Monday, March 11, 2024

The End of the Tuolumne River! (It's not as bad as it sounds...)

The slough at the headquarters area of Dos Rios State Park
Back in the 1980s, Douglas Adams published his hilarious "trilogy" of the Hitchhiker's Guide to the Universe. The second book, The Restaurant at the End of the Universe, was not about a restaurant at the edge of the Universe, but rather it was a place where you dined and watched the actual destruction of the Universe (you had to use a time machine to get there). 

Today's blog is about the end of the Tuolumne River. But it isn't as bad as it sounds: it's about the spot where the Tuolumne River ends by flowing into the San Joaquin River. The confluence was on privately-owned ranch lands for many years, but a profound change is coming that will touch lives across our county and Central California. It is becoming California's newest State Park!

The confluence of the Tuolumne and San Joaquin Rivers
Dos Rios State Park is the product of years of cooperation between the owners of the Dos Rios Ranch, River Partners, and the Tuolumne River Trust. In the last decade or so, the partners worked to return the former croplands to a landscape that functions like the original primeval environment that existed before the invasion of industrial agriculture. In other words, a riot of canopy trees like oak and cottonwood with a tangled undergrowth of willows, elderberries and numerous other native plants. This floodplain woodland acts as a giant sponge, absorbing and slowing down floodwaters and helping to recharge the groundwater underneath.
The lower Tuolumne River near the confluence. The state park is on the right-side shore
The riparian environment provides a marvelous habitat for the wildlife that once thrived throughout the Great Valley of California (only about 5% of that original habitat remains). Dos Rios State Park will be a fantastic place to search for hundreds of bird species (more than 200 are known from just across the river at the San Joaquin River National Wildlife Refuge), and all manner of animal and plant species. The highly endangered Riparian Brush Rabbit is only found in an extremely small area within the San Joaquin Delta and the wildlife refuge across the river. I was told they intended to transplant a small group from the refuge to the park, but that the rabbits confounded the plan by crossing the river somehow and establishing a population all by themselves!

There are a number of ancient remnant environments tucked away in corners of the park. The most striking was a growth of valley oaks growing on a slightly elevated hill adjacent to the San Joaquin near the south end of the new park. There was a cacophony of bird songs in the canopy above, including Yellow-rumped Warblers, Oak Titmouse, White-crowned Sparrows, Tree Swallows, and Bush-tits.
The oak forest is a two mile walk from what will be the park headquarters area, and there are ideas of developing the site into an environmental walk-in campsite where local children can experience wilderness only a few miles outside their cities.
Much of the park will be a trailless, roadless morass of trees and brush on the floodplain. This is the area meant to serve for flooding relief, where it might remain underwater for weeks at a time. Volunteers have spent a decade planting native vegetation, and many of the trees are already tens of feet tall. They were irrigated for three years, but they will be able to survive on their own in the years to follow, watered by the higher groundwater table and occasional floods.
A "bunny hill" on the right side, a floodplain to the left.
Several elevated areas across the park provide refuge for mammals during flooding events. I believe they called them "bunny hills". I've seen these in action during floods across the river at the wildlife refuge, where everywhere I turned, rabbits were waiting for the floodwaters to subside.
The tangled thicket of native vegetation: the valley floodplain as it once was.

One of the most valuable aspects of the park is that it will allow visitors to experience the valley habitat as it once was, and how many parts can once again be. On our tour, we mentioned the wonderful resource of the Great Valley Museum at Modesto Junior College where I teach. Visiting the museum, children can view dioramas of the natural environments of the valley and even see a few live animals. But what if...they could learn about these environments, and then drive a short distance and actually experience them? That's the incredible value of the Dos Rios State Park.
Double-crested Cormorant in the slough
When our tour ended, I spent a few moments wandering the only developed part of the park. There is a picnic area that has been constructed adjacent to the farm buildings serving as the park headquarters for the moment. There is a slough below the picnic structures with a short walkway providing panoramic views. It didn't take long to find some interesting birds, like the Double-crested Cormorant drying its wings on a stump.
I only occasionally see Downy Woodpeckers along the Tuolumne upstream, but it was the first one I sighted today. I also saw Northern Flickers and Nuttall's Woodpeckers.
A Great Egret was watching for fish on the far side of the slough. 
Turtles were basking on logs down in the slough below.
Dos Rios State Park will open this coming summer with the picnic area and slough area open for visitation. A master plan will be developed over the next few years, with proposals for a campground, trails, and all manner of interpretive programs. Even better, the park will function as an environmental buffer, providing habitat and flood protection. The park is starting with about 2,100 acres, but other adjacent tracts are being "de-developed" to resemble their original habitat. 
It was a real privilege having the opportunity to see this park and renewed floodplain in the making. I'm looking forward to seeing what lies ahead for this beautiful new park in coming years. It is a marvelous resource for our community.
Source: River Partners and the Tuolumne River Trust

