via.wnep.com
Rare Ice Circle Forms in Washington State River
NORTH BEND, Wash. -- Hikers in Washington State were treated to an unusual natural phenomenon Saturday morning -- an ice circle spinning in the Snoqualmie River. The thin circular slab of ice is sometimes referred to as an ice disc and it forms on the outer bends in rivers where accelerating water creates a rotation. As the ice spins, it grinds against other surrounding ice smoothing it into a circle.