces in rock. When the sun sets and the temperature drops, the water freezes and expands by 9 percent, exerting pressure on the surrounding rock. When the sun rises again, the frost melts and the water flows deeper into the expanded crack, where it freezes after sunset.

The most obvious evidence of frost wedging is the flat, plate-like surface created when the expanded rock joints finally split. Huge rock formations shaped by glaciers often display such sharp, flat faces. Frost wedging occurs only in climates that are cool to cold throughout the year. Canada, Scandinavia, northern Russia and Antarctica are particularly prone to this kind of weathering.

All types of weathering take place over time. However, biological factors that weaken rock serve as catalysts, decreasing the amount of time necessary for drastic change to happen. For example, moss and lichen weaken and destabilize small cracks in the rocks where they grow, making the material more vulnerable to the effects of expanding frost.

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Related Questions

  • Q:

    What are some causes of physical weathering?

    A:

    A few causes of physical weathering, also known as mechanical weathering, are swiftly moving water, ice and growing plants. Physical weathering refers to the process that breaks rock structures apart but does not change their chemical composition.

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  • Q:

    How does ice wedging cause rocks to weather?

    A:

    According to CK-12, ice wedging causes rocks to weather because water expands as it changes from a liquid form to a solid form. Over time, the changes in form wedge the rock apart. For this reason, ice wedging is very effective at weathering rock.

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    How does climate affect the rate of weathering?

    A:

    Climate affects the rate of weathering in several ways: humidity, physical erosion and temperature all impact the rate at which rocks and earthen materials wear and fade. Climate influences weathering over short and longer periods of time. This weathering takes place naturally, through the process of physical weathering, and in the form of chemical weathering, which involves rain, snow and other precipitation with synthetic compounds.

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  • Q:

    What does "physical weathering" mean?

    A:

    Physical weathering, also called mechanical weathering, refers to the process of breaking rocks apart while retaining their chemical composition, according to the American Geosciences Institute. It means that rocks slowly wear away due to physical changes, such as temperature changes, freezing and thawing, wind, rain and waves, explains the BBC.

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