Thursday, March 7, 2024

What's the Most Awesome Thing You've Ever Seen? Musing on Solar Eclipses, Part 1

Totality of the solar eclipse of 1991 from San Jose del Cabo. The corona, an aura of plasma and gases, is only visible during totality. Photo by Dr. William Luebke.

There is a major celestial event coming up next month, a total solar eclipse that is going to sweep across a wide swath of North America. I'm here to say that if you can, make the effort to see it. Why? It's a truly unique experience that has mystified (and terrified) humans during our entire existence. Seeing a partial eclipse is interesting. A glimpse of a total eclipse is truly awesome. I can't make it this time, but I have seen two of them in my life, and I want to relate if I can just what a stunning experience it can be. So here is the account of my first experience in 1991. This is from a post I wrote in 2017:

What's the most incredible thing you experienced? 
There are lots of answers to such a question, and many different contexts and meanings. I had an abrupt reminder tonight of one of the most incredible things I ever took part in. We're putting in new carpeting (no, that's not the incredible experience), so I've spent the week organizing 26 years of accumulated papers and books to clear the floors throughout the house. It's as much trouble as moving, only there's no truck to stuff everything in. I was close to finishing when I got into a cabinet that had been blocked by other boxes for literally years. There was an old photo album. I opened it and was immediately transported back to 1991 when I experienced a total eclipse of the sun at the tip of Baja California in Mexico.
The "diamond ring" effect just before totality as the last of the sun's disk disappears behind the moon. Solar prominences are jets of gas shooting from the sun's surface. Photo by Dr. William Luebke
The 1991 eclipse was going to be visible from mainland Mexico, the tip of Baja California, and Hawaii. I was in my third year of teaching at Modesto Junior College, the new guy (needless to say, I'm not the new guy in the department anymore; I'm actually the senior member). Our astronomy professor, William Luebke, had made plans to fly to Hawaii for the event, but I found out that a relative (the mother-in-law of my sister-in-law) kept a condominium in San Jose del Cabo that she was willing to let us use. We jumped at the chance. All we had to do was get there. There were five of us and flights were expensive, so we decided to borrow a school van and make the 900 mile drive to the tip of the peninsula.

The drive was quite the adventure, and if I can locate the slides and scan them, I will perhaps tell the story. But we made it, and settled in for a few days to prepare (and get sunburnt while snorkeling). We selected what appeared to be an abandoned condominium plot and set up shop.
Who IS that young man?
The hillside was perfect, commanding a twenty mile long view of the coast. Soon others gathered, including an entire busload of Japanese astronomy enthusiasts who said they had rented the entire plot for themselves. After a few minutes of delicate negotiations, they allowed us to stay.

The length of totality was going to exceed four minutes, one of the longest eclipses of the century. We had three or four telescopes with us, so Dr. Luebke could concentrate on photographing the entire event, while I and Mrs. Geotripper could work with a telescope of our own that we shared with the many people on the hillside. During totality, thirty or forty people were able to take a quick look.
The eclipse was unlike anything I had ever seen in my life. In the hours before totality (which happened around noon), the air grew stiflingly hot, over a 100 degrees. The skies were almost free of clouds, and the sunshine was blindingly bright. The moon started to move across the disk of the sun, and we had quite a bit of time to watch the passage. Before totality, the sky remained bright. But then the last flash of the "diamond ring" effect took place and the sky suddenly darkened.
Not just darker. Dark. Stars and planets suddenly became visible, and the temperature dropped 15-20 degrees. Looking at the sun without needing glasses, I had little trouble appreciating the meaning that the ancients applied to eclipses. It was otherworldly; I almost found myself chanting for the dragon to release the sun from its prison.
Yes, the picture below was taken with a flash. It was that dark. Then it began to end. Bailey's Beads, the first dots of sunshine, broke through canyons and mountain passes on the surface of the moon, and the sky turned bright again. In a few more minutes, it was over. We packed up and headed home the next day (a whole other adventure).

