Wednesday, March 22, 2017

Two Death Valleys in One: Travels in Death Valley Version 1.0

It's certainly not the first time I've talked about Death Valley, Version 1.0 (see this post, for instance), but it's also a story of unending fascination. The deep and very long fault graben that forms the main axis of Death Valley National Park is only the latest in a series of fault valleys that have formed here over millions of years. One of the most popular stops in the park, Zabriskie Point, reveals the uplifted remains of a desert graben that existed several million years before the present valley formed.
The Death Valley region prior to about 15 million years ago was part of a vast high altitude plain that sloped west towards the Pacific Ocean, several hundred miles away. This feature, sometimes called the Nevadaplano, predated the latest uplift of the Sierra Nevada, so rivers flowed across the otherwise gentle terrain of rolling hills towards the sea. Much of this surface had been covered by eruptions of rhyolite ash that spread from vast calderas off to the east. But the tectonic arrangement of the American West was transforming (literally; the newly forming San Andreas fault was becoming a transform boundary) and big changes were coming.
Because of intense extension, the crust of eastern California and Nevada fractured into a series of faults that subsided and sank into deep basins. The newly formed mountains around them started shedding sediments and volcanic materials into these basins, and ultimately thousands of feet of strata had accumulated. We divide the sediments at Zabriskie Point into three formations, the Artist Drive, the Furnace Creek, and the Funeral. The Artist Drive is mostly volcanic material, including ash deposits that weather and oxidize into a rainbow of bright colors (the Artists Palette is a popular site for viewing them). The 6 million year old Furnace Creek formation, composed of clay and silt deposits, tends to weather into badlands, barren gullies that support little in the way of plant life. The Funeral formation includes sand and conglomerate formed in large alluvial fans, as well as basaltic lava flows.
The three formations that I've described above are the kinds of rocks one would expect to find deep in the accumulated sediments of a graben like Death Valley, where they would mostly be deeply buried and hidden from view. But geologic events conspired to push these rocks upward: the direction of the extension changed, and a new graben, that of Death Valley, began forming about 4 million years ago. The rocks in the Furnace Creek graben were twisted and faulted upward, and erosion began to tear away at the newly exposed rocks. These were the rocks that lined the highway that we followed into Furnace Creek, and we stopped in several places to have a look.
Part of the intense interest in these rocks lay in the fact that they held vast amounts of borate minerals, a rare commodity in the late 1800s. The discovery led to the exploration of Furnace Creek and the establishment of many mines in the area. The Furnace Creek Resort complex was an outgrowth of the mining boom, and the trademark "20-Mule Team" Borax originated with the wagons that carried the minerals 150 miles to railroads near Barstow. Some of the mines were still active just a few years ago (the mineral claims were grandfathered in when Death Valley became a park).
The rocks are always interesting to see, but the ongoing rain left the slopes wet, which seemed to intensify the color. It's true that I would have preferred slightly more bland coloration in favor of a sunny day, but here in my armchair several weeks later, I can deeply enjoy the color show, and the privilege of watching streams of water flowing in the driest of American deserts.

Sunday, March 19, 2017

Spring is Coming, and Flowers are Awakening in the Sierra Nevada Mother Lode

It's still a bit early to see the awesomeness to come, but the spring wildflowers are beginning to make a splash of color in the Sierra Mother Lode. With the record and near record amounts of rain in Northern California, the slopes are primed to produce a wildflower show to compete with the "super-blooms" taking place in the California deserts this year. We were exploring a portion of the southern Mother Lode in the vicinity of Mariposa and Coulterville yesterday, and I took my attention off the rocks for a few moments to catch some pictures of the early-blooming flowers. Above is a Fiddleneck (Amsinckia species), often one of the first of the wildflowers to bloom in this region. It can be poisonous to livestock, and yet was used as a food and medicine source by Native Americans.
Near the Pinetree-Josephine Mine we saw a number of Brodiaea, or Blue Dicks (Dichelostemma capitatum). These beautiful flowers grow from bulbs that were also an important source of food to the Native Americans of this region.
I don't know as many wildflower species as I should, as much as I appreciate their beauty. In a few places there were carpets of small yellow flowers (Goldfields, in the Lasthenia genus, thanks to Siera Nystrom in the comments).
Seeing some of the flowers growing in the usually poisonous serpentine soils reminded me that it is time to head up to the Red Hills soon, a Mother Lode locality known for a large number of endemic species.
As per Jane Strong in the comments, Orobanche fasciculata, clustered broomrape. Thanks for the identification!
And finally, the ever-present and always beautiful Indian Paintbrush (Castilleja species). There are some 200 species of this flower.

