Multiple Snow Layers avalanche conditions. On the There are three main causes that contribute to surface of a mountain is the snowpack. This is the snow that has fallen and accumulated over the past weeks and months Usually, there are several layers of snow on the mountain. The first layer al snow is called the"bed layer." Some of this snow will melt away. leaving a seco thin layer of ice particles on top of the might take several weeks before another heavy snowfalr The da comes when third layer of snow falls. If it is made of light, loose or fluffy the"weak snow(not heavy wet snow), the danger starts, This third layer is called the or slab ayer" A cak uayer snow lying on top orice and bed layers nieans that an avalanche is more likely to occur,