California's (not) Biggest, (not) Most Recently Active, and (not) Most Dangerous Volcano

Photo by Mrs. Geotripper

Mt. Shasta is no doubt the most dominating volcano in all of California. It's huge, topping out at well above 14,000 feet, and is visible from over a hundred miles in a number of directions. It was the first main stop on our recent journey exploring the Pacific Northwest and Northern Rocky Mountains, and it really stood out as we essentially circled it on our way to Lava Beds National Monument.

It's big, it's active, and it's potentially destructive. So how bad could it be? Is Shasta the biggest, most recently active and most dangerous volcano in the state? Actually...no. California has a great many volcanic features, and even though some are not as familiar to many of us, they do actually present a hazard for a great many more people than you might suspect. That's not to say that Shasta is not dangerous, however.

Castle Crags in the Klamath Mountains of northern California (photo by Mrs. Geotripper)

As Interstate 5 winds northward into the Klamath Mountains north of Redding, Shasta occasionally peeks out between the trees (the top picture), but for a brief moment near Dunsmuir a totally different set of mountain spires appear off to the west. They are the Castle Crags, a granite stock (an intrusive body of granite exposed over an area of less than 40 square miles; batholiths are larger).

Castle Crags (seen below in a picture from a plane flight a few years back) were relevant to our explorations because they represent a volcano from inside out. About 160 million years ago, the land surface was five or six miles above, and molten magma was moving up through the crust. Some of the magma reached the surface to flow in volcanic eruptions, building up volcanoes maybe similar to Shasta and others of the Cascades. The rest of the molten rock cooled slowly for tens of thousands of years, forming the crystalline granitic rock exposed today at the Crags.

Moments later, we made the imaginary journey up through the crust and onto the flanks of the modern volcanic edifice of Mt. Shasta. We followed the Everitt Highway up the mountain to the about the 7,500 foot level to have a look around. Even though we were on the first day of a crippling heat wave in California, the air was cool, and the snowbanks made it clear that winter was not yet entirely over.

Bunny Flats was the end of the road for us on this particular day. The last two or three miles of pavement above were covered by snow. The road used to end at a ski area, but the resort was closed years ago, due to avalanche danger (as I understand it; there is a newer resort on the lower slopes of the volcano). Working and playing on the slopes of a volcano does have its hazards...

There are a lot of hazards around Shasta. Lava flows might seem to be one of them, but andesite lava tends to be sluggish and slow. Lava doesn't worry me so much. Ash eruptions are certainly a danger, due to their speed and mobility. Shasta has had such eruptions, but they haven't been the usual modus operandi over the years. But...lava or ash flowing onto thick snow: that's a problem. The melting snow and debris quickly turns into a mudflow that can travel for tens of miles at high rates of speed. The Indonesians called them lahars, and the name has stuck. Most of the lower flanks of Shasta are mantled with lahar deposits, and the towns of Weed and Shasta City are built on them. Mudflows have even happened when there have been no eruptions. Meltwater can build up under the glaciers that cover much of the mountain and burst out with no warning (Icelanders call these glacial bursts jökulhlaups). All in all, it's a pretty dangerous volcano.

And it's active. There have been a number of eruptions in the last 10,000 years, including those that built up Shastina and Black Butte. The entire upper part of Shasta, the Hotlum Cone, is less than 9,000 years old. The volcano may have erupted in 1786. So is it the most recently active volcano in California? Nope.

From our vantage point at Bunny Flat, we had an unobstructed view southeast towards Lassen Peak and Brokeoff Mountain. Lassen is the winner of the "most recently active" designation. The plug dome began making noise in 1914, and let loose in 1915 with a lava flow, a destructive lahar, and an ash eruption that interrupted train service out in Winnemucca, Nevada. The eruption produced a mushroom cloud five or six miles high. Geothermal activity continues today in what is now Lassen Volcanic National Park.

