Sperry Glacier Then and Now: Repeat Photography in Glacier National Park

In 1988, Lisa McKeon walked out onto Grinnell Glacier with her parents, among other hikers exploring and photographing the ice. She didn't know then that she'd spend the next three decades hiking to Glacier National Park's glaciers — and her career studying them for the U.S. Geological Survey (USGS).

McKeon helped create the USGS repeat photography project, which documents the park's glaciers in pictures. In the park's archives, she copied old glacier photographs by early Euro-American scientists such as George Bird Grinnell and her USGS predecessor William Alden. Then, pictures in hand, she hiked into the high country to find the exact spot each one was taken from, and took a new photo from the same angle — showing how the landscape had, or hadn't, changed. That's repeat photography, or rephotography.

Lisa McKeon at Grinnell Glacier in 2020. When she tried to repeat her own 1988 photo, so much ice had melted that the spot was in meltwater.

Timing is everything

People offer in June to take photos for her, McKeon says, but they have to wait: the seasonal snow must melt off the glacier first — at the earliest the end of August, maybe September. In most years the window is narrow, late August to late September, between the melting of last winter's snow and the first autumn snowfall. Only then is the glacial ice clearly visible. Historic photos, too, have to be chosen for having little seasonal snow in them.

Sexton Glacier in early summer. Seasonal snow is much whiter and cleaner than glacial ice, which is covered in rock and dirt — here the snow hides the ice. NPS

The first step to a good repeat photo is telling snow from permanent ice. The old photographer's position can be estimated on a map or Google Earth, but where the landscape has changed a lot, finding the spot can still take hours.

Sperry Glacier arm below Mount Edwards

One of the first glaciers McKeon rephotographed was Sperry Glacier. Morton J. Elrod photographed this view in 1907; McKeon repeated it 96 years later, in 2001.

1907. Morton J. Elrod

2001. Lisa McKeon, USGS

Years later, repeating McKeon's own photos shows how the glaciers keep changing. The same view was taken again in 2023:

2023

Sperry Basin: a viewpoint that no longer exists

Elrod took another picture, around 1930, looking north at the glacier's end. When McKeon went to repeat it in 2009, she realized Elrod must have been standing on the glacier. That ice has since melted away, so his viewpoint can't be reached any more.

Around 1930. Morton J. Elrod

2009. Lisa McKeon, USGS

2023

The 2023 repeat shows the glacier hasn't advanced back into the frame. Future repeats could show plants moving in where ice used to be.

Sperry Basin with lakes: 1981 and 2023

The USGS archives also hold photos from the early 1980s. Paul Carrara took these on August 23, 1981, and they were repeated on September 8, 2023.

August 23, 1981. Paul Carrara, USGS

September 8, 2023

A new baseline

The glaciers of McKeon's youth have all shrunk. Her collection of repeat photographs records a century of change — and sets a new baseline for measuring changes still to come.

More: Glacier's repeat photography album · the park's Headwaters podcast, whose "Confluence | Many Glacier" and "Becoming | Stained by History" episodes explain how repeat photography works · USGS repeat photography project · next in the series: Repeat Photos of Grinnell Glacier.

Sources

Based on "Repeat Photos of Sperry Glacier," part of the series Photographing Change in Glacier National Park, National Park Service; a work of the United States government in the public domain. It draws on the Headwaters podcast and the USGS repeat photography overview. A family photograph of McKeon on Grinnell Glacier in 1988 is not reproduced.