Monday, March 31, 2014

Geotripper is for the Birds: Life persists in the midst of horrific drought

It was on my morning stroll that I realized that Dry Creek was flowing. The creek has its headwaters in the Sierra Nevada foothills, and drains a region about thirty miles long before joining up with the Tuolumne River in downtown Modesto. It might seem extraordinary to be impressed by such a thing, but Dry Creek in recent decades tends to flow all year, from winter and spring rain runoff, and from irrigation overflow during the rest of the year. We had about two-thirds of an inch of rain yesterday, and in this drought year, that was finally enough to stop just infiltrating into the ground in the headwaters and begin flowing down the channel. In the twenty-five years I've been here, I've never seen such dry conditions. The rain is welcome, giving a last bit of moisture to fuel the growth of vegetation before the long dry season sets in. But it does little to alleviate the drought; we'd need something on the order of a foot of rain in the Great Valley and many feet of snow in the mountains in the next few weeks to fill the reservoirs.

As many of my readers know, I got a new camera a few months ago, and the powerful zoom lens has allowed me to explore a world that has been largely hidden to me until now: birds. Living in the Great Valley is wonderful for the access it provides to the incredible geological wonders of the Sierra Nevada, the Coast Ranges and the Cascades, but during the winter months when most field studies aren't happening the valley can seem a boring place. But not for the birds; for the birds, the valley is life itself. Millions of migratory birds winter on the valley floor, primarily in the federal and state bird refuges that have been established up and down the San Joaquin and Sacramento Valley floors. Over the last few months we have been frequenting some of the wildlife refuges, and the variety and number of bird species has been stunning to me (the neophyte birder). But the lingering drought is going to have an effect on their populations.

In some ways, the most surprising aspect of the bird-watching has been the variety of species I've found in my local neighborhood.  I documented some of them back in January in this post, but I have seen some more as the rain has finally come, and a few migrants have arrived back in the valley for the spring and summer. Here is a selection of the birds I have seen in the last week or two.
Cooper's Hawk (Accipiter cooperii)
The nicest discovery from this morning was a pair of Cooper's Hawks near Dry Creek (they could also have been Sharp-shinned Hawks, a closely related species; I invite corrections!). Even with the zoom lens, the raptors have been surprisingly shy about getting photographed. The hawks this morning were paying more attention to each other.
Western Bluebird (Sialia mexicana)
I saw quite a few Western Bluebirds during January and February, but I thought they had migrated higher up into the mountains, having not seen any for weeks. But here was one that was hanging out in the cow pasture a few blocks from my house. I love his colors.
Lesser Goldfinch (Carduelis psaltria)
There has been no lack of Lesser Goldfinches around my house. They are one of the most common visitors at our birdfeeders. This morning was the first time I've caught them foraging in the wild (the wild in this case being the grass along the highway north of my little farm town). The flowers in the background are Fiddlenecks and Purple Vetch.
Black Phoebes (Sayornis nigricans)
I love the little flycatchers in our area called the Black Phoebe. They are a western species, found commonly only in California, Arizona, and New Mexico, and many points south as far as Argentina. The Great Valley seems to be the northernmost end of their range. I'd never noticed them in the past, but I've seen dozens of them in the last three months.
Western Scrub Jay (Aphelocoma californica)
It's hard to miss the Western Scrub Jays around here. They're obnoxious and loud sometimes, and they're always chasing the other birds away from our feeders. On the other hand, they are one of the most colorful birds in our area. I always enjoy getting a close look at one.
Barn Swallow (Hirundo rustica)
One the recent arrivals in our area have been the Barn Swallows. They winter in Central and South America and migrate into our region for the summer. I photographed one for the first time just a few days ago. I'm seeing flocks of them lately building nests under the bridges around our irrigation canals.
Nuttall's Woodpecker (Picoides nuttallii)
I was very surprised to find a species unique to California living in my neighborhood. I thought "rare" endemics are hard to find. The Nuttall's Woodpecker hangs out in oak woodlands of California and nowhere else. I've now seen them several times in the walnut trees next to the cow pasture (and on telephone poles).
Great-tailed Grackle males (Quiscalus mexicanus)

