Revealing the Riddle of the Red Rocks

 It's pretty amazing the places that didn't get made into national parks. It's pretty amazing that tens of millions of people visit Las Vegas and never make it just a few miles west of the city limits to see an incredible place where the rocks are red, and the rocks are a bit of a riddle. The problem? The rocks on the top, the gray limestone seen on the distant ridges is 300 million years older than the red rocks underneath. They are out of proper order.

The red rocks are the Aztec Sandstone, a Jurassic aged sand dune deposit that is correlated with the Navajo Sandstone, found in national parks like Zion, Arches and Capitol Reef. They developed in an immense sand dune "sea" that once extended from Wyoming to Arizona to eastern California.

The red color comes from iron oxide (the mineral hematite, or natural rust) coating the sand grains. I haven't found a lot of agreement over whether the red staining is a secondary effect, or a primary feature of the sandstone.

In either case, the outcrops are colorful, in shades of white, pink, red and brown. The rock exposures also display beautiful crossbedding, the sloping layers representing the slip faces of the ancient dunes, frozen in time by calcite or other mineral cement. In many places the rocks are broken up as if they have been through a gigantic nutcracker.

Which, by the way, they have.

Faults run through the region, an earlier set representing intense compression related subduction off the western coast of North America, and a later set formed during the extension that led to the development of the Basin and Range Province. The compressional thrust faults had the effect of pushing the older limestone rocks up and over the younger Jurassic sandstone during the Sevier Orogeny towards the end of the Mesozoic Era (that's the one with the dinosaurs). There are several such faults in the area, but the best known is the Keystone Thrust.

The later normal faulting dropped the valley floors and lifted the mountains, exposing the older faults to view. Erosion has resulted in the spectacular outcrops that make up the conservation area we see today.

Red Rock Canyon National Conservation Area is a wonderful place to visit, whether you've blown all your money at the casinos and can't afford to do anything else (hold back $10 for park admission!), or if you came to Vegas for the expressed purpose of visiting this wonderland of rocks. It is a much better use of your time if you ask me!

Out in America's Never Never: Desert Water...Gambling with 30 Million People

This water is flowing in one of the driest places in America (and naturally, too)

Water. Nothing in the world makes you appreciate it more than not having it.

In the desert, water is the factor that decides life. An organism adapts to the lack of it, or that organism disappears. The plants of America's Never Never either store it, have deep taproots, or they wither and die until the next flash flood. The animals either live near the few precious springs, or get their water from the plants that they eat.

Source: http://en.wikipedia.org/wiki/Colorado_River

The region between the Sierra Nevada and the western edge of the Colorado Plateau includes some of the driest landscapes in the world. Nearby Death Valley averages 1 or 2 inches of rain per year, and in some years receives none. The most it has ever received was 4.5 inches or so.

One single thread of water winds its way through this parched land. From the Wind River Range in Wyoming and the Colorado Rocky Mountains, the Colorado River gathers the snow melt from countless high mountain ridges and flows for 1,450 miles through one of the driest environments on the planet. In the five million years that it has existed in its present course, the river has excavated untold cubic miles of rock, filled in the huge delta at the head of the Gulf of California, and filled numerous hidden groundwater aquifers. Only in the last 100 or so years has the river been altered from this condition, due to the intervention of a unique new species on the planet. We have changed everything about the river and the balance of water use in the region. But for how long?

We spent a day traversing this dry landscape between the Mojave Desert and the edge of the Colorado Plateau near St. George, where we got a sense of just how dry this land is, and also how we have altered the balance of water use in the region. Our stops included the aptly named Valley of Fire State Park, and Lake Mead National Recreation Area.

The red sandstones of Valley of Fire are called the Aztec Sandstone, a Jurassic layer that is related to the Navajo Sandstone that makes up much of the scenery on the Colorado Plateau. Here in Valley of Fire, the rock has been jointed and fractured, and spheroidal weathering has turned the rocks into a wonderland of jumbled rounded boulders. The rocks were caught up in a compressional event in Cretaceous time called the Sevier Orogeny. Older Paleozoic rocks were pushed up and over the Aztec along a series of thrust faults. When the Colorado River established its present course, headward erosion along the tributary streams (in this case, the Virgin River) exposed the deeply buried rocks.

Water was available along the Virgin River, so Ancestral Puebloans and other cultures have lived here for thousands of years. They left a visible record of their existence in the form of petroglyphs in the desert varnish that covers many of the rocks. Their villages were small, in keeping with the limitations imposed on them by the lack of water.

