Rock and Light: The Primal Elements of Death Valley, Monochrome Edition

Sorry for going all pseudo-Ansel Adams on you all. I was playing with the photo-editing program with the pictures that I used in yesterday's post, and at one point I switched to black and white. I'm enchanted by the colors of our planet, but it is easy to forget that features can often be better discerned in monochrome photos.

It's almost as if the blinding sun, so unexpected, blinded me to the textures and depth of the rocks revealed in the slopes of the northern Black Mountains of Death Valley National Park.  Monochrome imagery is something that really has only existed since the advent of photography, and its value today is in the unexpectedness of the image. We expect color, but it's not there. As Wikipedia (the ultimate authority) would put it, monochromatic images "are not direct renditions of their subjects, but are abstractions from reality". And yet, science illustrators often prefer to show objects of research in black and white, or even as drawings to emphasize the ultimate reality of their findings.

It occurs to me that monochrome images do have an impact on the human psyche, and it exists at a very fundamental level. Our vision at night is monochrome, and humans evolved with a certain primal fear of the darkness. One can't see approaching predators in the dark, and in low light one would be highly attuned to noticing small changes or movement in one's field of vision. Black and white images capture our attention in a way that color images just can't.

In any case, I was mainly looking for an excuse to put up some pictures that I found interesting. Badlands topography has always been a good subject for black and white photography because of the strong contrasts between light and shadow, and the Furnace Creek Formation is the ultimate expression of badlands.

Rock and Light, the Primal Elements of Death Valley

When one has been under gloomy overcast conditions punctuated by periods of rain for days, the novelty can run short, even in a place where rain is scarce. We had been on the road for three days and in that time we saw no sunshine, and in fact had lived through a night of record rainfall and localized flooding. What made the mood worse was that the weather forecasts had us expecting sunshine on the third day and we got rain instead.

The students were just great actually, showing all kinds of patience. They were in Death Valley after all, and they weren't in a classroom. At least not the kind with four walls. Just the same, I was pining for just a bit of sunlight, and the evening was coming quickly. We had just finished an exercise at Gower Gulch at the north end of the Black Mountains and we walking back to the vehicles when a sliver of sky opened up. The sun blazed forth in all its glory.

There are two sure things in places like Death Valley, rock and light. Deserts have dust storms at times, of course, but much of the time the air is free of pollution and humidity. The sun shines with an intensity not usually experienced in urban settings (my students traditionally come home with winter sunburns despite our warnings to use sunscreen).

And the rock...Death Valley has perhaps the greatest variety of rock types to be found in any national park. They range in age from 1.7 billion to practically yesterday. They include all of the types, plutonic, volcanic, sedimentary, and metamorphic. The rocks occur in nearly all the colors of the rainbow, sometimes in a single outcrop (google Death Valley's Artist Palette if you want to see what I mean). And in most parts of the park there is no vegetation or soil to obscure their complicated structures and relationships.

It's hard to imagine a more dramatic moment for the two elements to intersect. The sun was low in the sky, the rocks were wet from the recent rain storm, so the colors were intensified and the rocks seemed to glow with an inner light.

The rocks we were looking at were part of the Mio-Pliocene sediments and ash/lava flows of the Furnace Creek, Funeral, and Artist Drive formations. They accumulated in a fault basin not totally unlike the present-day Death Valley graben. There were ephemeral lakes, alluvial fans, floodplains, and volcanoes. The plains probably supported a rich fauna of camels, horses, mastodons, birds and predatory cats, who left their tracks in similar-aged rocks elsewhere in the park.

It was a dramatic moment, but as with so many such moments, it was fleeting. The clouds closed in again, and we thought the show was over, except that a few moments later while we drove the highway north of Furnace Creek, the skies opened up one more time to reveal a brilliant rainbow (see the opening picture...as if you somehow missed it!). The moment felt perfect.