At the time, we knew that the next solar eclipse that would be accessible to us would not be until August of 2017. It seemed such a long time into the distant future. I had no idea the many changes that would take place in my life, but suddenly it is upon us, on August 21. The path of totality is shown on the map below. If you have any chance at all, make your way and have a look. It is one of the most astounding sights you will ever see.
By the way, it turned out that Hawaii would not have been a good idea. Thousands of people flew there to see the eclipse, but low clouds obscured the skies and the only people who saw it were at the observatories beyond the end of the closed road on Mauna Kea. We were incredibly lucky to have had perfect weather in Baja.

It turns out that I had a second great opportunity to see a total eclipse in 2017. Read about soon in Part 2

Thursday, February 22, 2024

Echoes of a Watery Paradise in a Forsaken Hellscape - The Brief Return of Death Valley's Lake Manly

Imagine a lake that's six miles across flanked by dramatic mountain peaks reaching heights greater than 10,000 feet. We're in California, so it's got to be Lake Tahoe, right? But it's not. It is the lowest and driest place in North America, and the hottest place in the world. It's Death Valley. And big lakes are not a normal part of the scenery here. Badwater Basin is normally a dry salt flat. What has happened here?
In a word, it's rain. An extraordinary amount of rain has fallen in and around Death Valley this year, around 300% of what is normal. That sounds more dramatic than saying that 4.8 inches has occurred so far. A "normal" year to this point would see about 1.5 inches. And the rain did not fall in Death Valley alone. Death Valley is the lowest basin in a very large drainage system, and the surrounding landscape received even more. It was primarily the result of two events: the remnants of Hurricane Hilary in late August 2023 provided the floodwaters that resulted in the first iteration of the lake. In the hot months that followed, much of the accumulated water evaporated, but then the first week of February brought an atmospheric river storm to California that rejuvenated the shrinking lake. We were lucky to arrive a week later.

This kind of thing doesn't happen often. Some water was present on the valley floor in 2010, and earlier in 2005. But both of those years, floods had damaged the road to Dante's View so I haven't had a birds-eye view of the lake in at least three decades. It was fantastic.

When I and my students travel to Death Valley they get a packing list, but I tend not to put 'kayak' or 'raft' on that list. But we knew the lake would be there, so our long-term friend and trip volunteer Ryan actually packed one, so we had the spectacle of the Hollister family rafting Death Valley. 

The lake has been in the news, so we weren't surprised to see a multitude of tourists gathered in the parking lot at Badwater. I didn't think they'd all opt to go walking in the slimy muddy salty water, but you can see that they did. I was much happier to have stopped along the lake a mile to the south where there was no one but ourselves.

It was along that quiet shoreline that I was able to hear the echoes of a distant past when Death Valley was a watery paradise rather than the hellscape it is today (albeit a very beautiful and dramatic hellscape). That is what is revealed by the geological evidence scattered along the normally parched lake margins. 

At the south end of Death Valley there is an old basalt cinder cone with a strange name: Shoreline Butte. In the picture above, the shoreline terraces are highlighted by the "Superbloom" of 2016 (with all the rain this year, there is at least a possibility of another superbloom in a few weeks). Each of those horizontal terraces was carved by wave action. This and other clues scattered around the margins of the basin are evidence of a lake that existed here for thousands of years. It was as much as 600 feet deep, and more than 100 miles long. 

Where did all that water come from?

Along Beatty Cutoff Road, there is a beach berm covered by rounded flattened pebbles. This was along the northern shoreline of Lake Manly when it was 450 feet deep.
Evidence suggests that Lake Manly existed during a period from 186,000–120,000 years before present, dried up, and then returned again between about 35,000 to 10,000 years ago. It can't be a coincidence that these dates are identical to the dates established for the Tahoe and Tioga stage glaciations that took place in the Sierra Nevada. No glacier ever reached Death Valley, but the Sierra glaciers contributed vast amounts of meltwater to the dry basins east of the mountains. These waters filled present-day Mono Lake to overflowing. It spilled over and flowed in the Owens River to Owens Lake, which actually persisted into the modern era when LA water diversions caused it to dry up in the 1920s.