The Great-tailed Grackles just recently arrived on the CSU Stanislaus campus. They arrived raucously, with one of the loudest calls I've heard during my bird travels of late.The males are dark black (above), while the females are brown (and much smaller).
Great-tailed Grackle females (Quiscalus mexicanus)

Yellowlegs Sandpiper (Tringas species); I don't know if it is the Greater or the Lesser.
I found the Yellowlegs Sandpiper in the slowly filling irrigation canal a few blocks from my house. They winter in our area before heading north into Alaska and Canada.
Yellow-rumped Warbler (Setophaga coronata)

I've briefly seen the Yellow-rumped Warbler flitting about in the grass on my campus, and even  chasing insects on my back porch one morning, but I walked out of my classroom on the third floor of our new Science Community Center the other day, and there was this little one right there in front of me. He politely waited until I had taken a few pictures before flying off.
Yellow-billed Magpie (Pica nuttalli), a Central Valley original

The Yellow-billed Magpie is endemic to the Central Valley. I see them all the time, and they are beauties. They are also in grave danger. The West Nile Virus reached our region in 2004, and the Yellow-billed Magpies were particularly vulnerable to the infection, with something like a 95% fatality rate. The population dropped by half in two years when the infection began. According to some web sources, they are rebounding somewhat from the disaster. I hope so; they are one of the prettiest of our local species.

So why all these birds on my geology site? Well, mainly because it's my blog, and I write about whatever interests me at the moment. But in the larger picture, the native species of a region are shaped by the geological forces acting on that area. These birds are adapted to the Mediterranean climate of the Great Valley and the riparian areas (rivers) and grasslands found within. They have survived hundreds of droughts in the past, and presumably are equipped to survive those of the present and the future. They have persisted through the vast floods which sometimes turn our valley into a vast lake. They are products of the geological forces shaping our valley just as surely as the rocks and sediment beneath our feet. And like so many of the wonderful geological sites in our state, they are interesting and often beautiful.

Sunday, March 30, 2014

The BIG ONE is COMING! Well, yeah, but...

The San Andreas fault in the San Francisco Bay area. The two reservoirs are Crystal Springs and San Andreas, which gave California's most important fault its name. Photo by Geotripper.

It seems like there has been a bit of shaking going on in California over the last few weeks. There was the 6.9 quake off the coast of Eureka on March 9, a 4.4 magnitude tremor in the San Fernando Valley on the 17th, and now the 5.1 magnitude quake in La Habra. It's enough to make people paranoid about quakes in general, and the BIG ONE in particular. Are these precursors to the BIG ONE? Are they relieving some of the stress that will prevent the BIG ONE from being so bad? We love to talk about the BIG ONE, and if the media outlets have their way, we will worry and fret about it, enough so as to tune in to their stations for more scary updates (to keep those ratings afloat). I've rarely been impressed by media coverage of earthquakes, and this week has been no exception. I've heard through tweets that some media outlets trumpeted official statements warning of bigger quakes to come in 24 hours while conveniently forgetting to mention the "5% chance of" statement that preceded the word "bigger".

Of course, in some ways it's worse. We're not waiting for the BIG ONE in California. We are waiting for the BIG ONES. The San Andreas fault gets lots of attention, but there are numerous active fault zones in California, and the San Andreas itself behaves like four independent fault systems. There was the devastating earthquake near San Francisco in 1906 that garners much attention, but there was an equally large quake near Fort Tejon in Southern California in 1857, and the Salton Sea region was shaken around 350 years ago. These different segments of the San Andreas seem to move every century or so. A huge quake shook the eastern Sierra Nevada in 1872, killing a tenth of the population in the Owens Valley (28 people). Each of these quakes were in the range of magnitude 7.7-7.9, although some estimates range as high as magnitude 8. Add to this list the 1952 Tehachapi quake (7.3-7.6), the Landers quake of 1992 (7.3-7.5), the Hector quake of 1999 (7.1), the El Mayor quake of 2010 (7.2, just over the border in Baja), and the Cascadia Subduction Zone quake of 1700 that no doubt affected the northernmost part of the state. It was very likely a magnitude 9 event.