This is only the very beginning of what promises to be a wonderful year for wildflowers. I hope to be bringing many more such scenes to your attention in coming weeks!

Monday, March 13, 2017

New Exhibit at the Great Valley Museum: Homo Naledi and MJC's Dr. Debi Bolter

If you've read my blog for any amount of time, you know that I work in a wonderful Science Community Center, which has a the marvelous Great Valley Museum (the GVM) taking up most of the bottom floor. The museum has existed for more than thirty years, but spent most of that time in a cramped 1930's vintage house. It had been a dream for decades that the museum could grow into a larger facility, but it wasn't until about three years ago that it finally happened.

The museum is equipped with a world-class planetarium, a Science on a Sphere, a live animal exhibit, and a permanent set of exhibits on the natural history of the Great Valley. There is a nice storage facility and curation laboratory, and quite soon there will be an Outdoor Education Laboratory (you'll be hearing lots more about this part). It also has a large space for rotating exhibits, and I'm happy to report on the latest: A New Star in the Ancient Human Family: Homo naledi and Modesto Junior College's Dr. Debi Bolter.
You may have heard the news about the discoveries of a new Hominin species in the Rising Star Cave in South Africa. It was in the headlines in 2014, and was a cover story in National Geographic. Fewer people may realize the close connection between the discovery and one of the anthropology professors at Modesto Junior College. Dr. Debi Bolter was part of the team who analyzed the teeth and skeletal elements found in the cave.
Dr. Debi Bolter of Modesto Junior College

Denise Godbout-Avant has worked with MJC and the GVM for many years, and lately as a volunteer has been collaborating with Dr. Bolter and other professors across our campus to produce a comprehensive exhibit about the discovery of Homo naledi. I was privileged to be in attendance at a sneak preview of the exhibit this evening.
Denise Godbout-Avant, curator of the Homo naledi exhibit
One of the unique aspects of the exhibit has been the use of some very complex 3-D printing to produce very detailed models of some of the skeletal material discovered in the Rising Star Cave. It was one of the unusual aspects of the research that the programs for the detailed scans was made available freely to other researchers. Printing these bones is a long and arduous process undertaken by MJC professors Joel Hagen and Dave Martin. Richard Avant painted and prepared the samples, while a number of MJC students assisted in other aspects of the exhibit.
Homo naledi is the middle skull, with a modern human on the right


The geology of the site is an important aspect of the research, as the cave is uniquely inaccessible. The bones lie in a chamber at the end of the "Superman Crawl" and the "Dragon's Back", extremely narrow passageways that make the accumulation of the bones in the particular chamber somewhat of a mystery. How did they get in there? Did they crawl in? Were they thrown into the chamber? Was there another entrance at one time or another?
The Great Valley Museum is a scientific treasure in a region that is often lagging in scientific education. The people of our region voted to support science education when they passed a bond issue a decade ago that resulted in the construction of the Science Community Center and the expansion of the Great Valley Museum. If you have not yet had an opportunity to visit the museum and take in the exhibits and maybe even a planetarium show, now is a great time to stop by! Bring the kids, for there is plenty for them to do as well. Information on hours and location can be found on the museum website at http://www.mjc.edu/instruction/sme/gvm/index.php. Follow the GVM on Twitter at https://twitter.com/GVMatMJC

Saturday, March 11, 2017

Liveblogging the Deluge: It Ain't Over 'til the Fat River Drains...A Six Month Flood is in Process

The flooding in California hasn't been in the news all that much of late, but that doesn't mean the threat is over. The atmospheric river storms that have been hitting the state like an out-of-control fire hose have been turned off for more than two weeks, and no storms are in the ten-day forecasts, at least not in my area along the drainage of the Tuolumne River.

