Saturday, May 30, 2015

How Strange Has the Weather Been? This was the Death Valley Region only a week ago

Zabriskie Point in late May. It's usually over 100 degrees and sunny this time of year.
The weather was a last week as we hit the road to the southwest. We meant to drive over Tioga Pass, and made it to Crane Flat, only to find the pass was closed by snow. We headed back down to the Central Valley and crossed the mountains at Tehachapi. From there we arrived in Death Valley for two nights of camping. It's late May, the temperature is usually well over 100 degrees, but this is what greeted us at Furnace Creek:

We actually needed a light blanket in our tent the first night. We followed Highway 190 east to Death Valley Junction, trying to thread our way between storms. We watched the gully-washer turn Eagle Mountain into shadows.

We passed a small herd of wild horses near Death Valley Junction. They seemed unperturbed by the downpour.

The town of Shoshone is a small outpost of civilization east of Death Valley. It was wet too. There has been odd weather across the country of late. Seeing May snow in the Death Valley high country and rain across the valley floor certainly fit the pattern. I have no conclusions to draw from this, but it's strange to see droughts and record heat in California and the Alaskan rainforest, along with intense flooding in Texas and Oklahoma. Strange and interesting...

An "Island" of Endemic Species: Not Hawaii, not the Galapagos, but Ash Meadows in Nevada

Desert surrounds Ash Meadows, an unlikely oasis in western Nevada

The formations are described as two coiled rattlesnakes, although to the geologist, this is a trick of erosion. The barren limestone layers overlook one of the most unlikely ecosystems in the United States. It is the largest "island" of endemic species in the lower 48 states.
Crystal Springs at Ash Meadows. More than 15 feet deep, the springs put out 2,600 gallons of warm water each minute.
Endemic species are those that occur nowhere else on the planet. The boundaries of endemism are usually the shorelines of islands, because new species arise from isolation. Hawai'i is the absolute leader in endemic species in the United States, being one of the most remote islands on the planet. There are literally thousands of endemic plants and animals on the islands that are found nowhere else in the world. The Galapagos Islands are a famous example of numerous endemic species. There are lots of endemic species within the boundaries of the lower 48 states, but there are relatively few found in any specific area. There are simply too many pathways for species to spread out over a wide region.
"Meadow" is sometimes a strong term for the scrubby vegetation found in parts of the refuge. The alkalai soils are unique.

But there are "islands" in the lower 48. They are the opposite of Hawaii or Galapagos in the sense that these are islands of water in an ocean of dry barren desert. One such island is the oasis of Ash Meadows in western Nevada. Within the 37 square miles of the National Wildlife Refuge are (or were) nearly three dozen endemic species of plants and animals, species found nowhere else on the planet. They exist in this one isolated location because of the geology, which has funneled the groundwater of a vast region into a series of three or four dozen springs that emit tens of thousands of gallons per minute. Water in the desert is life. Lots of water in one spot of the desert is almost miraculous, and that is the situation at Ash Meadows.
The creek that flows from Crystal Spring. An ADA accessible boardwalk provides access

The unique lifeforms found here include four living species of fish (along with one extinct species), eleven species of snails, three aquatic bugs, two species of bee, one extinct mammal (the Ash Meadows Montane Vole), and nine plant species.
Longstreet Spring at Ash Meadows

The desert that surrounds Ash Meadows is every bit as much a barrier to species travel as the open seas that surround Hawaii or the Galapagos. The meadows are only a few miles from Death Valley, the hottest place on the planet. So how did these water species come to be here in these springs and pools? Much of the explanation lies with the Pleistocene Ice Ages. A dozen or more times in the last 1.8 million years, the climate cooled and glaciers developed in the Sierra Nevada mountains off to the west. Meltwater from the glaciers filled the intermontane valleys of the Great Basin, forming a series of huge lakes and connecting rivers. These precious tendrils of water allowed fish and other aquatic species to invade the former deserts, but as each ice age stage ended, the dry conditions returned, and a few survivor species found safe harbor in isolated springs and pools like those found at Ash Meadows.
Devil's Hole, home of the extremely endangered Devil's Hole Pupfish. The pool in the cavern opening is their only home.