I should mention that I successfully predicted these quakes. We discussed earthquakes and the "art" of earthquake prediction in my classes two weeks ago. We pointed out that psychics predict earthquakes all the time, and that they are never wrong (how wrong can you be when you say "I see a major city being devastated by an earthquake this year" without specifying a day or location?). To prove the point, I predicted that a quake would happen in northern California within a few days, and that another would happen in the south state as well. I make this prediction every semester, and I am rarely wrong. All such predictions are crap, of course, and do no one any good.

No one can predict earthquakes, and anyone who says they can is lying or is deluded. But we can predict where they will happen, and we can determine the probability that they will take place within a certain time frame, usually 30 years. This is the nature of the maps that I am posting here from the U.S. Geological Survey, the Southern California Earthquake Center, and the California Geological Survey. Such maps are a most useful tool for educating the public about where the greatest seismic risks are located in the state (note how distressingly close they are to the most populated parts). There is a lot more to the tectonic framework of our state than just the San Andreas fault!

It is interesting to me that since these probability maps came out in 2007, we've already had a 6.9 quake in northern California, and if you count just over the border, we've had our predicted magnitude 7 quake in 2010. It is important to note that neither of these events had any particular effect on the stress levels that have built up on faults like the San Andreas, Hayward and San Jacinto. They are still just as likely to shake in the next 25 years or so. What do we take from this? The quakes are coming, and we need to be prepared for them (start here: Everyone who lives in California should have emergency supplies of water and food. Even if you live outside the high risk parts of the state, you will still be affected, as the energy grid will be damaged and emergency services we take for granted will be headed into the areas where damage is the worst.

Do these kinds of disasters make you rethink the idea of living in California? You could move to Kansas and put up with tornadoes. You could go to Nebraska and enjoy the Polar Vortex. You could go to Louisiana or Florida and deal with oil spills and hurricanes. You could move to Oregon or Washington and deal with volcanic eruptions. There really is no place that is free of natural disasters, and the processes that cause them may sometimes have the benefit of producing beautiful scenery and interesting geological outcrops. I'll pick California every time.

Friday, March 28, 2014

5.1 Magnitude Earthquake in Southern California near La Habra

Lots of my relatives and friends in Southern California are reporting that they are feeling shaken up tonight. The magnitude 5.1 earthquake (revised from 5.3) took place about 2 miles east of La Habra, which may place it on one of the strands of the Puente Hills blind thrust system, according the the U.S. Geological Survey. My friends are reporting minor damage, mostly in the form of broken glass and fallen flat-screen televisions and monitors. The fault has been responsible for a number of historical quakes, most notably the 5.9 Whittier Narrows quake of 1987, which killed 8 people and caused around 350 million dollars of damage. The 2008 Chino Hills quake 5.4 may have occurred on the same system.

The event on the Puente Hills blind thrust was oblique, with reverse (compressional) and right lateral displacement, as shown by the focal mechanism from the quake (below). It is called a blind thrust because it doesn't have a clear surface expression which makes it difficult to assess the hazard level and the history of the fault. It is thought to be capable of generating a magnitude 7.2-7.5 magnitude event, which would have catastrophic consequences for the urban areas of Los Angeles and Orange counties. Such events are thought to have taken place around four times in the last 11,000 years.

