Cornices


My brother and I took a quick trip up to the top of Berthoud Pass to take some photographs of snow cornices earlier this week.

According to Merriam-Webster Dictionary, a cornice is “the decorative top edge of a building or column”. A secondary definition, though, is “an overhanging mass of windblown snow or ice usually on a ridge“.

Cornices are overhangs of snow. This one is on the east side of Berthoud Pass, looking south.

Cornices are overhangs of snow. This one is on the east side of Berthoud Pass, looking south.

Cornices are made when winds reaching speeds of over a hundred miles an hour pick up snow and carries it to the edge of a cliff. When the howling winds cross the cliff edge, it puts the “pack” in “snowpack”, pounding the snow into a ledge of concrete-hardness. The snow builds up on the ever-lengthening ledge and, by spring, has formed a frozen white wave on the mountain top.

Cornices are created when the wind picks up snow on one side of a ridge and drops it on the far side. The wind then packs the snow down.

This photo is of a cirque, or bowl, at the head of a now melted glacier south across the valley from Berthoud Pass. You can see how the snow blown off the slope and into the cirque would have added to the glacier.

The area bare of snow has a much different ecosystem than the one just to windward of it. The bare area has to endure screaming winds, sub-zero temperatures and little moisture. Under the cornice, it is comparatively warm, wet and still.

This bowl, on the west side of Berthoud Pass, is ringed by frozen white waves of cornices.

This bowl, on the west side of Berthoud Pass, is ringed by frozen white waves of cornices.

 

 

 

 

 

 

About coloradogeography

Amy Law is a science geek. She feels about science the way some people feel about music, or art, or sports – a total and complete emotional connection. She thinks in science. For Amy, there’s nothing better than helping people see the beauty of science as she does. She loves to untangle a complicated subject into its parts, explaining it so that anybody can understand what’s happening. Let her show you her world...
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