Snow-filled crack in lower Tanana River ice Photo Credits: Chas Jones Snow blown into a refrozen crack on the lower Tanana River. A crack like this can create a hazard when traveling by snowmachine as it would be easy to catch a ski on the edge. Process Observed: Thick IceTravel Hazard Date Process Observed: Tuesday, March 16, 2010 Galleries: Thick, safe ice lower Tanana River Gallery