A Series of Hopefully Fortunate Events: Saying Goodbye to Yosemite's High Country (for now)

Our field studies trip to Yosemite National Park reached a climax when we reached Tioga Pass (9,943 ft / 3,031 m) at the east end of the park. The pass is the highest highway route in the state (a paved road in the White Mountains and the Bristlecone Forest reaches just a few feet higher, at 10,075 feet). The scenery at this elevation is spectacular. The surrounding peaks reach over 13,000 feet (nearly 4,000 meters), and glaciers have scoured much of the terrain to barren rock. Few trees can survive in this harsh environment.

There is not much in the way of granite east of the pass. The white expanse of plutonic rock in Tuolumne Meadows has given way to older, darker rocks that began their existence as volcanic rocks and oceanic sediments more than 200 million years ago. They have been baked and deformed by deep burial in the crust. There is also the remains of a caldera, a giant collapse depression similar to the one that formed Yellowstone or Long Valley, but in this instance we are seeing it from the base, the part that was once a mile or two underground.. 

This was the source region for the glaciers that scoured the Grand Canyon of the Tuolumne and Yosemite Valley. Numerous cirques, horns and aretes can be seen along the Kuna Crest and the main Sierra Crest. There are even a few small glaciers tucked into the high canyons (Dana Glacier is accessible by trail).

It was the end of our field studies course, and I fervently hope that it will be the last chance of seeing Tioga Pass. For a while anyway. I had the fascinating but unfortunate privilege of seeing Tioga Pass on an early January day in 2012, because there had been no snow. It was strange walking across a solidly frozen Tenaya Lake (visible in the top picture) in a t-shirt and jeans when there should have been 10-15 feet of snow everywhere. We've had a disastrous run the last four years with an unprecedented drought, the worst in many generations, even centuries. There is hope that El Nino conditions in the Pacific Ocean will bring on more than the normal amount of rain and snow, but that remains to be seen. There have been a few weak storms already, and another system coming in Monday. Some hopefully fortunate events, as it were.

As beautiful as it is, I hope I won't have another chance to see Tioga Pass until May at the earliest.

A Scary Story for Halloween: Rainfall Totals in My Neck of the Woods

It's Halloween night, and a lot of children are no doubt disappointed that it is raining outside. We've had four kids in one group so far. Waiting for trick-or-treaters this evening has been a little like waiting for rainstorms in California over the last three years.

I love numbers and statistics. I've lived in the same location for the last 23 years and the first year I was there I got a nice rain gauge for Christmas. I've been using it to keep track of precipitation in my Great Valley town about 13 miles east of Modesto. We are roughly at the middle of the valley (the center of the Central Valley!), about 200 miles north of Bakersfield, and about the same distance south of Redding. The valley climate ranges from Mediterranean in the north to desert in the south (Redding averages about 34 inches of rain per year while Bakersfield averages just over 6 inches). Modesto's 108 year average is 12.15 inches. The highest recorded rainfall was 26.01 inches in 1983 with the lowest at 4.3 inches in 1913.

I now have nearly a quarter of a century of rainfall records from my backyard, so I thought I would make some comparisons with our nearby city. The average yearly rainfall in nearby Modesto since  1991 has been 13.04 inches per year, an inch higher than the long-term average. In my little town the average from 1991 to 2011 was 14.55 inches, with a high of 26.42 inches in 1998. Waterford has had higher rainfall than Modesto in 20 of the 23 years that I've measured. I am guessing this is because we are slightly higher in elevation (by a grand total of 70 feet or so), closer to the Sierra Nevada foothills, and farther from the rain shadow of the Coast Ranges.

The most rainfall I recorded in a single day was 2.32 inches on January 2, 2006, and the wettest single month was February of 1998 with 8.64 inches. Some of you in wetter climates may find these numbers amusing (I note a day in 2010 when Big Sur got 22 inches of rain...in 24 hours!). But as I've said, we live in an arid climate.  Irrigation is all that keeps most parts of it green.

