The Islands of Interior California: The Pygmy Mammoths and the Doomed Sky Islands

An 80,000-year-old pygmy mammoth tusk discovered on Santa Rosa Island. (Image credit: Daniel Muhs, USGS.)

The waves crash against the cliff, tearing at the rock on Santa Rosa Island off of Southern California. The face of the cliff is in constant retreat, changing yearly, and sometimes daily as more of the rock disappears into the surf. In one brief moment, a visitor notices a strange object exposed in the cliff. Is it a tree trunk? No, that white stuff is ivory...it's a tusk! There were elephants on the island! How in the world did that happen?

The presence of fossils of elephantine species on the island has been known since the late 1800s, and a survey in the late 1990s discovered at least 150 sites with remains of the creatures, now called the Pygmy Mammoth (Mammuthus exilis). There is little doubt that these creatures were descended from the mainland's Columbian Mammoth, but as their name suggests, they were small. A full-sized Columbian Mammoth stood 14 feet high, but the Pygmy Mammoth was only half as high at most, and perhaps a quarter the weight. A nearly complete skeleton discovered and excavated in 1994, and the adult was only 5.5 feet tall (below).

Pygmy mammoth skeleton found on Santa Rosa Island in 1994. It was 5.5 feet tall (Image: © Bill Faulkner, NPS)

It seems impossible that mammoths could have made it out to the islands, and under current conditions it probably would be. The nearest island is more than 20 miles away from the mainland. But things were much different 150,000 years ago. A phase of the ice ages was ongoing, and when a vast ice sheet covered Canada and 30% of the United States, sea level was around 300-400 feet lower than today. The four main Channel Islands (San Miguel, Santa Rosa, Santa Cruz, and Anacapa) would have been a single large island, which has been given the name Santarosae. The open water gap between the island and the mainland was only about 4.5 miles.

Elephants actually are excellent swimmers, what with having a natural snorkel and all. Present-day elephants have been documented as have swam more than 20 miles. So it is not hard to imagine mammoths on the mainland, perhaps suffering food shortages because of drought or wildfires, catching the scent of fresh vegetation on the islands and swimming out to investigate. A population was established, but then things began to change. The ice age was ending and the globe was warming up. The ice melted and sea rose to near today's level. The single large island was inundated, forming the four islands of today, and the total area was reduced by 76%. For the mammoths, this was a crisis. The islands were no longer big enough to support the mammoth population.

Outline of Santarosae and the present-day Channel Islands (Image credit: U. S. Geological Survey)

The outcome might come as a surprise because the cliché about evolution is sometimes misstated as "survival of the strongest". It is actually the survival of the best adapted. Although the biggest mammoths may have been able to consume much of the decreasing food supply, their dietary needs were also much higher. The evolutionary lottery favors those individuals who have the best adaptations for the specific environment, and it was the runts of the litter who could survive on less food. Over time the size of the adults decreased until they constituted a new species, the Mammuthus exilis. They survived on the islands for tens of thousands of years (from at least 80,000 years before present).

In the end, the Pygmy Mammoths also succumbed to extinction sometime around 12,000 years ago. Their disappearance coincided with the extinction of numerous other large mammals in North America, the "megafauna". Many reasons have been offered as hypotheses, but the cause (or causes) remain elusive. It needs to be noted that humans arrived on the islands around 11,000 years ago, and the small mammoths would have had few defenses against armed human beings.

As we can see, islands are places of refuge, but they can also be a prison of no escape. Which brings us to the doomed sky islands of the Mojave Desert.

The New York Mountains in the Mojave National Preserve (image credit: Garry Hayes)

People may envision a number of stereotypes of what constitutes a desert. Many people see vast seas of sand dunes, while others may see mesas and spires inspired by childhood memories of Roadrunner and Coyote cartoons. Others might see a landscape of huge saguaro cacti. These kinds of deserts exist of course, but except for several dune fields here and there, they don't exist in California. The deserts of eastern California (along with parts of Arizona and Utah, and all of Nevada) are within the Basin and Range Province, a region of the Earth's crust that has been stretched and broken into hundreds of high mountain ranges and deep faulted basins.

The Clark Mountains as seen from Kokoweef (image credit Garry Hayes)

Because the relief (the difference between the highest and lowest points) can range up to two miles, these mountain ranges encompass numerous life zones or ecosystems, from the hottest barren salt flat to alpine peaks. These mountains constitute rich biologic islands that are analogous to the Channel Islands off the coast of California. And like the Channel Islands, some of the inhabitants are ultimately doomed.

