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Frost Heaves and Connecticut Stone Walls Task

Standards Alignment:

Simulation Link: Frost Heaves and Connecticut Stone Walls

Introduction

Connecticut has more miles of stone walls than almost any other state — an estimated 50,000 miles of them weaving through forests and fields. When 18th-century farmers cleared their fields each spring, they were baffled to find new rocks at the surface every year, as if the Earth were growing them. Where were these rocks coming from?

The answer lies in a unique property of water. In this task, you will use the Frost Heaves and Connecticut Stone Walls simulation to plan and conduct an investigation that uncovers the mechanism behind this phenomenon.

Part 1: Make a Prediction

Before you begin your investigation, consider what you already know about water and ice.

  1. Recall: What happens to the volume of water when it freezes? How is this different from most other substances?

  2. Predict: The simulation starts with 30 rocks buried in typical Connecticut silt/loam soil at 60% moisture. Write a prediction: How many freeze-thaw cycles (years) will it take for the first buried rock to reach the surface? Explain your reasoning.

  3. Enter your prediction into the simulation’s prediction box before clicking Start.

Part 2: Baseline Investigation

Run the simulation with the default settings (Silt/Loam soil, 60% moisture, Moderate winter) and observe carefully.

  1. Observe: Click “Start” and watch the soil cross-section through several seasons. Describe what you see happening to the rocks during winter (when the temperature drops below 0°C) versus spring (when the temperature rises above 0°C).

  2. Record Data: Let the simulation run for at least 10 years. Use the Data Log table to record:
    • The year the first rock reaches the surface
    • The total number of surface rocks after 10 years
    • The frost depth during winter
  3. Compare: How did your prediction from Part 1 compare to the actual result? What surprised you, if anything?

Part 3: Systematic Investigation — Isolating Variables

A good investigation tests one variable at a time. You will now plan and conduct a controlled investigation to determine which factors have the greatest effect on frost heaving.

Reset the simulation between each trial.

Trial Set A: Soil Moisture

Keep soil type at Silt/Loam and winter severity at Moderate. Run three 15-year trials:

Trial Moisture Surface Rocks (Year 15) Frost Depth (Winter) Observations
A1 0% (Dry)      
A2 60%      
A3 100%      

Trial Set B: Winter Severity

Keep soil type at Silt/Loam and moisture at 60%. Run three 15-year trials:

Trial Winter Surface Rocks (Year 15) Frost Depth (Winter) Observations
B1 Very Mild      
B2 Moderate      
B3 Arctic      

Trial Set C: Soil Type

Keep moisture at 60% and winter severity at Moderate. Run four 15-year trials:

Trial Soil Type Surface Rocks (Year 15) Frost Depth (Winter) Observations
C1 Sand      
C2 Silt/Loam      
C3 Clay      
C4 Mystery Soil      

Part 4: Mystery Soil Analysis

The simulation includes a “Mystery Soil ?” option.

  1. Investigate: Run at least two trials with the Mystery Soil (varying moisture or winter severity). Record your data.

  2. Analyze: Compare the Mystery Soil’s heaving rate to Sand, Silt/Loam, and Clay. Which known soil type does it behave most like? Is it more or less effective at frost heaving?

  3. Claim: Based on your data, make a claim about the properties of the Mystery Soil. What characteristic (drainage, capillarity, particle size) would explain its behavior?

Part 5: Construct Your Explanation

Using the evidence you gathered from all your trials, construct a comprehensive scientific explanation of frost heaving. Your explanation must: