Pancake ice is a form of ice

Ice

Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...

 that consists of round pieces of ice with diameters ranging from a few inches to many feet, depending on the local conditions that affect ice formation. It may have a thickness of several inches.
Pancake ice features elevated rims with a nearly uniform height of a few inches. The rim is formed by piling the frazil ice/slush/etc. up the edges of pancakes when they collide, both due to random bumping into each other and because of periodic compressions at wave troughs. These rims are the first indication of the onset of the formation of the pancake ice from less consolidated forms of ice.

Pancake ice may be formed in two ways. It may be formed on water covered to some degree in slush

Slush

Slush can mean any of the following:* Slush — a slurry mixture of liquid and solid forms of water.* Slush — a pejorative and slang combination of the likewise derogatory terms slut and lush...

, shuga or grease ice

Grease ice

Grease ice is a very thin, soupy layer of frazil crystals clumped together, which makes the ocean surface resemble an oil slick. Grease ice is the second stage in the formation of solid sea ice after ice floes and then frazil ice....

. Alternatively, it may be created by breaking ice rind, nilas or even gray ice in the agitated conditions.

External links

• Definition of pancake ice from the Canadian Ice Service