What Is Termination Dust? It is a dusting of the tops of the mountains with a very light snow when it rains in the lower levels. The rain freezes and makes something that looks like soft ice cream on top of the mountains. This means fall in Alaska is OVER. This film was made about 4 years ago and shows LOTS of termination dust for your enjoyment. (and relaxing music). You also learn the definition of a “sludge cup.”