Goldstream Creek, at the Alaskan research site, is about 8 m wide and, prior to freezeup in October, it varies from 20 to 40 cm deep across the main test section. During the last 3 weeks prior to formation of a complete surface ice cover, the water temperature varies within a range of about 0.2C. Early in the nightly cooling cycle it drops to -0.01C to -0.05C for periods of several minutes up to several hours. Discs of frazil ice, 1 to 6 mm in diameter and 0.025 to 0.1 mm thick, form in the supercooled water and gradually raise its temperature to near 0C. At this stage, dendritic forms begin to grow on the discs. These adhere to the stream bottom and crystals continue to grow as turbulent flow of slightly supercooled water transports the heat of fusion to the stream's surface, where it is lost as long-wave radiation or by advection or evaporation. This process produces underwater ice. During breakup, in May, the streambed was always full of ice and the overflowing floodwaters peeled off the ice layers.