Earthquakes such as those tonight serve to remind all Californians that their home is earthquake country, and all who live in the region must take this into account. The Puente Hills fault is just one of numerous active faults in Southern California. The San Jacinto, Santa Susana, Cucamonga, Elsinore, Whittier Hills faults, and the granddaddy of them all the San Andreas are all capable of causing great mayhem. Education and preparation are the best defense against tragedy. Here is a good place to start:

Tuesday, March 25, 2014

Finding Gold in the Mother Lode (but not that kind): A bit of color in drought-stricken California

Our search for gold in the Mother Lode of the Sierra Nevada foothills was successful, but we weren't looking for that kind of gold. Yes, these gentle hills once hosted one of the greatest gold rushes in history, but the mines have been silent for many decades. Today, the Mother Lode is a tourist destination, and one of the attractions is the spring wildflower show. In the last post, we saw how a few endemics are showing up this week on the serpentine soils in the Red Hills Area of Critical Environmental Concern. Serpentine occurs in bands associated with the Melones Fault Zone which divides two major terranes, the Calaveras Complex and the Foothills Terranes. The Mother Lode gold-bearing quartz veins occur along this same boundary.
Highway 49 winds for 150 miles or so along the Mother Lode, and as we saw in the last post, the early flower shows are patchy, and are helped in places by runoff from the asphalt. The hills are green for the moment, but the green will not last long. In most normal years, 90% of the rain has fallen by now, and we have received maybe 25% of the rain we usually expect. It's the worst drought ever recorded. The green grass in these pictures will start turning brown in a few short weeks, and we can look forward to a hot, dry and fiery summer season.
So the early wildflowers are out, and if the expected storm arrives tomorrow, they might receive enough water to last a few more weeks. One thing I know from years of exploring southwest deserts, flowers in a dry place are precious to behold. So enjoy some of the color we discovered last weekend.
 There were occasional patches of Foothills Poppies.
The Redbuds were in bloom, adding bright splotches of purple or pink to the hillsides.
 Lupines seem to do well in lots of environments along the Mother Lode.
These pleasing-looking leaves are not good for touching or picking; this is the ever-present Poison Oak. The leaves are colorful and eye-catching throughout much of the summer season and into the fall.
We reached the Moccasin Creek area and saw where the Marshes Flat Road diverges from Highway 49 and heads west through the metavolcanics and metasedimentary rocks of the Foothills Terranes. These Jurassic rocks were deposited on the sea floor and scraped off into the vast subduction zone complex that once extended from Canada to Mexico and beyond. Today the rocks are tilted to an almost vertical attitude. On the meadowlands around Marshes Flat the rocks are rarely seen, as they are covered with fairly deep soils.
The road is a pleasant backcountry avenue that serves as access for several ranches. It's usually an uncrowded drive.
The metavolcanic rocks show up when the road starts down the steep slopes towards Don Pedro Reservoir. Although there was almost no water in the creeks, some of the slopes had pockets of blooming flowers, including these Shooting Stars.
 If these are Shooting Stars, are the two flowers below star-crossed lovers?
 Near a creek we found some wild onion blooming.
 And a moving rock. Seriously, why is there a track here, and what moved the rock?

We saw that the sun was getting low in the sky, and I had a lot of grading to attend to, so we headed home. I hope the blooms last long enough for another trip before summer sets in!

Saturday, March 22, 2014

Life in a Harsh Environment: Spring Wildflowers in the Red Hills Area of Critical Environmental Concern

