An avalanche is a mass of snow sliding down a mountain. There are different types including surface avalanches which involve layers of snow with different properties sliding over each other, and full depth avalanches where the entire snow cover from the ground up slides. Avalanches are caused by various environmental factors including heavy snowfall, steep slopes, vibration, warm temperatures and layers of snow and ice building up. They can damage life, property and infrastructure and cause flash flooding, but are also a natural part of mountain ecosystems. Understanding avalanche patterns and avoiding likely start zones are important for preventing danger.