Encore - Deep Blue Abyss on Godwin's Glacier

December 15, 2018

Blue Abyss
Today and every Saturday Earth Science Picture of the Day invites you to rediscover favorites from the past. Saturday posts feature an EPOD that was chosen by viewers like you in our monthly Viewers' Choice polls. Join us as we look back at these intriguing and captivating images.

: Julian Kegel
Summary Authors: Julian Kegel; Jim Foster

The photo above shows an amazing crevasse I stumbled upon while guiding hikers on a rainy summer's day on Godwin Glacier in Chugach National Forest, Alaska. I called it Godwin's Abyss. The entire crevasse is over several thousand feet long. The widest section, featured here, I estimated to be 60-70 ft across (18-21 m). Because this area of the ice was probably under the most stress, it opened very quickly and very recently, maybe even the night before we arrived. We know this because both rain and sunlight can decay solid glacier ice. When this happens, the ice looks particularly bright because the resulting air bubbles within the ice are quite effective at scattering light, much like in the head of a beer.

The beauty of this crack is not just the deep blue color emanating from the depths, but the fact that it's so deep (it's not known exactly how deep) the chasm appears to swallow light almost completely. In actuality, there are few air bubbles deep inside a glacier to reflect light back out, and the thick ice is absorbing nearly all wavelengths of visible light. Never in my many years of guiding had I ever seen such a magnificent gradient of color! Photo taken on July 27, 2011.

Photo Details: Camera Model: Canon EOS 5D Mark II; Lens: EF50mm f/1.4 USM; Focal Length: 50.0mm; Aperture: f/18.0; Exposure Time: 0.013 s (1/80); ISO equiv: 800.  

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