Ceanothus, Poppies, and Goldfields in the Red Hills area of the Sierra Nevada foothills.
Welcome to the Red Hills "Area of Critical Environmental Concern", a 7,000 acre preserve in the Sierra Nevada foothills near the village of Chinese Camp. We paid a visit today to see what flowers were out and about in this horrific drought year when much of the state has received hardly a quarter of the normal amount of rainfall. It's a fascinating area to explore, despite the somewhat plain appearance of the hills. The interest lies in the struggle for life in this tough environment.
Brodiaea, or Blue dicks, Dichelostemma capitatum. Can you see the tiny mite in the flower?
It's not exactly harsh as far as the climate is concerned. Sure, it gets hot in the summer and the rain falls only in the winter and spring. But it rarely gets cold enough for snow, and the nearby hills include thick forests and brush. In the Red Hills, one is struck by the near total lack of grass covering the hillsides. Although oak trees are common throughout the region, few if any take root in the Red Hills. And there are sharp vegetational boundaries. The oak woodland and grasslands simply end, and the barren ground begins.
Indian Paintbrush
The problem is the soils. The underlying rocks are composed of serpentine and other ultramafic rocks derived from the Earth's mantle, the thick layer that lies beneath the oceanic and continental crust. The mantle rocks are rich in iron, nickel, chrome, and other metals that are toxic to most plants. The soils are also deficient in nutrients that plants generally need.
I don't know these diminutive flowers. Any ideas? I'm guessing Baby Blue Eyes (Nemophila menziesii) PS: Nope, it's
Bird's Eyes (Gilia tricolor), thanks Russ Cary.
These tough conditions mean that many plants can't grow on these soils, but others that are usually crowded out by grass and weeds can either tolerate the serpentine soils, or even thrive. Some 250 plants have been found in the Red Hills, including a number of endemics that are not found outside the serpentine exposures.
Five spot (Nemophila maculata): It's strange, but for all the years we've been coming out here, I have never noticed this species before. It is quite pretty!
For years the Red Hills were an abused landscape. Despite the proximity of the Mother Lode gold veins, very little gold was found in the hills (serpentine is not a gold-bearing rock). Nothing of value could be grown in the soils, and so the land was used as an illegal garbage dump, shooting range, and off-road vehicle course. As the uniqueness of the hills became better known, the Bureau of Land Management acted to protect and clean up the region. Today there are trails and parking areas for visitors. It is especially popular in the spring when the wildflowers are at their best. As mentioned before, the year has been horrifically dry, and we are indeed in the midst of the worst drought ever recorded. The flowers are getting started, but it remains to be seen whether they will thrive through the spring (there is a possibility of some rain this week).
As we left, we saw a particularly rich patch of poppies and brodiaea, but such richness was the exception. For the most part, the flower show hasn't really started yet (if it starts at all).

We left the Red Hills and headed south on Highway 49 on the way to Marshes Flat Road. Along the way I took a deceptive picture (above). Yes, it sure looks like an explosion of California Poppies. It's enough to cause one to say "What drought?". But take a look at the larger context of the picture (below)...

The flowers thrive because runoff from the pavement gives the soil the extra moisture they need. There are few flowers beyond the edge of the highway. Still, the color was beautiful, and I hope the rain this week will keep the show going a little bit longer before the long, hot and dry days of summer.

There were more (and different) flowers on Marshes Flat Road. We'll see those in another post.

Out of the Valley of Death: Hitting the Lowest of the Low, the Driest of the Dry, and the Hottest of the Hot

Just how low can one go? Just how far can people descend in life before they hit bottom? In Death Valley National Park, there is a precise answer: -282 feet, or -85.5 meters at a spot called Badwater. That's also the lowest you can go in North America, but if you look at the big picture, there are seven other places around the world where you can sink even lower:

