The Sierra Beyond Yosemite: Wait! Is that...a Glacier?

People who visit Yosemite Valley often think about glaciers. Even those with no geologic background quickly become aware of the role of glaciers in forming the valley, but the thoughts are often of the past. It's been 11,000 or 12,000 years since any glaciers have been in the bottom of the valley, and it's been around 800,000 years since glaciers filled Yosemite Valley. The glaciers seem a part of the distant past.

When we reached the crest of the White Mountains on our fall field trip, we could see across the Owens Valley to the highest ridges of the Sierra Nevada. It was late September in one of the driest years ever recorded in California. And yet...there was still ice in the high country. How could any snow still be left after one of the hottest summers on record?

A closer look through the zoom lens told the story. The isolated patches weren't snow at all, they were ice, and the cracks and fractures tell us that the ice has been moving. In other words, these are glaciers!

Glaciers would not seem to be a California phenomenon. Too much sunshine, too many droughts, it just doesn't seem to be the kind of place where snow could accumulate and compress year after year, decade after decade, until the frozen mass starts to slip under the weight of 100-200 feet of ice. Indeed, the permanent snowline would be in excess of 15,000 feet or more, and no peaks in California are that high. But given certain areas with cold "microclimates", glaciers have persisted in the ranges, in the shaded hollows of the highest mountains where the sun almost never shines.

According to the U.S. Geological Survey, there are nearly 500 glaciers in the Sierra Nevada, but none of them is very large, the biggest being only a mile (1.6 km) wide and half a mile (0.8 km) long. The total area covered by glacial ice in the Sierra is only about 19 square miles (50 square km). We were looking at some of the largest remaining glaciers, those that persist beneath the peaks of the Palisades Crest, a group of 14,000 foot mountains on the east boundary of Kings Canyon National Park.

It is known that there was a much warmer period several thousand years ago following the last major ice age, so these are not remnants of those Tioga stage glaciers. Small glaciers like these would have melted completely away. There was a general worldwide cooling event in the 1700s, the so-called Little Ice Age, and it was in those decades that these glaciers accumulated.

If you want to see the remaining glaciers of the Sierra Nevada, make your plans now. Since the early 1900s, the glaciers have been shrinking, and they have already lost 50-80% of the volume that existed at the time of their discovery. Glaciers are one of the most sensitive indicators of global temperature, and most of them are shrinking worldwide (a precious few are expanding, but because of increased precipitation in some areas; their climate is still warming). Many or most of the Sierra glaciers will be gone in a matter of decades. That will lead to some serious changes to the alpine climates of the Sierra, especially as they will no longer be there to provide streamflow during the driest times of the year.

It's been a long time since I was able to visit a glacier in the Sierra (it was back in 1982. It was the biggest of the Palisades glaciers, the one in the picture above, and as I stood at the base of the ice, I was able to see the Sierra's youngest natural lake, a tarn produced as the glacier receded. The lake didn't exist in 1950. It's sad that these small reminders of the awesome power of ice will soon be gone. I hope I have at least one more chance to see them up close.

The Sierra Beyond Yosemite: A Stunning Impenetrable Wall of Solid Rock

Mount Whitney from the Alabama Hills in the Owens Valley

Impenetrable. The imaginary mountain barrier surrounding Mordor in the Lord of the Rings has nothing on this real-life wall of solid granite. For more than one hundred miles, from Mono Lake south to Owens Lake and beyond, there is a 10,000+ foot high crest that divides California from the rest of the country, which stops almost all precipitation from Pacific storms, and which denied immigrants an easy path to the gold-fields of the Mother Lode.

The Wheeler Crest from Bishop in the Owens Valley

The Sierra Nevada is a barrier to travel of all kinds: paths, wagon trails, roads, and railways cross the mountains in only a few places, and those few places present serious engineering challenges. No paved roads cross the mountains for well over 150 miles between Tioga Pass in Yosemite National Park, and Walker Pass south of Sequoia National Park (The only minor exceptions: Sherman Pass, a paved former logging road is inappropriate for heavy traffic, and a dead-end road that travels to Devils Postpile). The only freeways exist at Donner Summit and Tehachapi Pass.

The Sierra beyond Yosemite provides some of the most stunning scenery on the planet. On the previous day of our fall trip we had crossed the Sierra Nevada at Sonora Pass, and explored the ghost town of Bodie, but the sun was disappearing in the west by the time we arrived at our campsite in the little town of Bishop in the Owens Valley. For those on our trip who were seeing these lands for the first time, it was a revelation to wake up to the high remote ridges of granite and metamorphic rock that towered over the flat valley floor.

