Dana Glacier has a rich history of repeat photography. Owing greatly to its relative ease of access from Tioga Pass, the glacier has the greatest number of repeat photographs of any glacier in the Sierra Nevada. Israel Cook Russell first photographed Dana Glacier in 1883 while conducting surveys for the USGS. Little did he know that one of his photos would be purposefully repeated 32 times over the next 130 years by those seeking to maintain a photographic record of glacier change.
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| Dana Glacier 1883 – 2013, from Station 4. |
Russell documented the existence of Dana Glacier when the glaciers in the Sierra Nevada were near their recent maximum. In 1883, the glacier is in contact with the moraine and crevasses are observed indicating movement. Since that time the glacier has retreated. The first and most repeated of Russell’s photograph shows the glacier from the north shore of Dana Lake. A comparison with the 2013 repeat photograph shows that the glacier has retreated and lost surface area over the past 130 years.
Russell photographed the glacier from two other perspectives at closer range. These previously unrepeated frames further reveal the changes. A mid-range photo taken from above Dana Lake features the glacier directly. The glacier can be see in contact with the moraine. The repeat photograph taken from the same location reveals the loss in glacier area as well as a loss in volume.
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| Dana Glacier 1883 – 2013 from Station ric46. |
The third photograph by Russell was taken close to the glacier terminus. The historical photograph is dominated by undulating ice with an unusual textured glacier surface. The glacier has mostly retreated from the frame in the 2013 repeat image, which features an empty moraine and bare rock. Small cascading streams drain the remaining portions of the glacier at base of the Dana cirque headwall cliff.
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| Dana Glacier 1883 – 2013 from Station ric049. |
During my mapping survey I found evidence that the glacier continues to move. An open bergschrund outlines the top of the glacier and several smaller crevasses indicate areas of movement. While walking the terminus, the glacier would periodically thrust with the sound of sudden movement. Investigating an ice cave underneath the glacier showed the viscous flow of the glacier’s dirty bottom along the bedrock.
The ice at the glacier terminus is very thin. Melting at the glacier bed causes the glacier to collapse. It is impossible not to wonder how long the glacier will continue to move. When it stops moving, it will no longer be considered a glacier. Instead is will be redefined as a perennial ice field. What will Dana Canyon look like in another 130 years?
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| Underneath Dana Glacier. The bottom of the glacier takes its color from the bedrock as it grinds downward. (H. Basagic) |
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| The terminus of Dana Glacier in 2013. (H. Basagic) |
Repeat photographs of Dana Glacier continue to document the changes. These new comparison images contribute to the rich photographic history and reveal new unique perspectives not previously observed. The comparison images assist glacier mapping efforts and provide a better understanding of the rate of changes.