Earth’s Lowest Elevations (Courtesy of the National Park Service)
  • Dead Sea (Jordan/Israel) -1360 feet (-414 m)
  • Lake Assal (Djibouti, Africa) -509 feet (-155 m)
  • Turpan Pendi (China) -505 feet (-154 m)
  • Qattara Depression (Egypt) -435 feet (-133 m)
  • Vpadina Kaundy (Kazakstan) -433 ft (-132 m)
  • Denakil (Ethiopia) -410 ft (-125 m)
  • Laguna del Carb√≥n (Argentina) -344 ft (-105 m)
  • Death Valley (United States) -282 ft (-86 m)
  • Vpadina Akchanaya (Turkmenistan) -266 ft (-81 m)
  • Salton Sea (California) -227 ft (-69 m)
  • Sebkhet Tah (Morroco) -180 ft (-55 m)
  • Sabkhat Ghuzayyil (Libya) -154 ft (-47 m)
  • Lago Enriquillo (Dominican Republic) -151 ft (-46 m)
  • Salinas Chicas (Argentina) -131 ft (-40 m)
  • Caspian Sea (Central Asia) -92 ft (-28 m)
  • Lake Eyre (Australia) -49 ft (-15 m)
I had this awesome idea! I bet no one has ever thought to take their picture here before!
As the park service notes, most of these lowest points have a few things in common: they are very dry, and the origin of their low altitude is tectonic. The Basin and Range Province of which Death Valley is part of has been described as "The Broken Land" by Frank DeCourten, and indeed it is: fault after fault breaks up the Earth's crust into high mountain ranges (horsts) and deep fault basins (grabens). Death Valley is the ultimate expression of the process with relief of 11,330 feet between Telescope Peak (11,049 feet) and Badwater (-282 feet). The highest point in the United States outside of Alaska, Mt. Whitney (14,505 feet), is only 76 miles away as the crow flies.

If erosion wasn't a thing that happened, Death Valley would be even deeper. The sand and gravel that fills the Death Valley graben extends to a depth of about 9,000 feet, meaning if the gravel weren't there, the total relief would be 4 miles!
Fault scarps interrupt the smooth surface of this alluvial fan just south of Badwater.
From Badwater, it's not hard to see the evidence of the tectonic activity that formed the vast trough. In the picture above, two fault scarps are visible cutting across the relatively smooth profile of the alluvial fan. The earthquakes that caused these scarps happened in the last few thousand years, but they look fresh because of the lack of erosion in the dry climate.

Did we mention that Death Valley is also the driest place in North America? Average rainfall here is less than two inches a year. The Sierra Nevada and the other mountains of the Basin and Range province are very effective rain shadows (orographic barriers). Badwater lies at the edge of the Death Valley salt pan, a 200 square mile flat surface covered by salt and other evaporite minerals. It is hard to imagine a place more inhospitable to life on the planet. There are a few salt tolerant plants that grow on the edges of the pan, but I've heard of nothing that lives in the interior areas (except maybe some microbes here and there?).

To stand on the salt flat and look off in all directions is a lesson in isolation. Were it not for the vehicles and the ice chests and water bottles parked over against the mountain, this would be a moment of great concern. If it weren't February and summertime instead the concern would be near panic. We can easily forget the harsh nature of this environment when we are largely insulated from it. Furnace Creek, about a dozen miles north of this location, recorded a temperature of 134 °F (57 °C) in 1913. With the dethroning of the improperly recorded temperature in Libya from 1922, this is the hottest officially recorded temperature in world history. The hottest overnight temperature ever recorded, was 107 °F (42 °C) on July 12, 2012. That day, the average temperature was 117.5 °F (47.5 °C), the world's hottest 24-hours on record.

We talked about the geology and got back into the vans and headed north, up the valley towards Furnace Creek.

As we drove towards camp, we had a look at the edge of the vast turtleback fault surface at Badwater that forms the Proterozoic core of the Black Mountains (in the picture above). The long smooth slope in the shadow on the right is just about all fault surface. The sunlit rocks in the center  and on the left have slid off the fault to the north. They are composed of Miocene volcanic rocks of the Artist's Drive Formation.

The sunlight was a pleasant surprise. For much of the day the skies had been overcast, but in the latest part of the afternoon, the clouds parted for a moment and the rocks glowed orange and gold. The sediments and flows of the Artist's Drive formation are colored by oxidation of various metals in the volcanic ash and tuff layers, and are striking in almost any conditions, but they are especially bright at sunset.

The sun disappeared into the clouds again and the harsh edges of the valley blurred as the evening arrived. We headed back to our camp at Stovepipe Wells.