The scary part of the story is that of the last decade. There were a few wet years, but six of the last eight years have been well below average, only about 75% of what was once normal. Last year was the driest I've recorded. Our reservoirs are functionally empty and there has been little or no snowpack. We actually drove over Tioga Pass in January of 2012, and it was t-shirt weather. Tioga is usually closed from November to May because of snow, but not these days.

Here's hoping that tonight's storm, as disappointing as it is for the Halloween trick-or-treaters, is a harbinger of wetter times to come. It's a frightening situation all around.

Out of the Desert and Back to the Green Hills of Home

Today wraps up the story of a week-long journey through the deserts of the southwest. I've been telling the story as if in real time, so it sounds like I'm just now arriving home, but actually we finished the trip just over a month ago. It's a time warp of sorts. I'm about to leave on another trip, this time to British Columbia and Alberta.

Coming home. You can live in a boring place, a place that is the worst in the country even, but coming home is coming home. There is the familiar kitchen, the television, the well-worn couch. The weeds. The office. To me, home is something bigger. It's the landscape that surrounds my home region. Basically those places within a day's drive that I've seen over and over. My home starts at the summit of Tioga Pass in Yosemite National Park. It's a three hour drive from my house, but a trip doesn't really begin until we've gone over the summit, and on the return trip we feel home the moment we get there.

Compared to the dry lands we had just explored, the mountains have a richness of moisture. It's not nearly what it should be, for we are still in the grip of a horrendous drought, but some late spring snow was still lingering in the high places. We felt such a relief at the sound of babbling creeks.

Tuolumne Meadows is the accessible part of the Sierra Nevada crest in Yosemite National Park. The meadows lie at 8,000 feet, and the surrounding mountains reach elevations of just over 13,000 feet. This region was the source of glaciers that scoured the deep U-shaped valleys of Yosemite and Hetch Hetchy. At one time there was an ice cap at Tuolumne that was more than 2,000 feet thick that spilled out in several directions, including Tenaya Creek which holds beautiful Tenaya Lake (top picture).

John Muir talked about the Sierra Nevada high country as the "gentle wilderness", and that's been my experience most of the time. I've seen violent storms across the Basin and Range and Colorado Plateau, and some have been terrifying because we were camped out there and had nowhere to hide or take shelter. If a storm blows in while I'm exploring Yosemite, well, we just jump in the car and go home. We can come back the next day.

We had already driven three hundred miles this day, so the sun was getting close to the horizon. Photographers say that evening and morning are the best times for good shots, given the nice contrasting shadows instead of the washed out colors from a noonday sun.

There was a storm over the Basin and Range that we had just skirted. We got a few drops, almost enough to turn on the wipers. From a distance it looked menacing. But all was calm for us in the meadow.

We made a last stop at Olmsted Point for a look at the sunset on Half Dome. We then headed down the hill, and returned to our home. It was nice to be back, but of course a few days of sloth and we wanted to get on the road again. We are restless souls sometimes!

From a Land of Riches to the Barrens: The Basin and Range

We set off early today on our journey of exploration on the Colorado Plateau, but to get to the plateau we needed to travel nearly 500 miles from California's Great Valley to Las Vegas, passing through some of the loneliest landscapes to be found in the United States. I couldn't help but notice how we also passed from a land flowing literally with milk and honey (dairy farms and beekeepers among the thousands of farms) to a barren landscape where life must be grasped and fought for. We crossed Tioga Pass, which despite the frighteningly dry year was still mantled with some snowfields, and into the Basin and Range Province east of the Sierra Nevada. The difference was striking.

The Basin and Range Province happened because a high plateau-like region with rivers extending from at least central Nevada to the Pacific was stretched to the breaking point. About 29 million years ago, the subduction zone that had dominated the tectonic history of the Western United States for nearly 180 million years was destroyed by a process that resulted in the formation of the San Andreas fault. The crusted extended and broke into numerous fault block mountains (horsts) and deep fault valleys (grabens). The Sierra Nevada was the largest and highest of these fault blocks and as a consequence, the mountains prevent most of the rain and snow from ever reaching the lands to the east.