Because the mountain peaks are so isolated, one might not expect much diversity, but these environments are not static nor were they always isolated. They were influenced by the ice ages, even though the ice fields never reached the arid region. The climate was cooler and wetter so trees more characteristic of the Rocky Mountains or the Sierra Nevada were able to migrate into the region, including the Rocky Mountain White Fir. But as the ice age waned, the rising temperatures and growing aridity caused the trees to retreat higher and higher into the mountains. If the mountains weren't high enough, the trees were extinguished. In the present day, only three islands remain that possess the Rocky Mountain White Fir: the New York Mountains, Clark Mountain, and Kingston Peak.

Scene from the Kingston Peak area (Image credit: Bureau of Land Management)

None of these relict forests are easy to get to, and I have never had the privilege. And unfortunately I may never have the chance because these trees are ultimately doomed. They are at the very edge of survival, clinging to the cooler north-facing slopes in a micro-climate that is just wet enough to allow the trees to cling to life. As the world continues to warm up, the dry desert will continue creep up the mountain slopes, ultimately "flooding" the last trees in hot dry air.

Image credit: https://www.amargosaconservancy.org/native-plants-wildlife/

We will never fully comprehend the full effects the changes on our planet brought about by global warming and climate change. In the mountains of the Mojave Desert, the "islands" are not occupied just by fir trees. There are dozens of species that shelter within these small forests and they will disappear too. It's a small corner of the world rarely visited by humans, but climate change is global, and there are literally millions of micro-environments like these that will disappear without ever being studied or appreciated. It's a crying shame and all the more tragic considering we've lost three decades of time that we could have acted on behalf of our planet.

Image credit: https://www.amargosaconservancy.org/native-plants-wildlife/

The Islands of Interior California: A New Geotripper Series

I've always been fascinated by islands. I visit the Hawaiian Islands every chance I get, and I am literally haunted by the vast expanses of open ocean that separate the islands from any other landmasses. It's an odd combination of loneliness and wonder. It's not something you ever feel when you are staying in Waikiki hotels and sunning yourself on a crowded beach. The sense of isolation comes when you spend time in the rainforests, the alpine deserts, and the barren volcano slopes. When you read about and experience the incredible biological isolation, it becomes an incredible story of survival and adaptation that has produced hundreds of unique endemic species found nowhere else in the world.

Which leads to a question: what does that have to do with a bunch of pictures of localities in the California desert?

I was in Death Valley National Park for much of the past week, and while I was teaching a field course, I also had a few moments of observation and reflection about life in the desert. I was watching for bird species in particular, and I was struck by an odd contradiction: Death Valley (Furnace Creek specifically) has more bird species (339) than my county in California's Great Valley (315). It doesn't seem possible, since conditions are far more benign at home, and in fact the Great Valley can support vastly greater numbers of birds. But Death Valley has a way of forcing more species together in one place where they can be seen and recorded...it is a system of biological islands. The islands are made of water, and the intervening space is largely barren land.

The concept of biologic islands in a landscape is not a new concept at all, so I am not introducing any kind of new idea here. It's just that I sensed the concept more than usual during the recent trip. So in the next few posts I want to describe some of the unique and different "islands" that exist in the California desert, and the geological conditions that caused them. Some of these we explored last week, but as I considered the idea of a series, I thought of a few unique spots I've visited in earlier journeys, so I will include a few of them as well.

Coming up in the next post: the spot that made me think of islands in the first place...

Part 1: The Littlest Islands of All
Part 2: The Pygmy Mammoths and the Doomed Sky Islands
Part 3: There's a Reason Why I Don't Hug Ducks

Tales from the Semi-Super-Bloom Tour, Part 1: The Mojave Desert and El Paso Mountains

A lot of excitement has been generated this year with the plentiful precipitation in the California Desert and the resulting "Super-Bloom". Mrs. Geotripper and I didn't want to totally miss out on the sights, but we didn't want to be in the midst of crowds that we knew would be present in the places in the news like Anza Borrego or Lake Elsinore. So we zeroed in on the part of the California desert that hasn't been in the news: the Owens Valley and Death Valley National Park.

We knew from the start that we might not see a great many flowers because most of the storms had tracked more to the south, but there had still been considerable precipitation, just a bit later than other parts of the desert. So with proper expectations in place, we set out on the road a week ago. The nice thing about low expectations is that you have a good chance to be pleasantly surprised, and we were. It wasn't the 'super-bloom', but it was colorful enough, so we dubbed our journey the "Semi-Super-Bloom Tour".