Lassen Peak (left) and Brokeoff Mountain (right) from Bunny Flat

So what about the biggest? Surely a mountain 14,000 feet tall is the biggest volcano in the state of California? Well, it's certainly the tallest, and it is the most voluminous stratovolcano in the Cascades, but it actually isn't the biggest volcano in the state. When we camped that evening, we were ensconced on the flank of a massive shield volcano called Medicine Lake Highland. With the gentle slopes composed of basalt lava flows, it hardly looks like a volcano at all, but when you compare the width of the volcano in the picture below (it takes up three quarters of the skyline), you realize it is really big. It consists of around 130 cubic miles of lava, compared to about 108 for Mt. Shasta (which is the snow-capped peak on the right).

So it's the most dangerous, right?

Well...that's a hard concept to quantify. There are lots of volcanoes in California, and some are closer to population centers than others, and some are more capable of chaos and violence than others. The Clear Lake Volcanic Field, north of the Bay Area, has been active as recently as 10,000 years ago, and the Geysers Geothermal Area nearby shows that magma is still present at a relatively shallow depth. Several thousand people live in the general vicinity.

The Lassen Volcanic Center is an obvious threat, given the activity in 1914-17. There are only a few small villages in the immediate vicinity of the volcano, but it is a major tourist destination in the summer season. Lahars could presumably reach the Sacramento Valley.

The aforementioned Medicine Lake Highland is certainly still active, with eruptions as recently as 950 years ago. Although basaltic shields aren't known for violent eruptions, the presence of rhyolite plug domes around the summit area show that such eruptions are not out of the question. Like the others, the region is lightly populated.

Volcanism is also a possibility in Southern California, perhaps to the surprise of some. Young cinder cones dot parts of the Mojave Desert (the Lavic Lake Volcanic Center), and the Coachella Valley (the Salton Buttes). Some of the small volcanic cones are younger than 2,000 years old.

The "elephant in the room" in terms of volcanic hazards of California has to be the Long Valley Caldera, and the nearby Inyo-Mono Craters. Every time there is a jiggle on a seismometer in Yellowstone National Park the internet lights up with predictions of death and destruction, but the conspiracy nuts pretty much totally ignore California's version of a death volcano. An eruption that took place 760,000 years ago produced 125 cubic miles of ash that covered most of the American West (the three Yellowstone eruptions ranged from 67 to 600 cubic miles). Yellowstone has not had a volcanic eruption in 70,000 years. The volcanoes in the Long Valley area of California have erupted as recently as 300 years ago. No one is talking about a repeat of the catastrophe of the 760,000 years ago, but smaller eruptions could certain cause havoc in this very popular tourist area. There was a huge brouhaha in the 1980s that had a lot of implications for how public officials respond to potential geological disasters. I wrote an extensive blog post about the event a couple of years ago; you can read it here (it's one of my favorites).

So Mt. Shasta isn't the biggest volcano in the state, isn't the most recently active, and may or may not be the most dangerous. But does that mean we can disregard the volcano? Hardly. It could cause all kinds of mayhem in the wrong circumstances. And there is one more hazard here that is unique.

The area north of Mt. Shasta is a landscape characterized by a strange hummocky surface composed of volcanic rock, but the hummocks don't look like cinder cones or other volcanic features. Geologists didn't know what to make of this weird topography. Until Mt. St. Helens exploded on May 18th, 1980, that is. One of the most astounding events of that eruption was the collapse of the entire flank of the mountain into a debris avalanche that traveled for twelve miles down the Toutle River. It turned out that an ancient iteration of Mt. Shasta had a similar fate around 300,000 years ago, with a debris avalanche that traveled 28 miles, almost to the present location of the town of Yreka.

The debris avalanche on the north flank of Mt. Shasta. Shasta Lake, a reservoir, is on the left within the debris field (photo by Geotripper)..

It is hard to imagine events on this scale, but the geological world is full of events that challenge our perception. That was one of our themes as we set out on our two week journey, and it was only our first day on the road.

