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Members of the corps say the "snow-ice caves" are products of natural phenomenon peculiar to Mt. Paektu where winter lasts over 200 days with heavy snows, summer is short, temperature is low and wind is strong.
With the advent of warm spring, thaw begins in the deep valleys of Mt. Paektu. The surface is heated by sunshine in daytime allowing the snow melt at the bottom and it freezes at night with the temperature falling below zero.
The ice is different from the ordinary ice. It is a mixture of water from melted snow and pumice grain carried by wind blowing over snow.
With the repetition of this process, the upper layer becomes hard "snow-ice" while streams are created at the bottom of the valleys by water from melted snow flowing down from the upper part and gathering from mountain ridges. By this water course the holes are steadily widened to bring caves into shape.
In the meantime, the pumice grains carried by wind create a thick layer on the surface, which reduces the effect of solar radiation. This can be said to be the start of the formation of "snow-ice caves" in Mt. Paektu.
When summer comes, with the rise of temperature, the snow piled up in valleys melts and flows down in earnest. With the repetition of this process, the width, height and depth of the caves increase to take on the full looks of caves. But, when the short summer passes and autumn comes, the ceilings of the caves, soaked in water during summer, get frozen again to become "snow-ice."
When snow falls and temperature drops below zero in Mt. Paektu, the flow of water at the bottom completely stops and the snow-ice of ceilings gets harder to present grotesque patterns. The process is repeated every year.
The steeper and the deeper the valley is, the faster the "snow-ice caves" take shape.
Those caves look fantastic for the icicles from the ceilings, the ice columns standing up to the ceilings from the bottoms, the wonderful grooves on the bottoms and wavy patterns on the ceilings.