 The first place that made us pull over was a non-descript road junction on Highway 14 near Jawbone Canyon and the El Paso Mountains in the Mojave Desert. There were lots of small flowers on the desert floor, including Goldfields, Phacelia, Mallows and small Lilies (I welcome and expect corrections on flower identification).

The desert floor where we were traveling has been largely given over to utilitarian uses. In the immediate vicinity there are airports, military bases, and solar arrays, as well as the towns of California City and Mojave. There isn't much wilderness in this part of the desert.

The landscape is geologically interesting, as we were paralleling the Garlock fault, which divides the Mojave Desert from the Sierra Nevada and the Basin and Range Province. The fault is active, with forty miles of left-lateral offset, but it hasn't produced any historical earthquakes of consequence. The potential certainly exists.

Although the fault motion is primarily lateral, some warping and deformation has lifted a mountain range on the north side of the fault, the El Paso Mountains. The mountains are composed largely of older Paleozoic metamorphic rocks. The rocks had been quite deep in the crust, but were brought to the surface and eroded, and by around 12-15 million years ago had been eroded to a fairly flat surface. This surface was eventually covered by terrestrial sediments deposited in alluvial fans, grassy plains and ephemeral lakes that would remind a person of the African savannah. The comparison is apt, because the sediments contain fossils of a diverse fauna that included ancient camels, horses, antelope, elephants, and a number of predators including to the forerunners to our modern cats and canines.

The valley floor where we stopped certainly had flowers, but we could see that a real super-bloom was underway on the slopes of the El Paso Mountains off to the north. The usually dull gray slopes were covered in places with a veritable rainbow of flowers that must have including a great many poppies and lupines.

Our highway turned north, crossed the Garlock fault, and entered Red Rock Canyon State Park, which preserves the Neogene sediments containing the fossils mentioned above. Millions of people have seen Red Rock Canyon, but not necessarily in person. The brightly colored cliffs have been used as the backdrop for hundreds of Hollywood movies (they were the cliffs of 'Snakewater', Montana in the opening scenes of the original Jurassic Park).

We found that many of the Joshua Trees were blooming. The trees are a defining characteristic of the Mojave Desert and are found primarily in east California and portions of Arizona and Nevada. The trees are a potential victim of global warming. Their seeds once were spread in the scat of giant ground sloths during the last ice age, but the sloths are gone, and with the increasing heat, the trees (actually lilies) are unable to propagate up slopes where they can thrive. Ironically, the trees may disappear entirely in the national park that is named after them.

We left Red Rock Canyon and headed north on Highway 395 towards our turnoff to Death Valley at Owens Lake. Along the way we could see that the "foothills" of the Sierra Nevada were also bathed in color. We were headed to Fossil Falls and Red Hill, hoping to see what had changed in the six weeks since we were last there. That will be the subject of our next post...

An Incredible Spot in the Mojave Desert, the Hole in the Wall. You could see it for yourself this summer

Summer is coming soon. If you are casting about wondering what to do, how about the adventure of a lifetime? Our department is offering a dyad class, Geology 191/Anthropology 191, the Geology and Anthropology of the Colorado Plateau, and it is an incredible chance to check out some marvelous geology along our southwestern tier of states: California, Arizona, Colorado, Utah, and Nevada. I want to give you a bit of a preview of the kinds of places we will be visiting...

The Mojave National Preserve is one of our nation's newest parks (established in 1994). It was carved out from Bureau of Land Management lands in the eastern Mojave Desert, preserving one of the most awesome sand dune complexes in the country, the Kelso Dunes, a barren landscape of geologically recent volcanic cinder cones, one of the largest Joshua Tree forests in existence, and some of the highest mountain ranges in the Mojave Desert, with rocks as old as 1.7 billion years old, as ancient as those in the bottom of the Grand Canyon. The preserve also encompasses a California State Recreation Area, the Providence Mountains, and Mitchell Caverns, a unique limestone cave system. The caverns were closed during the recession, and then severely vandalized, but they have finally been reopened for visitation (see this Facebook page for updates).

One of the most interesting corners of the park is called Hole in the Wall, along with Banshee Canyon. We will be staying at the nearby campground our first night on the road on June 2. It is a wonderfully isolated spot, 25 miles off the main highway, and even farther from developments of any kind. It has some of the darkest night skies I've ever seen, and it is serenely quiet (except for crickets and coyote yowls).

