September 11, 2013 Posted by: BR - Park Ranger/Resources Management & Science Liaison

The Lyell Fork Tuolumne River with Mount Lyell and the Lyell Glacier in the background. Melt from the Lyell Glacier keeps the river flowing year round. 
The Lyell Fork Tuolumne River with Mount Lyell and the Lyell Glacier in the background. Melt from the Lyell Glacier keeps the river flowing year round. 

August 29 marked the 142nd Anniversary of the first recorded ascent of Mount Lyell, Yosemite’s highest peak (13,114 feet). J. B. Tileston made that ascent in 1871. He left his base camp at four in the afternoon the day before he summited. Darkness found him bivouacked high in the mountains where he

 …made some tea in a tin cup, and enjoyed the strange and savage scene around me. Immense precipices, great masses of snow, from which rose the black peaks of the summit, the roar of water descending by many channels and cascades over and among the rocks, and occasionally the rattling down of loosened stones, and the novelty of my situation alone in that wild place, made a scene which impressed itself on my mind. Soon the moon, nearly full, rose over a great line of precipices half a mile across a gorge up which I had come, and gave new attractions to the view. 

 I was up early next morning, toasted some bacon, boiled my tea, and was off at six. I climbed the mountain, and reached the top of the highest pinnacle (‘inaccessible,’ according to the state geological survey), before eight. I came down the mountain, and reached camp before one, pretty tired. 

John Boise Tileston 

When I first began working in Yosemite back in the late 1960s, one of my goals was to climb to the summit of Mount Lyell and see the Lyell Glacier, Yosemite’s largest and the second largest glacier by area in the Sierra Nevada. What could be more iconic of Yosemite’s ice carved scenery than the park’s largest glacier nestled in the rugged breast of Yosemite’s highest peak? In those days the journey involved walking up the glacier and stepping across a narrow part of the bergschrund, a cavernous break at the top of the ice. From there it was just a few more steps to a rocky plateau that led to the summit. Today, those few steps off the top of the glacier have become well over a hundred feet of rock climbing; more than half of the Lyell Glacier has melted away due to climate warming. Yosemite’s only other glacier, the McClure, has also melted back considerably. 

In the mid-nineteenth century, people did not understand that glaciers once covered mountains and filled canyons of the Sierra, including Yosemite Valley. John Muir developed an idea that flowing ice had sculpted Yosemite Valley and the high Sierra. To help him prove this, he decided to measure glacier movement. In 1872 he and his friend Galen Clark carefully documented movement of the McClure Glacier. They used two stationary locations in the rocks on either side of the ice to create a baseline. Muir and Clark drove stakes into the ice along that line. Returning 47 days later, they sighted along the baseline and found that the ice had carried the stakes downstream at the rate of about an inch a day. More than a hundred years later that groundbreaking experiment would be repeated.   

Comparing Lyell Glacier in 1901 to 2011

Comparing Lyell Glacier in 1901 and 2011Photographs taken over the years reveal a drastic reduction in the size of Yosemite’s remaining glaciers, especially in the last few decades. This documented change prompted park geologist Greg Stock to team up with Robert Anderson of the University of Colorado and repeat Muir’s measurements on the McClure Glacier exactly 140 years later to the day. They did the same for the Lyell Glacier. 

Stock and Anderson learned that the McClure Glacier was flowing at the rate of about one inch per day–the same as Muir’s measurements had detected. This seems odd because the size of the glacier is so much smaller than it was in Muir’s time. One possible explanation is that the glacier is melting so fast that the additional runoff lubricates the bottom of the ice allowing it to slide more easily across the rock. 

Photos of researchers measuring Lyell Glacier in 2011

They made the same measurements on the Lyell Glacier and after four years the stakes had remained stationary. The inevitable conclusion was that Yosemite’s largest glacier has stagnated. The ice continues to melt and by Yosemite National Park’s second centennial it may be completely gone. For hundreds of years, snow and ice melt from the foot of these two glaciers has fed the Tuolumne River and kept it flowing even in late summer and fall when other streams have dried. 

Over the years I’ve made several attempts to climb Mount Lyell and its glacier but each time lightning storms in summer or avalanche danger in winter prevented me from completing the ascent. Although this may be disappointing to me, I am truly saddened by the fact that the last of our glaciers, these icy icons of wildness, may disappear within the lifetimes of my children and with them a source of late summer water for streamside life along the Tuolumne River. 

