How can avalanches add snow to a glacier?

Avalanches contribute to the growth of a glacier by acting as a source of accumulation. When snow from adjacent slopes avalanches onto a glacier, it adds mass to the glacier's surface.1

This process is one of several ways a glacier gains mass, alongside direct snowfall, the formation of hoarfrost, rime, and the freezing of rain or meltwater. For a glacier to maintain a constant size, this income of mass must balance the loss caused by ablation, which includes melting, runoff, and the calving of icebergs.1