Our local rivers haven't received the message yet.

We were at the Merced National Wildlife Refuge yesterday, and as we were leaving we noticed that the Mariposa Slough, a usually dry watercourse, was in full flood mode, flowing over Dan MacNamera Road. Off to the west, water covered a huge area (below).
Today I was back on my own river, the Tuolumne, where it flows out of the Sierra Nevada onto the Great Valley floor. It is still flooding, and has been since January 4 when the most damaging of the atmospheric river storms began battering the state (the current flow is more than 11,000 cubic feet per second). One might think that once the rain stops, so will the flooding, but the situation is not so simple.

In the days before gigantic dams were built on Sierra rivers, huge tropical rainstorms would drop prodigious amounts of rain in the mountains, and monstrous floods would spread out across the floor of the Great Valley, looking much like the scene above, but extending for three hundred miles north, as far as Red Bluff in the north valley. The water would take weeks to flow out through the Carquinez Straits into San Francisco Bay. The last storm that did this took place in 1861-62. The vast flood caused the state to move its capitol to San Franscisco until the waters subsided. Besides 1862, evidence has been uncovered of similar intense events in 212, 440, 603, 1029, 1418, and 1605 (sediments from storm runoff are preserved in ocean basins offshore of the state). That adds up to around a 0.3% possibility in a given year; not common, but enough that emergency providers have to seriously consider the possible effects.
The giant reservoirs that have been built along the major rivers of the Sierra Nevada represent our last line of defense against such floods. They are designed to capture the biggest surges in such storms, holding the water until it can be released at lower flow rates spread out over time. Most years the dams do their job well, but they can be overwhelmed, as they were in 1997 when there was widespread flooding across the valley. Which brings us to the current situation on the Tuolumne River.

Don Pedro reservoir can hold just over 2 million acre-feet of water. Because of the brutal drought of the last five years, the lake was allowed to collect and hold much of the runoff from the early season storms of November and December, and by the end of the year, the lake was beginning to fill. And then the big storms of January appeared in the long-range forecasts. Operators at the dam realized they needed to make more room in the reservoir, so they ramped up the outflow of the river to a near flood level rate of 9,000 cubic feet per second. It's not usually allowed to go higher because of a local quirk of the geology.

The Tuolumne River is trapped in a narrow channel all the way through Modesto downstream, and has little room to spread out over the valley floor. In some ways that is a good thing: downtown Modesto and other cities downstream can't be flooded by overflowing rivers the way it can happen in Stockton or Sacramento (these towns require extensive levees for flood protection). Others who live downstream are not so lucky, as higher flows translate to deep-water flooding within the narrow floodplain. The floods can also overwhelm levees downstream on the flatter parts of the valley floor around Patterson and Tracy.

The unique channel and bluffs along the Tuolumne originated in the Pleistocene ice ages. During the time of maximum ice advance the swollen river (average flow was several times what it is today) was full of silt and mud which was distributed across the Great Valley flow in a vast alluvial fan. When the glaciers receded, the rivers started flowing clear and the faster flows cut into the surface of the alluvial fan, forming the distinctive terraces that can be followed from the Mother Lode to west of Modesto.

So here's the tricky part: this wasn't just a few tropical atmospheric river storms that dumped incredible amounts of rain. Many of these storms drew in arctic air masses and tremendous amounts of snow now coat the high country of the Sierra Nevada. The snowfall has accumulated to record depths and now something like two million acre-feet of water now drapes the slopes upstream of Don Pedro. If you are keeping track of all the numbers, that's enough to completely fill the reservoir, which happens to be nearly full already.

