Ice Needles: Sculptors of Stone Patterns in Frigid Landscapes
Ice Needles and Labyrinth Stones
In cold regions around the world, scientists have observed intricate patterns of stones and grooves etched into the ground. These patterns, including circles, rows, and swirls, are formed by the movement of stones as tiny, thread-like ice crystals, known as ice needles, emerge from the freezing ground.
As ice needles freeze and thaw, they push pebbles to one side, gradually forming the intricate shapes. These patterns are reminiscent of those found in Japanese zen gardens.
Laboratory Experiments and Computer Modeling
Researchers have long speculated that ice crystal spikes could move soil and rocks to form these patterns, but it has only recently been confirmed through laboratory experiments and computer modeling.
In a study published in the Proceedings of the National Academy of Sciences, researchers demonstrated how ice needles poking through the ground can gradually move rocks and soil into geometric and organic shapes.
Ice Needle Formation
Ice needles develop when the temperature of the air and the temperature of the moist soil are different. At night, some types of soil contract as temperatures drop, drawing water upwards and causing it to stick to the sides of narrow pores in the ground.
As the water is drawn out of the Earth, the cold air freezes it, turning it into small, sharp, crystal-like structures.
Creating Patterns in the Lab
To create the swirls and ridges in a lab setting, researchers placed pebbles on top of a pan filled with wet, fine-grained soil. They then froze and thawed the miniature landscape over and over, creating different conditions to observe how the pebbles moved as the ice melted.
When the wet soil was not frozen but the air temperature dropped below freezing, pins of ice poked through the soil like sprouting grass. The needles grew several centimeters high, raising the pebbles off the ground. When the temperature was increased, the stones fell off the ice and tumbled to one side.
Over Time: Formation of Stone Clusters and Patterns
Over time, the freeze-thaw process cleared patches of exposed soil, and eventually, stones shifted into clusters, creating larger patterns. On flat ground, the stones formed dizzying arrays of swirls and loops, while on sloped ground, they formed neat rows.
Factors Influencing Pattern Formation
The rate and shape of the patterns depend on various factors, including:
- Number and density of stones
- Soil moisture
- Height of ice needles
- Slope of the ground
Potential Martian Patterns
Some experts believe that a version of these freeze-thaw cycles may have created patterns observed on the surface of Mars. Soil on the Red Planet has shown evidence of tiny ice crystals, and as the soil heats up, it may expand only to contract again after it begins to cool.
Though the process is more subtle on Mars, it could be enough to shift pebbles and dust over time.
Implications for Climate Change
The study results demonstrate the power of combining laboratory experiments with computer modeling to understand natural landscape behavior. This approach may lead to a better understanding of how these behaviors could change as the climate warms.
By studying the formation of stone patterns in frigid landscapes, researchers can gain insights into the processes that shape our planet’s surface and the potential impacts of climate change.
