Rideau River Pancake Ice

January 31, 2013

Rideau River Pancake Ice

Photographer: Rick Stankiewicz
Summary Authors: Rick Stankiewicz

Hog’s Back Falls (officially known as the Prince of Wales Falls) are an artificially created set of rapids on the Rideau River at the point where the river splits from the Rideau Canal in Ottawa, Ontario. Here the water drops about 39 ft (12 m) over a run of about 1,970 ft (600 m). Although this particular spot along the canal is enjoyable year-round, what caught my attention on this visit was the back eddy of pancake ice (bottom center) in juxtaposition to the rapids. Pancake ice typically forms from accumulations of frazil ice in fast flowing water. The raised rims of the icy plates result from the swirling motion in the backwater of the falls and from the growing ice cakes randomly bumping into each other. These floating ice formations can range from several inches (4 cm) to several feet (1 m) across. As pictured above, they're likely several inches (1-3 cm) in thickness. Although more commonly found on larger bodies of water such as Arctic seas and bays, you may even discover such winter oddities in the middle of a mid-latitude city. Photo taken on January 7, 2012.

Photo details: Camera Model: Canon EOS DIGITAL REBEL XTi; Focal Length: 18mm; Aperture: f/8.0; Exposure Time: 0.0050 s (1/200); ISO equiv: 200; Exposure Bias: +0.67 EV; Metering Mode: Matrix; Software: Adobe Photoshop 7.0.