Addendum: Since we are talking the incredible fossil record of Death Valley, there is news this week of some horrible human beings who have stolen some of the precious fossil trackways I mentioned. I can only hope that the pictures of the probable thieves will lead to arrests and convictions. More information can be found here: http://vertpaleo.org/Society-News/SVP-Paleo-News/Paleontology-News/Fossils-Stolen-from-Death-Valley-National-Park.aspx

Stepping From a Valley Floor into a Mountain Range: Travels in Death Valley

To me, one of the most stunning things about exploring Death Valley is the abruptness of the landscape. There are no gentle transitions. You are either on the valley floor, or you are on a mountain. There is no in-between. I'm hard put to think of another place in the world where you can stand on a valley floor and place your hand on a mountain slope. It's just usually not the way of things.

But Death Valley is like that. The main valley is more than a hundred miles long, and 10 or 15 miles across. It's a place of wide open vistas that extend for miles. But if you approach a mountain range like the Black Mountains between Badwater and Furnace Creek, you walk up the gentle slope of an alluvial fan, and then you are stopped by the mountain. Because of the active fault scarp, it rises like a wall straight up out of the ground.

We had come down onto the floor of Death Valley after looking at the diversion of Furnace Creek into Gower Gulch, hoping to get some insight into the effects of flooding a small canyon with the debris and mudflows from a drainage area of 170 square miles. It was pretty awe-inspiring. In the 70 years since the diversion, Gower Gulch had scoured its channel through the Black Mountains, and eroded a deep channel into the surface of the Gower Gulch fan. There's a 25 foot high dry waterfall at the entrance to the canyon, but a trail clings to a narrow terrace of the old alluvial fan to the left (above). It's not hard to explore the narrow canyon above.

There was still a thin stream of water flowing through the canyon, a small remnant of the flash flood that had thundered through the canyon the previous night (Death Valley had just experienced a night of record rainfall for the date, 0.62 inches; of course we were camped out in the open). The debris had covered the highway just downstream.

It's a steep and rugged canyon, one of many that begs exploration by curious people. Treasures are to be found in these canyons...old mines, colorful rock exposures, fossils, and elusive life: Bighorn Sheep maybe, or a Kit Fox. Who knows?

In the end, it's all about the landscape itself. Naked rock exposures and faults. Alluvial gravels. Stepping from a valley floor into a mountain range in one step. There's no place in the world like this...

Travels in Death Valley: the Strange Story Told By a "Rock"...

A beautiful collection of colorful rocks lie scattered across the surface of an alluvial fan in Death Valley National Park a few miles south of Furnace Creek. There is a piece of vesicular (full of holes) basalt on the lower right, next to a piece of gray limestone. One might be just 10 million years old, while the other may be 300 million, containing the remains of long dead and extinct organisms. At the top left, a piece of orange-brown sandstone, possibly deposited on an ancient ocean shoreline, or maybe a lakeshore in a long-ago desert, maybe even a sand dune. Perhaps a piece of granite is in there somewhere, a rock that cooled four or five miles deep in the crust. What a long journey it had before it was exposed by erosion and carried down the desert wash! And then there is...wait...what is that at center left? That's no conglomerate! Well it sort of is, but isn't natural is it? That's a piece of pavement. What's going on here?

It's not a story that appears on National Park Service interpretive signs, and in fact I think the park service would rather that people not explore the particular canyon at all. It's sort of unstable, as in vertical walls made of loose and cracked chunks of claystone. And like the piece of asphalt pavement on the alluvial fan surface, it's not natural either. This canyon didn't exist 75 years ago.

Gower Gulch used to be a minor drainage in the Furnace Creek Formation badlands near Zabriskie Point which debouched onto the floor of Death Valley, forming a small alluvial fan. Badwater Road crossed the fan, which consisted of mostly fine-grained materials like silt and clay.

The problem is that nearby Furnace Creek drained a much larger region than Gower Gulch (170 square miles versus 2 square miles), and was prone to violent flashfloods and mudflows that damaged facilities at the Furnace Creek Resort about five miles downstream. Around 1941 someone thought to blast through the low ridge that separated Furnace Creek and Gower Gulch, forcing the entire drainage to flow through the badlands and onto the Gower Gulch fan downstream. The diversion caused profound changes upstream and downstream.

