Ice textures

Last weekend, in response to a request for a snow day from the kids, we drove up into the Sierras to Bear Valley near the intersection of Interstate 80 and California route 20. We’ve explored the area several times before, mostly in the winter when it is blanketed in snow. The South Fork of the Yuba River crosses through the area. More a stream than a river at this elevation, its bed is littered with large smooth boulders, each topped with caps of bright snow this time of year.

Umbilicaria sp. on a snow-covered boulder.

Conifers (pines and stately incense cedars), and the grey skeletons of dormant deciduous trees comprise the forest in the area. Where there are gaps in the snow (or on the steeper sides of rocks where snow doesn’t collect), there are vibrant green mosses and a palette of lichens from yellow to chocolate brown species. The brown species (an Umbilicaria I believe) has a peltate form, attaching to the rocks like a very stout mushroom, the margins of the plants unattached. There are black spots on the thalli, varying in size and shape that resemble tar spots. These are the apothecia of the fungi where spores are produced.

Tufts of moss in little ice caves.

The area is generally pretty, but not necessarily remarkable. Winter, with its cover of snow however, brings a freshness that accentuates the mystery of the landscape, rounding the shapes under the blanket, and revealing underlying bedrock or biota here and there. I spent some time looking closely at the ice surfaces, these remarkable in their detail. Here are some close-up photos of different ice shapes and textures.

Reference(s)

Brodo IM, Sharnoff SD, Sharnoff S. 2001. Lichens of North America. Yale University Press, New Haven.

Close-up view of the textured surface of icicles. Each irregular polygon, looking remarkably like a cluster of cells, was on hte order of a few millimeters in size. 

Brittle ice crystals over a bed of moss.