Where on Earth is Muir Glacier?
Muir Glacier is located below White Thunder Ridge in Glacier Bay National Park and Preserve, Alaska, USA at a latitude of 59.10° North and a longitude of 136.38° West. It is currently classified as a valley glacier because it resides in a valley between mountains. A century ago, Muir Glacier was first labeled as a tidewater glacier because its terminus emptied into the ocean. The glacier's dramatic retreat instigated a change in classification due to the new location of the terminus. Currently it is approximately 11 miles (18 kilometers) long and 0.4 miles (0.7 kilometers) at its widest.
It is named for John Muir who discovered it in 1879. Many early explorers investigated Muir Glacier. Both Frank LaRoche (standing in the 1893 grouping of photos below) and Harry Fielding Reid visited and surveyed the glacier in the 1890's.
The sketch to the left was done by Reid in 1890. His handwriting at the bottom says, "Front of Muir Glacier taken 775 ft. above camp on side of mountain on side of stream looking magnetic W. Sunday July 13, 1890 at 8pm."
"Muir Glacier is no longer visible, as it has retreated more than 50 kilometers (31 miles)"—USGS (2009)
Muir Glacier has been very well monitored and photographed over the last 120 years. Bruce Molnia created a project to take repeat photographs of Alaskan glaciers. He made many trips to the glacier and took a photo from the exact same location each time to photographically document the retreat of the glacier. The two bottom photos in the image at left were taken by Molnia. You can see in the 1976 photo that the vegetation had yet to take hold on the newly exposed ground, but by 2004 shrubs have taken over and Muir Glacier had receded further inland.
The U.S. Geological Survey keeps track of Muir Glacier as well as other Alaskan Glaciers. You can read about them on the USGS Repeat Photography of Alaskan Glaciers Web page.