Glacier Blanc. Glaciers are rivers of ice that form when compacted snow from high ground turns into ice and flows downhill under its own weight. Many years of snowfall are contained in the ice of the largest glaciers, flowing off high mountains down to the lowlands below. Waterfalls and streams (lower right) form in summer from meltwater from the glacier ice. Photographed in the Alps, in Ecrins National Park, in the Haute-Alpes region of France.