At the diversion point (above), the flash floods cut through the soft siltstone and shale like a hot knife through butter, cutting 40 feet or more in seven decades. The floods carry a heavy load of coarse-grained debris and gravel that acts as an abrasive on the channel floor. The canyon changes year to year as each flashflood causes slopes to be undercut, causing rockfalls and slope failures.

It's upstream where serious damage to the road occurs. The diversion caused a sudden steepening of the Furnace Creek channel, and the faster moving floods have eroded the channel in an upstream direction, a process called headward erosion. The deepening of the channel is apparent as far as two miles upstream, and in numerous places it has encroached onto Highway 190, washing away some of the pavement, and incorporating the fragments into the alluvial fan deposits downstream (as in the first picture above).

Downstream, the road damage occurs in a different way. The alluvial fan used to receive fine-grained silt and clay in relatively minor floods that did little damage to Badwater Road. Now the flashfloods are on steroids, so to speak, with more water, more debris, and far more speed. Badwater Road is regularly overwhelmed, as it was on the day we visited, with mudflow deposits. Boulders can sometimes be sizable. For example, check out the two fragments on the fan in the picture below. How big do you think they are?

Here's your answer: pretty big.

Death Valley is a monument to geologic changes over billions of years, but it is also a dynamic environment where geologic change happens on a daily and yearly basis as well. We saw plenty of evidence during our February trip.

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.

Death Valley is Really Second Generation Death Valley: A Look at Death Valley Version 1.0

Death Valley is a stunning example of a fault graben, a large area of crust that subsided because of extensional forces that produced widespread "normal" faulting (where the fault plane slopes towards the basin). The valley has relief of more than two miles, from the summit of Telescope Peak at 11,043 feet (6,168 meters) to Badwater Basin at minus 282 feet (-86 meters). Perhaps more extraordinary is the fact that the valley has filled with eroded sediments to a depth of as much as 9,000 feet. Remove the sediment and Death Valley would be nearly four miles deep!

One might imagine what it would look like if the sediments of Death Valley were somehow lifted up and dissected by erosion. What would one see? There would no doubt be layers of salt and gypsum, silt and clay, and conglomerate and breccia from the alluvial fans that line the margins of the valley. Volcanoes are found along the margins of the Death Valley today. Perhaps one could expect to see colorful exposures of lava and tuff in the deeply buried valley sediments.

What's fascinating about Death Valley is that we don't have to imagine what the valley fill would look like. It turns out that the graben that formed the valley is not the first to have existed in this area. It formed around two or three million years ago, but extensional forces have been stretching this region for something like 15-16 million years. Other grabens developed, filled with thousands of feet of sediment, and were lifted by faulting so that erosion revealed the underlying rock and sediment. One of these more ancient basins is revealed at Zabriskie Point, one of the most visited and dramatic of Death Valley's tourist destinations. The rock is called the Furnace Creek formation.

The rocks of Death Valley-Version 1.0, as seen in the Furnace Creek formation consist of fine-grained silt and clay interspersed with evaporate minerals like salt, gypsum, and most importantly for the miners of Death Valley, borates. There are layers of conglomerate and breccia from ancient alluvial fans, and colorful tuff and lava flows from associated volcanic activity. In the dry environment of Death Valley, the rocks have eroded into the intricate badlands that made Zabriskie Point a must-see part of any trip to the park.

The badlands are practically devoid of any kind of plant life. The barrenness results from the inability of stable soils to develop on the steep slopes. Any soils are quickly washed away during infrequent but violent cloudbursts.

The layers exposed in the Furnace Creek formation provide information about ancient environments that once existed in the Death Valley region, but also feed the imagination about the rocks hidden deep within today's fault graben, Death Valley-Version 2.0.

