Blackstone Glacier

March 23, 2011

Photographer: Nel Graham
Summary Author: Nel Graham; Jim Foster

The photo above shows the scenic Blackstone Glacier emptying into Blackstone Bay in southeastern Alaska. Blackstone Glacier is one of a number of tidewater glaciers in the College Fjord area of Prince William Sound. It seems to be rather stable at this time -- neither markedly advancing nor retreating. Note the blue ice in the ablation zone. The blue color results since longer wavelengths of sunlight (reds, oranges, yellows) are absorbed more readily by thick ice (several meters or more) than are the shorter wavelengths (blues and greens). Therefore, the further light travels in ice, the bluer its color.

College Fjord was near the epicenter of the intense Good Friday Earthquake, which rocked Alaska in late March of 1964. This 9.2 magnitude shaker (even more powerful than the quake that devastated northeastern Japan earlier this month) was the strongest earthquake in U.S. history. Photo taken in July of 2003.

Photo details: Camera Maker: OLYMPUS OPTICAL CO.,LTD; Camera Model: C3100Z,C3020Z; Focal Length: 19.1mm; Aperture: f/7.0; Exposure Time: 0.0031 s (1/320); ISO equiv: 100; Exposure Bias: none; Metering Mode: Matrix; Exposure: program (Auto); Flash Fired: No; Orientation: Normal; Color Space: sRGB.