Vagabonding Across the 39th Parallel: Clicking my heels, because....

...well, there's no place like home...

After a two week journey across the 39th parallel exploring the geology of Colorado, Utah, and Nevada, we were finally to the last stage, the last mountain range between us and home in the Central Valley. It was the Sierra Nevada of California

It's no small barrier: the Sierra Nevada is the largest single mountain range in the United States, and for 400 miles it rises as a nearly inaccessible wall of solid rock. It has been a barrier to human and animal travel for thousands of years. Along the highest part of the Sierra Crest, from Sequoia National Park to Yosemite National Park, a distance of  least 150 miles, only one throughgoing road crosses the crest, at Tioga Pass where we started our journey two weeks earlier. We crossed Sage Hen Summit, and the mountains came into view. Even though it was late July, snow still covered large parts of the high country. It had been that kind of year (compare to the extreme dry conditions we are seeing now).

The Sierra Nevada is such an extraordinary mountain range that it can dwarf other incredible mountains nearby. In any other region, a hundred mile long mountain range exceeding 14,000 feet in elevation would be world renowned. Instead, the White Mountains are barely known to most people, even in California. Likewise, a chain of thirty or so active volcanoes, some only a few hundred years old, would be getting far more attention in 2012 than good ol' Yellowstone. But they don't appear in the news very often, and not on the Discovery Channel either. As far as I can tell, there aren't even any conspiracy nuts weaving stories about UFOs and harmonic convergences at all.

We came across Highway 120 and wound our way around the north side of the Mono Craters (above), and stopped to enjoy a panorama of the Sierra Crest on the east boundary of Yosemite National Park. The prominent peaks in the picture below are Ritter and Banner, two spectacular mountains that were left outside the boundaries of Yosemite. I suspect the reason involved possible mineral sources in the metamorphic rocks (they are protected from development by their designation as a wilderness area).

A little further to the north we could see the Lyell Crest and the countryside near June Lake. The glaciers wreaked havoc with the topography there. In one spot the river flows towards the mountain range rather than away from it (by some incredible coincidence it is called Reversed Creek).

And then Mt. Dana, the second highest peak in Yosemite (below). We were close to our home territory, and it might have been quicker to go home the way we came two weeks earlier, but we still had a sense of curiosity about the other pass, Sonora, a little north of Yosemite National Park. We were tired, but we still wanted to explore...a little bit.

Something caught our eye in the foreground. There is almost nothing that can live on a surface of recently erupted pumice ash. Water simply percolates through and what little clay that forms in a few hundred years dries up within a few weeks of the last snows. But that was the kind of summer we had. Late July and spring was only beginning. The pumice flats east of the Mono Craters were alive with colorful wildflowers.

They certainly weren't tall. I was down on my hands and knees trying to get pictures of the common ones, like the magenta flowers above, that I assume is some kind of Monkeyflower (corrections are most welcome).

There were a few spindly lupines hanging on as well...

And some delicate yellow daisy types (again, any id is welcome!). We stopped for a sandwich in Lee Vining, and headed north on Highway 395, and then east in Highway 108 over Sonora Pass (9,624 feet). We stopped for a few minutes at the Leavitt Falls Overlook to see the snowmelt-swollen cascade pouring out of the hanging valley below the pass.

The road climbs steeply and becomes a narrow byway. If you have one of those RV's don't try this one! We passed meadows and waterfalls that had an air of familiarity. We were almost home. We had had a good trip, and seen a great many new places, and seen familiar places in a new way. But it was time to wrap things up.

What did we find? There's no place like home. Not the Dorothy's "We're not in Kansas anymore" kind of 'no place'. Literally: there is no place like home. One of the joys of teaching geology is the ability to say that you can never escape it (in a good sense, most of the time). Wherever you go there is a geological story that is distinct from everywhere else, and the story is almost invariably fascinating. We could have picked any line across the earth's surface, and we would have found something unique (but I must say the richness of the American West is unparalleled).