This has been another in an off and on series about our February visit to Death Valley. In the next installment, we'll be leaving Death Valley for other sights in the region, a detour made necessary by October flash floods that took out some of the park's roads. We'll be visiting a unique biological island in the desert...

Like a Gigantic Babushka Doll, One Death Valley inside Another Death Valley

Death Valley is a deep structural trough called a graben, formed by faults that stretched and broke the continental crust, mostly within the last two or three million years. It is just one of dozens that are present across the deserts of eastern California, all of Nevada, and much of western Utah, a region known as the Basin and Range Province.  But as grabens go, Death Valley stands out. It is almost twice as deep as the Grand Canyon, as the Panamint Mountains slope 11,000 feet down to the valley floor that sits below sea level. It's also one of the flattest places you can stand on planet Earth.

But the valley we see is only part of the story. As is always true of any mountain, if it sticks up into the atmosphere, it will be eroded. It doesn't matter how dry the climate is, erosion happens anyway, albeit at a slower pace perhaps. Sediments have been filling in these valleys. As high as the mountains are, another two miles are hidden by the sediments that fill the valley floor.

I imagine some people wonder what's under all that salt. Wouldn't it be cool to see some of the history revealed in those sediments?

All I can say is that Death Valley is one awesome piece of geology. Whatever you might seek about geological processes or history, there is probably a world-class example of it at the park. So you want to see what Death Valley would look like from the inside-out? We've got you covered! There have actually been two Death Valleys, and one of them has been turned on end for us to explore.

About 5 or 6 million years ago, extensional forces were stretching the crust in the Death Valley region, but from a different direction. A major fault graben opened up in a northwest/southeast direction, mountains rose on either side, and erosion began to fill in the trough. Eventually the sediments accumulated to a depth of a mile. Sometimes a permanent lake filled much of the valley, resulting in the deposition of layers of fine silt and clay. At other times, the lake dried up, leaving behind halite (table salt), gypsum, and borate minerals. Alluvial fans, composed of gravel and conglomerate, sometimes spread across the valley floor. There were occasional volcanic eruptions as well.

The sequence of sediments and lava flows is called the Furnace Creek formation. Few fossils are found in the rock, but trackways of horses, camels, mastodons, large cat and wolf ancestors, and birds have been found. These fossils point to a diverse ecosystem that was not quite as dry as that of today's Death Valley, but is certainly analogous to the Death Valley that existed during the ice ages.

Then things changed.

The regional stress pattern shifted and new faults formed, the faults that produced the present-day Death Valley graben. The deeply buried rocks of the Furnace Creek formation were pushed upwards, folded and tilted, and ultimately exposed to erosion. In the harsh desert climate soils do not develop on the fine silts, so the barren slopes give way to deep gullies and furrows called badlands topography.

And so today, we can have a look at Death Valley from the inside out.

Most tourists who visit Death Valley observe the Furnace Creek formation at the spectacular view from Zabriskie Point or from the resort area at Furnace Creek. We usually do a field exercise at Zabriskie, but the entire area was closed this year for renovation. So we headed up Twenty-Mule Team Canyon for a look at the colorful outcrops. The gravel road winds for several beautiful miles through the badlands.

The Furnace Creek formation was the greatest source of riches in the Death Valley region. Forget gold or silver or copper. The borate minerals, formed from geothermal hot springs in the graben of the Furnace Creek formation, were mined for their use as soaps and detergents, a flux in glass-making, in cosmetics, and numerous other applications. For a number of years in the late 1800s the only economic sources of the borate minerals in the world were in Turkey and Death Valley. They were still being mined in Death Valley as recently as 2005.

The Furnace Creek formation is a spectacular part of the scenery of Death Valley National Park, but the colorful exposures provide a window into the geologic history of the western United States as well. Peel away the surface layers and we find pieces of the past when conditions were far different. Peel back that layer, and we find another story.The Furnace Creek formation is but one of dozens of geologic strata exposing more than a billion years of changing environmental conditions. The park is one giant Babushka doll of geologic history.