Science: Needle ice

Needle ice is a phenomenon that occurs when the temperature of the soil is above 0°C and the surface temperature of the soil is below 0°C. The subterranean moisture is brought to the surface via capillary action.

The ice needles are typically a few centimetres long. While growing, they may lift or push away small soil particles. On sloped surfaces, needle ice may be a factor contributing to soil creep.

Sources: Wkipedia