We are facing a problem of water disposal not seen in modern times. The operators of the dam have to walk a fine line of preventing downstream flooding, but allowing for huge inflows of melting ice and snow in the coming weeks. The "fine line" included opening up the emergency spillway for the first time since 1997 and having the water rise to within an inch or two of overflowing in an uncontrolled manner. Outflow finally began exceeding inflow on the 25th of February, and the lake is now about 10 feet below the rim for the first time since January.

The threat is not so much more stormy weather (the rain season is tapering off now), but heat waves. It's going to reach 80 degrees around the valley floor next week, and the warm conditions are going to accelerate the rate of melting. So we can be sure that the water managers will be watching conditions carefully. I read that flows will continue at near flood levels for another three or four months!
My local stretch of the Tuolumne River (and the rest, of course) will be a changed place by the end of this extraordinary year. I will not be surprised if there are some new channels in a few places. Certainly the number of trees along the river will be changed. Several big ones on the Parkway Trail have already come down. A great many shrubs and thickets have been washed away as well. One very nice development is that the upstream sections of the river have been swept clean of the hated river hyacinth, an invasive species that has caused innumerable problems (I don't know the current situation with the hyacinth in the Sacramento Delta).

Learn more about the possibility of overwhelming atmospheric river storms here: USGS ARkStorm Report (PDF - 46 mb).

Thursday, March 9, 2017

A Place Where Water Once Was But Was No Longer, But Once Again Was (sort of) - Travels in Death Valley

Yes, I used that silly title a few weeks ago, but today it is in a very different context. We were continuing our exploration of the Death Valley region, and we were still dealing with the effects of the Bombogenesis storm that dropped so much precipitation across Southern California. We weren't able to reach Devil's Hole to see the rare pupfish because we almost got stuck in the mud. So we headed back west towards Death Valley as the storm finally seemed to be breaking up.

Highway 190 traverses a long northwestern-trending valley or trough flanked on the north by the steep and rugged Funeral Mountains. The mountains were just barely visible through the rainclouds, but we could make out thick gray sedimentary layers tilted to a high angle. Taken all together, the layers are very thick, approaching 20,000 feet, around four miles. There is quite a story in those rocks.
One of the challenges of taking new students into outdoor geological environments is getting them to recognize that the landscape that exists today is far different than those that came before. Nothing accomplishes that quite so well as releasing them onto the floor of an incredibly dry desert valley, and letting them discover that the rocks underfoot were chock-full of fossils that originated on the bottom of a shallow tropical sea. The rocks layers that make up the Funeral Mountains once lay offshore of the North American continent. California simply didn't exist 300-400 million years ago. There was only ocean.
One could argue that this was an exceedingly boring time as far as geological activity was concerned. For 200 or 300 million years there was quiet deposition of layers of lime-rich mud and not much else. It maybe wasn't exciting at the time, but to a paleontologist this is intellectual treasure beyond compare. It's rare around the planet to find places where deposition took place for hundreds of millions of years without interruption, and equally rare for such places to preserve the myriads of life forms that lived in these shallow seas.

The Grand Canyon is a justly famous and spectacular monument to the forces of geology, but the Paleozoic layers there are only 4,000 feet thick, and entire periods (the Ordovician and Silurian) are missing. The fossil record is incomplete. Death Valley National Park on the other hand has layers dating from every period within the Paleozoic era, as well as Cenozoic layers that are entirely missing from the Grand Canyon. It has one of the greatest fossil records to be found anywhere in the national park system. That what we were out to find that afternoon: fossils!
It shouldn't have be said, but we were outside of the boundaries of the national park. Collecting within the park boundaries is quite logically not allowed. We do enough damage to the resource as it is without hauling it off, to be lost to science.
A huge number of fossils lay scattered across the desert floor. The predominant fossils were the bits and pieces of crinoid stems (sea lilies) that once covered the floor of the sea like waving fields of wheat. Even though the crinoids were anchored by roots and had stems, they were most certainly animals, specifically echinoderms. This is the animal phylum that includes starfish, sand dollars, sea biscuits, and urchins. All of these animals are related by a kind of five-fold symmetry: the five legs of the starfish, the five feeding grooves on the surface of the sand dollars. The symmetry can be seen in the "star" shape in the middle of the stem fragment (above).
Other finds of the day included corals and brachiopods. For the students, it was the beginning of an understanding that the desert beneath their feet was truly a place where water once was, but was no longer. And with the continuing rain, it was a place where water was once again, however termporary.