For another perspective of Lyell Glacier, read a fellow ranger's blog post "Ode to the Lyell Glacier."

BR, Water-Rock-Wind, Tuolumne Meadows, Science in the Park

4 Comments Comments Icon

  1. Yosemite National Park
    November 19, 2013 at 01:52

    @Mazama: 1) It is correct that the earliest documentation of the Lyell and Maclure Glaciers occurred near the peak of the Little Ice Age (circa 1300-1850 AD). The first map of the glaciers, published in Russell (1885), indicates that the glaciers were up against the Little Ice Age moraines. It is also correct that the glaciers were considerably smaller before the Little Ice Age, and were quite likely non-existent during the middle Holocene. Although retreat of the Lyell and Maclure Glaciers since they were first documented clearly demonstrates that the climate has warmed since the end of the Little Ice Age, it does not speak directly to the cause of that warming. It is only through association with other climate records, which preserve information both on temperature and on greenhouse gas concentrations, that we infer that the present melting of the glaciers is at least in part anthropogenic. 2) Lyell Glacier is the second largest glacier in the Sierra Nevada by area (the Palisade Glacier is the largest), and the largest in Yosemite National Park. The Lyell and Maclure Glaciers have been the focus of recent study by the National Park Service, but the historical record of NPS research does include the Dana and Conness Glaciers. Area change for all four of these glaciers was evaluated by Basagic and Fountain (2011), and all four showed roughly similar reductions in area (40-64%) since 1903. Nevertheless, it is correct that glaciers in close proximity can behave quite differently; witness the Maclure Glacier, which presently moves about 22 feet/year, and the adjacent (and larger) Lyell Glacier, which has stagnated.

  2. Mazama - Winthrop, WA
    November 14, 2013 at 07:45

    Karen, thanks for sharing your wonderful story - below - about climbing Mt. Lyell in the 1950s with the legendary ranger Carl Sharsmith. I believe he started leading YNP visitors on climbs in the 1930s and also lead trips up Mt. Conness and, presumably other peaks near Tuolumne Meadows.

  3. Mazama - Winthrop, WA
    November 14, 2013 at 07:38

    Thanks for this interesting posting and the related links. I also have hiked and bagged summits in the highest parts of YNP and immediate area - Lyell, Dana, Kuna, Ritter, etc. and read several books and papers on the glaciers in this area. Two comments: 1) We need to keep in perspective that the earliest "discovery", photography and measurement of these glaciers occured in the late 1800s which was at or near the climax of the "Little Ice Age" which commenced arond 1500. Of course we like these mountains to stay the way we've experiened them in our short lifespans but whose to say what the "normal" condition should be. Geologists know that the Sierra has been much more dry and devoid of snow in various epochs preceding our current time of "climate change" and, presumably, are on track to revert to something like those prior (normal?) conditions. Yes, Lyell Glacier has been recognized at the second largest in the park but there are several nearby glaciers that lie just outside the YNP boundary on Dana, Kuna, Conness and Matterhorn Peak/Sawtooth are as well as the Banner/Ritter/Minaret range. Are those areas being studied and, if so, how do the (presumably shrinking) conditions compare with those on Lyell/Maclure. Sometimes glaciers in close proximity behave quite differently from each other.

  4. Karen - HERMOSA BEACH, CA
    September 11, 2013 at 10:15

    In the 1950's, rangers Carl Sharsmith and Will Nealey led annual 3 day hikes to climb Mt. Lyell. Campers could sign up for the adventure and the Tuolumne Meadows Pack Station packed the gear to The Upper Base Camp. My 11 year old sister and I climbed the peak with them in the summer of 1956, shod only in tennis shoes. My memories include being amazed at the insects captured in the ice, the various ice forms, the bergschrund's amazing icicle cavern, the incredible view, the sky pilot blooming at the summit and being buzzed by birds there as well. I climbed it with Carl Sharsmith again in about 1971 on a Yosemite Institute class of The Living Glaciers of the Sierras. On both occasions during the evening campfire (no longer allowed) Carl recited Robert W. Service's poem, "The Cremation of Sam McGee." He also told tales of his previous adventures on Lyell and McClure including being carried out on a mule litter due to a broken back. What a privilege it was to be introduced and educated to hiking in Tuolumne Meadows by this grand, gentle man.


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