Glaciers Of The Sierra Nevada

Does the Sierra Nevada of California have glaciers? Yes, and quite a few of them at that. While the Sierra glaciers are generally quite small, they are great in number. Hard to say how many exist today, but studies from about twenty years ago show more than 130 glaciers in California and most of those in IAG’s home base of the Sierra Nevada.

What is a glacier? A commonly accepted definition calls a glacier a body of ice that moves. If it is a permanent snowfield that creeps downslope or a stagnant body of ice that just stays still, it is not a glacier. Many of the Sierra glaciers lack some of the features present in their cousins found in other mountain ranges of the world such as extensive crevasse fields and ice falls, but glaciers they are. All of the Sierra glaciers are what are known as cirque glaciers that occupy shady pockets high among the craggy granite peaks.

How old are they? Not very…in geological terms. In fact, 800 years ago it’s safe to say there were no glaciers in the Sierra Nevada. All of our Sierra glaciers are a result of what is known as the “Little Ice Age” which occurred approximately from 1450AD through about 1850AD with it’s peak probably about 200 years ago. During that time much of the Northern Hemisphere saw a period of glacial advance as temperatures cooled and precipitation increased (In the Alps of Europe glaciers even invaded inhabited valleys such as the Chamonix Valley in France). Of course there were many larger glacial periods or “ice ages” stretching back hundreds of thousands of years with the last large one about 10,000 years ago. But 900 years ago there wasn’t a glacier to be found in the High Sierra.

Who discovered them? John Muir, the iconic early environmentalist, mountaineer and amateur geologist, is credited with discovering the first glacier in the High Sierra. In 1875, acting on a hunch, he simply placed markers on the ice and then came back at a later time to find they had moved downslope. He was ridiculed by the academics of the day because he had no formal schooling. But he was right, as he was about many other things concerning his beloved range of light.

How are they doing? Well, they are all receding as our current climate is not conducive to the maintenance of glaciers. However, many folks may be surprised to learn that not all glaciers are visible and some glaciers thought to have melted away may simply be hiding in plain sight. Glaciologists have fairly recently discovered the phenomenon of rock glaciers. These are moving bodies of ice that are completely covered in rock debris with little or no ice showing on the surface. As they move down slope they carry their blanket of rock with them. Most of these were full glaciers that melted and receded away until the only part of them left was under the very rock debris they created. The Sierra Nevada apparently has many of these. The boulders (talus) that cover these rock glaciers shield them from solar radiation, which prolongs their life. Even visible Sierra Nevada glaciers are usually larger than they appear since the lower end, or snout, of the glacier tends to burrow under rock debris and to not show any ice.

Are they difficult to climb? Not especially. The techniques we use for climbing the glaciers of the Sierra Nevada, are not the traditional glacier climbing techniques such as “long roping” in which teams travel 25-40 feet apart to protect against a trapdoor crevasse fall. This is mainly due to the fact that almost all of our glaciers have no crevasse fields. However, just about all of them have what is called a bergshrund. This is the large crevasse at the top of the glacier where it separates from the non-moving ice above it. These “shrunds” are usually the only crevasse on a Sierra glacier and can occasionally prove tricky to negotiate, sometimes requiring technical ice climbing skills. 

The small glaciers of the High Sierra Nevada are well worth exploring!

(If this article has peaked your interest in California’s glaciers (or glaciation in general), a recommended read is the book “Glaciers of California” by Bill Guyton. University of California Press).