The refuge at Ash Meadows includes a single pool of water called Devil's Hole that contains the rarest fish species on the planet, the Devil's Hole Pupfish. The pool is an outlier of Death Valley National Park. Two other species of pupfish are found at Ash Meadows, the Ash Meadows Amargosa and the Warm Springs Pupfish. The Ash Meadows Speckled Dace is also found here. The Ash Meadows Killifish was driven to extinction in the 1950s as a result of spring alteration and agricultural development.
King's Spring can also be visited by an ADA accessible boardwalk.

It is remarkable that Ash Meadows ever came to be a protected ecosystem because water in the desert attracts another species, one capable of altering the landscape and erasing from existence the other species that have survived in isolation for tens of thousands of years. The water at Ash Meadows caught the attention of desert travelers more than a century ago, and the water was used to irrigate alfalfa fields and other crops. Many of the springs were put into piping systems and numerous invasive species arrived to compete with the native ones. It's hard to believe, but as recently as the 1980s, a proposal to build casinos, strip malls, and 30,000 houses almost became reality.

If you have visited Ash Meadows in the past, you will find some major changes. A marvelous new visitor center opened only a few months ago. There was plenty of excellent information about the geology and biology of the refuge, but I was especially impressed with the paleontology exhibits. We spent an entire day visiting and could have spent more.
Western Kingbird at Point of Rocks in Ash Meadows
Death Valley National Park is one of the greatest national parks in our country, and if you visit, you will find more than enough to keep you busy for many days. But if you find you have a day to spare, drive on over to Ash Meadows. It's only forty or so miles away from Furnace Creek.

To wrap up, have a look at an Ash Meadows Amargosa Pupfish defending its territory at Longstreet Spring. These are fascinating creatures, and true survivors.

Monday, May 25, 2015

The World's Rarest Fish is Where? The Most Restricted Vertebrate Habitat on Earth

There is a lonely nondescript mountain of limestone in the barren desert east of Death Valley National Park. There is a hole at the base of the slope, the entrance to a cavern. Lurking within are prisoners, creatures that have been trapped in the cave for perhaps 20,000 years or more. They are mutants, no longer the same as their cousins who live freely just a few miles away. They are alone in the world.

That sounds kind of dramatic I suppose, but all of it is technically true. The story becomes a bit stranger when one realizes that the trapped creatures are fish. In one of the driest climates in North America.

During the Ice Ages between 1.8 million and 10,000 years ago, glaciers in the Sierra Nevada were constantly melting in their lower reaches, and some of the resulting streams and rivers drained into the desert regions to the east. The faulted valleys would fill with water and spill over into the next so that at times an entire network of lakes and rivers existed. At some point a connection was made with the Colorado River system and fish worked their way into the widespread habitats. Dozens of species thrived in the freshwater lakes.

But then conditions began to change. The climate grew warmer and the glaciers mostly melted away. One by one the lakes dried up as the rivers that once fed them turned to trickles and then disappeared. Most of the fish died out, but here and there springs or remnant lakes allowed some species to survive. The most isolated species of them all lives in this one hole, the Devil's Hole. The Devil's Hole Pupfish (Cyprinodon diabolis) is in all likelihood the rarest fish in the world. There have never been more than five or six hundred of them, and their population has reached lows of only three dozen at times. They are living at the extremes, as the water is at a constant temperature of 93 degrees. Only a few other species of pupfish can survive those kinds of temperatures (you can read about some of the other species here: ).

Their rarity explains the monitoring equipment and fencing that surrounds the cavern opening. The pool is visible from in side a caged tunnel, but the individual fish are a bit difficult to see. They're only an inch long, and the viewing platform is around a hundred feet away. I saw nothing on my previous visit five or six years ago, but this time I did.