Hoover Dam and Lake Mead

Contrast the existence of these small villages with the huge metropolis of Las Vegas. Or Phoenix. Or Los Angeles. For in the same way that the Virgin River made a small villages possible, the Colorado River allowed huge cities to exist in the desert. Phoenix survived for years with groundwater, but the water accumulated in the ice ages, and can never be replaced. A water table that began at a depth of 30 feet now lies hundreds of feet lower. The Central Arizona Project allows Phoenix to put a big straw in the Colorado River and draw out large amounts of water. Los Angeles got along with water they accessed (stole) from the eastern Sierra Nevada and Owens Valley, but they grew too much and needed more. Canals draw water into the Imperial Valley and further towards reservoirs that ring the L.A. Basin. Las Vegas is the most dependent; groundwater provides only 15% of their water. The rest comes from the river's big storage facility, Lake Mead. To their credit, they put some of it back. A permanent river with a constant flow of thousands of gallons per minute flows from their water treatment plants back into Lake Mead (remember, downstream users, you get what Las Vegas flushed away!). None of the river's water flows into the Gulf anymore.

Photo by Mrs. Geotripper

We stopped briefly at Callville Bay (in part to "add" some water back to Lake Mead), and were shocked to see the problem that faces these cities, and all the other stakeholders in Colorado River water. All the white, bleached area in the photo above is supposed to be under water. It hasn't been underwater in a long time, due to a horrific drought that has gripped the region for the last decade (and the drought continues). Lake Mead has dropped to historic lows, less that 50% of capacity.

Lake Mead is the largest reservoir in the United States, holding around 28 million acre feet of water, equal to two years of "normal" flow for the Colorado River. The reservoir is perilously close to "dead pool" level where it won't be able to generate hydroelectric power. What happens when the water runs out?

Photo by Mrs. Geotripper

At Valley of Fire, we were amused by the antics of the small Antelope Ground Squirrels. When they got too hot, they buried themselves in the sand to cool off.

Unfortunately, we don't have the choice of burying our heads in the sand. We take for granted that we turn a knob and water comes out. It may not always be that way. The inhabitants of the American Southwest have some hard decisions coming as global warming continues to change our environment.

Oh, the dog in the opening photo? It's cooling off in Rogers Spring, one of the natural springs that flows out of a fault zone on the north side of Lake Mead near Valley of Fire. There is a bit of water to be found even in the driest places.

Out in America's Never Never: Exploring the Grand Canyon...in Las Vegas?

Photo by Mrs. Geotripper

I'm sure no one needs to be told that visiting Las Vegas is a surreal experience. I can't even begin to imagine the army of psychologists who through the years have advised casino owners on the best ways to separate tourists from their money. I've been appalled at the... well, I can't come up with any term better than excess. Las Vegas serves as a fine definition of the word.

I wonder what the point is of seeing the canals of Venice, a circus, New York, and the Egyptian pyramids when one could presumably see the real thing? One of my stranger experiences was the time I left the South Rim of Grand Canyon and arrived at a casino decorated as...the Grand Canyon. Complete with animatronic deer and raccoons. And plastic pine trees.

And yet, strangely enough, one can explore the Grand Canyon in Las Vegas, at least in one sense, and more easily than one can in the National Park. Our journey through the American Never Never took us from the Mojave National Preserve to Sin City because of the access it provides to the Proterozoic and Early Paleozoic rocks that in the park are only found deep in the canyon at the end of a hugely strenuous hike.

Photo by Mrs. Geotripper

Frenchman Mountain rises east of the city, at the boundary between the city limits and the Lake Mead National Recreation Area. The mountain mostly falls under the jurisdiction of the Bureau of Land Management, which for decades let the land languish as a shooting gallery and trash dump. Geologists have known for years (especially since the 1960s publication of John Shelton's Geology Illustrated) that the rocks exposed on the flanks of the mountain were the same as the formations found in the deepest part of the Grand Canyon. One can easily lay one's hand across 1.2 billion years of geologic history at the exposure of the Great Unconformity (it's at my feet in the picture above, sloping up to the right). One can see the cross-bedded sandstones of the Cambrian Tapeats Formation, the remains of a shallow sea that transgressed across the western margin of the North American continent. And in the small canyon above these exposures, one can pick out trails, burrows and the discarded carapaces of some of the earliest complex life forms to be found on our planet, from the Bright Angel Shale.