Monday, March 6, 2017

Travels in Death Valley: An Island of a Different Kind in Ash Meadows

Welcome to one of the most remarkable places in the United States. It's a large island in the middle of the hottest and driest desert in the country. I freely admit that the unprepossessing photograph above is one of the least likely real estate ads ever, but it reveals the landscape of one of the most biologically unique spots in the continental United States, and this picture could have been a real estate ad in the early 1980s.
Crystal Spring at Ash Meadows
Ash Meadows National Wildlife Refuge is not in Death Valley proper, but instead lies about 30 miles east of Death Valley National Park. It is administered not by the National Park Service, but by the U.S. Fish and Wildlife Service. But it does enclose an outlier of Death Valley National Park, and it preserves critical habitat and nearly 30 endemic animal and plant species that were nearly extirpated in the 1970s and 1980s. The fact that it exists at all is entirely due to geology.

During the Pleistocene ice ages during the last two million years, the climate in this dry desert was often cooler and wetter. Rain and snow fell on the high mountain ranges to the north and east and soaked into the ground. Over the millennia the groundwater flowed slowly to the southwest, along river valleys and even through fissures right through mountain ranges. Bedrock ridges and gouge-filled fault lines forced the "fossil water" to the surface as a series of 30 or so seeps and springs. The amount of water flowing here is tremendous; some of the springs have flows measured in thousands of gallons per minute. For example, Crystal Springs in the pictures above and below has a flow of 2,800 gallons per minute. The presence of so much water in the desert makes Ash Meadows an island, but in this case it is an island of water in a landscape of dryness. It is one of the few oases left in the American desert, and has the highest concentration of endemic species in a small area anywhere on the continent.
Water in the desert attracts (and isolates) many kinds of plants and animals. Many are survivors, relics of wetter times who could not otherwise live in the desert. That would include the four native species of fish (a fifth is already extinct), and ten species of water snail (an eleventh is also extinct).
The proposed Calvada Lakes development from the 1980s

Water in the desert can also attract invasive species which can do great damage to the fragile ecosystem. Mosquito Fish, which are an important species in other settings, can upset the life balance in the pools and springs. So can abandoned aquarium fish. But the worst invasive species of all, Homo sapiens, nearly destroyed the entire complex.

It happened first when farmers began to manipulate the springs into irrigation systems. They piped the water flows and started pumping groundwater so intensely that the water table started to drop, threatening the species that lived in the ponds. Lawsuits ensued and one eventually reached the Supreme Court. In 1976, the court ruled that pumping had to be limited to the extent that water tables would not drop. The farming corporation sold the properties to a land developer, which led to an even greater threat to Ash Meadows.

The real estate development is in retrospect nearly unbelievable: more than 30,000 homes, along with shopping centers, casinos, theatres, and industrial parks. An instant city in the midst of barren desert. Even today, I can't imagine 50,000 people or more simply deciding to move out to the middle of nowhere. "But Las Vegas!" is an obvious response, but other desert town developments have faltered and disappeared when people realized how truly miserable the summer temperatures could be (and that's not to mention the winter winds and dust storms). Calvada Lakes would have been a disaster on so many levels.
Luckily, Congress stepped in and established the Ash Meadows National Wildlife Refuge in 1984, and most of the developer's lands were purchased by the Nature Conservancy in 1986. The lands were then re-sold to the federal government, and the refuge became a reality. Today, there is a marvelous new visitor center and three handicapped accessible boardwalks that explore some of the most interesting springs.
Devil's Hole Pupfish
The rain was still falling when we arrived at the refuge during our recent Bombogenesis trip to the Death Valley region. It had indeed been falling all night, so I should have known what was going to befall us when we tried to drive the gravel-clay road to Devil's Hole to see the most restricted vertebrate habitat on the planet. The vans very nearly got stuck in the slick mud, and we only made it out by getting out and pushing the van back onto semi-solid ground. We didn't make it, in other words. But we have in the past, and I'm providing a few pictures of the event.

