Frost Wedging: How Ice Splits Rock

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This passage explains frost wedging as a mechanical weathering process. Aligned with NGSS MS-ESS2-1 (Earth’s systems) and ESS2-2 (surface processes), it details how water expansion in cracks fractures rocks. Examples include alpine landscapes (Matterhorn), road potholes, and potential Martian weathering. The text meets CCSS.ELA-LITERACY.RST.6-8.3 for sequencing scientific processes and emphasizes climate dependence (temperatures near 0°C) and rock properties (porosity). Applied connections to erosion hazards and planetary geology are highlighted.

Written by Workybooks TeamPublished by Workybooks

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Frost wedging (or freeze-thaw weathering) is a mechanical weathering process where water seeps into cracks in rocks, freezes, and expands—prying the rock apart over time. This powerful force shapes mountains, cliffs, and landscapes in cold or temperate regions.

How It Works

Water Enters Cracks: Rain or meltwater fills fractures in bedrock.
Freezing Expansion: When temperatures drop, water freezes and expands by 9%, exerting pressure (up to 2,100 kg/cm²).
Rock Fractures: Repeated cycles widen cracks until chunks break off.

Key Features

● Climate Dependence: Most effective where temperatures fluctuate around 0°C (32°F).

● Rock Type: Works best in porous rocks (sandstone, granite) with many cracks.

● Resulting Landforms: Creates talus slopes, jagged peaks, and shattered boulders.

Examples

● Alpine Mountains: Frost wedging sculpts the Matterhorn’s steep faces.

● Potholes in Roads: The same process damages asphalt in winter.

● Mars: Frost action may contribute to rock breakdown in polar regions.

Frost wedging is a key part of the rock cycle, breaking down bedrock into sediment. Understanding it helps predict erosion risks and landscape evolution.

Fun Fact: Water is the only common substance on Earth that expands when it freezes, increasing by about 9% in volume! This unique property makes frost wedging powerful enough to split boulders weighing several tons and even crack engine blocks when radiator fluid freezes.

What is the first step in frost wedging?

Ice melts rapidlyWater enters rock cracksRocks chemically dissolveWind blows sand into fractures

How much does water expand when freezing?

1%5%9%20%

Which climate is ideal for frost wedging?

Consistently hotStable subzero temperaturesFluctuating around 0°CArid desert

What landform does frost wedging create?

Sand dunesTalus slopesCoral reefsLava tubes

Why is granite vulnerable to frost wedging?

It’s impermeableIt lacks cracksIt’s porous with fracturesIt dissolves in water

Where is frost wedging not a major force?

AlpsCanadian ShieldSahara DesertRocky Mountains