The region is quite unlike other parts of the Mojave. Instead of deeply eroded mountain ranges and wide flat valleys, the area around Hole in the Wall is composed of mesas and plateaus that seem to share more in common with the Colorado Plateau province just to the east. But these mesas aren't like Arizona's either. They are composed not of sedimentary layers, but of volcanic tuff, rock derived from unimaginably huge volcanic explosions the likes of which modern humans have never experienced.

Twenty million years ago, the region was one of low relief, the result of tens of millions of years of erosion and relative stability. But conditions were changing as the crust was stretched and broken up into a series of tilted fault blocks. The release of pressure on the underlying mantle allowed partial melting to take place, and volcanic activity exploded across the region.

The first eruptions took place about 18.5 million years ago when the Peach Springs tuff coated the entire region from an eruption center near Oatman, Arizona. The eruption involved as much as 150 cubic miles (640 km³) of powdery white ash that was so hot that in many places it welded into solid rock as it landed.

Shortly afterward (in geologic terms anyway, as it was 700,000 years later), a second caldera developed. It was located even closer, in the adjacent Woods Mountains. The eruptive "crater", actually a collapse pit, was about 5-6 miles across, roughly similar in size to Crater Lake. Once again, all life was obliterated for hundreds of square miles as hot ash blanketed the landscape. The Wild Horse Mesa Tuff makes up most of the rock found at Hole in the Wall.

The strange holes that gave Hole in the Wall its name are called tafoni. Small differences in the degree of solidification or cementation cause depressions to form which end up staying wet longer, and the minerals decay into small fragments that can easily wash or blow away.

A short trail (1.5 miles) loops around Banshee Mountain and explores the best of the eroded tuff. Starting at the small visitor center, the trail drops through a rugged narrow canyon. There are some drop-offs, but rings have been attached to the canyon wall, making it a lot easier to climb up or down. Once past the narrows, the trail has a gentle gradient, and provides interesting views in all directions. There is a nice collection of petroglyphs on some of the boulders around the south end of the mountain.

If you want to visit this fascinating corner of the desert with us this June, please check out the previous post for details. We will be on the road for two weeks, and this will be only the first of many wonders that we will explore.

Dreams of Summer and Southwest Travels: Hole in the Wall, Mojave National Preserve

Christmas is over and suddenly the snow and blizzards aren't so fun any more. I find myself dreaming of warmer places and times, including a great journey we took last summer across the southwest with my students. Since my current travels are over until February, I'm going to travel through the archives to check out some marvelous geology along our southwestern tier of states: Arizona, New Mexico, Colorado, Utah, and Nevada. But really, no place is more southwestern than California, where we will start this journey.

The Mojave National Preserve is one of our nation's newest parks (established in 1994). It was carved out from Bureau of Land Management lands in the eastern Mojave Desert, preserving one of the most awesome sand dune complexes in the country, the Kelso Dunes, a barren landscape of geologically recent volcanic cinder cones, one of the largest Joshua Tree forests in existence, and some of the highest mountain ranges in the Mojave Desert, with rocks as old as 1.7 billion years old, as ancient as those in the bottom of the Grand Canyon. The preserve also encompasses a California State Recreation Area, the Providence Mountains, and Mitchell Caverns, a unique limestone cave system. The caverns were closed during the recession, and then severely vandalized, but there are hopes that they will reopen in 2016 (see this Facebook page for updates).

One of the most interesting corners of the park is called Hole in the Wall, along with Banshee Canyon. We stayed at the nearby campground our first night on the road. It is a wonderfully isolated spot, 25 miles off the main highway, and even farther from developments of any kind. It has some of the darkest night skies I've ever seen, and it is serenely quiet (except for crickets and coyote yowls).

The region is quite unlike other parts of the Mojave. Instead of deeply eroded mountain ranges and wide flat valleys, the area around Hole in the Wall is composed of mesas and plateaus that seem to share more in common with the Colorado Plateau province just to the east. But these mesas aren't like Arizona's either. They are composed not of sedimentary layers, but of volcanic tuff, rock derived from unimaginably huge volcanic explosions the likes of which modern humans have never experienced.

Twenty million years ago, the region was one of low relief, the result of tens of millions of years of erosion and relative stability. But conditions were changing as the crust was stretched and broken up into a series of tilted fault blocks. The release of pressure on the underlying mantle allowed partial melting to take place, and volcanic activity exploded across the region.

The first eruptions took place about 18.5 million years ago when the Peach Springs tuff coated the entire region from an eruption center near Oatman, Arizona. The eruption involved as much as 150 cubic miles (640 km³) of powdery white ash that was so hot that in many places it welded into solid rock as it landed.

