Mount Lyell (California)

Mount Lyell
Mount Lyell, June 2005
Highest point
Elevation	13,120 ft (3,999 m)  NAVD 88
Prominence	1,927 ft (587 m)
Parent peak	Mount Ritter
Listing	U.S. National Park High Point 10th California county high point 7th SPS Emblem peak Western States Climbers peak
Coordinates	37°44′22″N 119°16′18″W / 37.739424367°N 119.271568894°W / 37.739424367; -119.271568894Coordinates: 37°44′22″N 119°16′18″W / 37.739424367°N 119.271568894°W / 37.739424367; -119.271568894
Geography
Mount Lyell Show map of California Mount Lyell Show map of the US
Location	Madera and Tuolumne counties, California, U.S.
Parent range	Cathedral Range, Sierra Nevada
Topo map	USGS Mount Lyell
Climbing
First ascent	August 29, 1871 by John Boies Tileston
Easiest route	Exposed scramble, class 3

Mount Lyell is the highest point in Yosemite National Park, at 13,114 feet (3,997 m). It is located at the southeast end of the Cathedral Range, 1.2 miles (1.9 km) northwest of Rodgers Peak. The peak as well as nearby Lyell Canyon is named after Charles Lyell, a well-known 19th century geologist. The peak had one of the last remaining glaciers in Yosemite, Lyell Glacier. The Lyell Glacier is currently considered to be a permanent ice field, not a living glacier. Mount Lyell divides the Tuolumne River watershed to the north, the Merced to the west, and the Rush Creek drainage in the Mono Lake Basin to the southeast.

The most common approach to Mount Lyell is from Tuolumne Meadows on a highly traveled section of the John Muir Trail. The round trip is approximately 25 miles (40 km) and involves 4,500 feet (1,370 m) of elevation gain when starting from the Tuolumne Wilderness Office. The hike is easy from Tuolumne Meadows, following the Tuolumne River to the head of the Lyell Canyon, and becomes moderate as it approaches Donohue Pass. Before reaching Donahue Pass, the route leaves the trail and heads south towards Mount Lyell.

Most summit ascents are done either over or around the Lyell Glacier. Seasonal and year-to-year variations on the glacier make it necessary to assess current conditions before choosing a route to the summit. The northwest Ridge, from the saddle between Mount Lyell and nearby Mount Maclure, offers class 2 to 3 climbing with high snow levels on the glacier. Low snow levels increases the grade to class 3 to 4 on the exposed granite ledges, in which cases it may be easier to ascend the glacier more directly to the summit.

The summit block of Mount Lyell is composed of dark volcanic granite, similar to its neighbors do the southeast, Rodgers Peak, Mount Davis, Banner Peak, and Mount Ritter. This rock is very loose and unstable for climbing, making the ascent to the summit plateau dangerous when the glacier is low, exposing the lower reaches of the summit block. For this reason, some climbers consider Mount Lyell and nearby Mount Maclure to actually be geologically part of the Ritter Range.