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Difficulty: MediumWeathering and Mass Wasting Processes

Arrange the sequential stages involved in the process of frost shattering (freeze-thaw weathering) in chronological order, starting from the initial entry of moisture to the final disintegration of the rock face.

  1. 1Water percolates into pre-existing joints, cracks, and fissures of an exposed rock face during warmer daytime conditions.
  2. 2Temperatures drop below 0∘C0^\circ\text{C}, causing the trapped water to freeze into ice and expand in volume by approximately 9%9\%.
  3. 3Repeated diurnal freeze-thaw cycles progressively widen, deepen, and propagate the internal fractures within the rock mass.
  4. 4Angular rock fragments shatter completely from the cliff face and accumulate at the base as scree or talus deposits.

Answer

The correct sequence begins with liquid water percolating into rock joints during warmer temperatures, followed by water freezing and expanding by about 9%9\% as temperatures fall below 0∘C0^\circ\text{C}. This frost wedging progressively widens rock fractures over repeated freeze-thaw cycles, eventually causing angular rock fragments to dislodge and form scree slopes at the base of the rock face.
The process of frost shattering follows a clear mechanical progression: liquid water must first occupy pre-existing fractures in the rock face; sub-zero temperatures then cause the trapped water to freeze and expand by roughly 9%9\%, creating intense lateral pressure; recurrent freeze-thaw cycles continuously strain and widen these micro-fractures; and ultimately, angular fragments detach from the parent cliff and accumulate downslope as scree deposits.

Step-by-Step Solution

1
Identify the initial moisture entry requirement.
Water must first collect inside pre-existing rock joints and fissures.
Physical freeze-thaw weathering cannot take place without trapped liquid water inside open rock spaces.
2
Determine the physical change triggered by freezing conditions.
Water turns to ice below 0∘C0^\circ\text{C} and expands by 9%9\%.
The anomalous expansion of freezing water exerts immense outward pressure on fracture walls.
3
Trace the structural deterioration over time.
Repeated thermal cycling widens and extends internal fractures.
Continuous pressure fluctuations weaken the cohesive strength of the rock along lines of weakness.
4
Establish the end product of the weathering process.
Angular rock fragments break free and accumulate as talus or scree at the mountain base.
Complete mechanical failure occurs when fractures sever the fragment from the main outcrop.

Key Concept

Mechanism and Stages of Frost Shattering (Freeze-Thaw Weathering)
Estimated Time:1m 15s
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Topics

Weathering and Mass Wasting Processes

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