Lake Louise, Canadian Rockies. Dramatic afternoon lighting accentuates the color of the deep-cerulean waters of Lake Louise in Banff National Park. The waters of this lake take on a cerulean hue in summer as the meltwater from Victoria Glacier flows into the lake with its burden of ground-up glacial silt. Suspended in the water of the lake, this milky solution absorbs the light at the short end of the visible-light spectrum causing the water to appear blue green. A short lake-side trail leads to the base of this glacier as it flows beneath the high summit cliffs of 11,365-foot Mount Victoria. These valleys were filled with enormous glaciers at the maximum extent of the ice sheets at the height of the Pleistocene Epoch about 20,000 years ago. As these ice sheets melted, they left in their wake a string of glistening lakes all along this valley.