The efforts to protect the fish almost became their undoing when a 2004 flash flood dumped the monitoring platform and other debris into their pool. Something like a third of the population was lost. The platform was gone and there was a limited amount of equipment. And, there were three squares of what looked like white astroturf in the water. I don't know their purpose, but one idea is that they may protect eggs. Or maybe someone was making it possible to see the fish from so far away.

The fish feed from the algae covered bench on the near side of the pool. That bench was the crux of a Supreme Court decision in 1976 that prevented the extinction of the fish. At the time developers were digging deep industrial wells to promote the agricultural development of the adjacent valley, and the water level at Devils Hole began to drop. The court put a stop to the drilling, and the surrounding region became the Ash Meadows National Wildlife Refuge. It turns out to have been an astonishingly lucky turn of events, as the refuge has the largest concentration of endemic species in the continental United States (Hawaii is the only state with more endemic species).
In any case, I got to see the Devils Hole Pupfish, the rarest fish on the planet, for the first time ever. Thank goodness for a good zoom lens (bring binoculars or a good camera if you ever visit). The squares are only a foot or so across, but one could make out the shapes of the fish as they swam over the light colored material.

So here is the cropped and enlarged version of the image above, which doesn't show much, but remember I was more than 100 feet away.
If it helps, here (from the interpretive sign at the site) is what they really look like:

I even managed to get a very short video of the fish (all of 8 seconds or so).
It's not every day that one can see the rarest of anything. If you ever find yourself in the Death Valley region, don't pass up the opportunity to see these fascinating creatures. They could be extinct any day despite our incredible efforts.

Wednesday, May 20, 2015

Hitting the Trail for a Few Days

After a flurry of posts this week, I got kind of close to finishing my series on the most dangerous plate boundary, but school is out, and I've got a brief window of opportunity. The open road calls, and I'll be out in the middle of nowhere for a while. I may send out a few dispatches now and then, but otherwise, it will be a little quiet around here. Hoping for some continued cool weather in Death Valley. And for warm weather on the North Rim!

Driving Through the Most Dangerous Plate Boundary in the World: In the Pleistocene, a Different Kind of Danger

An Egret and Tule Elk at the San Luis National Wildlife Refuge near Los Banos
The Great Valley began as a shallow sea (a forearc basin) between the Mesozoic subduction zone and the Ancestral Sierra Nevada volcanic arc. As noted in the previous post, the sea filled with thousands of feet of sediments, and as the subduction zone transitioned to a transform boundary, the sea gave way to land, and the one of the most fertile valleys in existence emerged. The Great Valley has become one of the most important agricultural regions on the planet. 95% of the original landscape has been altered to grow food and feed. If the land isn't covered by crops, it's covered by pavement and cities.
The Cosumnes River Preserve north of Stockton

As I said in the previous post, the agricultural development isn't necessarily a bad thing. With an increasing population of mouths to feed in the world, it would be silly not to utilize the richest soils on the planet. But we do live in a highly interconnected ecosystem, and we need to preserve what we can of the richness and diversity of life in our world. A few wetlands have been protected from development to allow the survival of some of the migratory birds that overwinter in our valley, like the Sandhill Crane, the Ross's Goose, the Snow Goose, and many others. Some of the rivers flowing through the valley are still allowed to reach the sea, preserving salmon and other aquatic species. There is a great deal of conflict about where to define the limits of water and land use, especially in this horrific drought year.
The Cosumnes River north of Stockton

This past year I spent as a new birder has been a revelation as I have sought out those small corners and edges of the valley that preserve something of the original ecological richness. I was stunned to find that flocks of tens of thousands of cranes and geese spend their winters just a few miles from my home near Modesto.
Snow Geese and Ross's Geese at the Merced National Wildlife Refuge
Tule Elk, among the largest members of the deer family (aside from the Moose), used to live in the valley by the millions as well. One subspecies was down to a single breeding pair in the late 1800s, but they were protected by a rancher, and several thousand now survive in some widely separated refuges. The wolf was driven to extinction, as was the terrifying California Grizzly Bear. Other species retreated into the Coast Ranges and Sierra Nevada foothills.
The Tule Elk herd at the San Luis National Wildlife Refuge

