The snowpack of a massif – like the Massif du Sancy – consists of the stratified accumulation of snow layers, that each have different characteristics. The snowpack is therefore made up of a mixture of ice crystals and air, to which water in liquid state is added when the temperature approaches 32°F (0°C) or after rainfall. Other particles (sand, volcanic ashes, black carbon, etc.) can also be deposited on top by winds.