Mt. Humphreys (13,996 feet) above Bishop, California in the Owens Valley

Many would say that Death Valley is the ultimate expression of basin and range style geography, and in many ways it is extraordinary, but few valleys in the world can match Owens for pure grandeur. One one flank, the Sierra Nevada rise to elevations exceeding 14,000 feet. On the other, the White Mountains average 11,000 feet, culminating in White Mountain Peak at 14,252 feet. Given the roughly 4,000 foot elevation of the floor of Owens Valley, the declivity is twice as deep as the Grand Canyon. Comparisons are unfair, of course, since the Grand Canyon is water-carved, and the Owens is of fault origin, but the scale of the landscape is grand in any case.

The origin of the wonderful scenery is a two-edged sword, of course. The faults that formed the Owens Valley are still very active. In 1872, the Owens Valley fault was responsible for one of the biggest earthquakes in the state's recorded history. The magnitude 7.8 event killed 27 people (out of a total population of around 300), and shifted the ground dozens of feet along a scarp more than eighty miles long.

The Palisades Group of peaks on the Sierra Crest from Sierra View in the White Mountains

One of the most spectacular ways to see the mountain wall is to climb into the White Mountains and see most of the Sierra escarpment from one view point. It's called (by incredible coincidence) Sierra View, which is a pullout on the equally spectacular road to the Ancient Bristlecone Pine Forest. From the one view, one can see the Sierra Crest from the Tioga Pass area to south of Mt. Whitney, a distance of over 100 miles. We were blessed with a clear morning despite the fires raging throughout the region.

Later in the day we drove south to Lone Pine, which lies on the floor of the Owens Valley beneath Mt. Whitney, which at 14,505 feet is the highest point in the lower 48 states. After a number of stops, we ended up at an old mine, the Reward, and watched the sun sink over the high ridges.

Sunsets for the people of the Owens Valley are different. There is no horizon over which the sun emerges or sets. There are only high ridges. When the conditions are right, the light show is wonderful.

A Gallery of Sierra Nevada Scenes: Part II

Alabama Hills near Movie Flats

I picked out some more scenes from our recent field studies class in the eastern Sierra Nevada and Owens Valley. Above, the Alabama Hills expose granitic rock essentially similar to that of the rugged high Sierra. It looks different because it weathered beneath the surface, possibly in more subtropical conditions. Cracks and fractures allow water to seep onto the surface of the granite, breaking the feldspar minerals down to clay and removing corners and edges over time.

Devil's Postpile National Monument near the headwaters of the San Joaquin River

The Devil's Postpile is a famous example of a different process of breaking up rock. When lavas flows back up and form pools, the cooling rock contracts and fractures into hexagonal shapes (although columns with 4, 5, and 7 sides are known). It is somewhat unusual to see such straight columns; they usually are far more irregular.

Mamie Lake at Mammoth Lakes

The Mammoth Lakes are a series of beautiful glacially carved tarns (some enhanced by small power generating dams). Mamie Lake is seen above, and the Twin Lakes below.

A storm blew through in the midst of our journey. The morning after brought smoke-free conditions and beautiful sunlight through the clouds. The picture below shows Mt. Tom and Mt. Humphreys west of the town of Bishop in the Owens Valley.

One of the best ways to see the Sierra Nevada is to view the range from the next ridge over. The White Mountains in any other setting would be a celebrated National Park. It is a stunning wall of rock with unique topography and unique biology. We climbed the road to the Schulman Grove of Bristlecone Pines across from the Palisades Crest of the Sierra Nevada.

Palisades Crest from the White Mountains. The Owens Valley is in the foreground.

The Palisades Crest is home to the largest remaining glaciers in the Sierra Nevada. The biggest is about a half mile long and a mile wide. In this drought year, few snow patches were left...pretty much all the ice you see in the picture above is a glacier.

The Bristlecones are special trees. Besides living in one of the toughest environments of any tree in the world (two miles in elevation, with a two or three month growing season), they grow to great antiquity. The oldest discovered thus far is more than 5,000 years in age.

The trees subsist in nutrient poor soils, but even poor soils are better than the barren debris formed on pure quartzite. The forest ends abruptly where the Cambrian quartzite begins.

The day included a spectacular view of clouds curling around the summit of Mt. Whitney (14,505 feet; 4,421 meters), the highest mountain in the lower 48 states. The spheroidally weathered boulders of granite in the Alabama Hills can be seen in the foreground.

The last day of our trip was clear, providing a beautiful view of the metamorphic rocks above Convict Lake south of Mammoth Lakes, and the tufa towers at Mono Lake. Some detailed geologic descriptions of these fascinating places are in the works for a future blog post.