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.

Pareidolia and Fall Foliage Art from the Sierra Nevada

Pareidolia is a trick of our minds that can cause us to interpret random images or patterns of light and shadow as faces. We were in the Sierra Nevada the other day ahead of Sunday's storm, looking for some fall colors around the meadows along the Clark Fork of the Stanislaus River near Sonora Pass.

I was mostly looking upwards towards the trees, but eventually my attention was deflected downward at the many aspen leaves that had already fallen to the forest floor. The bright yellow color of the leaves was giving way to brown, but the pattern was different on every leaf. The first one above immediately made me think of a face, or even a jack-o'-lantern (thus making a connection to tonight's candy obsession).

Conditions are changing rapidly up in the high country. We've been able to travel to the highest elevations all summer, but the latest storms have begun to drop snow over the passes. Sonora and Tioga closed Saturday in anticipation of the big storm on Sunday. They might reopen if conditions stay dry in coming weeks, but the writing is on the wall (and on the leaves): winter is coming.

The leaves were almost gone from the aspen trees up on Clark Fork. I hope the omens are good for a big snow year. We need a break from the horrific and continuing drought here in California and the Southwest.

Scenes from a Shield: Traversing California's Biggest Volcano

Continuing on with our late September exploration of the California Cascades, we prepared to leave Lava Beds National Monument. The main paved access is from the north at Tulelake, but our interests lay to the south over the top of the biggest volcano in California: Medicine Lake Highland. MLH is a shield shaped edifice, but the history and composition of volcano suggests a complicated history that is quite distinct from shields like those in Hawaii and elsewhere. Lava Beds National Monument covers about 10% of the shield complex on the north flank. We headed up the good gravel road to the highest corner of the park where we could investigate the source of the lava flows and tubes at Mammoth Crater.

Before reaching Mammoth Crater, we stopped at Heppe Caves to catch an unusual sight: water! Very few sources of open water exist at the Lava Beds. Fracturing of the basalt allows water to seep into the ground quickly and no streams or canyons can be seen in the park. At Heppe Cave, a deep layer of ice allows a small pool of water to persist in the lowest part of the huge cavern in most years. Birds and other animals depend on the pool, despite its diminutive size.

We had gained several hundred feet from the vicinity of the park campground and visitor center, and the cooler wetter climate allowed for the growth of ponderosa pines, and to my surprise, a small aspen grove! These stunted trees are not a common sight in the area.

A few hundred yards up the road brought us to Mammoth Crater, the source of the lava flows that cover about 70% of Lava Beds National Monument (and which produced many of the lava tubes). During the eruptions, the crater would have been a lake of molten lava, spilling over in several directions. In the waning phases of the eruption, the lava drained away, leaving a pit a quarter of a mile across and several hundred feet deep.

People often think that volcanoes erupt only from their summit, but we were quite a few miles short of the summit of Medicine Lake Highland. The mountain is covered with cinder cones and lava flows that originated from vents on the flanks of the volcano.

 It took a few false starts, but I finally located the obscure track that left the main "highway" and took us to these unusual holes in the lava. Does anyone want to speculate what they might be??

The two holes above joined about two feet down. People can reach in and hold hands underground. A few of the mysterious holes are quite large and deep. The deepest sometimes have snow all summer.

Another one or two miles through the thick forest brought us to the edge of the Medicine Lake Highland caldera. It is about as wide as the Crater Lake, some four or five miles, but beyond the horizontal distance, there are few similarities. Crater Lake has cliffs that drop straight into the lake, where MLH has rounded glaciated knobs and peaks. Crater Lake has a nearly 2,000 foot deep lake, where MLH as a lake that barely makes it past 100 feet in depth. Mt. Mazama, the mountain that existed prior to Crater Lake erupted just 7,000 years ago. The eruptions that produced the caldera on MLH took places tens of thousands of years earlier.

Medicine Lake technically shouldn't exist on a mountain that notoriously sucks up all the water. It seems that the glaciers that formed on the mountaintop produced and scraped up enough clay to seal the bottom of the lake and keep the water from draining away.

It was in the low to mid forties while we stood on the shoreline, and it was drizzling. But the sign said "swimming beach", so my students, who always follow what the signs say...

 ...did just that: went swimming in a subalpine lake. I make no judgements here, but I had a bone-chilling cold day, and it didn't help to see them swimming away!

Our next stop: the last thing you would expect to see on a basaltic shield!