We crossed the pass and started down the canyon of the Stanislaus River. In two hours the vagabonds were relaxing once again in their own home. The dog and the cat were certainly happy to see us again. It was good to be back, but it wasn't a week before we wished we were on the road again.

For those of you who have been following this series, I hope you have enjoyed the journey!



Vagabonding across the 39th Parallel: Mono Lake, the Barren, Worthless Wasteland

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. Our rules were simple: see something new, or see something we'd seen before, but in a new way. We had been to Mono Lake many, many times (our previous visit was only a few days earlier), but in all our visits we had never spent the night or watched the sun set there. We grabbed some sandwiches at the Whoa Nellie Deli and parked on the near by hill top to watch the twilight envelope the barren Mono Lake basin. Click on the panorama picture above to see what we saw...

What a wasteland! It's dry, so there are vast areas of nothing but sagebrush. There's the lake, but the lake is so salty that no fish can live in it, just fairy shrimp and disgusting brine flies and their wiggling grubs. Nobody goes sailing or swimming in the scummy water. It's a worthless piece of real estate...

That's the way we judge a place, isn't it? Real estate...monetary value. And that's the way Mono Lake was judged too, for a long time. The water flowing into the lake was going to waste, so Los Angeles diverted the incoming streams, and the lake started to shrink. It was destined to become another dry lake, like Owens Lake did in the 1920's.

During the ice ages, glacial meltwater filled the fault basin, and the water overflowed into the adjacent basins, eventually flowing into Death Valley. The lake was 600 feet deeper than it is today, and covered a much larger area. As late as 1940, the lake was 45 feet deeper than it is now.

Migratory birds discovered Mono Lake thousands of years ago, and found the fairy shrimp and brine flies a rich source of protein to sustain them on their long journeys. As more and more wetlands disappeared along the coast and in the Central Valley because of human development, the Mono Lake area became an ever more important stop on the migratory flyways. Dozens of bird species (and many millions of individual birds) depend on this lake for survival. What is worthless to humans is life itself to the birds.

The fight to save the ecosystem at Mono Lake began in the 1970s as researchers started to realize the importance of the lake to the migratory birds. A 1994 decision by the California State Water Resources Control Board required that diversions be reduced, and the level of the lake be stabilized at 17 feet above the lowest post-1941 level. The problems are not all solved; the Mono Lake Committee is a good source of information on current issues.

What is the value of a place? If one tries to put a monetary value on a landscape, many places would be deemed worthless. Mono Lake basin once supported a modest agricultural economy, but the Great Depression destroyed the economy in the region, making it worthless enough for Los Angeles to move in. How many places across the country face similar choices...especially in today's economy? Surely it wouldn't hurt to build just one more dam here, or to build another housing development on farmlands, or drill another natural gas fracking well? It's a difficult issue of course. We have to have the homes, the energy, and the water. But who is looking out for the air, the water, the soil, and the other intangible values of a landscape that ultimately make life possible?

By the way, I bet you could pick up some cheap farmland in Texas right now...it's ripe for development.

I can talk about another aspect of the value of the Mono Lake Basin. It is one of the most stunning geological landscapes in the country. It is an active fault basin, with numerous scarps attesting to recent earthquake activity. Some of the youngest volcanic features in the U.S. are present on the south shore of the lake at Panum Crater and the rest of the Mono Craters. The islands in the lake (Negit and Paoha are shown in the pictures above) include a recent cinder cone and uplifted lake sediments from intrusions below the surface. The tufa towers, built by the action of algae and freshwater springs, have become a world-famous attraction for tourists.

What a shame that the state of California has decided to close their part of the lake, Mono Lake State Park, because the legislature can't see their way to an agreement to fund the park and 69 others that are slated to close next year. Maybe we can sell the worthless land to someone who can profitably develop it?