The Sierra Nevada is the realm of the cool dark forests and the high glaciated peaks. The Basin and Range is a place where sagebrush reigns, and practically the only trees are dumpy little pinyon pines and juniper. It's a hard dry land. We crossed Montgomery Pass into Nevada and had a close look at Boundary Peak, which at 13,147 feet (4,007 m), is the highest point in Nevada. Ironically it is not the highest peak in the mountain range in which it is situated. Adjacent Montgomery Peak is 13,441 feet (4,097 m) tall, but as the name suggests, the state boundary falls between the two. A bit farther south, White Mountain Peak soars to 14,252 ft (4,344 m), the third highest peak in California.

It's a hard land, but that doesn't mean that life doesn't thrive. We were lucky to see some members of the Montgomery Pass herd of wild horses right next to the highway. Horses came to America with the Spaniards in the 1500s and escapees over the centuries formed naturalized herds across the west. In a sense though, these horses are returnees to a long-lost homeland. The horses evolved in North America, and migrated to Asia over the Bering Land Strait, but about 12,000 years ago they became extinct in the land of their origin.

I took a new road today, the highway through Dyer and Fish Lake Valley. It is a beautiful place, and few hundred ranchers and farmers make a living off the small streams that flow off the White Mountains and from the copious amounts of Pleistocene groundwater that lies hidden beneath the valley floor (a nonrenewable resource though; they're using up the water that arrived there during the Ice Ages).

Others tried to wrest life from the land, but in a different way. When the California Gold Rush petered out in the 1850s, hungry miners scoured the lands to the east for the next great Mother Lode. Their searches were most often futile, but a few rich mines were discovered (such as the Comstock Lode), and other towns were built on dreams of avarice, but not much more. Such was the fate of Palmetto in western Nevada. There are only a few structures remaining, carved out of the rhyolite tuff that covers much of the region. For a time, several hundred miners pitched camp here, looking for plays of valuable minerals in the rocks, but they found little and quickly abandoned the site.

The desert has reclaimed much of the old town, except a few buildings which stand only because...well, I don't know how the wall below is still standing.

The miners could look out a window and see the sometimes snow-capped summit of White Mountain Peak in the distance, dreaming of water and riches, but having neither. A barren land, yes, but rich in other ways. The geology exposed in these barren mountains is fascinating, and volcanoes and earthquakes show that the crust here is still very active.

This is one of my favorite regions on the planet...

The Right Place at the Wrong Time: A January Day at Tioga Pass

If anyone had told me anytime in all the years that I have lived here in Central California that I would be where I was today, I would not have believed them. It just doesn't happen. Tioga Pass in Yosemite National Park always closes in November or early December. Always (ok, in 2000 it was open for one day in January). Everyone in the Sierra knows that the pass closes and no one gets to go up there except for the hardy cross-country skiers until May or June. But that's the kind of year we are having here in California; water managers should be terrified. The snowpack is at 15% of normal, and after today, I'm saying "What snowpack?"

So off we went today, to see what we could see. There have been few storms yet this year or last, but it is plenty cold. Cold enough that Tenaya Lake and all the other high country lakes and ponds are completely frozen over. If you click on the photo above, you'll see ice-skaters out on the lake. It is a strange sight to see; frozen lakes, but no snow to speak of on the surrounding peaks.

Being a Californian born and bred, I admit to not knowing much about the dynamics of lakes freezing over, but I am pretty sure that these are pressure ridges caused by expansion of the surface of the lake as it freezes. It was a fascinating thing to see.

Oddly enough, the temperatures were in the forties and fifties, and I wore a short-sleeved shirt all day. We drove past Tenaya Lake and made our way to Tuolumne Meadows. Again, there was ice everywhere, but no snow other than scattered patches in the forest. The moon rose over Cathedral Peak (or is that Unicorn?)