Shortly afterward (in geologic terms, anyway, as it was 700,000 years later), a second caldera developed. It was located even closer, in the adjacent Woods Mountains. The eruptive "crater", actually a collapse pit, was about 5-6 miles across, roughly similar in size to Crater Lake. Once again, all life was obliterated for hundreds of square miles as hot ash blanketed the landscape. The Wild Horse Mesa Tuff makes up most of the rock found at Hole in the Wall.

The strange holes that gave Hole in the Wall its name are called tafoni. Small differences in the degree of solidification or cementation cause depressions to form which end up staying wet longer, and the minerals decay into small fragments that can easily wash or blow away.

A short trail (1.5 miles) loops around Banshee Mountain and explores the best of the eroded tuff. Starting at the small visitor center, the trail drops through a rugged narrow canyon. There are some drop-offs, but rings have been attached to the canyon wall, making it a lot easier to climb up or down. Once past the narrows, the trail has a gentle gradient, and provides interesting views in all directions. There is a nice collection of petroglyphs on some of the boulders around the south end of the mountain.

If you want to visit this fascinating corner of the desert, you'll have to search it out. It's not a quick roadside stop, but is instead a place to take a bit of time to explore. The time is well worth it!

Barren Cliffs Reveal a Rich and Violent Past: Red Rock Canyon State Park

Deserts have such a fearsome reputation around the world, but deserts can be both beautiful and at certain times of the year a pleasant place to visit. The dry lands of the American Southwest are no exception. For geologists, the treat is made better by the marvelous exposures of barren rock that tell stories of the past when the landscape was very different. This is one of those places: Red Rock Canyon State Park in California. We paid a visit on our way to Death Valley a few weeks ago.

The Garlock fault cuts across the boundary between the Basin and Range province and the Mojave Desert, forming a high linear ridge called the El Paso Mountains. Erosion has stripped away the alluvial cover, exposing the underlying continental sedimentary rocks. The rocks, candy-striped in tones of red, pink and white, formed in a deep basin between 12.5 to 7.5 million years ago, accumulating to a depth of more than a mile. The sediments include arkosic sandstone, siltstone, shale, along with volcanic ash and lava flows recorded several dozen eruptive events. The environment was perhaps semiarid, but certainly wetter than the current day. The fossil record suggests an Upper Sonoran paleobotanical zone, with Black Locust, Mexican pinyon pine, cypress, California live oak, red-root, acacia, desert thorn and palm. Similar plants are found today in the high mountain ridges between San Jacinto and Santa Rosa Peaks in southern California (a region I explored often in my youth).

The steep cliffs have attracted filmmakers for decades, making appearances in all manner of movies, including a lot of westerns, and one of my favorites, the opening scenes of "Jurassic Park".  But instead of dinosaurs, paleontologists have discovered a treasure trove of late Cenozoic mammals, reptiles, amphibians, and birds. More than 100 species have been found thus far.

What kinds of animals lived in the western North America around 10 million years ago? It was a diverse ecosystem with many unexpected species for those who think that deer, antelope and buffalo cover all the bases. Thanks to David Whistler, we have a rather comprehensive list of the animals who lived here.

On the open plains, one would have seen two different rhino species, ten species of horse, four kinds of camels, three antelope species, two elephant-like gomphotheres, vultures, two large land tortoises, pika, two ground squirrel species, deer mice, and rabbits. 

In the brush covered woodlands, one would have found two oreodonts (extinct sheep-like animals), peccary, three-toed browsing horse, short-legged camel, ringtailed cat, skunk, two weasel-like animals, wolverine,  four distinctly different spiny lizards, night lizard, rosy boa, racer snakes, hedgehog, chipmunk, two gopher-like rodents, two different pocket mice, a bat, three small perching birds, mole, four different shrews, a small, rear-fanged snake, and two alligator lizard species.

This rich selection of plant eating animals represented a huge source of walking protein, so there were predators, lots of them. There were six different species of canids (ancestors to the wolves, foxes, and coyotes), a very large bear-like animal, and three large ancestors to the cats including a an early form of sabertooth.

We spent our time learning the basics of stratigraphy, practiced a rudimentary form of geologic mapping, and interpreted the environment of deposition from the nature of the sediments exposed in the cliff. I wandered between groups of working students, answering questions, but my eyes kept ranging across the cliffs, thinking how incredible it is that we live in a time when we can discern the past history of our planet, and in so doing, understanding how we came to be. We are both a part of the Earth's ecosystem, and yet exist outside that ecosystem (for better or worse).