Anyway, what a beautiful, peaceful sunset, with the moon rising over the Mono Craters. Despite any misunderstandings about my title for this blogpost, Mono Lake is a treasure, one worth protecting.

A Convergence of Wonders, Day 16: Our Home Mountains, Giant Swimming Reptiles, and a Bunny

After 15 days and 4,200 miles, we woke up to the last day of our Convergence of Wonders, the geological tour of the Pacific Northwest and Northern Rocky Mountains. It was June 30th. We had traveled through the Cascades and the Coast Ranges, the present-day manifestation of convergence along the Cascadia Subduction Zone. We had traveled across the Columbia Plateau and the Channeled Scablands, and looked at evidence of past convergence in Montana's Glacier National Park, and Sun Canyon. We explored the inner parts of the earth's crust along the Beartooth Highway, and saw the evidence for a gigantic mantle plume (hot spot) at Yellowstone National Park. We saw the vast heavings of fault lines in the crust at Grand Teton National Park. And now, after a series of adventures in Utah and Nevada, we were finally headed home.

In the most technical sense, we could have started driving and made it home for a late lunch. But we couldn't pass up several of the most spectacular geological sights of our trip. We were almost home, but we could still be distracted by geological sights!

When we arrived at Berlin-Ichthyosaur State Park very late the previous night, not a few of our students were just a bit spooked by finding we were spending the night in a ghost town. The menacing looking ruins of the dark night were a little less nerve-wracking in the morning sun, so we packed and headed up to the quarry for a tour. Berlin-Ichthyosaur is a two-fer park: it preserves a late 1800's gold mining town, and a 200 million year old paleontology dig.

The ichthyosaurs were the dolphins/whales of the dinosaur era, the Mesozoic, aside for being in the wrong biological class. Whales and dolphins are mammals, of course, and the mammals were a rather minor part of the Mesozoic ecosystem, and as far as I know, none of them were adapted to marine conditions. Ichthyosaurs were air-breathing reptiles that were wonderfully adapted to life in the sea. They had the four limbs of their terrestrial ancestors, but their body shape was streamlined for fast swimming in the oceans. There were many species, ranging in length from a meter (3 feet) to 20 meters or more (65 feet). They had huge eyes, exceeding the size of pie plate in some of the larger species. That's a full-scale model of a Shonisaurus popularis in the picture above (the fat one is Geotripper himself, providing scale), the species found at Berlin-Ichthyosaur.

The bones of the ichthyosaurs were first noted by the miners, who used the massive vertebrae as doorstops and dinner plates. The site was excavated by paleontologists in the 1950s and 60s, who discovered more than three dozen more or less complete specimens. Nine or ten specimens were left in place for public viewing, and a structure was built over the site.

The bones don't differ overmuch in color from the surrounding rock, but the shapes are fairly obvious. The parallel bones above are ribs. Below are a number of vertebrae.

The skulls were the most delicate part of the skeleton, and were often crushed during preservation. Some portions of a skull are present in the photo below. Few teeth were found at the site.

One of the mysteries is why so many of the ichthyosaurs ended up dead in this one place. Numerous ideas have been suggested, including strandings, volcanic eruptions, spawning behaviour and others, but the favored explanation of the moment based on available evidence is that they died from mass poisoning, much as marine animals are killed today by red tides (toxic microorganisms). For more information on the topic, check out vignette 14 in Geology Underfoot in Central Nevada, by Orndorff, Wieder and Filkorn.

After our excellent tour by ranger Robin Riggs, we hit the road, and after a few hours we passed a welcome sign, the one that said we were back in California. Our beautiful home mountains, the Sierra Nevada, filled the horizon.

 Highway 167 is a very straight road in this part of the country!

