The peculiar phenomenon known by this name, which means literally "frost-pillars," has provoked some curiosity among the resident learned. These frost-pillars are first seen after a bright cold night in early winter, and always in damp, friable soil, the fine uppermost layer of which is borne upwards on their surface, so that one may fail to notice them until, in walking, the foot crushes down two or three inches -sometimes even five or six inches-into what had looked like firm ground; but often they cling to the high sides of shady lanes. Examined singly, they present the appearance of tiny hexagonal columns, or rather tubes, of ice; but they generally occur in clumps or bundles half melted together, and the longer ones sometimes curl over like shavings. Sometimes joints can be perceived in them, and at each joint a minute particle of earth. The late Dr. Gottfried Wagener explained the phenomenon as follows:-"When the surface of damp soil, in which the water is divided into slender canals, cools at night by radiation, the water at the exits of the canals hardens into ice. This ice then assists the hardening of the adjacent particles of water, which also congeal before the soil itself has fallen to freezing-point, and before therefore the water can freeze fast to the particles of earth. The ice then extends in the direction of least resistance, that is, upwards. In this manner, one molecule of ice after another pushes its way out of the slender canals,-a process which also explains the thread-like structure of the frost-pillars. These push up with them, in their growth, the minute particles of earth which lie between their extremities, and which also are cooled by radiation and stick to the ice. They form a crust which itself protects the underlying soil against further radiation. This accounts for the fact that the soil on which the frost-pillars stand, far from being frozen, is so soft and wet that a thin cane may easily be stuck deep into it. That the ice needles really grow from below and force their way up out of the soil, is proved by the circumstance that in shady places, where they are not melted during the day and can therefore continue to grow for several nights in succession, several sharply defined thin layers of earthy particles may be distinguished in the pillars. Frost-pillars are also formed under a thin covering of snow, when the upper surface of this latter melts during the day-time. The water then penetrates into the lower layer of snow, and thence into the soil. The thin snow-covering freezes during the night, and the hardening process, as above described, proceeds on into the canals below ground."
So far as our experience goes, frost-pillars, as here described, are unknown in Europe. An English gentleman long resident in Virginia tells us, however, that they occur there, going by the local name of "frost-flowers."
Book recommended - Our quotation is from a short paper by Dr. Wagener, in Part 12 of the German Asiatic Transactions.