The Great Gorge

The Great Gorge of the Ruth Glacier is one of the most spectacular gorges on earth. At nearly 35 miles long, it feeds off the slopes of Denali and Mt. Silverthrone. Numerous forks of the glacier merge into the huge icefield known as the Don Sheldon Amphitheater (aka Ruth Amphitheater). This vast snow arena encompasses some 25 square miles. Then, with nowhere else to go, the great mass of ice is pushed down a mile-wide constriction rimmed by walls up to 5,000 feet high. With so much ice being squeezed through such a narrow slot, it’s no wonder that the glacier has been measured to be more than 3,800 feet deep and moving at a rate of over three feet per day.

The black lines in the glacier are lateral moraines, formed along the sides of the glacier. As the glacier scrapes along, it tears off rock and soil from both sides of its path. This material is deposited at the top of the glacier’s edges. Lateral moraines are usually found in matching ridges on either side of the glacier. The glacier pushes material up the sides of the valley at about the same time, so lateral moraines usually have similar heights.

Technical Details

Composite: No
EF 28-135mm @ 41mm; f/4 @ 1/8000 sec, ISO 400

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Woah what a view. I’m glad you explained the dark lines. A lot of Wisconsin geology is based in glacial moraines left behind in the Wisconsin glaciation event in the last ice age. The ice sheet was much, much larger and so the moraines are only really apparent from the air. When you walk on or near them, they are just hillsides.

Thank you, Ms. Smith. We flew out of Talkeetna with Sheldon Air Service, now managed by Don’s daughter Holly. Our pilot was her husband David Lee. They know the area better than any other service. We had spectacular weather and David knew and shared so much about the history and topography of the High One. We spent most of a day flying over Denali, including landing on a glacier at the base camp used by climbers. If you ever have an opportunity to visit, I would encourage you to fly with them.