This blog series has mostly been about the "most dangerous plate boundary" in the world, referring to the geologic hazards inherent in living near an active subduction zone: earthquakes, tsunamis, and volcanic eruptions. But a different kind of danger lurked in the Great Valley when humans first arrived: the so-called "megafauna": an ecosystem of large mammals that mostly went extinct just 10,000 or so years ago.
Wooly Mammoth at the Paige Museum
One of the most imposing creatures would have been the mammoths. These elephant relatives were widespread across Asia, Europe and North America, and passed into oblivion only a few thousand years ago. They were gone from the continents by 10,000 years ago, but a small population (both in stature and in numbers) survived on Wrangell Island in eastern Russia until 4,300 years ago.
There were giant ground sloths (above), and camels. Lots of camels, so much so that they are one of the two most common animals found in the Fairmead paleontological site near the Great Valley town of Madera. The Fairmead excavations have been the most important source of fossil material on the valley floor (the fossil species are also well known from the La Brea Tar Pits in Los Angeles.

The other common fossil is the horse. Most people think horses came to America with the Spaniards in the 1500s, but they actually evolved in North America and spread to other parts of the world before going extinct in their ancestral home around 10,000 years ago. There were also species of deer and pronghorn, and the buffalo roamed the valley as well.

Though any of these creatures could have injured humans in self-defense, it was their predators that would have made life in the valley terrifying. There were huge Sabertooth Cats. There were Jaguars and American Lions (pretty much the same as African Lions).

The California Grizzly Bear was dangerous enough, but even larger bears lived in the valley as well. The Short-faced Bear was a good 50% larger than a Grizzly, and may have been the largest terrestrial mammal predator ever. They were five feet high at the shoulder, and stood 11-12 feet tall if they chose to. Terrifying indeed.

They were smaller than the cats or bears, but the Dire Wolves hunted in packs, and that made them perhaps even more dangerous than the others. They were 25% larger than today's wolves.

The Great Valley would have been a dangerous place for humans when they arrived 13,000 years ago or earlier. It's possible that the megafauna is extinct today because humans had tools for hunting and defense, but the connection is not yet clear. Climate change could have played a role too, or disease, or any other number of possible explanations. In any case, I feel a sense of loss when I wander through the few remaining pieces of original habitat imagining the creatures that used to live here. A sense of loss, but at least I am not so fearful of being maimed or killed.

Are you interested in seeing more of these creatures? If you are ever traveling in the Great Valley for any reason, make the time to stop at the Fossil Discovery Center in the Madera area. The very famous La Brea Tar Pits are the other great source of information on the extinct megafauna. The Paige Museum at the tar pits is an excellent place to visit when you are in Los Angeles.

Tuesday, May 19, 2015

Driving Through the Most Dangerous Plate Boundary in the World: The Sea Floor that Became the Greatest Agricultural Region on Earth

Welcome to one of the strangest places on the planet! It's the size of West Virginia, but flatter than the Mississippi River Valley. It was once America's Serengeti, but 95% of the original landscape has been altered. It originated as the bottom of a sea, but now grows most of the nation's produce, and practically all of the nation's walnuts, almonds, and pistachios. It has been a major oil and natural gas producer. It is the Great Valley of California.
The Great Valley originated as a forearc basin, the seaway that is sometimes present between an oceanic trench/subduction zone and the margin of the continent. Tens of thousands of feet of sediment were deposited between the Jurassic Period and the mid-Cenozoic. As noted in the last post, the sediments have yielded up a fascinating collection of fossils over the years, including mosasaurs, plesiosaurs, ichthyosaurs, and even the fragmentary remains of a few dinosaurs. The valley was a seaway for the better part of 200 million years.

