Saturday, February 22, 2014

Ice Cracks

Stress causes the cracks seen in exposed ice. New ice has fewer cracks compared to older ice since older ice has endured many warm-cold cycles. Warm and cold temperature cycles expand and contract ice.

Cracks in the frozen glacial meltwater of Lake Fryxell

Ice is not as resistant to thermal shocks as other solids. The expansion and contraction due to temperature changes creates a system of cracks.

Sometimes sinuous, sometimes rectilinear, these ribbon-like discontinuities form a graceful and intricate visual poetry on a frozen but ever-changing canvas.

We observe this intricate canvas of cracks as one might observe the last snapshot arriving from the past into the station of our sensory present.

A thundering pop summons us to sound.


The stresses causing ice cracks make somewhat expected snapping and popping sounds, but also make incongruous howling and screeching sounds.
The ice was here, the ice was there,
The ice was all around;
It cracked and growled, and roared and howled,
Like noises in a swound!

Samuel Taylor Coleridge, from Part I of The Rime of the Ancient Mariner
When ice warms and expands, sounds emanate along the stressed surfaces. Similarly when ice cools and contracts, sounds emanate from the source of the disturbance.