It is an interesting story just explaining how rocks of the Grand Canyon came to be exposed here in the Las Vegas Valley. In short, the rocks were transported 50 miles westward by extreme extensional faulting in Miocene time, around 23 to 6 million years ago. A major detachment fault system is presumed to underly the region (below).

Source: Stephen Rowland, UNLV

It's an important and significant geologic locality, one that would be worthy of an interpretive sign and trail. In the 1990s, students and volunteers associated with the University of Nevada, Las Vegas put in a tremendous amount of work to construct such a site. It was very nicely done, with a brick walkway, sturdy interpretive signs, and a short nature trail.

This was the roadside interpretive sign that explained the value of the site (source: Stephen Rowland, UNLV)

But no good deed goes unpunished. The site was in place by 2001, and within a few short years it was completely obliterated by vandals. It sickens me beyond words that such people exist who feel compelled to destroy the good works of others.

Still, it is a great place to visit and learn a bit of geology. The signs are gone, but so is most of the trash and garbage, and a walk up the hill provides a stunning view of the most unlikely city in existence. Download the information from the UNLV website at http://geoscience.unlv.edu/pub/rowland/Virtual/virtualfm.html and you won't need the signs anyway.

Next time you find yourself in the city of casinos, here is something you can do that doesn't remove money from your pocket! Check it out...it's at the end of Lake Mead Boulevard in the northeastern part of the city on the way to Lake Mead.

Seeing Things Upside Down in the Red Rocks: What To Do When You Get Bored With Las Vegas

Bored in Las Vegas? Really? Okay, the town is such an aberration in the desert that one can hardly get bored, but my attention was really elsewhere as we tried to get ready to meet the people traveling with us through the western Colorado Plateau. It took only three hours to get our rental vehicles, and it took some wrangling to get the last person to the hotel from the airport, but by 4:30 we had everyone, and most of them were ready and willing to check out some geological sights west of town. We headed to Red Rock Canyon National Conservation Area.

I made an appropriate first impression by missing the turnoff to the park, and taking the crew on an impromptu crossing of the Spring Mountains. But good ole Captain Eagle-Eye Wrong-Way eventually got us back to the road we wanted, and we headed towards one of the more stunning sights in the Basin and Range Province.

The Keystone Thrust was a Cretaceous structure that developed during the Sevier Orogeny, involving a section of the Earth's crust being compressed and pushed over the adjoining rocks. Rocks brought up from the depths are often older, so at Red Rock Canyon NCA, 500+ million year old Cambrian Bonanza King Limestone got pushed up and over the younger Jurassic sediments called the Aztec Sandstone. The site pretty much defines the term "contrast". Dark limestone forms the high Wilson Cliffs, while bright colored sandstone livens up the Calico Hills

There was also a lot of green. For some reason lots of flowers were evident (despite the desert environment, we were at well over 4,000 feet in elevation). The plants had attracted all manner of bugs and beautiful hummingbirds (top picture).

From the high point on the park loop, we were treated to an awesome view of the imposing cliffs of the Spring Mountains and the Keystone Thrust.

 The rocks maybe weren't really upside down so much as out of order. But the lizard climbing on the big boulder of sandstone was definitely upside down. I wish I could climb rocks that way!

I also wish for an eventful trip this week (in a good way) as we make our way tomorrow to Peach Springs and a drive to the bottom of the Grand Canyon. More later!

Time Beyond Imagining Becomes a "Book" (or: "Where I've Been Hiding These Last Few Weeks)!

A best-seller if there ever was one! In fact, I think the first run will sell out (15 copies in the first printing, so not really a surprise). If you've been following Geotripper for very long, you will maybe have seen that one of my first blog series was called Time Beyond Imagining (link is here), and that it was a series that introduced the history of the Colorado Plateau over the course of around 70 posts. I always felt that all that writing should be rounded up into a single narrative some day, and that day kind of arrived when I decided to lead a trip through the plateau country with some geologists and their families from the American Association of Petroleum Geologists. I started on the project 18 months ago and made a lot of progress, but the first trip in 2012 was cancelled, and I so let the project simmer for awhile.

We scheduled the course again this year, and by May we realized we had enough participants to run the trip, which meant I had a strict deadline...which unfortunately coincided with the end of the semester, AND the big move into our new Science Community Center. So I disappeared more or less for the last few weeks furiously writing and rewriting a narrative and field guide for the trip. It felt a lot like finishing my thesis way back when, but back then I was taking care of an infant. This time I had a son who is an expert anthropologist who wrote an extensive section for the book on the cultural history of the region. The book and guide went to the printer this evening, and we leave for Las Vegas on Friday.