It is no longer a seaway. In the last few million years, California's tectonic framework underwent huge changes. The subduction zone was extinguished in the central and southern parts (subduction continues in the north state). A new plate boundary emerged: the San Andreas transform fault. Compressional forces along bends in the fault line raised the Coast Ranges, and the seaway of the Great Valley slowly gave way to river deltas, and then alluvial fans. In the last five million years, the Great Valley has been a terrestrial environment, with numerous river channels, gigantic lakes and vast grasslands. Large herds of grazing animals wandered the plains, pursued at times by terrifying predators (look for them in the next post of the series). Countless millions of birds made use of the wetlands during their long seasonal migrations.

The biggest and most far-ranging change in the Great Valley during the last five million years may have been that which took place only in the last 150: agricultural development. Millions of acres of grasslands, lakes and wetlands were drained and plowed. The rivers were dammed and diverted into artificial watercourses that took them hundreds of miles from their natural channels. Thousands of wells were drilled that brought prehistoric groundwater to the surface. Parts of the valley subsided thirty feet or more as the water was withdrawn. A mere 5% of the valley floor retains its natural character. Most of the animals are gone, shot to extinction (the California Grizzly Bear, for instance), or pushed to marginal environments in the Sierra Nevada or the Coast Ranges. The migratory birds are crowded into a few precious wildlife refuges up and down the valley.
I'm not really writing this to criticize the agricultural development of the valley. We have billions of people on the planet, and they insist on eating, so it would be foolish not to utilize some of the richest soils on the planet. I would even suggest to people who don't live in the valley that they might have a bit more respect for the people who work hard for low wages to plant and harvest the food that you eat. On the other hand, we do a lot of things wrong in our approach to agricultural development, and the waste of water is one of those things. The ongoing four-year drought has exacerbated the problem. There are problems with the overuse of pesticides and antibiotics, and with agricultural waste disposal. In many ways we are fouling (and paving over) our nest.

Still, living here does have some benefits. Given our journey through the most dangerous plate boundary on the planet, the Great Valley doesn't exactly look geologically menacing. It is relatively far away from the most active earthquake faults of the state, and is even farther away from the most dangerous of the state's volcanoes. We don't get hurricanes, violent thunderstorms or blizzards, and tornadoes are exceedingly rare. The idea of dangers from landslides is laughable (except that I know of at least one fatality in Modesto caused by a slide). But we do have two threats: droughts and flooding.We are in the midst of the worst drought in recorded history, but with the development of an El Nino weather pattern in the Pacific, we could have catastrophic floods in only a few months. We can never really predict what can happen. In 1861-62 the floods were widespread that the state capitol had to be removed to San Francisco for a few months. The valley was a gigantic lake twenty miles wide in places.
Flooding on the San Joaquin River in 2006.

The map below shows what could happen if we get a repeat of the 1861-62 floods, an event the meteorologists call an atmospheric river storm (ARKStorm). They also refer to this as the "other big one", because the potential for damage is greater than that of a major earthquake, at least in the Great Valley.
In the Great Valley, geology conspired to transform a sea floor into the richest agricultural region on the planet. For all the flat lands, it is an interesting place to study. In the next post we'll take a look at the strange things we've found just beneath the surface. In a garbage dump of all places.

Monday, May 18, 2015

Driving Through the Most Dangerous Plate Boundary in the World: Into the Realm of the Drowning Dinosaurs

The sediments of the Great Valley Group form the parallel ridges trending diagonally across the photograph.
California has a lot of potential for geological mayhem, with the San Andreas and many other faults, mountain-building, and volcanoes of many kinds. But it once was worse. During the Mesozoic era and the early part of the Cenozoic, the entire California coast was rimmed by a massive subduction zone. The huge earthquakes produced as the plate sank beneath the western edge of the continent would have produced horrific tsunamis. The sinking plate eventually produced bodies of molten rock that found their way to the surface, producing huge volcanoes, much like those found in the Andes Mountains today.

