Braided melt pattern seen during breakup on the Athabasca River, AB (Canada), April 20, 2000
Freeze-up ice jams (hummocky ice covers) are a common feature on the Athabasca River near Fort McMurray, Alberta. When breakup rolls around, these undulating ice covers melt out unevenly – with the thinner sections melting first. This creates the braided melt pattern you see here. You can also see what I call a “baby jam” in this picture – the typical first sign that the dynamic breakup is underway on the Athabasca.
(photo by UofA River Ice Group: Nikon E950, f/7.7, FL 8 mm, 1/215 sec.)