The guidebook is imaginatively called "The Geology and Cultural History of the Western Colorado Plateau, with a geological road guide to Grand Canyon, Zion and Bryce Canyon National Parks". It currently includes a section outlining the chronology of geological events and descriptions of the rock units on the Plateau, another on the cultural history of the different people groups in the western part of the plateau, and road guide for a six-day trip looping out of Las Vegas through the three national parks, and a lot of places in-between.

And there are some truly fascinating places in between! Our trip includes a journey to the bottom of the Grand Canyon on the Diamond Creek Road out of Peach Springs on the Hualapai Reservation. It will also include a visit at Antelope Canyon, a surreal labyrinth on the Navajo Reservation near Page, Arizona (picture below).

We will also explore a portion of Grand Staircase-Escalante National Monument by following the forty-plus mile long Cottonwood Wash Road along the Cockscomb Monocline, a truly spectacular drive through some really distorted rocks.

The monument also includes the beautiful Grosvenor Arches in one of the most isolated corners of the country. As recently as 1949, the National Geographic Society called their visit to the region an "expedition" (which probably elicited a laugh from the local ranchers...).

Our trip will include a visit to one of the gems of the Utah State Parks system, Kodachrome Basin State Park. It contains extensive exposures of Entrada Sandstone with dozens of strange clastic pipes that tower over the trails and campground. The trip wraps up with a tour of Bryce Canyon and Zion National Park, though with a twist. We intend to take the road to Lava Point, which gets missed by the vast majority of Zion National Park visitors. When Zion Canyon proper is sizzling hot and dry, there are cool meadows and pine forests among the sandstone cliffs, and a lot of fairly recent lava flows and cinder cones.

In general, I've written the narrative portions at a fairly basic level (I included a "geology basics" at the beginning), and the road guides as to be understood by anyone with a geology class or two under their belt.

I would hope that there would be some interest in the book and road guide, but I know I'll need to do some serious fact-checking and mileage confirmations (the numbers never quite add up right, which has been true for every guide I've written) while on the trip next week. And I also need to find a cheap way to print it, because the 160 page guide ran $30 apiece at Kinkos (I know they call it something else now, but I can't remember what!). I would love any ideas you might have!

Despite the long nights and all, I've been having a lot of fun revisiting one of my favorite corners of the planet, and I'm thrilled to be hitting the road in a couple of days (one week with AAPG, and then two weeks with my students). I'll try to post some pics from the road, and not be quite as invisible as I have been the last few weeks.

What's Missing From This Picture? Only a billion years or so...

Geology is good for perspective. The bookends of this particular day: the very very long hour spent trying to restart a dead car in a remote canyon, and a billion years in one hand. I'm on the road researching a field seminar for the AAPG in Arizona and Nevada, and I saw some incredible things.

1.7 billion years ago, fragments of continental crust were colliding to form the core of a new North American continent. Those mountains climbed to the sky, rivaling the Himalaya or the Andes in their grandeur. The time was so ancient that not a bit of life existed on the mountain flanks. The only lifeforms at all were single-celled organisms in the oceans.

The forces pushing the mountains upwards ended, and the ice and rain tore away the flanks. The gigantic peaks eroded to hills, and in hundreds of millions of years, the hills eroded to nearly flat plains. They were gone, but the rocks that formed the roots of those mountains remained. Around 530 million years ago, the continent had begun to break up, and the edges subsided slowly while a shallow sea advanced. The beach sands swirled back and forth across the roots of the ancient mountains.

An unconformity is a buried erosional surface. Sometimes the time missing might be a few hundred thousand or a few million years. The unconformity in the Grand Canyon is profound, representing a gap of a one thousand million years. Get to the right place, and you can place your hand across 1,000,000,000 revolutions around the sun: nearly a quarter of the age of the Earth.

The problem with the Great Unconformity, as the early geologists called it, is that it is mainly exposed in the bottom of the Grand Canyon. There are only a few ways to see it and touch it: you can float down the Colorado River in a raft, or you can walk down the long difficult trails from the rim of the canyon. Or, as it turns out, you can drive.

I left Las Vegas this morning and traveled up Lake Mead Boulevard. The growth of the town has slowed with the depression, but over the last twenty years I've watched the urbanization of the valley wash up the slopes of Frenchman Mountain on the eastern edge of town like a tsunami. Fortunately, the wave stopped at the boundary of the city limits and the federal lands around Lake Mead. It turns out that the rocks making up the Great Unconformity are exposed no more than a mile from the residential neighborhoods of Sin City. The sand layers of the Tapeats Sandstone cover the weathered granite and schist of the 1.7 billion year old basement complex.

