Fall Colors in the Eastern Sierra Nevada!

We've returned from a field studies expedition to the eastern Sierra Nevada, and I can report that fall has arrived! We've had a very warm summer, and the heat waves continued into September, but then we had a sudden cold snap, and even some snow. Tioga and Sonora Passes briefly closed, but opened again in time for our trip. The aspens and cottonwoods have responded to the sudden cold conditions.

Our route took us over Sonora Pass, where fresh snow still lingered on the high slopes. It's a sight I'm not used to. We spent a lot of time in the Bodie area and in the White Mountains where there aren't many deciduous trees, but late in the weekend we moved into the canyons below the Sierra Crest.

One of the special places is Convict Lake, which is dammed by a moraine of the Tioga glaciation that ended about 13,000 years ago. Aspens and cottonwoods crowd the shoreline, providing vivid color.

On our last day, we took the June Lake Loop, and stopped to explore Silver Lake. The canyon of Reversed Creek and Rush Creek is a spectacular glacial valley with high peaks above, and a string of beautiful lakes.

As we wandered among the trees, we heard a rockfall on the slopes high above. It wasn't all that big, leaving little dust in the air, but it was exciting to listen to geology in action.

It's been a long summer, but the drought finally broke, and the forest was looking healthy. Our mountains might not have the color range of the eastern hardwood forests, but then again, those forests don't have the mountain backdrop of our beloved Sierra Nevada.

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.