Lest the students get lazy, we still had a few classes to go! We stopped in at Mono Lake County Park to sit in the grass under the Cottonwood trees. Mono Lake is an interior drainage lake; water flows in, but doesn't flow out. During the ice ages, glacial meltwater filled the basin, forming a lake 600 feet deeper that overflowed into adjacent basins, with water ultimately reaching Death Valley. In recent times the lake was 45 feet deeper than it is today, but in 1940, Los Angeles started diverting water from the incoming streams, and the lake started drying up.

 The spot we were walking on (below) was underwater half a century ago...

The lake is a critical stop for millions of migratory birds, as it has plentiful food in the form of fairy shrimp and brine flies. The birds need the nourishment to allow them to complete their long journeys. The conflict of human use and ecosystem preservation has dominated the politics of the region for decades. Recent agreements may stabilize the situation...maybe.

The mountains on the skyline are the Mono Craters, a series of rhyolite plug domes that have all erupted within the last 35,000 years or so. The last eruptions were only a few centuries ago. That makes this 9,000 foot ridge the youngest mountain range in the country.

Freshwater springs in the lake caused the formation of tufa towers, masses of calcium carbonate that stand like frozen sentries in the water.

After a quick lunch at the Whoa Nellie Deli, we headed over Tioga Pass and passed through Tuolumne Meadows in Yosemite National Park. By now, even the instructors wanted to go home, despite the incredible scenery. We will go see this stuff on a day trip later! Meanwhile we stopped for a wrap-up lecture and group photo at Olmsted Point. Half Dome loomed in the distance...

I snapped a quick picture of Mt. Conness and Tenaya Lake, and we got in the vans for the final hundred mile drive to Modesto.

We got in about 6 o'clock, and there were many happy shouts of reunions with loved ones. There was also a huge mess, but most of the students were cool enough to stay and help clean up. I love these folks! We were home. Mrs. Geotripper and I headed to the house said hi to our animals and managed to hang around the house for ten days before we got restless and hit the road again.

 As promised, here is the bunny. Mrs. Geotripper caught it in the early morning at Berlin-Ichthyosaur.

 It didn't fully cooperate in the careful posing category...

And that is the end of our Convergence of Wonders! I hope you enjoyed traveling with us!

My First Day of "Summer"...

Well, this is what a "compressed academic schedule" looks like...my first day of summer employment hiatus. A few years back the school wanted to run three full semesters a year, so shortened our fall and spring semesters to 15 weeks, adding a few minutes to every class and laboratory section. Some people like it, but it has had an unfortunate impact in the sciences, as we went from 17 labs to only 15. You can't spread the content of the two missing labs very well among the others. Unfortunately the summer semester was decimated by the California budget crisis, so I am presently idle, as my summer classes were canceled.

Well, I don't want to vegetate, so I am off to the eastern side of the Sierra Nevada for a conference of the National Association of Geoscience Teachers. To get there, we had to drive over Carson Pass on Highway 88 through Kirkwood Ski Resort, to Genoa, Nevada, then to Lee Vining and Bishop, a little over 300 miles. It's April 30, and it was snowing in the mountains yesterday! Luckily, the roads were dry and clear today.

The snow pack is obviously still pretty thick, so the geology is a bit obscure, but along the way to Carson Pass we passed Caples Reservoir, where we could see the high peaks composed of andesite lahar deposits from around 10-20 million years ago. They have been extensively modified by the Pleistocene glaciers, and make a beautiful backdrop to the lake.

We made our way south to Conway Summit, where we had a startling view of Mono Lake and Mono Craters. Mono Lake is the very salty remnant of an ice age lake that was hundreds of feet deeper, and once spilled over into the Owens Valley. The only way the water leaves to day is by evaporation. The story of the near destruction of the lake ecosystem because of the diversion of water by Los Angeles could fill many blog posts (and probably will before too long).

The Mono Craters are actually rhyolite plug domes that have erupted between about 35,000 years to only 600 years ago (the youngest, Panum Crater, is the small one in the foreground). They may be part of an evolving caldera, but mass destruction is probably hundreds of thousands years away.