Pluvial lakes of Eastern California. Source: Philip Stoffer of the U.S. Geological Survey

Ice-age Owens Lake reached a depth of 300 feet and spilled over into China Lake, then Searles Lake, Panamint Lake, and finally Lake Manly in Death Valley. These ice-age bodies of water are called pluvial lakes. The cooler wetter conditions allowed two other river systems to contribute water, the Amargosa River out of Nevada, and the Mojave River out of the San Bernardino Mountains in Southern California. There may have even been a temporary connection with the Colorado River, which resulted in one of the most surprising aspects of Death Valley biology: fish!

Salt Creek Pupfish from the middle of Death Valley

Yes, there are fish in Death Valley! In fact, there are several species. They survive in widely scattered springs and short stretches of perennial streams that exist in the desert. The pupfish (cyprinodon) are of particular interest because they probably once were a single widespread species, but when isolated in springs that were either hot or cold, or salty or fresh, they were forced to evolve or perish. Today there are four species in the confines of the park and several others in outlying areas, especially the Owens Valley and Ash Meadows in Nevada. I've found their story to be intriguing and I've written about them a number of times. These diminutive fish survive in the saltiest and hottest water of any known fish species.

Mammoth bones on display at the Shoshone Museum, east of Death Valley

Imagining this vast ice-age lake meant led to another vision of past worlds. In the early 1980s, some students on a geology field trip were hanging out near their camp in the Shoshone area when they discovered bones sticking out of a gully wall. These bones proved to be specimens of Columbian Mammoths and other ice age mammal species (the specimens are currently on display in the Shoshone Museum east of the park). The Death Valley region was a much cooler and more verdant environment during the ice ages, and the shoreline of Lake Manly was populated by grazing animals including the aforementioned mammoths, camels, horses, bison, and the carnivores that would have preyed upon them, including the large cats and perhaps relatives to today's wolves and coyotes.

Looking at the shore of Lake Manly at Badwater from a vertical mile above from Dante's View
To see a lake that only comes into existence every decade or so is a spectacle (in the best sense). But to understand the deeper implications suggested by these lakes that speak of past worlds is the magic of geology. See it if you can. It won't last much longer!

Wednesday, February 14, 2024

Discover the Wonders of the Hawaiian Islands with Geotripper and Modesto Junior College -May 30-June 11, 2024!

Are you looking for a bit of adventure? 

I invite you to join our Modesto Junior College Anthropology 190/Geology 190: Field Studies in the Hawaiian Islands from May 30 to June 11, 2024. This once-in-a-lifetime journey spans nine days on the Big Island of Hawai'i and four days on Kaua'i. 

There is still time to join us for 13 days exploring volcanoes, coral reefs, tropical rainforests, tropical deserts, ancient foot trails, petroglyphs, and archaeological sites! Our itinerary includes Hawaii Volcanoes National Park, Mauna Kea, Hilo, the archaeological parks of the Kona Coast, and on Kauai we'll visit Waimea Canyon (the "Grand Canyon of the Pacific") and the Na Pali Cliffs, and much, much more.

The total cost for lodging, transportation, and inter-island flight is $2,850. Students are required to make their way to Hawaii and arrange their own meals. 

Contact instructor Garry Hayes (that's me) ( for more information.

This is a Zero-Textbook-Cost Class. We are writing our own!

Links for the Informational Brochure, Registration form, and the Tentative Itinerary can be found at the bottom of my MJC Faculty Page at MJC People Finder: Garry Hayes. Although some deadlines mentioned in the brochures have passed, we still have room for several more travelers, and would love to have you join us!