Tuolumne Meadows was pretty as always, maybe even more so. I was happy to be able to visit in January, an absolutely new experience for me. I just worry about what this means for our water supply this year. These are Texas kinds of numbers, drought-wise, and no storms are in the long-term forecast.

We stopped at the top of Tioga Pass. On January 5. It was beautiful. And weird. Standing at 10,000 feet in the dead of winter and not dying of hypothermia. The last time my ancestors did something like this, very bad things happened (hint: my ancestors included the Donner family...look it up if you don't know the story).

Heck, we came this far, why not cross the Sierra? We headed a few miles down the road towards Lee Vining. We were tempted to hit the Whoa Nellie Deli for dinner, but we realized that an incredible sunset might be developing. We turned around and headed back towards Tioga Pass, but not before snapping a picture of Ellery Lake (also completely frozen over).

We stopped to walk on the Dana Fork of the Tuolumne River (below). The silence of the frozen landscape was eerie. No water was flowing anywhere.

 A lenticular cloud formed over the Sierra Crest. Or was it a UFO?

One more oddity. We did have an unusual storm earlier this year. It involved no rain or snow, but it did include hurricane force winds. Driving down from Tioga Pass I noticed hundreds of Lodgepole Pines that had been literally ripped from the ground. They were all pointing west. Again, an eerie day.

We headed back to Tenaya Lake and Olmsted Point to see how sunsets differ when the sun is setting far to the south of where it sets in summer or fall. Look for it in my next post.

Vagabonding across the 39th Parallel: Crossing the Sierra Nevada

Vagabonding across the 39th Parallel is an informal exploration of the geology of an interesting slice of the American West that I followed in July. One of our rules on the trip was to seek out new routes we hadn't seen before. When leaving our home base in the Central Valley, that's not so easy to do. There are only a few paved crossings of the Sierra Nevada, and we've followed most all of them. So we found ourselves on the shortest route, through Yosemite National Park.

A trip to Yosemite National Park to many people means a visit to Yosemite Valley, the most heavily populated seven square miles in a park that covers more than a thousand.  If one is on a tour, or has limited time, they will obviously want to see the main attraction, but there is much more to the park. There are the paved highways to Wawona, Glacier Point, Hetch Hetchy, and Tuolumne Meadows, and there are the hiking routes along the John Muir Trail to the east and south, and the vast untrammeled wilderness of north Yosemite and the Grand Canyon of the Tuolumne River.  We were crossing the Sierra Nevada, so we were following Highway 120 over Tioga Pass.

From Crane Flat (the turnoff to Yosemite Valley), the road to Tioga Pass climbs from 6,000 feet to just short of 10,000 feet. The first miles are in a thick forest of red fir, but as one crosses into the drainage of the Tuolumne River, granitic rock starts to appear in large outcrops. If one is unfamiliar with the process of exfoliation, this road is a great place to learn.

When the weight of overlying rock is removed by erosion, the underlying granitic rock expands outward, parallel to the surface, and fractures into exfoliation sheets. The process tends to remove corners and edges first, resulting in a dome-like shape. An example can be seen in the picture above.

Roadcuts expose the exfoliation sheets very nicely. They are a few feet thick, and frost-wedging does a nice job of breaking the slabs loose and sending them downslope. Unless the roadbuilders do it first...

The road winds through the upper drainage of Yosemite Creek (which ends in Yosemite Valley at Yosemite Falls). The highest peaks, around Mt. Hoffman (see the picture at the top of the page), are close to 11,000 feet high. The view from Hoffman (a moderate hike with a small bit of rock scrambling at the summit) is spectacular. A photojournal of a hike we took there in 2001 can be seen here.

The road climbs to 8,000 feet and more and more of the high country becomes visible. Clouds Rest is at the upper end of Yosemite Valley, and is one of the largest exposures of barren granite to be seen anywhere. The parallel depressions running down the slopes are avalanche chutes. The constant sliding snow prevents trees and soil from accumulating. Most people stop at Olmsted Point to look at Clouds Rest and Half Dome, but we stopped at an unmarked point that framed Clouds Rest nicely instead.