In the late afternoon, we crossed through the Long Valley Caldera, which did cause massive destruction across the entire region 760,000 years ago. An eruption explosively tossed 130 cubic miles of ash across most of the western United States, and the ground over the magma chamber collapsed to form a hole that is 10 miles by 18 miles, and once may have been two miles deep. The high peaks of the Sierra Crest that form the western and southern edge of the caldera are composed of Paleozoic and Mesozoic metasedimentary and metavolcanic rocks that have been intruded by Cretaceous granitic rocks.

Tomorrow we will be geotouring through region, and more pictures will undoubtedly follow! Mrs. Geotripper took the top and bottom photos, I took the others.

Back from the Eastern Sierra Nevada

We are back from our journey to the east side of the Sierra Nevada, mostly in one piece, mostly not sore, and quite not thrilled to be back in a stuffy classroom! We spent four days touring the length of the Owens Valley, Mono Lake basin, the White Mountains, and the barren hills around the ghost town of Bodie.

The Sierra Nevada is a discrete block of continental crust that is considered to be sort of a micro-plate that is moving northwestward, stretching and breaking the crust in its wake, causing the formation of the deep fault valleys of the Basin and Range province. Owens Valley is one of the deepest of these, with a floor at 4,000 feet, and mountains on either side reaching 14,000 feet (a valley nearly twice as deep as the Grand Canyon, but not carved in any way by rivers). The Sierras include numerous granitic intrusions interspersed with roof pendants of older metamorphic rocks. The lesser-known White Mountains on the east side of Owens Valley are composed of some granite, but mostly of late Proterozoic and early Paleozoic sedimentary and metasedimentary rocks (the Cambrian sediments alone are around 3 miles thick).

Growing up, I thought the eastern face of the Sierra Nevada would be a great stand-in for the Mountains of Mordor in the Lord of the Rings by J.R.R. Tolkien. The rocks make a nearly impassable barrier for something like 100 miles with only an occasional pass at less than 10,000 feet. To say the mountains are scenic is a gross understatement...the first of today's photos is the range crest in the vicinity of Mt. Williamson near the village of Independence.

Farther north, the mountain front is only slightly less rugged, but other factors make for a fascinating geology field trip. In the center photo one can see the inland sea of Mono Lake in the foreground, some of the plug domes of the Mono Craters in the middle distance, and the high peaks just east of Mammoth Lakes on the skyline (the view is from the viewpoint near Conway Summit on Highway 395).

Mono Lake is an ice-age relic that has no outlet (a pluvial lake), so water leaves the region only by evaporating. There are no fish (it is three times saltier than sea water), but there are plenty of brine flies and their larva, and there are trillions of brine shrimp. This is a tasty mix for the millions of birds that use the lake as a stop-over on their seasonal migrations. The lake lost much of its volume when Los Angeles diverted many of the streams that fed the lake in 1942. Recent litigation has led to an agreement to bring the level of the lake to something approximating its original depth (not really, but at least enough to keep the shrimp and flies alive). Parts of the shoreline are decorated by the eerie looking tufa towers that form where fresh water springs flow into the brine.

The Mono Craters have very few actual craters. They are instead a curving line of rhyolite plug domes that began erupting around 35,000 years ago, and it is a safe bet to say they are not done yet; the last episodes of volcanic activity were only 600 years ago, at Panum Crater and Inyo Craters.

The last photo shows one of the oldest living things in existence: a bristlecone pine. Some of these trees have survived for 4,500 years in the harsh environment at 10,000 feet on the flanks of the White Mountains. The tree in the picture is not dead; a thin line of bark and a few needle-covered branches show that it still lives. It is one of the old ones, though. The fierce winter winds have abraded and polished the resin-rich wood where the bark is gone. Even the dead trees persist; a dendrochronology of the living and dead trees reaches back at least 7,000-8,000 years, giving us an accurate record of droughts and climate change over the time period.

Four days is not nearly enough time to see all the geologic wonders in this region...