We've been making our way on a blog journey through this most dangerous plate boundary. The remains of the subduction zone have been lifted and exposed by erosion in the Coast Ranges. So far we have been observing the rocks of the accretionary wedge, the intensely deformed material that has been churned up within the trench of the subduction zone (see this post for an example). In our last post, we crossed through the oceanic crust of the Coast Range Ophiolite in Del Puerto Canyon in the Diablo Range. At the end of that post we crossed the Tesla-Ortigalita fault and entered into the exposures of the sediments of the Great Valley Group. We are now in the rain shadow of the Coast Ranges, and the slopes are barren of trees.
This large slump in the lower part of Del Puerto Canyon is the location of the discovery of the first dinosaur fossil ever found in California, in 1937.
The rocks of the Great Valley Group were deposited in a sea that lay between the trench and the western shoreline of the North American continent. The shallow ocean environment is called a forearc basin. The sediments consist of primarily of sandstone, siltstone, and shale that cascaded off the submerged edge of river deltas along the shoreline. The underwater landslides were called turbidity currents. The sediments pushed on the crust, and subsidence allowed vast thicknesses of sediment to accumulate. In the region around Del Puerto Canyon east of the Bay area, the layers total as much 25,000 feet. At the south end of the valley near Bakersfield, the rocks are around twice that.
All in all it doesn't sound like a good place to search for dinosaur fossils. The rocks are the right age, Cretaceous, but the dinosaurs were terrestrial creatures. They no doubt roamed the slopes of the the volcanoes and coastal plains of the continent, but few are known to have spent much time in the oceans. Finding a dinosaur fossil here seems about as likely as finding a cow or coyote skeleton at the bottom of the sea in the modern day. 
So, a hypothetical question: what if you did find a cow or a coyote skeleton on the sea floor? Could you explain it? It might take a moment, but one could imagine an intense flash flood along one of the rivers that flow off the Sierra Nevada and through the Great Valley, trapping and drowning a few cows or other creatures along the way. Their carcasses would have floated downstream, and eventually the bones could have sunk to the sea floor. I bring up this point because the sediments of the Great Valley Group have in fact yielded a few dinosaur fossils, and they probably did originate in a river flood.
The first dinosaur ever found in the state was found in 1936 in our own county, Stanislaus, by a 17 year old boy named Al Bennison. He was searching for shell fossils in Del Puerto Canyon near the landslide seen in the photo above when he found some bone fragments on the hillside. They proved to be the remains of a duck-billed dinosaur (or hadrosaur), possibly a creature called a Saurolophus.
These were big creatures, as much as 30 or 35 feet long. They were plant-eaters, and were among the last of the dinosaurs, along with Triceratops and the tyrannosaurs. Bennison's discovery made news at the time, but few people in our county are aware of the awesome paleontological heritage of our region today. I'm hoping that will be changing soon as we prepare a display for the new Great Valley Museum of Natural History at Modesto Junior College.
But Bennison wasn't done yet. A year later in another canyon nearby he found the remains of a fearsome marine reptile called a mosasaur. Mosasaurs were probably the top predators of the Late Cretaceous seas, possibly even consuming sharks (yeah, that's a mosasaur you are seeing in the Jurassic World movie trailers, acting like a Sea World Orca). They are descended from ancient terrestrial lizards similar to the Komodo Dragon.
Bennison's mosasaur was a new species and now bears his name: Plotosaurus bennisoni. Like the hadrosaur, few people are aware that they once lived in this region. We have a four-foot long skull of a mosasaur on display in the museum, and a more extensive display is in the planning stages.
Another species of mosasaur, Plotosaurus Tuckeri, was found a few years later a bit further to the south. As can be seen in the diagram below, these creatures approached the size of whales, and would be a terror if they lived in today's oceans.

There have been many other discoveries of Mesozoic dinosaurs and other reptiles like plesiosaurs and ichthyosaurs. The best resource for learning about these fascinating creatures is the book Dinosaurs and Other Mesozoic Reptiles of California by Richard Hilton of Sierra College. Check it out!
From Dinosaurs and other Mesozoic Reptiles of California, by Richard Hilton
I reached the mouth of Del Puerto Canyon and was met with a disturbing sight that was emblematic of the conflict between humans and the natural landscape that we inhabit. More on that in the next post.