The entire race of the Devil's Hole Pupfish lives in the shallow cavern opening on the side of a limestone hill. The water is constantly warm, almost 90 degrees, is oxygen poor, and the food supply for the fish is extremely limited. But somehow the fish have survived, and have diverged from their relatives who live in pools just a few miles away. They are thought to have been isolated for a minimum of 20,000 years, but some studies suggest as much as 60,000 years (an outlier study takes a different position, suggesting only a few centuries of isolation).

Access to the cave opening is for obvious reasons highly restricted. There is a caged platform from which the pool can be viewed from about 80 feet away. It's clearly hard to see the individual fish, but my camera has a great zoom lens. I'm not sure why they were there, but the white tiles in the pool allowed me to catch some video of the rarest fish in the world (below).

The cavern opening where the entire population of Devil's Hole Pupfish lives

Sunday, March 5, 2017

So You Were in Death Valley During Bombogenesis...Did You Get Any Rain?

Explosive cyclogenesis (also referred to as a weather bomb, meteorological bomb, explosive development, or bombogenesis) refers in a strict sense to a rapidly deepening extratropical cyclonic low-pressure area. One of those things hit Southern California a few weeks back, at the very moment that we were exploring Death Valley National Park. It caused some serious flooding problems across the Southland, and we knew we were in the path of it.
It's kind of ironic that during the latter stages of California's staggering five-year drought that Death Valley had more precipitation than normal, and last spring that rain delivered a so-called Super-bloom, one of the greatest wildflower shows in decades (see some of our pictures from last year right here). Then, this year when most all of California was being pounded with storm after storm, leading to record accumulations of snow in the mountains, Death Valley stayed dry. Less than a quarter inch of rain had fallen in the five months before our arrival.
It didn't stay that way, of course. We got doused the night before in Bakersfield, and the rain stayed with us for most of the day. We got a lucky break of several hours as we set up camp at Stovepipe Wells in Death Valley, but the rain began falling again during the night, and it was constant for quite a few hours. Somewhere around 0.5 inches fell on us. That may not seem like very much to those who live in wetter climes, but it is overwhelming for a desert environment like Death Valley, which is lucky to receive 2 inches in an entire season. The desert soils look rocky, but the pebbles often hide a layer of clay and calcite deposits that are largely impermeable to water. Instead of sinking into the gravels, the water runs off, and our campsite turned into a muddy morass.
It wasn't just the campsite. We again had a lucky break as far as morning rain was concerned. There was a hiatus that allowed us to pack up and hit the road in an attempt to see what we could of the park. No roads were closed overnight, but raging torrents had clearly passed through during the hours of darkness.
It has been rare during my 28 years of bringing students to Death Valley that we've seen the mountains draped in rain clouds, so the scenery was quite stunning. Above one can see the view of Grapevine Mountains from our campsite.
Driving the highways demanded constant attention, as puddles covered the roads in several places. The Furnace Creek resort had experienced quite a bit of runoff. They've had quite a year, with a fire several months ago that destroyed the laundry room and several other buildings (below).
We made our way past the resort and headed east towards Ash Meadows National Wildlife Refuge, hoping to miss the brunt of the precipitation that was still falling that morning. Debris was everywhere, but never so bad as to prevent our passage. Many of the roads are carefully designed to let the debris flow over the highway without causing damage. Sometimes it works, but there are limits. The highway at Scotties Castle was completely destroyed by an unprecedented flash flood a few years ago, and has yet to be rebuilt.
The rain did add a special perspective though. The rocks of Death Valley are always colorful, but wetness seems to bring out an intensity of color that is rarely seen most years. A bit of inconvenience and discomfort was balanced by some very pretty scenery as we drove along.