This rich variety of animals in Miocene time occurred because the climate provided rich sources of food, and diversity of the ecosystem was the result. Today, if a climate is not to our liking, we alter the ecosystem to our own ends. We build our shelters, we travel in little cocoons with air-conditioning and stereophonic sound, and we import vast amounts of resources and fuels to maintain our chosen lifestyle. We tend to ignore the other elements of the ecosystem where we live and visit. We don't embrace our environment, we cut ourselves off from it. It's when I'm in a place like Red Rock that I am reminded of where we come from, our ultimate heritage. We are children of the Earth. And there are limits.

Out in America's Never Never: Getting There

Photo by Mrs. Geotripper

A journey into the Never Never of America has to have a beginning in the green lands. From our base in the fertile Central Valley, we traveled through 200 miles of irrigated farmlands. They would be part of the desert were it not for a massive water project drawing water from northern California. We crossed the Sierra Nevada at Tehachapi Pass and continued into the Mojave, a desert that exists because of the rain shadow effect. Pacific storms are wrung dry by the imposing walls of the Coast Ranges, Sierra Nevada and Transverse Ranges.

Photo by Mrs. Geotripper

The western Mojave could hardly be mistaken for wilderness outback. Los Angeles has spilled over the mountains, with hundreds of thousands of people living in towns like Palmdale and Lancaster. Power lines and railroads crisscross the desert, as well as numerous paved highways.

We made a short stop at the massive open pit mine at Boron, one of the world's largest sources of borate minerals. The mine, operating since the 1920s, is now 500 feet deep, a mile long, and half a mile wide. A visitor center perched on the edge provides a marvelous view of the operation.

As we continued eastward, the trappings of civilization began to fall away. Barstow is a crossroads town of just over 20,000 people. At the north end of town, a road provided access to Fort Irwin (eerily accompanied by a lot of white crosses from traffic fatalities), but our route took us on a side road to Rainbow Basin.

19 to 13 million years ago, the Barstow region was not a desert. It was a savanna, with wandering streams and ephemeral lakes. The grasslands included groves of palm trees, and numerous grazing animals that were the ancestors to the elephants, antelope, horses, and camels that are familiar to us today. The grazers were preyed upon by a collection of primitive canines and felines, as well as amphicyon, a large carnivore that can visualized as an ancestor to the bears and dogs. The sediments that collected in the isolated basins accumulated to a depth of more than 3,000 feet, with a brightly colored assemblage of freshwater limestone, sandstone, siltstone, conglomerate, along with a series of volcanic ash layers that made it possible to date the formation.

The layers were later caught up in the deformation that began as the San Andreas and other faults warped and twisted the crust. In the center of Rainbow Basin, the Barstow Formation was deformed into a textbook example of a syncline, a downward pointing fold in the rocks. This is the syncline I wrote about a few weeks ago. I used the outcrop as an introduction to basic stratigraphic principles, and the students sketched the relationships, and outlined a sequence of events to account for the scene ahead of us. Here is the sketch as I would have done it...

The principle of superposition tells us that the oldest rocks will be found at the base of the sequence, so the Barstow Formation is the oldest rock visible. The principle of original horizontality tells us that most sediments are laid down in flat layers, so we can state that the Barstow Formation has since been twisted from its original position. The principle of lateral continuity shows us that the red and green layers of the Barstow have been eroded, because they end against an overlying layer instead of the edge of the original basin. The erosion surface is termed an unconformity. The principle of cross-cutting relationships tells us that the faulting took place after the deposition of the Barstow Formation, but before the erosion that produced the unconformity. And after all of this, erosion exposed the rocks for us to see on a warm Saturday in June at the start of our long journey.

We headed east from Barstow on Interstate 40, and all evidence of civilization disappeared, with the exception of the narrow strip of pavement we were following. The desert spread out for miles in every direction. As the sun disappeared beneath the horizon, we made the turn north to Hole in the Wall within the Mojave National Preserve, a national park for all intents and purposes except for the right of a few to shoot wild "game". When the vans were parked, the silence was striking. We had reached the land I'm calling Never Never.

For the first time in many months, I just stared at the sky. Early on, the sky was dominated by the quarter moon, but later, when the moon had set, the sky filled with stars. I did a time exposure over Woods Mountains...

It was a beautiful and peaceful night, the first for me in a long time. It was dreamtime.