Sunday, January 7, 2024

A Rare Day for the Great Valley: The Sierra Crest, and a bit of Half Dome

California's Great Valley is many things: one of the most important agricultural regions in the world, America's Serengeti Plains where millions of migratory birds spend the winter, and one of the most polluted air basins in the country. The pollution is a shame, causing all manner of health problems for those who live here, and obscuring the incredible mountains that ring the valley. Except on a few select days out of the year. Today was one of those days.
Gray, Red and Merced Peaks in Yosemite National Park
We had a fairly intense storm last night, and it was followed up by windy cold conditions that cleared the air. I took my customary walk along the Tuolumne River Parkway Trail. A section of the trail follows the bluff and on days like this, I get a wonderful panorama of the Sierra Nevada covering Yosemite National Park. A zoomed-in look provides a view of Gray, Red and Merced Peaks in the southern part of Yosemite (above).
A shift to the north reveals the high peaks of the Sierra Crest, including Mt. Maclure, Rodgers Peak, and Mt. Lyell, three of the higher peaks in Yosemite National Park (Mt. Dana, the 2nd highest, isn't visible). Some of the foreground peaks are rather famous as well. Mt. Starr King and Sentinel Dome are visible, and at the very left edge of the photo is the top portion of Half Dome! It's hard to pick out, but the CalTopo provides some identification of the different peaks. 
There are better views of Half Dome from the valley floor (the intersection of Oakdale-Waterford Highway and Keyes Road is much clearer on days like this). I couldn't get any pictures today, but here's one from a different day (see some more at 
A wonderful day.

Tuesday, December 12, 2023

Geotripper Goes to the Movies: Review of Unconformity (2022)

Copyright: Jonathan DiMaio
One of my earliest blog posts, back in 2008, was a top-ten list of the depiction of geologists in movies. I've revisited it a few times, most recently in 2018 when I added in the movie "San Andreas" (the real hero in the movie was Paul Giamatti's role as a geologist, not the Rock). It seems I need to update that list once again. An independent movie was released last year called "Unconformity", and it has perhaps the most honest depiction of a geologist that I've seen in film. Directed and produced by Jonathan DiMaio, it is the story of Alex (portrayed by Alex Oliver), a young woman graduate student who is dealing with betrayal and misogyny in her academic pursuits. A series of events leads her to doing research alone in some of the most deserted parts of the Basin and Range in eastern Nevada. Along the way she develops a friendship with a young man Nick (Jack Mulhern), who works a nearby ranch with his father. It's a quiet reflective movie, and it's a credit to the director and writer that the developing friendship is not the usual stereotypical romance, but more a growing understanding between two people who are hurting. 

Copyright: Jonathan DiMaio
The cinematography is simply astounding, with broad sweeping vistas of some of the wildest parts of North America. I caught glimpses of the House Range with the sheer cliff of Notch Peak (where I actually did some field work in my graduate school days), and the Snake Range with Wheeler Peak, the centerpiece of the very remote Great Basin National Park. The movie's unobtrusive soundtrack nicely compliments the wilderness landscape.

Copyright: Jonathan DiMaio

Now, about the geology. Most movies simply assume that the viewer is ignorant and won't care about the particulars of the science detailed in the movie. The Tom Hanks-produced miniseries "From the Earth to the Moon" had an episode ("Galileo Was Right") that was one of the best depictions of a geologist I've ever seen. It involved the efforts of Professor Lee Silver to train the Apollo astronauts to explore the moon with the eyes of a geologist, and it captured the essence that drives geologists to want to understand geologic processes and history. But it was so jarring in that episode to see a geologist refer to what was clearly a chunk of olivine basalt as simply "granite". That doesn't happen in DiMaio's movie.

Copyright: Jonathan DiMaio
Alex is shown doing field work, using a Brunton compass more or less properly, using topographic maps to plot geology, and measuring stratigraphic sections. She uses the proper end of the rock hammer when getting and preparing rock samples. She is shown making thin sections of rock samples (the thin section images of minerals used in the opening credits are beautiful). Her profound discovery is plausible (finding fossils of the Ediacaran fauna) given the regional geology of where she was working, and the implications of her discovery are clearly explained in the movie. This leads to a better understanding of why her thesis advisor would have been inclined to take advantage of her work by taking credit for it. The fossils themselves are accurate as to species, and genuine-looking in the movie (although just a bit 'too' perfect?).

Notch Peak in the House Range of western Utah has a sheer cliff more than half a mile high.Copyright: Jonathan DiMaio 
In total, the movie is a nice diversion for anyone who enjoys character-driven dramas, but it's extra special for the geologists out there who pine away for an accurate portrayal of a geologist in the cinema. It is streaming now on Prime Video, and can also be watched on YouTube with the link below.

