in Thoreau’s Journal:
The slight robin snow of yesterday is already mostly dissipated, but where a heap still lingers the sun on the warm face of this cliff leads down a puny, trickling rill, moistening the gutters on the steep face of the rocks where patches of umbilicaria lichens grow, of rank growth, but now thirsty and dry as bones and hornets’ nests, dry as shells which crackle under your feet. The more fortunate of these, which stand by the moistened seam or gutter of the rock, luxuriate in the grateful moisture as in the spring, their rigid nerves relax, they unbend and droop like limber infancy, and from dry ash and leather color turn a lively olive green.
You can trace the course of this trickling stream over the rock through such a patch of lichens by the olive green of the lichens alone. Here and there the same moisture refreshes and brightens up the scarlet crown of some little cockscomb lichen, and when the rill reaches the perpendicular face of the cliff, its constant drip at night builds great organ pipes, of a ringed structure, which run together buttressing the rock. Skating yesterday and today.