Needle Ice

Looking down at ice formations on the Au Sable trail, Hartwick Pines State Park, MI

Sleeve closeup showing soil caps and individual cylinders

On a recent hike in Hartwick Pines State Park, known for its virgin stands of not just white pines, but hemlocks and jack pines as well, a swampy stretch sounded crunchy enough to bring Melissa Damaschke and myself to a halt. In the middle of the trail were clumps of what looked like fairy-tale tree trunks, made of ice, 3 to 4 inches tall, and about a quarter-inch thick. Most wore a cap of soil, and some had a secondary cap where what appeared to be an extrusion process had halted, then resumed. To me, they looked like a fluted cake-decorating tube just below ground level had pushed up the "trunks."

We wondered if each little trunk was formed around a blade of grass or twig, but they were ice and only ice. Each clear formation turned out to be composed of tiny cylinders, some dozens. We took pictures and headed back to Hartwick Pines' beautiful Visitor's Center, to show forester Craig Kasmer. Then we came back to Detroit and I began googling.

I found very few photos of what we saw (with about half including the question, "anyone know what the heck these are?") but some were close to dead ringers. Craig Kasmer answered my email query promptly with the identification "needle ice" and this link, with a description of how the little towers are formed. The photos in the link show formations much tidier and more organized-looking than we saw, but obviously the same type of phenomenon. The accompanying explanation gives the incredible statement that needle ice can get as tall as 16 inches.

We saw clusters as big as 9 or so inches in diameter, with dozens of individual stems , and some small clumps of only two or three. If there had been more snow, I doubt we'd have noticed them at all. If our experience is typical, listen for crunching beneath your feet when hiking through swampy areas on below-freezing days, perhaps when the ground is beginning its deep freeze for the winter.

Post and photos by Sierra Club volunteer Rebecca Hammond