Unconformity Film (film website) (director's website)

Unconformity (2022) | Full Movie - YouTube

Watch Unconformity | Prime Video (

In closing, a quick apology to Mr. DiMaio. He wrote me about the movie over a year ago, offering to let me see an advance copy, but the email ended up lost for most of last year. I regret not seeing the movie earlier. Check it out!

Saturday, October 28, 2023

Why did the Road Cross the San Andreas Fault? 21 Years of Geologic Change (a new Update)

I've been leading geology field studies trips to lots of places in the American West for 30 years and started to take digital pictures in 2001. I sometimes struggle to find new things to photograph when I visit a place for the 30th time, but in some cases it is not a problem. There are geologic changes that happen on a yearly basis, and with twenty-one years of photos (minus two due to Covid), the changes become obvious. This is a continuing update from a post in 2013, and I'll probably continue updating for the foreseeable future.
Highway 25 in the California Coast Ranges connects the town of Hollister with the access road to Pinnacles National Park (formerly Pinnacles National Monument). Along the way the highway crosses the San Andreas fault in a section where the fault creeps an inch or so each year (36°35'54.27"N, 121°11'40.19"W). Most years we've stopped to have a look at the effect the movement has on the pavement. In 2002 and 2004, the damage was obvious.
By 2008 someone had patched the road, and no fault motion was evident.
Little damage was evident in 2009 either. But by 2010 cracks had begun to appear as the fault stressed the pavement.
The fact that the fault creeps in this region is a good thing. It means that stress is not building along the fault surface, but instead is being released gradually. The sections of the fault to the north and south of the creeping section are locked by friction, and are building up the ominous stress that will eventually produce quakes with magnitudes in the range of 7.5 to 8.0. The quakes are coming and we need to be as prepared as possible.
By 2012, the road had been completely repaved, and  yet the shearing was already evident.
It became even more pronounced by 2013 and in 2014. Just by chance, the person working as a scale was the same individual as in 2004.

In 2015 the fractures were moderately larger. They'll need to start thinking of road repairs before long.
In 2016 Laura once again provided scale, as she did in 2014 and 2004.
Here in 2017, long-time trip volunteer Mary provides scale. The cracks in the road are just a bit larger, but they didn't look appreciably different than the previous year except for a twist (pun intended).

On Dec. 2, 2018, the break to my eye seems more continuous. It's now been six years since the road was completely repaved.

Last year the paint was deformed (twisted), but not split (below).
The offset paint strip reminds me of illustrations of elastic rebound theory, the idea that stress builds up on a fault line over time. In that model, the land on either side of the fault is distorted over time until the frictional resistance is overcome and the rock snaps back to its original shape. That won't be happening with the paint. Last year in 2017 I said "if they don't repair the road (as they often do; see above), it will probably show a clear break by next year." Here's what transpired:

First, a close-up on 2017's center stripe...
And here's how it looked on Sunday, Dec. 2, 2018:
As predicted, the break in the paint is complete...

In 2019 (those last few halcyon days before Covid) long-time volunteer Paul provided scale (he has been assisting MJC with field trips for 25 years!). The crack continues to grow, and I wouldn't have been surprised if it was patched by next year.
 The paint on the center strip is split even more.
November 2019
And then Covid happened and for a few years we were not able to conduct our field studies classes. In 2022 we made a return visit with our students and here is the then-current condition of the highway. It didn't appear that any repairs have been conducted yet. Our host is once again Laura, who was with us back in 2004 and subsequent years!
November 2022
Fault creep is not a constant. I didn't see a whole lot of change over the last three years, although I didn't get as many close-up shots. Here's a closer look with Paul, our other long-time volunteer. What do you see that is different?
November 2022
Which brings us to the current year, 2023. The road has continued to become more deformed, and the passing traffic produced an audible thump as it passed over the fault. Our host since 2004, Laura, was not able to join us, so her husband Ryan stood in her place.
Oct. 28, 2023
These little changes that happen at a rate visible in human lifetimes add up to huge changes when multiplied by thousands or millions of years. The nearby eroded volcano of Pinnacles National Park has been displaced 195 miles (315 kilometers) in the last 20 million years or so by movement along the San Andreas.