The geologists at the University of Nevada, Las Vegas knew of the treasure in their backyard. Years ago they set up a trail and some very nice interpretive exhibits. I regret to say that vandals and garbage dumpers destroyed the exhibits in a short time, but you can still see the rocks.

If the exposure lacks anything, it is grandeur. The oldest rocks of the Grand Canyon are at the bottom of one of the deepest and longest gorges in the world, and there is much to be said for seeing the rocks in their full perspective, underneath a mile of subsequent sedimentary layers. When time or health is short, hiking or rafting is not feasible. But I was on a mission today, to see the only place in all of the Grand Canyon where one can drive to the Great Unconformity. It is well-known to rafters as it is the take-out point for the river voyagers. It's called Diamond Creek, and Peach Springs Canyon. The road starts at the administrative headquarters of the Hualapai Nation in Peach Springs, and winds 19 miles and 3,500 feet down to the Colorado.

Anyone who has seen the Grand Canyon, either in pictures or in person, has to wonder how any road could intrude into such rugged terrain. There are so many cliff-forming layers that a road seems next to impossible (which it is, given that only one exists). But Grand Canyon is also crossed by faults and folds, and the disruption of the cliff-forming layers is what makes roads and trails possible. The road starts innocently enough, dipping into rolling terrain composed of Mio-Pliocene sediments that have huge significance in understanding how the Grand Canyon was carved. We actually follow canyons that originated at the end of the age of the dinosaurs (the Cretaceous Period) and were subsequently filled, and then exhumed in the last hiccup of geological time.

Heading deeper into the canyon, we see some evidence of deformation; in the picture below, we can see a gentle monocline crossing the picture where the layers step down in elevation without splitting. A major fault zone, the Hurricane fault, crosses the canyon in front of the fold. The road turns and follows the fault zone.

The gorge becomes deeper and deeper, and we pass into older and older layers. The Mississippian Redwall limestone forms the highest cliffs, and the lower cliffs are dominated by the Devonian Temple Butte limestone and Cambrian Muav limestone. The gentler slopes cover exposures of the Cambrian Bright Angel shale. The rocks on the left side of the canyon sit around a thousand feet lower than the rocks on the right due to displacement along the Hurricane fault.

The cliffs grow higher and higher, and we finally reach the base of the Paleozoic rocks with exposures of the Tapeats sandstone, the same layer seen at Frenchman Mountain in Las Vegas. The Tapeats can be seen in the first picture of this post, forming the prominent layers at the lower left. The orange-brown rocks at the base of the cliff are the 1.7 billion year old granite and schist.

It would take only a moment's walk to lay one's hand on the unconformity, but we also wanted to see the Colorado River. We were nearly 16 miles into the canyon, with only three to go. We got into the car, turned the key....and nothing. Not a click, not a warning light, nothing. 16 miles into the depths of the Earth, and we had a dead car.

So we had the longest hour I've ever felt (aside from the births of my children), trying anything and everything to get the car going again. A construction crew stopped by, five guys in one truck, and we did the engine worship thing where all six of us stood around the open hood and jiggled connections. A river runner came up the road with his boat trailer. He had room, so Mrs. Geotripper jumped in to go arrange for a tow truck. River runners like this guy drive this road all the time, so the Missus had a regular Mr. Toad's Wild Ride up the bumpy road. Meanwhile, I stayed with the car, pretty much preparing to camp out for the night. The ranger for the Hualapai tribe showed up, and we did some more jiggling of engine connections, and he helped me get the transmission unstuck, but we still weren't getting anything when I turned the key. In final desperation, we tried the obvious, and pulled out the jumper cables. They worked.

I zoomed up the road, picked up Mrs. Geotripper, and sped on to Williams without turning the car off once. Thus, our unexpected night in a motel, and a delay, looking for a saturday mechanic before we head on to Grand Canyon tomorrow. And internet access! We'll see what surprises tomorrow holds for us.

By the way, the ocotillos were blooming in the lower canyon...enjoy!

NOTE: Tourism is almost the sole source of income for the Hualapai tribe. You need to pay an exploration fee of $25/person at the Hualapai Motel in Peach Springs. Looking at the town of Peach Springs, I was glad to give them some support.