 Tenaya Lake is one of the most beautiful glacially carved lake to be found anywhere. The origin is a bit unusual however, and ties into why Yosemite Valley, which is downstream, is so deep. The Merced River, which flows through Yosemite Valley, has a relatively small drainage basin, so the glaciers that abraded the canyon during the last 2 million years should not have carved such a deep basin. The tributary of Tenaya Creek has an even smaller drainage, so it should not have contributed very much ice.

The Tuolumne River basin is much larger, and in fact had the longest glacier system in the Sierra Nevada during the ice ages. The Grand Canyon of the Tuolumne is actually several thousand feet deeper than Yosemite Valley (although it generally lacks the sheer cliffs that make Yosemite so exceptional). The ice was so thick coming out of Tuolumne Meadows that some of the ice spilled over a low divide and flowed down Tenaya Creek towards Yosemite Valley, adding considerably to the carving power of the ice down-canyon. Beautiful Tenaya Lake was also the beneficiary of the extra ice.

The lake is a nice place for discovering glacial polish, striations, grooves, and erratics. It is also a popular picnic spot (this sentence is an understatement; Tenaya is one of the most popular Yosemite destinations outside the valley).

A few more turns and we arrived in Tuolumne Meadows. One of the first features to be seen is Pothole Dome (below). It is a nice example of a roche moutonnée, a glacially shaped rock exposure that is smooth on one side from the abrading of debris-laden ice, and steep on the other, due to the plucking action of the ice.

Tuolumne Meadows is a huge subalpine meadow complex that provides nice views of the high country of Yosemite. It is a major trailhead for trips in all directions. It is one of the few places where the Yosemite visitor can see some rocks that are not granitic in origin. The high peaks on the Sierra Crest include metamorphic rocks that predate the granite intrusions that dominate most of the park.

There will be much to say about Tuolumne Meadows at another time. We were actually trying to cross the Sierra Nevada on this trip. We reached the summit of Tioga Pass (9,945 feet), and made a brief stop at Dana Lake on the other side (below).

Tioga Pass is a col, a U-shaped pass formed by glacial erosion. Because cols have a flat floor, they are most often utilized as transportation corridors where people need to cross mountain ranges. Tioga has been used this way for many centuries. Crossing the summit of Tioga, the asymmetry of the Sierra Nevada is immediately apparent. The mountains have the overall shape of a tilted block of rock, with a gentle western slope, and steep eastern side. We had been climbing gradually for the last 100 miles or so, but we dropped into the town of Lee Vining in less than 12.

The east side of the Sierra Nevada is also the rain shadow side of the mountains. Moisture from Pacific storms falls mostly on the western slopes of the mountains, and the east side is thus fairly arid. Just the same, a fairly substantial system of glaciers flowed down Lee Vining Canyon, leaving some excellent erosional features. Below is the deep U-shaped valley left behind by the glaciers (the scar on the left side of the canyon is the highway) .

Looming high above the road is an excellent example of a hanging valley. A small tributary glacier could not carve as deep as the main trunk glacier, so the valley floor remains high above. Hanging valleys often have waterfalls spilling over the edge.

From a different angle a little farther down the road, there is a nice view up the hanging valley to the cirque valley, the bowl shaped valley that was the source area for the glacier. The cliffs were formed by the plucking action of the glacier as it pulled away from the rock wall.

The road has to get down the hill somehow, so they built it across the massive talus slope on the north wall of the canyon. Talus is composed of the boulders that break loose from the cliffs and fall and bounce down the slopes. I bet they don't have too many engineering/maintenance problems on that section...

We had successfully crossed the Sierra Nevada! My relatives in the 1840's couldn't do it and got stuck in the snow and some of them ate each other. We did it in 6 hours, including extended photo stops. Such are the advances of technology. We found the last spot available in a corner of the RV park in Lee Vining and set up for the night. RV Parks are not always the best spot for a tent camper, but the view was very nice, even if we tenters were a bit crowded together. We got dinner and went to look at Mono Lake. That's the subject of the next post.